Geoarchaeology of the karstic area of Mirambello, North-East Crete (Greece): palaeoenvironmental investigations and human settlement implications

NASA Astrophysics Data System (ADS)

Ghilardi, M.; Kunesch, S.; Robert, V.; Farnoux, A.; Wurmser, H.

2009-04-01

The present work aims to detail the preliminary researches dealing with the geomorphologic, topographic and archaeological setting from two major settlements located in north east Crete. The project undertook by the French school of Archaeology in Athens aims to reconstruct the palaeoenvironmental evolution of the whole area during the last millennia. Fieldworks, including coring, had already been done in August 2006, April 2007 and September 2008; we propose to present the main results. The settlements of Latô and Dreros belong to the area of Mirambello characterized by its spectacular karstic processes and landforms, different karstic depressions with different size can be identified and classified into Dolines and Poljés. As far as the archaeological interest is concerned, villages and cities were occupied during the hellenestic period; several remains are still present around and inside these depressions. Using a G.I.S., the first step consisted in establishing a local geomorphological mapping, taking into account the geological background and the historical occupation of the area. The second step consisted in establishing topographic cross sections of the doline, where the ancient settlement of Latô is located, based on various DGPS surveys. Several questions concerning the occupation of this depression arose : how and for which reasons people decided to leave close to this specific landform ? Which type of activities (farming, grazing, cultivation…) existed and did they were related with natural resources exploitation ? A project associating the local greek archaeological services (Ephoria of Aghios Nikolaos, Director Ms. Apostolakou), the mayor of Nea Polis, the University of Paris 12 (GEONAT EA 435) and the French School of Athens tries to depict the historical evolution of the landscape. Four boreholes (up to a maximum depth of 5 meters) had been drilled in the poljé of Dreros and in a doline situated 1 km away from the ancient settlement of Lat

A review on the establishment and research in hydrological experimental areas (catchments) in plain areas in China and abroad

NASA Astrophysics Data System (ADS)

Yang, Hai; Wang, Chuanhai; Hua, Wenjuan

2017-04-01

This paper reviewed some specific conceptions of hydrological experimental areas (catchments) while found that the traditional definition of 'catchment' may be difficult to meet in plain areas. According to the review of development history and current situation of hydrological experimental areas (catchments) in plain areas in China, 4 stages were shown besides the recent 10 years, i.e., 'golden stage(1952-1966)', 'backward stage(1966-1986)', 'short recovery stage(1986-1989)' and 'stagnant stage(1986-2006)'. It gets new impetus since 2006 with some investigation work promoted by the government. Furthermore, some historic problems during establishing experimental areas (catchments) in plain areas were revealed based on the document literature and a few meaningful lessons were drawn from the past. It was also the first time to collect and classify the details of both 11 representative experimental areas in China and abroad, after that a brief comparison about the measurement level and research directions was made between two regions. Additionally, we took the experimental research work in the plain of Taihu Lake Basin as example and introduced the particular research goals and the corresponding establishing process, including how to design the experimental area, eg, size, location, land use type, arranging the measurement instruments et al. We hope such case can provide a reference for newly-building, recovering and extending hydrological experimental areasin plain areas in the future. Finally, this paper prospected the future development in establishment and research in hydrological experimental areas (catchments) in plain areas. It may be more common to see the cooperation between model scientists and field experts. Because of the comprehensive goals in water problems, researchers from various fields would work together in the future experimental research work. Scale study and modelling in plain areas will be a promising branch after some typical experimental areas

The Population Burden of Cancer: Research Driven by the Catchment Area of a Cancer Center.

PubMed

Tai, Caroline G; Hiatt, Robert A

2017-01-01

Cancer centers, particularly those supported by the National Cancer Institute, are charged with reducing the cancer burden in their catchment area. However, methods to define both the catchment area and the cancer burden are diverse and range in complexity often based on data availability, staff resources, or confusion about what is required. This article presents a review of the current literature identifying 4 studies that have defined various aspects of the cancer burden in a defined geographical area and highlights examples of how some cancer centers and other health institutions have defined their catchment area and characterized the cancer burden within it. We then present a detailed case study of an approach applied by the University of California, San Francisco, Helen Diller Family Comprehensive Cancer Center to define its catchment area and its population cancer burden. We cite examples of how the Cancer Center research portfolio addresses the defined cancer burden. Our case study outlines a systematic approach to using publicly available data, such as cancer registry data, that are accessible by all cancer centers. By identifying gaps and formulating future research directions based on the needs of the population within the catchment area, epidemiologic studies and other types of cancer research can be directed to the population served. This review can help guide cancer centers in developing an approach to defining their own catchment area as mandated and applying research findings to this defined population. © The Author 2017. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

A karstic origin for the north polar lakes reveals a soluble Titan

NASA Astrophysics Data System (ADS)

Dhingra, Rajani; Barnes, Jason W.; Radebaugh, Jani; Hedman, Matthew M.

2017-10-01

We quantitatively test the karst hypothesis for the formation of Titan's lakes by comparing their morphometry to that of terrestrial karst lakes.Titan is the only place in our solar system other than the Earth known to harbor stable surface liquids. While much has been studied and predicted about the liquid composition and distribution, the origin of the lake basins remains unknown. We use spatial regularity derived from the morphology of these lakes to test the hypothesis that they could be karstic in origin. Earth’s karstic lakes are closed depressions that form when the bedrock is dissolved. Karstic depressions have several distinct features, such as their elongation index and their diameter distributions. These are lognormal, a relationship that holds under the assumption that these lakes originated and evolved over a comparatively short period of time. Furthermore, the spread in sizes of depressions is small, indicating tightly constrained formation processes. In our study, we use statistics to ascertain whether Titan’s lakes follow similar karstic geomorphometric patterns. Cassini RADAR and ISS observations of Titan’s north pole show that the equivalent radii of 224 lakes indeed follow a lognormal distribution just like Earth’s karstic lakes, thus suggesting Earth-like processes may be forming Titan’s lakes.

SUSTAINABLE AGRICULTURE FOR THE WATER CATCHMENT PROTECTION AREA IN NTISAW, CAMEROON

EPA Science Inventory

We expect that the catchment area will increase food output for the community in addition to preserving the water source. Increased food output will benefit needy residents and allow them to focus more on education and economic development. Additionally, an area of sustainable...

Analysing the impact of urban areas patterns on the mean annual flow of 43 urbanized catchments

NASA Astrophysics Data System (ADS)

Salavati, B.; Oudin, L.; Furusho, C.; Ribstein, P.

2015-06-01

It is often argued that urban areas play a significant role in catchment hydrology, but previous studies reported disparate results of urbanization impacts on stream flow. This might stem either from the difficulty to quantify the historical flow changes attributed to urbanization only (and not climate variability) or from the inability to decipher what type of urban planning is more critical for flows. In this study, we applied a hydrological model on 43 urban catchments in the United States to quantify the flow changes attributable to urbanization. Then, we tried to relate these flow changes to the changes of urban/impervious areas of the catchments. We argue that these spatial changes of urban areas can be more precisely characterized by landscape metrics, which enable analysing the patterns of historical urban growth. Landscape metrics combine the richness (the number) and evenness (the spatial distribution) of patch types represented on the landscape. Urbanization patterns within the framework of patch analysis have been widely studied but, to our knowledge, previous research works had not linked them to catchments hydrological behaviours. Our results showed that the catchments with larger impervious areas and larger mean patch areas are likely to have larger increase of runoff yield.

Critical level of water recharges in the catchment areas of Manna watershed Bengkulu Province Indonesia

NASA Astrophysics Data System (ADS)

Amri, Khairul; Nugraha, Loparedo; Barchia, Muhammad Faiz

2017-11-01

Land use changes in Manna watershed are caused degradation in the watershed functions. When water infiltration goes down, some water runs off flowing to Manna River cause submerged on the downstream. The aim of this study is to analyze how the Manna watershed overcoming environmentally degraded conditions. The critical level of the Manna catchment areas was determined by overlaying some digital maps based on procedure applying in the Ministry of Forestry, Republic of Indonesia (P.32/MENHUT-II/2009). Measuring the critical level of the catchment also needed natural and actual infiltrations map, and the interpretation process of the analysis used ArcGIS 10.1 software. Based on the spatial data analysis by overlaying maps of slope, soils, and rainfall, the natural infiltration rate in the Manna watershed categorized high level (44.1%). While, the critical level of the catchment areas of the Manna watershed classified in good condition cover about 64,5 % of the areas, and starting to degraded state cover about 35,5 % of the watershed areas. The environment degradation conditions indicated the land use changes in the Manna watershed could deteriorate infiltration rates. The cultivated agricultural activities neglected conservation rule could accelerate the critical catchment areas in the Manna watershed.

Karstic slope "breathing": morpho-structural influence and hazard implications

NASA Astrophysics Data System (ADS)

Devoti, Roberto; Falcucci, Emanuela; Gori, Stefano; Eliana Poli, Maria; Zanferrari, Adriano; Braitenberg, Carla; Fabris, Paolo; Grillo, Barbara; Zuliani, David

2016-04-01

The study refers to the active slope deformation detected by GPS and tiltmeter stations in the Cansiglio karstic plateau located in the western Carnic Prealps (NE Italy). The observed transient deformation clearly correlates with the rainfall, so that the southernmost border of the Plateau reacts instantly to heavy rains displaying a "back and forth" deformation up to a few centimeters wide, with different time constants, demonstrating a response to different catchment volumes. We carried out a field survey along the southern Cansiglio slope, to achieve structural characterization of the relief and to verify the possible relation between structural features and the peculiar geomorphological setting dominated by widespread karstic features. The Cansiglio plateau develops on the frontal ramp anticline of the Cansiglio thrust, an about ENE-WSW trending, SSE-verging, low angle thrust, belonging to the Neogene-Quaternary front of the eastern Southern Alps. The Cansiglio thrust outcrops at the base of the Cansiglio plateau, where it overlaps the Mesozoic carbonates on the Miocene-Quaternary terrigenous succession. All along its length cataclastic limestone largely outcrop. The Cansiglio thrust is bordered by two transfer zones probably inherited from the Mesozoic paleogeography: the Caneva fault in the west and the Col Longone fault in the east. The carbonatic massif is also characterized by a series of about northward steeply dipping reverse minor faults and a set of subvertical joints parallel to the axes of the Cansiglio anticline. Other NNW-SSE and NNE-SSW conjugate faults and fractures perpendicular to the Cansiglio southern slope are also identified. This structural setting affect pervasively the whole slope and may determine centimetre- to metre-scale rock prisms. Interestingly, along the topmost portion of the slope, some dolines and swallow holes show an incipient coalescence, that trends parallel to the massif front and to the deformation zones related to the

School Catchment Area Evasion: The Case of Berlin, Germany

ERIC Educational Resources Information Center

Noreisch, Kathleen

2007-01-01

This paper seeks to examine the ways in which school segregation plays out in a pure catchment area system and to what extent residential composition is directly mirrored in schools. The research examines the data for the districts in Berlin and, more specifically at the school level, for the district of Tempelhof-Schoneberg. The research is based…

Quantitative microbial faecal source tracking with sampling guided by hydrological catchment dynamics.

PubMed

Reischer, G H; Haider, J M; Sommer, R; Stadler, H; Keiblinger, K M; Hornek, R; Zerobin, W; Mach, R L; Farnleitner, A H

2008-10-01

The impairment of water quality by faecal pollution is a global public health concern. Microbial source tracking methods help to identify faecal sources but the few recent quantitative microbial source tracking applications disregarded catchment hydrology and pollution dynamics. This quantitative microbial source tracking study, conducted in a large karstic spring catchment potentially influenced by humans and ruminant animals, was based on a tiered sampling approach: a 31-month water quality monitoring (Monitoring) covering seasonal hydrological dynamics and an investigation of flood events (Events) as periods of the strongest pollution. The detection of a ruminant-specific and a human-specific faecal Bacteroidetes marker by quantitative real-time PCR was complemented by standard microbiological and on-line hydrological parameters. Both quantitative microbial source tracking markers were detected in spring water during Monitoring and Events, with preponderance of the ruminant-specific marker. Applying multiparametric analysis of all data allowed linking the ruminant-specific marker to general faecal pollution indicators, especially during Events. Up to 80% of the variation of faecal indicator levels during Events could be explained by ruminant-specific marker levels proving the dominance of ruminant faecal sources in the catchment. Furthermore, soil was ruled out as a source of quantitative microbial source tracking markers. This study demonstrates the applicability of quantitative microbial source tracking methods and highlights the prerequisite of considering hydrological catchment dynamics in source tracking study design.

Variability of rainfall over Lake Kariba catchment area in the Zambezi river basin, Zimbabwe

NASA Astrophysics Data System (ADS)

Muchuru, Shepherd; Botai, Joel O.; Botai, Christina M.; Landman, Willem A.; Adeola, Abiodun M.

2016-04-01

In this study, average monthly and annual rainfall totals recorded for the period 1970 to 2010 from a network of 13 stations across the Lake Kariba catchment area of the Zambezi river basin were analyzed in order to characterize the spatial-temporal variability of rainfall across the catchment area. In the analysis, the data were subjected to intervention and homogeneity analysis using the Cumulative Summation (CUSUM) technique and step change analysis using rank-sum test. Furthermore, rainfall variability was characterized by trend analysis using the non-parametric Mann-Kendall statistic. Additionally, the rainfall series were decomposed and the spectral characteristics derived using Cross Wavelet Transform (CWT) and Wavelet Coherence (WC) analysis. The advantage of using the wavelet-based parameters is that they vary in time and can therefore be used to quantitatively detect time-scale-dependent correlations and phase shifts between rainfall time series at various localized time-frequency scales. The annual and seasonal rainfall series were homogeneous and demonstrated no apparent significant shifts. According to the inhomogeneity classification, the rainfall series recorded across the Lake Kariba catchment area belonged to category A (useful) and B (doubtful), i.e., there were zero to one and two absolute tests rejecting the null hypothesis (at 5 % significance level), respectively. Lastly, the long-term variability of the rainfall series across the Lake Kariba catchment area exhibited non-significant positive and negative trends with coherent oscillatory modes that are constantly locked in phase in the Morlet wavelet space.

Natural and induced endoreic hydrological conditions in the Alta Murgia karstic region (Apulia, Southern Italy)

NASA Astrophysics Data System (ADS)

Canora, F.; Fidelibus, M. D.; Spilotro, G.

2009-04-01

A study aimed at understanding the hydrological processes in karst areas related to the presence of natural and artificial endoreic basins and their modification due to land use change, as well as the influence of above factors on the infiltration rate has been carried out in the Alta Murgia region (Apulia, Southern Italy). The region is a Cretaceous limestone plateau of the Apulian platform, characterized by a mature karstic landscape: due to its elevation, climatic conditions and lithology, the plateau constitutes the main recharge area of the Murgia aquifer. The typical karst topography is essentially related to the subterranean drainage (sinkholes, caves, conduit): surface and subsurface karst geomorphology is strictly interrelated with hydrology. The morphological features of the karstic plateau are defined by the high density of surface karstic forms (mainly dolines), the presence of exposed karst and karren fields, as well as by the extensive outcrop of fractured rocks. Karst surface shows, on the bottom of the morpho-structural depressions called "lame", natural distribution of modest deposits of "terra rossa" and regolith. The "lame" work as streams during and after intense rainfall events, often outlining a primordial ephemeral hydrographical network, frequently convergent towards dolines, poljes or endoreic basins. Alta Murgia shows many natural endoreic basin conditions in a quite flat morphology. In this environment, when intense rainfall events cover large areas and rainfall intensity exceeds the infiltration capacity of soils and/or sinkholes, significant runoff amounts are produced and stored in the basins causing floods. Most of the natural endoreic basins are small and independent: while the majority of them continue functioning as endoreic even in presence of extreme events of high return time, others (quasi-endoreic), under the same circumstances can start contributing to other basins, due to exceeding their water storage capability. This way

Conceptualization of Karstic Aquifer with Multiple Outlets Using a Dual Porosity Model.

PubMed

Hosseini, Seiyed Mossa; Ataie-Ashtiani, Behzad

2017-07-01

In this study, two conceptual models, the classic reservoir (CR) model and exchange reservoirs model embedded by dual porosity approach (DPR) are developed for simulation of karst aquifer functioning drained by multiple outlets. The performances of two developed models are demonstrated at a less developed karstic aquifer with three spring outlets located in Zagros Mountain in the south-west of Iran using 22-years of daily data. During the surface recharge, a production function based on water mass balance is implemented for computing the time series of surface recharge to the karst formations. The efficiency of both models has been assessed for simulation of daily spring discharge during the recession and also surface recharge periods. Results indicate that both CR and DPR models are capable of simulating the ordinates of spring hydrographs which drainage less developed karstic aquifer. However, the goodness of fit criteria indicates outperformance of DPR model for simulation of total hydrograph ordinates. In addition, the DPR model is capable of quantifying hydraulic properties of two hydrologically connected overlapping continua conduits network and fissure matrix which lays important foundations for the mining operation and water resource management whereas homogeneous model representations of the karstic subsurface (e.g., the CR) do not work accurately in the karstic environment. © 2017, National Ground Water Association.

Fungicides transport in runoff from vineyard plot and catchment: contribution of non-target areas.

PubMed

Lefrancq, Marie; Payraudeau, Sylvain; García Verdú, Antonio Joaquín; Maillard, Elodie; Millet, Maurice; Imfeld, Gwenaël

2014-04-01

Surface runoff and erosion during the course of rainfall events are major processes of pesticides transport from agricultural land to aquatic ecosystem. These processes are generally evaluated either at the plot or the catchment scale. Here, we compared at both scales the transport and partitioning in runoff water of two widely used fungicides, i.e., kresoxim-methyl (KM) and cyazofamid (CY). The objective was to evaluate the relationship between fungicides runoff from the plot and from the vineyard catchment. The results show that seasonal exports for KM and CY at the catchment were larger than those obtained at the plot. This underlines that non-target areas within the catchment largely contribute to the overall load of runoff-associated fungicides. Estimations show that 85 and 62 % of the loads observed for KM and CY at the catchment outlet cannot be explained by the vineyard plots. However, the partitioning of KM and CY between three fractions, i.e., the suspended solids (>0.7 μm) and two dissolved fractions (i.e., between 0.22 and 0.7 µm and <0.22 µm) in runoff water was similar at both scales. KM was predominantly detected below 0.22 μm, whereas CY was mainly detected in the fraction between 0.22 and 0.7 μm. Although KM and CY have similar physicochemical properties and are expected to behave similarly, our results show that their partitioning between two fractions of the dissolved phase differs largely. It is concluded that combined observations of pesticide runoff at both the catchment and the plot scales enable to evaluate the sources areas of pesticide off-site transport.

Using stable isotopes and multi-spatial variable parameters in characterising the karstic aquifer of the Ajloun area, NW-Jordan - A case study of the Tanour and Rasoun springs

NASA Astrophysics Data System (ADS)

Hamdan, Ibraheem; Wiegand, Bettina; Ptak, Thomas; Licha, Tobias; Toll, Mathias; Margane, Armin; Sauter, Martin

2015-04-01

Key words: Karst systems, Groundwater vulnerability, Stable isotopes, Jordan. Water resources are extremely scarce in Jordan, which is considered as one of the poorest countries in the world with respect to water resources availability (UNDP 2014), with more than 90% of the country receiving less than 200 mm/year of rainfall (Al Kharadsheh et al. 2012). The most important aquifer for drinking-water purposes in Jordan is the upper Cretaceous limestone aquifer. The karstic springs of Tanour and Rasoun, located in the Ajloun governorate around 75 kilometres northwest of the capital of Amman, have been selected for this study. These springs are the main source for the local domestic water supply, with an average discharge between the years 2000 and 2012 of 200 m3/h and 60 m3/h, respectively (MWI, 2013). During the past few years, the water supply from these two springs had to be discontinued due to high contamination of the groundwater either by microbiological contaminants or by wastewater from local olive oil presses. This wastewater is locally called 'Zeebar'. Understanding of the karst aquifer system, the pathways and movement within the epikarst, and estimation of the travel and residence time within the aquifer is important for managing and evaluating the pollution risk, which affects the usability of groundwater for drinking purposes. For a better understanding of the karstic system and its behaviour, different methods are applied: 1. Analysis of the stable isotope composition of δ2H and δ18O during the winter season for both (a) Tanour and Rasoun groundwater, and (b) rainfall samples collected from several locations at different elevations within the catchment. 2. Analysis of major ion concentrations in groundwater of the Tanour and Rasoun springs. 3. Long-term measurements of different physico-chemical parameters from the Tanour and Rasoun springs (temperature, conductivity, turbidity, TOC, etc.) using multiparameter probes with telemetric data transfer. 4

Flash flood warning in mountainaious areas: using damages reports to evaluate the method at small ungauged catchments

NASA Astrophysics Data System (ADS)

Defrance, Dimitri; Javelle, Pierre; Ecrepont, Stéphane; Andreassian, Vazken

2013-04-01

In Europe, flash floods mainly occur in the Mediterranean area on small catchments with a short concentration time. Anticipating this kind of events is a major issue in order to reduce the resulting damages. But for many of the impacted catchments, no data are available to calibrate and evaluate hydrological models. In this context, the aims of this study is to develop and evaluate a warning method for the Southern French Alps. This area is of particular interest, because it regroups different hydrological regimes, from purely Mediterranean to purely Alpine influences. Two main issues should be addressed: - How to define the hydrological model and its parameterization for an application in an ungauged context? - How to evaluate the final results on 'real' ungauged catchments? The first issue is a classic one. Using a 'observed' data set (154 streamflow stations with catchment areas ranging from 5 to 1000 km² and distributed rainfall available on the 1997-2006 period), we developed a regional model specifically for the studied area. For this purpose, the AIGA method, initially developed for Mediterranean catchments was adapted, in order to take into account snowmelt and to produce baseflows. Then, different parameterizations were tested, derived from different simple regionalisation techniques: - the same parameters set for the whole area defined as the median of the local calibrated parameters; - the same technique as the previous case, but by considering different sub-areas, defined as "hydro-climatically" homogeneous by previous studies; - and finally the neighbour's method. The second issue is more original. Indeed, in most studies the final evaluation is done using gauged stations as they were 'ungauged', ie keeping the at-site discharge data only for validation ant not for calibration. The main disadvantage of this approach is that the evaluation is made at the scale of the gauged catchments, which are in general greater than the catchments impacted by flash

Perylene in Lake Biwa sediments originating from Cenococcum geophilum in its catchment area

NASA Astrophysics Data System (ADS)

Itoh, Nobuyasu; Sakagami, Nobuo; Torimura, Masaki; Watanabe, Makiko

2012-10-01

Perylene, which is composed of five benzene rings, is commonly found in sediments throughout the world at concentrations and distributions that are different from those of other polycyclic aromatic hydrocarbons. The only information available on the origin of perylene comes from 4,9-dihydroxyperylene-3,10-quinone (DHPQ), which originates from fungal component symbiosis or from parasites on plants; however, there is no direct evidence of a mechanism of perylene formation. In this study, we examined the relationship between sedimentary perylene and Cenococcum geophilum (C. geophilum) in a catchment area at Lake Biwa. Sclerotium grains of C. geophilum containing DHPQ were found in this catchment area (approximately 40 balls kg-1 dried soil for >1 mm-ϕ), and small sclerotium grains were frequently found in the sediment. In the sediment sample, we also found broken particles containing perylene, and they had a porous structure characteristic of sclerotium grains. Furthermore, the particles contained DHPQ in different transformation stages to perylene via 3,10-perylenequinone (3,10-PQ). This finding was consistent with results from elemental analysis (oxygen/carbon). Because a remarkable amount of DHPQ originating from C. geophilum also exists in the humic acids of soils and because the inputs of compounds to the lake depend strongly on the rivers, perylene in the Lake Biwa sediment originates mainly from the DHPQ of C. geophilum in its catchment area.

Extended principle component analysis - a useful tool to understand processes governing water quality at catchment scales

NASA Astrophysics Data System (ADS)

Selle, B.; Schwientek, M.

2012-04-01

Water quality of ground and surface waters in catchments is typically driven by many complex and interacting processes. While small scale processes are often studied in great detail, their relevance and interplay at catchment scales remain often poorly understood. For many catchments, extensive monitoring data on water quality have been collected for different purposes. These heterogeneous data sets contain valuable information on catchment scale processes but are rarely analysed using integrated methods. Principle component analysis (PCA) has previously been applied to this kind of data sets. However, a detailed analysis of scores, which are an important result of a PCA, is often missing. Mathematically, PCA expresses measured variables on water quality, e.g. nitrate concentrations, as linear combination of independent, not directly observable key processes. These computed key processes are represented by principle components. Their scores are interpretable as process intensities which vary in space and time. Subsequently, scores can be correlated with other key variables and catchment characteristics, such as water travel times and land use that were not considered in PCA. This detailed analysis of scores represents an extension of the commonly applied PCA which could considerably improve the understanding of processes governing water quality at catchment scales. In this study, we investigated the 170 km2 Ammer catchment in SW Germany which is characterised by an above average proportion of agricultural (71%) and urban (17%) areas. The Ammer River is mainly fed by karstic springs. For PCA, we separately analysed concentrations from (a) surface waters of the Ammer River and its tributaries, (b) spring waters from the main aquifers and (c) deep groundwater from production wells. This analysis was extended by a detailed analysis of scores. We analysed measured concentrations on major ions and selected organic micropollutants. Additionally, redox-sensitive variables

Predicting forested catchment evapotranspiration and streamflow from stand sapwood area and Aridity Index

NASA Astrophysics Data System (ADS)

Lane, Patrick

2016-04-01

Estimating the water balance of ungauged catchments has been the subject of decades of research. An extension of the fundamental problem of estimating the hydrology is then understanding how do changes in catchment attributes affect the water balance component? This is a particular issue in forest hydrology where vegetation exerts such a strong influence on evapotranspiration (ET), and consequent streamflow (Q). Given the primacy of trees in the water balance, and the potential for change to species and density through logging, fire, pests and diseases and drought, methods that directly relate ET/Q to vegetation structure, species, and stand density are very powerful. Plot studies on tree water use routinely use sapwood area (SA) to calculate transpiration and upscale to the stand/catchment scale. Recent work in south eastern Australian forests have found stand-wide SA to be linearly correlated (R2 = 0.89) with long term mean annual loss (P-Q), and hence, long term mean annual catchment streamflow. Robust relationships can be built between basal area (BA), tree density and stand SA. BA and density are common forest inventory measurements. Until now, no research has related the fundamental stand attribute of SA to streamflow. The data sets include catchments that have been thinned and with varying age classes. Thus far these analyses have been for energy limited systems in wetter forest types. SA has proven to be a more robust biometric than leaf area index which varies seasonally. That long term ET/Q is correlated with vegetation conforms to the Budyko framework. Use of a downscaled (20 m) Aridity Index (AI) has shown distinct correlations with stand SA, and therefore T. Structural patterns at a the hillslope scale not only correlate with SA and T, but also with interception (I) and forest floor evaporation (Es). These correlations between AI and I and Es have given R2 > 0.8. The result of these studies suggest an ability to estimate mean annual ET fluxes at sub

Sediment yield during typhoon events in relation to landslides, rainfall, and catchment areas in Taiwan

NASA Astrophysics Data System (ADS)

Chen, Chi-Wen; Oguchi, Takashi; Hayakawa, Yuichi S.; Saito, Hitoshi; Chen, Hongey; Lin, Guan-Wei; Wei, Lun-Wei; Chao, Yi-Chiung

2018-02-01

Debris sourced from landslides will result in environmental problems such as increased sediment discharge in rivers. This study analyzed the sediment discharge of 17 main rivers in Taiwan during 14 typhoon events, selected from the catchment area and river length, that caused landslides according to government reports. The measured suspended sediment and water discharge, collected from hydrometric stations of the Water Resources Agency of Taiwan, were used to establish rating-curve relationships, a power-law relation between them. Then sediment discharge during typhoon events was estimated using the rating-curve method and the measured data of daily water discharge. Positive correlations between sediment discharge and rainfall conditions for each river indicate that sediment discharge increases when a greater amount of rainfall or a higher intensity of rainfall falls during a typhoon event. In addition, the amount of sediment discharge during a typhoon event is mainly controlled by the total amount of rainfall, not by peak rainfall. Differences in correlation equations among the rivers suggest that catchments with larger areas produce more sediment. Catchments with relatively low sediment discharge show more distinct increases in sediment discharge in response to increases in rainfall, owing to the little opportunity for deposition in small catchments with high connectivity to rivers and the transportation of the majority of landslide debris to rivers during typhoon events. Also, differences in geomorphic and geologic conditions among catchments around Taiwan lead to a variety of suspended sediment dynamics and the sediment budget. Positive correlation between average sediment discharge and average area of landslides during typhoon events indicates that when larger landslides are caused by heavier rainfall during a typhoon event, more loose materials from the most recent landslide debris are flushed into rivers, resulting in higher sediment discharge. The high

Land use change impacts on discharge analysis using SWAT model at Ciherang Pondok DAM catchment area

NASA Astrophysics Data System (ADS)

Utamahadi, M. A.; Pandjaitan, N. H.; Rau, M. I.

2018-05-01

The prompt increase of population influenced the requirement for new regions to fulfill people’s primary needs. Its increased land use change and caused many impacts on the environment, including watersheds as well. Ciherang Pondok DAM catchment area is part of Cisadane watershed and was selected as the research area. This research aimed to analyse the water supply and water discharge change caused by the Urban Planning (RTRW) in 2020. The analysis was conducted using soil and water assessment tools (SWAT) model. Stages of this research were catchment area delineation, HRU identification, calibration and validation of models, and prediction of discharge and water demand. The result showed that RTRW of 2020 increased the maximum discharge of 1.6 m3/s and decreased the minimum discharge of 0.01 m3/s, hence the maximum and minimum discharge ratio increased 0.26% from 2016. Output discharge in 2020 at Ciherang Pondok Dam Catchment Area was classified as well, with discharge of 6.72 – 126.2 m3/s, and could fulfil water demand. For the best result, it is better to use climate data from weather stations inside the study area and it is required an improvement in data archiving system.

Gene expression in caged fish as indicators of contaminants exposure in tropical karstic water bodies.

PubMed

Rodríguez-Fuentes, Gabriela; Luna-Ramírez, Karen S; Soto, Mélina; Richardson, Kristine L

2012-04-01

Karstic areas in Yucatan are very permeable, which allows contaminants to move rapidly into the aquifer. In the present study, we evaluated gene expression of vitellogenin (VTG) and cytochrome P-450 1A (CYP1A) in caged juvenile zebrafish deployed for 15 days in 13 different water bodies, cenotes and aguadas, throughout karstic region of the Yucatan peninsula. Gene expression was evaluated using qRT-PCR. Results indicated induction of VTG in 7 water bodies with respect to reference cage. The highest relative VTG expression, about 3000 times higher than reference cage, was found in an aguada close to a cattle farm. CYP1A induction with respect to reference cage was observed in 3 water bodies, all of them located near villages or used for tourist activities. Pollutants and biomarkers of effect should be monitored in these water bodies in order to have a better understanding of the actual levels of pollutants that are present at Yucatan's aquifer and the potential risk to human and environmental health. Copyright © 2011 Elsevier Ltd. All rights reserved.

A geographical information system (GIS) as a tool for microbial risk assessment in catchment areas of drinking water reservoirs.

PubMed

Kistemann, T; Dangendorf, F; Exner, M

2001-03-01

The main tributaries of three drinking water reservoirs of Northrhine-Westfalia (Germany) were monitored within a 14-month period mainly for bacterial and parasitic contamination. In this context a detailed geo-ecological characterisation within the differing catchment areas was carried out to reveal a reliable informational basis for tracing back the origin of microbial loads present in the watercourses. To realise a microbial risk assessing geo-ecological information system (MRA-GIS), a Geographical Information System (GIS) has been implemented for the study areas. The results of the microbiological investigations of the watercourses showed an input of pathogens into all three of the tributaries. It could be demonstrated that the use of MRA-GIS database and some GIS-techniques substantially support the spatial analysis of the microbial contamination patterns. From the hygienic point of view, it is of the utmost importance to protect catchment areas of surface water reservoirs from microbial contamination stemming from human activities and animal sources. This constitutes essential part of the multi-barrier concept which stresses the importance of reducing diffuse and point pollution in catchment areas of water resources intended for human consumption. MRA-GIS proves to be helpful to manage multi-barrier water protection in catchment areas and ideally assists the application of the HACCP concept on drinking water production.

Improved methods to estimate the effective impervious area in urban catchments using rainfall-runoff data

NASA Astrophysics Data System (ADS)

Ebrahimian, Ali; Wilson, Bruce N.; Gulliver, John S.

2016-05-01

Impervious surfaces are useful indicators of the urbanization impacts on water resources. Effective impervious area (EIA), which is the portion of total impervious area (TIA) that is hydraulically connected to the drainage system, is a better catchment parameter in the determination of actual urban runoff. Development of reliable methods for quantifying EIA rather than TIA is currently one of the knowledge gaps in the rainfall-runoff modeling context. The objective of this study is to improve the rainfall-runoff data analysis method for estimating EIA fraction in urban catchments by eliminating the subjective part of the existing method and by reducing the uncertainty of EIA estimates. First, the theoretical framework is generalized using a general linear least square model and using a general criterion for categorizing runoff events. Issues with the existing method that reduce the precision of the EIA fraction estimates are then identified and discussed. Two improved methods, based on ordinary least square (OLS) and weighted least square (WLS) estimates, are proposed to address these issues. The proposed weighted least squares method is then applied to eleven urban catchments in Europe, Canada, and Australia. The results are compared to map measured directly connected impervious area (DCIA) and are shown to be consistent with DCIA values. In addition, both of the improved methods are applied to nine urban catchments in Minnesota, USA. Both methods were successful in removing the subjective component inherent in the analysis of rainfall-runoff data of the current method. The WLS method is more robust than the OLS method and generates results that are different and more precise than the OLS method in the presence of heteroscedastic residuals in our rainfall-runoff data.

Catchment Area Treatment (CAT) Plan and Crop Area Optimization for Integrated Management in a Water Resource Project

NASA Astrophysics Data System (ADS)

Jaiswal, R. K.; Thomas, T.; Galkate, R. V.; Ghosh, N. C.; Singh, S.

2013-09-01

A scientifically developed catchment area treatment (CAT) plan and optimized pattern of crop areas may be the key for sustainable development of water resource, profitability in agriculture and improvement of overall economy in drought affected Bundelkhand region of Madhya Pradesh (India). In this study, an attempt has been made to develop a CAT plan using spatial variation of geology, geomorphology, soil, drainage, land use in geographical information system for selection of soil and water conservation measures and crop area optimization using linear programming for maximization of return considering water availability, area affinity, fertilizers, social and market constraints in Benisagar reservoir project of Chhatarpur district (M.P.). The scientifically developed CAT plan based on overlaying of spatial information consists of 58 mechanical measure (49 boulder bunds, 1 check dam, 7 cully plug and 1 percolation tank), 2.60 km2 land for agro forestry, 2.08 km2 land for afforestation in Benisagar dam and 67 mechanical measures (45 boulder bunds and 22 gully plugs), 7.79 km2 land for agro forestry, 5.24 km2 land for afforestation in Beniganj weir catchment with various agronomic measures for agriculture areas. The linear programming has been used for optimization of crop areas in Benisagar command for sustainable development considering various scenarios of water availability, efficiencies, affinity and fertilizers availability in the command. Considering present supply condition of water, fertilizers, area affinity and making command self sufficient in most of crops, the net benefit can be increase to Rs. 1.93 crores from 41.70 km2 irrigable area in Benisagar command by optimizing cropping pattern and reducing losses during conveyance and application of water.

Extraction and representation of nested catchment areas from digital elevation models in lake-dominated topography

NASA Astrophysics Data System (ADS)

Mackay, D. Scott; Band, Lawrence E.

1998-04-01

This paper presents a new method for extracting flow directions, contributing (upslope) areas, and nested catchments from digital elevation models in lake-dominated areas. Existing tools for acquiring descriptive variables of the topography, such as surface flow directions and contributing areas, were developed for moderate to steep topography. These tools are typically difficult to apply in gentle topography owing to limitations in explicitly handling lakes and other flat areas. This paper addresses the problem of accurately representing general topographic features by first identifying distinguishing features, such as lakes, in gentle topography areas and then using these features to guide the search for topographic flow directions and catchment marking. Lakes are explicitly represented in the topology of a watershed for use in water routing. Nonlake flat features help guide the search for topographic flow directions in areas of low signal to noise. This combined feature-based and grid-based search for topographic features yields improved contributing areas and watershed boundaries where there are lakes and other flat areas. Lakes are easily classified from remotely sensed imagery, which makes automated representation of lakes as subsystems within a watershed system tractable with widely available data sets.

Risk assessment in fractured porous media with particular reference to water catchments

NASA Astrophysics Data System (ADS)

Enzenhoefer, R.; Helmig, R.; Nowak, W.; Binning, P. J.

2009-04-01

About 75% of the drinking water in Germany is drawn from groundwater. Karstic features can enhance the migration of contaminants to well fields, thus causing an elevated risk of contamination. In order to delineate well-head protection zones, the karstic flow and transport processes have to be understood and areas of high vulnerability have to be known from the perspective of a water constructor or manager. The trend in European legislation is to require probabilistic risk analysis in water supply management (see Water Safety Plan [WHO]). This will require to assess the 50 day line, and other indicators for well vulnerability, within stochastic frameworks. Also, the economic principles of risk (expected damage) minimization or cost/benefit optimization require probabilistic assessment of well vulnerability and well down time after contamination. The aim of this study is to provide a quantitative probabilistic approach to assess well vulnerability in a karstic system, meeting the future needs of water managers and expected legal requirements. To this end, we use a risk concept based on the four intrinsic well-vulnerability measures by Frind [2006], and transfer them to a probabilistic framework. The four vulnerability criteria are: (1)The time between a spill event and peak concentration arrival at the well, (2)The level of peak concentration relative to the spill concentration, (3)The time to breach a threshold concentration (e.g. drinking-water standard) and (4)The time of exposure (i.e., the time during which the threshold concentration is exceeded). This information helps the water manager to prioritize quantitatively the most sensitive areas with the highest risk to the well. To these areas the most efficient protection measures can be applied. Also, contamination sites can be ranked in the relevance of their remediation necessity. In order to model flow and transport processes in a karstic system, the aquifer has to be represented by a stochastic model concept

Before and After Integrated Catchment Management in a Headwater Catchment: Changes in Water Quality

NASA Astrophysics Data System (ADS)

Hughes, Andrew O.; Quinn, John M.

2014-12-01

Few studies have comprehensively measured the effect on water quality of catchment rehabilitation measures in comparison with baseline conditions. Here we have analyzed water clarity and nutrient concentrations and loads for a 13-year period in a headwater catchment within the western Waikato region, New Zealand. For the first 6 years, the entire catchment was used for hill-country cattle and sheep grazing. An integrated catchment management plan was implemented whereby cattle were excluded from riparian areas, the most degraded land was planted in Pinus radiata, channel banks were planted with poplar trees and the beef cattle enterprise was modified. The removal of cattle from riparian areas without additional riparian planting had a positive and rapid effect on stream water clarity. In contrast, the water clarity decreased in those sub-catchments where livestock was excluded but riparian areas were planted with trees and shrubs. We attribute the decrease in water clarity to a reduction in groundcover vegetation that armors stream banks against preparatory erosion processes. Increases in concentrations of forms of P and N were recorded. These increases were attributed to: (i) the reduction of instream nutrient uptake by macrophytes and periphyton due to increased riparian shading; (ii) uncontrolled growth of a nitrogen fixing weed (gorse) in some parts of the catchment, and (iii) the reduction in the nutrient attenuation capacity of seepage wetlands due to the decrease in their areal coverage in response to afforestation. Our findings highlight the complex nature of the water quality response to catchment rehabilitation measures.

Elaboration of a complex GIS application in a catchment area.

PubMed

Németh, T; Szabó, J; Pásztor, L; Bakacsi, Zs

2002-01-01

Rearrangement of land resources after political changes has not yet been finished in Hungary. It is almost impossible to collect information necessary for planning activities on outer areas of settlements. The data are distributed among various organizations and can be found in diverse forms or there are no available data at all. However water quality protection has become legally ordered concerning municipal activities around Lake Balaton which is considered as the most important recreation area and tourist target in Hungary and is also affected by a number of factors providing sources of environmental conflicts. Settlements in a catchment area (Tetves Creek) on the southern shoreline of Lake Balaton in Central Hungary tendered a complex project for collecting sources of authentic data of the Hungarian rural areas along with systematizing and saving these data in a uniform GIS. An application using Autodesk MapGuide Program for Internet realization was developed. The implemented web-based system can be used in Internet and Intranet environments.

Validation of a simple distributed sediment delivery approach in selected sub-basins of the River Inn catchment area

NASA Astrophysics Data System (ADS)

Reid, Lucas; Kittlaus, Steffen; Scherer, Ulrike

2015-04-01

For large areas without highly detailed data the empirical Universal Soil Loss Equation (USLE) is widely used to quantify soil loss. The problem though is usually the quantification of actual sediment influx into the rivers. As the USLE provides long-term mean soil loss rates, it is often combined with spatially lumped models to estimate the sediment delivery ratio (SDR). But it gets difficult with spatially lumped approaches in large catchment areas where the geographical properties have a wide variance. In this study we developed a simple but spatially distributed approach to quantify the sediment delivery ratio by considering the characteristics of the flow paths in the catchments. The sediment delivery ratio was determined using an empirical approach considering the slope, morphology and land use properties along the flow path as an estimation of travel time of the eroded particles. The model was tested against suspended solids measurements in selected sub-basins of the River Inn catchment area in Germany and Austria, ranging from the high alpine south to the Molasse basin in the northern part.

Relations between the structure of storage and the transport of chemical compounds in karstic aquifers

NASA Astrophysics Data System (ADS)

Vaute, L.; Drogue, C.; Garrelly, L.; Ghelfenstein, M.

1997-12-01

Study of the movement of chemical compounds naturally present in the water, or which result from pollution, are examined according to the reservoir structure in karstic aquifers. Structure is represented by a simple geometrical model; slow flow takes place in blocks with a network of low-permeability cracks. The blocks are separated by highly permeable karstic conduits that allow rapid flow, and these form the aquifer drainage system. The karst studied covers 110 km 2. It is fed by an interrupted stream draining a 35 km 2 non-karstic basin, contaminated at the entry to the karst by effluents from a sewage treatment station. The underground water reappears as a resurgence with an annual average flow of approximately 1 m 3 s -1, after an apparent underground course of 8 km in the karst. Several local sources of pollution (effluent from septic tanks) contaminate the underground water during its course. Sixteen measurement operations were performed at 12 water points, between the interrupted stream and the spring. Some sampling points were at drains, and others were in the low-permeability fissured blocks. Comparison at each point of the concentrations of 14 chemical compounds gave the following results: when pollutant discharge occurs in a permeable zone, movement is rapid in the drainage network formed by the karstic conduits, and does not reach the less permeable fissured blocks which are thus protected; however, if discharge is in a low-permeability zone, the flow does not allow rapid movement of the polluted water, and this increases the pollutant concentration at the discharge. This simple pattern can be upset by a reversal of the apparent piezometric gradient between a block and a conduit during floods or pumping; this may reverse flow directions and hence modify the movement of contaminants. The study made it possible to site five boreholes whose positions in the karstic structure were unknown, showing the interest of such an approach for the forecasting of the

Impacts of Spatial Distribution of Impervious Areas on Runoff Response of Hillslope Catchments: Simulation Study

EPA Science Inventory

This study analyzes variations in the model-projected changes in catchment runoff response after urbanization that stem from variations in the spatial distribution of impervious areas, interevent differences in temporal rainfall structure, and antecedent soil moisture (ASM). In t...

Source Areas of Water and Nitrate in a Peatland Catchment, Minnesota, USA

NASA Astrophysics Data System (ADS)

Sebestyen, S. D.

2017-12-01

In nitrogen polluted forests, stream nitrate concentrations increase and some unprocessed atmospheric nitrate may be transported to streams during stormflow events. This understanding has emerged from forests with upland mineral soils. In contrast, catchments with northern peatlands may have both upland soils and lowlands with deep organic soils, each with unique effects on nitrate transport and processing. While annual budgets show nitrate yields to be relatively lower from peatland than upland-dominated catchments, little is known about particular runoff events when stream nitrate concentrations have been higher (despite long periods with little or no nitrate in outlet streams) or the reasons why. I used site knowledge and expansive/extensive monitoring at the Marcell Experimental Forest in Minnesota, along with a targeted 2-year study to determine landscape areas, water sources, and nitrate sources that affected stream nitrate variation in a peatland catchment. I combined streamflow, upland runoff, snow amount, and frost depth data from long-term monitoring with nitrate concentration, yield, and isotopic data to show that up to 65% of stream nitrate during snowmelt of 2009 and 2010 was unprocessed atmospheric nitrate. Up to 46% of subsurface runoff from upland soils during 2009 was unprocessed atmospheric nitrate, which shows the uplands to be a stream nitrate source during 2009, but not during 2010 when upland runoff concentrations were below the detection limit. Differences are attributable to variations in water and nitrate sources. Little snow (a nitrate source), less upland runoff relative to peatland runoff, and deeper soil frost in the peatland caused a relatively larger input of nitrate from the uplands to the stream during 2009 and the peatland to the stream during 2010. Despite the near-absence of stream nitrate during much of rest of the year, these findings show an important time when nitrate transport affected downstream aquatic ecosystems, reasons

A Novel Low-Cost Approach to Estimate the Incidence of Japanese Encephalitis in the Catchment Area of Three Hospitals in Bangladesh

PubMed Central

Paul, Repon C.; Rahman, Mahmudur; Gurley, Emily S.; Hossain, M. Jahangir; Diorditsa, Serguei; Hasan, ASM Mainul; Banu, Sultana S.; Alamgir, ASM; Rahman, Muhammad Aziz; Sandhu, Hardeep; Fischer, Marc; Luby, Stephen P.

2011-01-01

Acute meningoencephalitis syndrome surveillance was initiated in three medical college hospitals in Bangladesh in October 2007 to identify Japanese encephalitis (JE) cases. We estimated the population-based incidence of JE in the three hospitals' catchment areas by adjusting the hospital-based crude incidence of JE by the proportion of catchment area meningoencephalitis cases who were admitted to surveillance hospitals. Instead of a traditional house-to-house survey, which is expensive for a disease with low frequency, we attempted a novel approach to identify meningoencephalitis cases in the hospital catchment area through social networks among the community residents. The estimated JE incidence was 2.7/100,000 population in Rajshahi (95% confidence interval [CI] = 1.8–4.9), 1.4 in Khulna (95% CI = 0.9–4.1), and 0.6 in Chittagong (95% CI = 0.4–0.9). Bangladesh should consider a pilot project to introduce JE vaccine in high-incidence areas. PMID:21813862

Advancing Land-Sea Conservation Planning: Integrating Modelling of Catchments, Land-Use Change, and River Plumes to Prioritise Catchment Management and Protection.

PubMed

Álvarez-Romero, Jorge G; Pressey, Robert L; Ban, Natalie C; Brodie, Jon

2015-01-01

Human-induced changes to river loads of nutrients and sediments pose a significant threat to marine ecosystems. Ongoing land-use change can further increase these loads, and amplify the impacts of land-based threats on vulnerable marine ecosystems. Consequently, there is a need to assess these threats and prioritise actions to mitigate their impacts. A key question regarding prioritisation is whether actions in catchments to maintain coastal-marine water quality can be spatially congruent with actions for other management objectives, such as conserving terrestrial biodiversity. In selected catchments draining into the Gulf of California, Mexico, we employed Land Change Modeller to assess the vulnerability of areas with native vegetation to conversion into crops, pasture, and urban areas. We then used SedNet, a catchment modelling tool, to map the sources and estimate pollutant loads delivered to the Gulf by these catchments. Following these analyses, we used modelled river plumes to identify marine areas likely influenced by land-based pollutants. Finally, we prioritised areas for catchment management based on objectives for conservation of terrestrial biodiversity and objectives for water quality that recognised links between pollutant sources and affected marine areas. Our objectives for coastal-marine water quality were to reduce sediment and nutrient discharges from anthropic areas, and minimise future increases in coastal sedimentation and eutrophication. Our objectives for protection of terrestrial biodiversity covered species of vertebrates. We used Marxan, a conservation planning tool, to prioritise interventions and explore spatial differences in priorities for both objectives. Notable differences in the distributions of land values for terrestrial biodiversity and coastal-marine water quality indicated the likely need for trade-offs between catchment management objectives. However, there were priority areas that contributed to both sets of objectives. Our

A Needs Assessment of Phoenix South Catchment Area Children: The Responses of Parents, Neighbors, and Teachers.

ERIC Educational Resources Information Center

Balk, David

Summarized in this document are results from a survey conducted from 1975 to 1977 with parents, neighbors, and fifth-grade teachers as part of a needs assessment of Phoenix, Arizona, South Catchment Area children. A questionnaire consisting of 34 items, generated from studies reviewed in the area of children's behavioral symptoms and strengths,…

A new perspective on catchment storage gained from a nested catchment experiment in Luxembourg (Europe)

NASA Astrophysics Data System (ADS)

Pfister, Laurent; Klaus, Julian; Hissler, Christophe; François Iffly, Jean; Gourdol, Laurent; Martinez-Carreras, Nuria; McDonnell, Jeffrey J.

2014-05-01

Recent hydrological process research focussed on how much water a catchment can store and how these catchments store and release water. Storage can be a valuable metric for catchment description, inter-comparison, and classification. Further storage controls catchment mixing, non-linearities in rainfall-runoff transformation and eco-hydrological processes. Various methods exist to determine catchment storage (e.g. natural tracer, soil moisture and groundwater data, hydrological models). Today it remains unclear what parts of the catchment storage are measured with the different models. Here we present a new hydrometric approach to answer the question how much water a catchment can store. We tested our approach in a dense hydro-climatological monitoring network that encompasses 16 recording streamgauges and 21 pluviographs in the Alzette River basin in Luxembourg (Europe). Catchment scales are ranging from 0.47 to 285 km2 and they have clean- and mixed combinations of distinct geologies ranging from schists to marls, sandstone, dolomite and limestone. Previous investigations in the area of interest have shown that geology largely controls winter runoff coefficients. Here, we focus at how catchment geology is ultimately affecting catchment storage. We used the approach of Sayama et al. (2011) to compute catchment dynamic storage changes for each winter season over the period 2002-2012 (based on precipitation as input; discharge and evapotranspiration as output). We determined dynamic storage changes for each winter semester (October to March) in all 16 catchments over the period 2002-2012. At the beginning of each hydrological winter season, all catchments showed similar trends in storage change. A few weeks into the winter season, catchments with lowest permeability (e.g. marls) started to plateau. The highest storage values were reached several months later in the season in catchments dominated by permeable substrate (e.g. sandstone). For most catchments, we found

An enhanced two-step floating catchment area (E2SFCA) method for measuring spatial accessibility to primary care physicians.

PubMed

Luo, Wei; Qi, Yi

2009-12-01

This paper presents an enhancement of the two-step floating catchment area (2SFCA) method for measuring spatial accessibility, addressing the problem of uniform access within the catchment by applying weights to different travel time zones to account for distance decay. The enhancement is proved to be another special case of the gravity model. When applying this enhanced 2SFCA (E2SFCA) to measure the spatial access to primary care physicians in a study area in northern Illinois, we find that it reveals spatial accessibility pattern that is more consistent with intuition and delineates more spatially explicit health professional shortage areas. It is easy to implement in GIS and straightforward to interpret.

Some climatological factors of pine in the lake toba catchment area

NASA Astrophysics Data System (ADS)

Nasution, Z.

2018-02-01

The article deals with climatological factors of Pine at the Lake Toba Catchment Area also called drained basin, Pinus merkusii is a plant endemic in Sumatra. A central population of Pine in North Sumatra is located in the Tapanuli region to south of Lake Toba. Junghuhn discovered the species in the mountains range of Sipirok. He provisionally named the species as Pinus sumatrana. The article presents a detail analysis of approaches to climate factors, considers rainfall, air temperature, humidity, stemflow, throughfall and Interception following calculation of regression to determine relationship between precipitation with stemflow and interception. Stemflow, it is highly significant with significance of difference between correlation coefficients and z normal distribution. Temperature and relative humidity are the important components in the climate. These components influence the evaporation process and rainfall in the catchment. Pinus merkusii has the big crown interception. Stemflow and Interception has an opposite relation. Increasing of interception capacity will decrease stemflow. This type of Pine also has rough bark however significant channels so that, it flows water even during the wet season and caused the stemflow in Pinus merkusii relatively bigger.

Small karstic Dobra River (Croatia) suggested as natural laboratory for impactite research

NASA Astrophysics Data System (ADS)

Frančišković-Bilinski, Stanislav; Bilinski, Halka; Sikder, Arif M.

2016-04-01

An unexpected anomaly of magnetic susceptibility (MS) was observed in stream sediments of the upper course of the karstic Dobra River (Croatia). Preliminary results pointed to a possible impactite, formed by a shock event caused by a meteorite impact or by volcanic processes [1]. In addition to geophysical experiments, petrological and geochemical studies are reported [2, 3]. The multidisciplinary work for identification and confirmation of impact structure is still in progress. Results will be presented and the difficulties due to weathering and transport processes will be discussed and compared with recent literature [4, 5]. In reported results numerous evidences exist, which are in support of impact origin, such as vesicular glass with quench texture, ballen textures in the lechatelierite, presence of Troilite, etc. We suggest that the Dobra River from its source to the abyss in Ogulin (Upper Dobra) is a possible natural laboratory for studying processes of mixing between impactite material and fluvial sediments within a small area, including spherules exposed to water and in the overbank sediments. Especially the introduction of isotope studies in this research and enlargement of multinational team of experts are suggested. Literature: [1] Franči\\vsković-Bilinski, S., Bilinski, H., Scholger, R., Tomašić, N., Maldini, K. (2014): Magnetic spherules in sediments of the sinking karstic Dobra River (Croatia). Journal of soils and sediments 14(3), 600-614. [2] Franči\\vsković-Bilinski, S., Sikder, A.M., Bilinski, H., Castano, C.E., Garman, G.C. (2015): Traces of meteorite impact in the sediments of karstic Dobra River (Croatia). 15th International multidisciplinary scientific geoconference SGEM 2015 Conference proceedings, Vol. 1, 507-514. [3] Sikder, A.M., Franči\\vsković-Bilinski, S., Bilinski, H., Castano, C.E., Clifford, D.M., Turner, J.B., Garman, G.C. (2015): Petrographic analysis of the magnetic spherules from the sediments of karastic Dobra River

Advancing Land-Sea Conservation Planning: Integrating Modelling of Catchments, Land-Use Change, and River Plumes to Prioritise Catchment Management and Protection

PubMed Central

Álvarez-Romero, Jorge G.; Pressey, Robert L.; Ban, Natalie C.; Brodie, Jon

2015-01-01

Human-induced changes to river loads of nutrients and sediments pose a significant threat to marine ecosystems. Ongoing land-use change can further increase these loads, and amplify the impacts of land-based threats on vulnerable marine ecosystems. Consequently, there is a need to assess these threats and prioritise actions to mitigate their impacts. A key question regarding prioritisation is whether actions in catchments to maintain coastal-marine water quality can be spatially congruent with actions for other management objectives, such as conserving terrestrial biodiversity. In selected catchments draining into the Gulf of California, Mexico, we employed Land Change Modeller to assess the vulnerability of areas with native vegetation to conversion into crops, pasture, and urban areas. We then used SedNet, a catchment modelling tool, to map the sources and estimate pollutant loads delivered to the Gulf by these catchments. Following these analyses, we used modelled river plumes to identify marine areas likely influenced by land-based pollutants. Finally, we prioritised areas for catchment management based on objectives for conservation of terrestrial biodiversity and objectives for water quality that recognised links between pollutant sources and affected marine areas. Our objectives for coastal-marine water quality were to reduce sediment and nutrient discharges from anthropic areas, and minimise future increases in coastal sedimentation and eutrophication. Our objectives for protection of terrestrial biodiversity covered species of vertebrates. We used Marxan, a conservation planning tool, to prioritise interventions and explore spatial differences in priorities for both objectives. Notable differences in the distributions of land values for terrestrial biodiversity and coastal-marine water quality indicated the likely need for trade-offs between catchment management objectives. However, there were priority areas that contributed to both sets of objectives. Our

Runoff and Solute Mobilisation in a Semi-arid Headwater Catchment

NASA Astrophysics Data System (ADS)

Hughes, J. D.; Khan, S.; Crosbie, R.; Helliwell, S.; Michalk, D.

2006-12-01

Runoff and solute transport processes contributing to stream flow were determined in a small headwater catchment in the eastern Murray-Darling Basin of Australia using hydrometric and tracer methods. Stream flow and electrical conductivity were monitored from two gauges draining a portion of upper catchment area (UCA), and a saline scalded area respectively. Results show that the bulk of catchment solute export, occurs via a small saline scald (< 2% of catchment area) where solutes are concentrated in the near surface zone (0-40 cm). Non-scalded areas of the catchment are likely to provide the bulk of catchment runoff, although the scalded area is a higher contributor on an areal basis. Runoff from the non-scalded area is about two orders of magnitude lower in electrical conductivity than the scalded area. This study shows that the scalded zone and non-scalded parts of the catchment can be managed separately since they are effectively de-coupled except over long time scales, and produce runoff of contrasting quality. Such differences are "averaged out" by investigations that operate at larger scales, illustrating that observations need to be conducted at a range of scales. EMMA modelling using six solutes shows that "event" or "new" water dominated the stream hydrograph from the scald. This information together with hydrometric data and soil physical properties indicate that saturated overland flow is the main form of runoff generation in both the scalded area and the UCA. Saturated areas make up a small proportion of the catchment, but are responsible for production of all run off in conditions experienced throughout the experimental period. The process of saturation and runoff bears some similarities to the VSA concept (Hewlett and Hibbert 1967).

Hydro-geophysical observations integration in numerical model: case study in Mediterranean karstic unsaturated zone (Larzac, france)

NASA Astrophysics Data System (ADS)

Champollion, Cédric; Fores, Benjamin; Le Moigne, Nicolas; Chéry, Jean

2016-04-01

Karstic hydro-systems are highly non-linear and heterogeneous but one of the main water resource in the Mediterranean area. Neither local measurements in boreholes or analysis at the spring can take into account the variability of the water storage. Since a few years, ground-based geophysical measurements (such as gravity, electrical resistivity or seismological data) allows following water storage in heterogeneous hydrosystems at an intermediate scale between boreholes and basin. Behind classical rigorous monitoring, the integration of geophysical data in hydrological numerical models in needed for both processes interpretation and quantification. Since a few years, a karstic geophysical observatory (GEK: Géodésie de l'Environnement Karstique, OSU OREME, SNO H+) has been setup in the Mediterranean area in the south of France. The observatory is surrounding more than 250m karstified dolomite, with an unsaturated zone of ~150m thickness. At the observatory water level in boreholes, evapotranspiration and rainfall are classical hydro-meteorological observations completed by continuous gravity, resistivity and seismological measurements. The main objective of the study is the modelling of the whole observation dataset by explicit unsaturated numerical model in one dimension. Hydrus software is used for the explicit modelling of the water storage and transfer and links the different observations (geophysics, water level, evapotranspiration) with the water saturation. Unknown hydrological parameters (permeability, porosity) are retrieved from stochastic inversions. The scale of investigation of the different observations are discussed thank to the modelling results. A sensibility study of the measurements against the model is done and key hydro-geological processes of the site are presented.

Assessment of the water balance over France using regionalized Turc-Pike formula

NASA Astrophysics Data System (ADS)

Le Lay, Matthieu; Garçon, Rémy; Gailhard, Joël; Garavaglia, Federico

2016-04-01

With extensive use of hydrological models over a wide range of hydro-climatic contexts, bias in hydro-climatic data may lead to unreliable models and thus hydrological forecasts and projections. This issue is particularly pregnant when considering mountainous areas with great uncertainties on precipitations, or when considering complex unconservative catchments (e.g. karstic systems). The Turc-Pike water balance formula, analogous to the classical Budyko formula, is a simple and efficient mathematical formulation relating long-term average streamflow to long-term average precipitation and potential evaporation. In this study, we propose to apply this framework to assess and eventually adjust the water-balance before calibrating an operational hydrologic model (MORDOR model). Considering a large set of 350 french catchments, the Turc-Pike formula is regionalized based on ecohydrologic criterions to handle various hydro-climatic contexts. This interannual regional model is then applied to assess the water-balance over numerous catchments and various conditions, such as karstic, snow-driven or glaciarized and even anthropized catchments. Results show that it is possible to obtain pretty realistic corrections of meteorological inputs (precipitations, temperature or potential evaporation) or hydrologic surface (or runoff). These corrections can often be confirmed a posteriori by exogenous information. Positive impacts on hydrologic model's calibration are also demonstrated. This methodology is now operational for hydrologic applications at EDF (Electricité de France, French electric utility company), and therefore applied on hundreds of catchments.

Downscaling catchment scale flood risk to contributing sub-catchments to determine the optimum location for flood management.

NASA Astrophysics Data System (ADS)

Pattison, Ian; Lane, Stuart; Hardy, Richard; Reaney, Sim

2010-05-01

The recent increase in flood frequency and magnitude has been hypothesised to have been caused by either climate change or land management. Field scale studies have found that changing land management practices does affect local runoff and streamflow, but upscaling these effects to the catchment scale continues to be problematic, both conceptually and more importantly methodologically. The impact on downstream flood risk is highly dependent upon where the changes are in the catchment, indicating that some areas of the catchment are more important in determining downstream flood risk than others. This is a major flaw in the traditional approach to studying the effect of land use on downstream flood risk: catchment scale hydrological models, which treat every cell in the model equally. We are proposing an alternative ideological approach for doing flood management research, which is underpinned by downscaling the downstream effect (problem i.e. flooding) to the upstream causes (contributing sub-catchments). It is hoped that this approach could have several benefits over the traditional upscaling approach. Firstly, it provides an efficient method to prioritise areas for land use management changes to be implemented to reduce downstream flood risk. Secondly, targets for sub-catchment hydrograph change can be determined which will deliver the required downstream effect. Thirdly, it may be possible to detect the effect of land use changes in upstream areas on downstream flood risk, by weighting the areas of most importance in hydrological models. Two methods for doing this downscaling are proposed; 1) data-based statistical analysis; and 2) hydraulic modelling-based downscaling. These will be outlined using the case study of the River Eden, Cumbria, NW England. The data-based methodology uses the timing and magnitude of floods for each sub-catchment. Principal components analysis (PCA) is used to simplify sub-catchment interactions and optimising stepwise regression is

Identification of glacial melt water runoff in a karstic environment and its implication for present and future water availability

NASA Astrophysics Data System (ADS)

Finger, D.; Hugentobler, A.; Huss, M.; Voinesco, A.; Wernli, H.; Fischer, D.; Weber, E.; Jeannin, P.-Y.; Kauzlaric, M.; Wirz, A.; Vennemann, T.; Hüsler, F.; Schädler, B.; Weingartner, R.

2013-03-01

Glaciers all over the world are expected to continue to retreat due to the global warming throughout the 21st century. Consequently, future seasonal water availability might become scarce once glacier areas have declined below a certain threshold affecting future water management strategies. Particular attention should be paid to glaciers located in a karstic environment, as parts of the melt water can be drained by souterrain karst systems. In this study tracer experiments, karst modeling and glacier melt modeling are combined in order to identify flow paths in a high alpine, glacierized, karstic environment (Glacier de la Plaine Morte, Switzerland) and to investigate current and predict future downstream water availability. Flow paths through the karst underground were determined with natural and fluorescent tracers. Subsequently, tracer results and geologic information were assembled in a karst model. Finally, glacier melt projections driven with a climate scenario were performed to discuss future water availability in the area surrounding the glacier. The results suggest that during late summer glacier melt water is rapidly drained through well-developed channels at the glacier bottom to the north of the glacier, while during low flow season melt water enters into the karst and is drained to the south. Climate change projections reveal that by the end of the century glacier melt will be significantly reduced in the summer, jeopardizing water availability in glacier-fed karst springs.

The combined effects of topography and vegetation on catchment connectivity

NASA Astrophysics Data System (ADS)

Nippgen, F.; McGlynn, B. L.; Emanuel, R. E.

2012-12-01

The deconvolution of whole catchment runoff response into its temporally dynamic source areas is a grand challenge in hydrology. The extent to which the intersection of static and dynamic catchment characteristics (e.g. topography and vegetation) influences water redistribution within a catchment and the hydrologic connectivity of hillslopes to the riparian and stream system is largely unknown. Over time, patterns of catchment storage shift and, because of threshold connectivity behavior, catchment areas become disconnected from the stream network. We developed a simple but spatially distributed modeling framework that explicitly incorporates static (topography) and dynamic (vegetation) catchment structure to document the evolution of catchment connectivity over the course of a water year. We employed directly measured eddy-covariance evapotranspiration data co-located within a highly instrumented (>150 recording groundwater wells) and gauged catchment to parse the effect of current and zero vegetation scenarios on the temporal evolution of hydrologic connectivity. In the absence of vegetation, and thus in the absence of evapotranspiration, modeled absolute connectivity was 4.5% greater during peak flow and 3.9% greater during late summer baseflow when compared to the actual vegetation scenario. The most significant differences in connected catchment area between current and zero vegetation (14.9%) occurred during the recession period in early July, when water and energy availability were at an optimum. However, the greatest relative difference in connected area occurs during the late summer baseflow period when the absence of evapotranspiration results in a connected area approximately 500% greater than when vegetation is present, while the relative increase during peak flow is just 6%. Changes in connected areas ultimately lead to propose a biologically modified geomorphic width function. This biogeomorphic width function is the result of lateral water

A Demographic and Epidemiological Study of Naval Hospital Charleston’s Catchment Area Population

DTIC Science & Technology

1993-08-01

Management Project examines the military beneficiary population in the Naval Hospital Charleston Catchment Area to determine what demographic attributes...are exhibited, and what medical demands the beneficiaries have placed on the Military Health Service System between 01 and 30 June 1992. Various data...closure or realignment of the military treatment facility. 14. SUBJECT TERMS 15. NUMBER OF PAGES 304Demographic and Epidemiological Study 16. PRICE CODE 17

The GRASP project - a multidisciplinary study of hydrology and biogeochemistry in a periglacial catchment area

NASA Astrophysics Data System (ADS)

Johansson, Emma; Lindborg, Tobias

2017-04-01

The Arctic region is sensitive to global warming, and permafrost thaw and release of old carbon are examples of processes that may have a positive feedback effect to the global climate system. Quantification and assumptions on future change are often based on model predictions. Such models require cross-disciplinary data of high quality that often is lacking. Biogeochemical processes in the landscape are highly influenced by the hydrology, which in turn is intimately related to permafrost processes. Thus, a multidisciplinary approach is needed when collecting data and setting up field experiments aiming at increase the understanding of these processes. Here we summarize and present data collected in the GRASP, Greenland Analogue Surface Project. GRASP is a catchment-scale field study of the periglacial area in the Kangerlussuaq region, West Greenland, focusing on hydrological and biogeochemical processes in the landscape. The site investigations were initiated in 2010 and have since then resulted in three separate data sets published in ESSD (Earth system and Science Data) each one focusing on i) meteorological data and hydrology, ii) biogeochemistry and iii) geometries of sediments and the active layer. The three data-sets, which are freely available via the PANGAEA data base, enable conceptual and coupled numerical modeling of hydrological and biogeochemical processes. An important strength with the GRASP data is that all data is collected within the same, relatively small, catchment area. This implies that measurements are more easily linked to the right source area or process. Despite the small catchment area it includes the major units of the periglacial hydrological system; a lake, a talik, a supra- and subpermafrost aquifer and, consequently, biogeochemical processes in each of these units may be studied. The new data from GRASP is both used with the aim to increase the knowledge of present day periglacial hydrology and biogeochemistry but also in order to

Catchment-scale evaluation of pollution potential of urban snow at two residential catchments in southern Finland.

PubMed

Sillanpää, Nora; Koivusalo, Harri

2013-01-01

Despite the crucial role of snow in the hydrological cycle in cold climate conditions, monitoring studies of urban snow quality often lack discussions about the relevance of snow in the catchment-scale runoff management. In this study, measurements of snow quality were conducted at two residential catchments in Espoo, Finland, simultaneously with continuous runoff measurements. The results of the snow quality were used to produce catchment-scale estimates of areal snow mass loads (SML). Based on the results, urbanization reduced areal snow water equivalent but increased pollutant accumulation in snow: SMLs in a medium-density residential catchment were two- to four-fold higher in comparison with a low-density residential catchment. The main sources of pollutants were related to vehicular traffic and road maintenance, but also pet excrement increased concentrations to a high level. Ploughed snow can contain 50% of the areal pollutant mass stored in snow despite its small surface area within a catchment.

Environmental health aspects of drinking water-borne outbreak due to karst flooding: case study.

PubMed

Dura, Gyula; Pándics, Tamás; Kádár, Mihály; Krisztalovics, Katalin; Kiss, Zoltánné; Bodnár, Judit; Asztalos, Agnes; Papp, Erzsébet

2010-09-01

Climate change may increase the incidence of waterborne diseases due to extreme rainfall events, and consequent microbiological contamination of the water source and supply. As a result of the complexity of the pathways from the surface to the consumer, it is difficult to detect an association between rainfall and human disease. The water supply of a Hungarian city, Miskolc (174,000 inhabitant), is mainly based on karstic water, a vulnerable underground water body. A large amount of precipitation fell on the catchment area of the karstic water source, causing an unusually strong karstic water flow and flooding, and subsequent microbiological contamination. The presence of several potential sources of contamination in the protective zone of the karstic water source should be emphasized. The water supplier was unprepared to treat the risk of waterborne outbreak caused by an extreme weather event. Public health intervention and hygienic measures were taken in line with epidemiological actions, focusing on the protection of consumers by providing safe drinking water. The contamination was identified, and measures were taken for risk reduction and prevention. This case study underlines the increasing importance of preparedness for extreme water events in order to protect the karstic water sources and to avoid waterborne outbreaks.

Identification of glacial meltwater runoff in a karstic environment and its implication for present and future water availability

NASA Astrophysics Data System (ADS)

Finger, D.; Hugentobler, A.; Huss, M.; Voinesco, A.; Wernli, H.; Fischer, D.; Weber, E.; Jeannin, P.-Y.; Kauzlaric, M.; Wirz, A.; Vennemann, T.; Hüsler, F.; Schädler, B.; Weingartner, R.

2013-08-01

Glaciers all over the world are expected to continue to retreat due to the global warming throughout the 21st century. Consequently, future seasonal water availability might become scarce once glacier areas have declined below a certain threshold affecting future water management strategies. Particular attention should be paid to glaciers located in a karstic environment, as parts of the meltwater can be drained by underlying karst systems, making it difficult to assess water availability. In this study tracer experiments, karst modeling and glacier melt modeling are combined in order to identify flow paths in a high alpine, glacierized, karstic environment (Glacier de la Plaine Morte, Switzerland) and to investigate current and predict future downstream water availability. Flow paths through the karst underground were determined with natural and fluorescent tracers. Subsequently, geologic information and the findings from tracer experiments were assembled in a karst model. Finally, glacier melt projections driven with a climate scenario were performed to discuss future water availability in the area surrounding the glacier. The results suggest that during late summer glacier meltwater is rapidly drained through well-developed channels at the glacier bottom to the north of the glacier, while during low flow season meltwater enters into the karst and is drained to the south. Climate change projections with the glacier melt model reveal that by the end of the century glacier melt will be significantly reduced in the summer, jeopardizing water availability in glacier-fed karst springs.

How size matters: exploring the association between quality of mental health services and catchment area size.

PubMed

Ala-Nikkola, Taina; Sadeniemi, Minna; Kaila, Minna; Saarni, Samuli; Kontio, Raija; Pirkola, Sami; Joffe, Grigori; Oranta, Olli; Wahlbeck, Kristian

2016-08-12

The diversity of mental health and substance abuse services (MHS) available to service users is seen as an indicator of the quality of the service system. In most countries MHS are provided by a mix of public, private and third sector providers. In Finland, officially, the municipalities are responsible for organizing the services needed, but the real extent and roles of private and third sector service providers are not known. Our previous study showed that the catchment area population size was strongly associated with diversity of mental health services. It is not known whether this was due to some types of services or some provider types being more sensitive to the size effect than others. The aim of this study was to investigate the association between area population size and diversity of mental health services, i.e. which types of services and which service providers' contributions are sensitive to population size. To map and classify services, we used the ESMS-R. The diversity of services was defined as the count of main types of care. Providers were classified as public, private or third sectors. The diversity of outpatient, residential and voluntary services correlated positively with catchment area population size. The strongest positive correlation between the size of population and services available was found in third sector activities followed by public providers, but no correlation was found for diversity of private services. The third sector and public corporations each provided 44 % of the service units. Third sector providers produced all self-help services and most of the day care services. Third sector and private companies provided a significant part (59 %) of the residential care service units. Significant positive correlations were found between size of catchment area population and diversity of residential, outpatient and voluntary services, indicating that these services concentrate on areas with larger population bases. The third sector

An approach to predict water quality in data-sparse catchments using hydrological catchment similarity

NASA Astrophysics Data System (ADS)

Pohle, Ina; Glendell, Miriam; Stutter, Marc I.; Helliwell, Rachel C.

2017-04-01

An understanding of catchment response to climate and land use change at a regional scale is necessary for the assessment of mitigation and adaptation options addressing diffuse nutrient pollution. It is well documented that the physicochemical properties of a river ecosystem respond to change in a non-linear fashion. This is particularly important when threshold water concentrations, relevant to national and EU legislation, are exceeded. Large scale (regional) model assessments required for regulatory purposes must represent the key processes and mechanisms that are more readily understood in catchments with water quantity and water quality data monitored at high spatial and temporal resolution. While daily discharge data are available for most catchments in Scotland, nitrate and phosphorus are mostly available on a monthly basis only, as typified by regulatory monitoring. However, high resolution (hourly to daily) water quantity and water quality data exist for a limited number of research catchments. To successfully implement adaptation measures across Scotland, an upscaling from data-rich to data-sparse catchments is required. In addition, the widespread availability of spatial datasets affecting hydrological and biogeochemical responses (e.g. soils, topography/geomorphology, land use, vegetation etc.) provide an opportunity to transfer predictions between data-rich and data-sparse areas by linking processes and responses to catchment attributes. Here, we develop a framework of catchment typologies as a prerequisite for transferring information from data-rich to data-sparse catchments by focusing on how hydrological catchment similarity can be used as an indicator of grouped behaviours in water quality response. As indicators of hydrological catchment similarity we use flow indices derived from observed discharge data across Scotland as well as hydrological model parameters. For the latter, we calibrated the lumped rainfall-runoff model TUWModel using multiple

Contaminant sequestration in karstic aquifers: Experiments and quantification

NASA Astrophysics Data System (ADS)

Li, Guangquan; Loper, David E.; Kung, Robin

2008-02-01

A karstic aquifer typically has significant secondary porosity consisting of an interconnected system of caves or conduits. Conduit-borne contaminants can enter the contiguous limestone matrix, remain inside for a longer time than in the conduit, and subsequently be flushed out. This retention or sequestration can significantly influence the fate of contaminants within the aquifer and alter the shape of the breakthrough curve. The mechanisms involved in sequestration have been identified and quantified by analysis of the breakthrough curves generated by a set of laboratory experiments in which a conduit, porous limestone matrix, and conservative contaminant were simulated by a porous-walled pipe, chamber of closely packed glass beads, and salt, respectively. Experiments were conducted with both active and passive transfer of water between conduit and matrix, simulating differing hydrogeologic regimes. In active transfer the primary control parameter is the volume of water transferred; sequestration is primarily due to advection with the effects of diffusion and dispersion being minimal. In passive transfer the control parameters are the conduit Reynolds number and the duration that contaminant resides in the conduit; sequestration is caused by the combined effects of the conduit pressure drop, pressure variation due to bedform, and diffusion. Active and passive transfer can be unified by analyzing the ratio of the scale of pressure variation to the conduit length. In accordance with the resolved mechanisms a variety of models have been constructed to recover solute distributions in the matrix and to regenerate breakthrough curves. These analyses and models provide a potential approach to investigate contaminant migration in karstic aquifers.

The Concept of Directly Connected Impervious Areas and Its Implication on Sustainable Development in Urban Catchments

NASA Astrophysics Data System (ADS)

Seo, Yongwon; Hwang, Junsik; Choi, Hyun Il

2017-04-01

The concept of directly connected impervious area (DCIA) or efficient impervious areas (EIA) refers to a subset of impervious cover, which is directly connected to a drainage system or a water body via continuous impervious surfaces. The concept of DCIA is important in that it is regarded as a better predictor of stream ecosystem health than the total impervious area (TIA). DCIA is a key concept for a better assessment of green infrastructures introduced in urban catchments. Green infrastructure can help restore water cycle; it improves water quality, manages stormwater, provides recreational environment even at lower cost compared to conventional alternatives. In this study, we evaluated several methods to obtain the DCIA based on a GIS database and showed the importance of the accurate measurement of DCIA in terms of resulting hydrographs. We also evaluated several potential green infrastructure scenarios and showed how the spatial planning of green infrastruesture affects the shape of hydrographs and reduction of peak flows. These results imply that well-planned green infrastructure can be introduced to urban catchments for flood risk managements and quantitative assessment of spatial distribution of DCIA is crucial for sustainable development in urban environment.

Multi-modal two-step floating catchment area analysis of primary health care accessibility.

PubMed

Langford, Mitchel; Higgs, Gary; Fry, Richard

2016-03-01

Two-step floating catchment area (2SFCA) techniques are popular for measuring potential geographical accessibility to health care services. This paper proposes methodological enhancements to increase the sophistication of the 2SFCA methodology by incorporating both public and private transport modes using dedicated network datasets. The proposed model yields separate accessibility scores for each modal group at each demand point to better reflect the differential accessibility levels experienced by each cohort. An empirical study of primary health care facilities in South Wales, UK, is used to illustrate the approach. Outcomes suggest the bus-riding cohort of each census tract experience much lower accessibility levels than those estimated by an undifferentiated (car-only) model. Car drivers' accessibility may also be misrepresented in an undifferentiated model because they potentially profit from the lower demand placed upon service provision points by bus riders. The ability to specify independent catchment sizes for each cohort in the multi-modal model allows aspects of preparedness to travel to be investigated. Copyright © 2016. Published by Elsevier Ltd.

Terrain representation impact on periurban catchment morphological properties

NASA Astrophysics Data System (ADS)

Rodriguez, F.; Bocher, E.; Chancibault, K.

2013-04-01

SummaryModelling the hydrological behaviour of suburban catchments requires an estimation of environmental features, including land use and hydrographic networks. Suburban areas display a highly heterogeneous composition and encompass many anthropogenic elements that affect water flow paths, such as ditches, sewers, culverts and embankments. The geographical data available, either raster or vector data, may be of various origins and resolutions. Urban databases often offer very detailed data for sewer networks and 3D streets, yet the data covering rural zones may be coarser. This study is intended to highlight the sensitivity of geographical data as well as the data discretisation method used on the essential features of a periurban catchment, i.e. the catchment border and the drainage network. Three methods are implemented for this purpose. The first is the DEM (for digital elevation model) treatment method, which has traditionally been applied in the field of catchment hydrology. The second is based on urban database analysis and focuses on vector data, i.e. polygons and segments. The third method is a TIN (or triangular irregular network), which provides a consistent description of flow directions from an accurate representation of slope. It is assumed herein that the width function is representative of the catchment's hydrological response. The periurban Chézine catchment, located within the Nantes metropolitan area in western France, serves as the case study. The determination of both the main morphological features and the hydrological response of a suburban catchment varies significantly according to the discretization method employed, especially on upstream rural areas. Vector- and TIN-based methods allow representing the higher drainage density of urban areas, and consequently reveal the impact of these areas on the width function, since the DEM method fails. TINs seem to be more appropriate to take streets into account, because it allows a finer

The distribution of catchment coverage by stationary rainstorms

NASA Technical Reports Server (NTRS)

Eagleson, P. S.

1984-01-01

The occurrence of wetted rainstorm area within a catchment is modeled as a Poisson arrival process in which each storm is composed of stationary, nonoverlapping, independent random cell clusters whose centers are Poisson-distributed in space and whose areas are fractals. The two Poisson parameters and hence the first two moments of the wetted fraction are derived in terms of catchment average characteristics of the (observable) station precipitation. The model is used to estimate spatial properties of tropical air mass thunderstorms on six tropical catchments in the Sudan.

Importance of bottom-up approach in water management - sustainable development of catchment areas in Croatia

NASA Astrophysics Data System (ADS)

Pavic, M.; Cosic-Flajsig, G.; Petricec, M.; Blazevic, Z.

2012-04-01

Association for preservation of Croatian waters and sea SLAP is a non-governmental organization (NGO) that gathers more than 150 scientist, hydrologist and civil engineers. SLAP has been established in 2006 and since then had organized many conferences and participated in projects dealing with water management. We have started our work developing plans to secure water supply to the 22 (21) villages in the rural parts of Dubrovnik (Pozega) area and trough the years we have accumulated knowledge and experience in dealing with stakeholders in hydrology and water management. Within this paper we will present importance of bottom-up approach to the stakeholders in water management in Croatia on two case studies: (1) Management of River Trebizat catchment area - irrigation of the Imotsko-Bekijsko rural parts; (2) Development of multipurpose water reservoirs at the River Orljava catchment area. Both projects were designed in the mid and late 1980's but due to the war were forgotten and on halt. River Trebizat meanders between Croatia and Bosnia and Herzegovina and acquires joint management by both countries. In 2010 and 2011 SLAP has organized conferences in both countries gathering all the relevant stakeholders from representatives of local and state governments, water management companies and development agencies to the scientist and interested NGO's. The conferences gave firm scientific background of the topic including presentation of all previous studies and measurements as well as model results but presented in manner appropriate to the stakeholders. The main result of the conference was contribution to the development of joint cross-border project sent to the EU Pre-Accession funds in December 2011 with the aim to strengthen capacities of both countries and prepare larger project dealing with management of the whole Trebizat catchment area to EU structural funds once Croatia enters EU in 2013. Similar approach was taken for the Orljava catchment in the northern

Catchment area-based evaluation of the AMC-dependent SCS-CN-based rainfall-runoff models

NASA Astrophysics Data System (ADS)

Mishra, S. K.; Jain, M. K.; Pandey, R. P.; Singh, V. P.

2005-09-01

Using a large set of rainfall-runoff data from 234 watersheds in the USA, a catchment area-based evaluation of the modified version of the Mishra and Singh (2002a) model was performed. The model is based on the Soil Conservation Service Curve Number (SCS-CN) methodology and incorporates the antecedent moisture in computation of direct surface runoff. Comparison with the existing SCS-CN method showed that the modified version performed better than did the existing one on the data of all seven area-based groups of watersheds ranging from 0.01 to 310.3 km2.

Remote sensing and GIS for mapping groundwater recharge and discharge areas in salinity prone catchments, southeastern Australia

NASA Astrophysics Data System (ADS)

Tweed, Sarah O.; Leblanc, Marc; Webb, John A.; Lubczynski, Maciek W.

2007-02-01

Identifying groundwater recharge and discharge areas across catchments is critical for implementing effective strategies for salinity mitigation, surface-water and groundwater resource management, and ecosystem protection. In this study, a synergistic approach has been developed, which applies a combination of remote sensing and geographic information system (GIS) techniques to map groundwater recharge and discharge areas. This approach is applied to an unconfined basalt aquifer, in a salinity and drought prone region of southeastern Australia. The basalt aquifer covers ~11,500 km2 in an agriculturally intensive region. A review of local hydrogeological processes allowed a series of surface and subsurface indicators of groundwater recharge and discharge areas to be established. Various remote sensing and GIS techniques were then used to map these surface indicators including: terrain analysis, monitoring of vegetation activity, and mapping of infiltration capacity. All regions where groundwater is not discharging to the surface were considered potential recharge areas. This approach, applied systematically across a catchment, provides a framework for mapping recharge and discharge areas. A key component in assigning surface and subsurface indicators is the relevance to the dominant recharge and discharge processes occurring and the use of appropriate remote sensing and GIS techniques with the capacity to identify these processes.

Relict rock glaciers in alpine catchments: A regional study in Central Austria

NASA Astrophysics Data System (ADS)

Kellerer-Pirklbauer, Andreas; Pauritsch, Marcus; Winkler, Gerfried

2013-04-01

Alpine catchments represent an important freshwater source in many regions. Catchments in the subalpine to nival altitudinal levels are generally characterised by higher precipitation, lower evapotranspiration and consequently higher discharge rates compared to lower elevated areas of the montane and foothill levels of the same region. Particularly in crystalline mountain regions in the mid- to high latitudes glacial and periglacial sediments cover larger areas and form important aquifers in alpine catchments. Typical periglacial landforms in mountain areas are rock glaciers. Relict rock glaciers consist of sediment accumulations without permafrost at present. This rock glacier type has a strong influence on water storage capacities and discharge behaviour of the catchments. The hydraulic properties of rock glaciers have a positive impact on flood-risk reduction and the riparian ecology below rock glacier springs during dry periods. Furthermore, the exceptional high discharge rates at springs at the front of relict rock glaciers compared to nearby non-rock glacier springs are also of economic interest. Knowledge about morphometric characteristics of rock glacier catchments helps to increase the understanding of the groundwater system and discharge dynamics of rock glaciers. In this context the main objectives of our study are (a) to assess and quantitatively describe rock glacier catchments at a regional scale by analysing different morphometric parameters of the catchments and (b) to combine the rock glacier catchment properties with water balance data. In doing so, at first an inventory of 295 rock glacier catchments was established for the 2440 km² large study area (Niedere Tauern Range, Styria) in Central Austria ranging from 590 to 2862 m a.s.l.. In a second step, the inventory data were combined with area-wide precipitation, discharge and evapotranspiration data. Results reveal that 108 km² or 4.4% of the entire study area belongs to rock glacier catchments

Identification of phosphorus emission hotspots in agricultural catchments

PubMed Central

Kovacs, Adam; Honti, Mark; Zessner, Matthias; Eder, Alexander; Clement, Adrienne; Blöschl, Günter

2012-01-01

An enhanced transport-based management approach is presented, which is able to support cost-effective water quality management with respect to diffuse phosphorus pollution. Suspended solids and particulate phosphorus emissions and their transport were modeled in two hilly agricultural watersheds (Wulka River in Austria and Zala River in Hungary) with an improved version of the catchment-scale PhosFate model. Source and transmission areas were ranked by an optimization method in order to provide a priority list of the areas of economically efficient (optimal) management alternatives. The model was calibrated and validated at different gauges and for various years. The spatial distribution of the emissions shows that approximately one third of the catchment area is responsible for the majority of the emissions. However, only a few percent of the source areas can transport fluxes to the catchment outlet. These effective source areas, together with the main transmission areas are potential candidates for improved management practices. In accordance with the critical area concept, it was shown that intervention with better management practices on a properly selected small proportion of the total area (1–3%) is sufficient to reach a remarkable improvement in water quality. If soil nutrient management is also considered in addition to water quality, intervention on 4–12% of the catchment areas can fulfill both aspects. PMID:22771465

Area characteristics and admission rates of people with schizophrenia and affective disorders in a German rural catchment area.

PubMed

Losert, C; Schmauß, M; Becker, T; Kilian, R

2012-12-01

Studies in urban areas identified environmental risk factors for mental illness, but little research on this topic has been performed in rural areas. Hospital admission rates were computed for 174 rural municipalities in the catchment area of the state psychiatric hospital in Günzburg in years 2006 to 2009 and combined with structural and socio-economic data. Relationships of overall and diagnosis-specific admission rates with municipality characteristics were analysed by means of negative binomial regression models. Admission rates of patients with a diagnosis of schizophrenia and affective disorder combined decrease with increasing population growth, population density, average income and green areas, while admission rates are positively correlated with commuter balance, income inequality, unemployment rates and traffic areas. Admission rates for schizophrenia are negatively related to population growth, average income and agricultural areas, but positively related to mobility index, income inequality and unemployment rate. Admission rates for affective disorders are negatively related to population growth, population density, average income and green areas, while higher admission rates are correlated with commuter balance, high income inequality, unemployment rate and traffic-related areas. Effects of wealth, economic inequality, population density and structural area characteristics influence psychiatric admission rates also in rural areas.

Effects of model structure and catchment discretization on discharge simulation in a small forest catchment

NASA Astrophysics Data System (ADS)

Spieler, Diana; Schwarze, Robert; Schütze, Niels

2017-04-01

In the past a variety of different modeling approaches has been developed in catchment hydrology. Even though there is no argument on the relevant processes taking place, there is no unified theory on how best to represent them computationally. Thus a vast number of models has been developed, varying from lumped models to physically based models. Most of them have a more or less fixed model structure and follow the "one fits all" paradigm. However, a more flexible approach could improve model realism by designing catchment specific model structures based on data availability. This study focuses on applying the flexible hydrological modelling framework RAVEN (Craig et al., 2013), to systematically test several conceptual model structures on the 19 km2 Große Ohe Catchment in the Bavarian Forest (Germany). By combining RAVEN with the DREAM algorithm (Vrugt et al., 2009), the relationship between catchment characteristics, model structure, parameter uncertainty and data availability are analyzed. The model structure is progressively developed based on the available data of the well observed forested catchment area. In a second step, the impact of the catchment discretization is analyzed by testing different spatial resolutions of topographic input data.

Spatially distributed rockfall activity inferred from talus deposits and corresponding rockwall areas in the Gradenbach catchment (Schober Mountains, Austria)

NASA Astrophysics Data System (ADS)

Götz, Joachim; Buckel, Johannes; Heckmann, Tobias

2013-04-01

The analysis of alpine sediment cascades requires the identification, differentiation and quantification of sediment sources, storages, and transport processes. This study deals with the origin of alpine sediment transfer and relates primary talus deposits to corresponding rockwall source areas within the Gradenbach catchment (Schober Mountains, Austrian Alps). Sediment storage landforms are based on a detailed geomorphological map of the catchment which was generated to analyse the sediment transfer system. Mapping was mainly performed in the field and supplemented by post-mapping analysis using LIDAR data and digital orthophotos. A fundamental part of the mapping procedure was to capture additional landform-based information with respect to morphometry, activity and connectivity. The applied procedure provides a detailed inventory of sediment storage landforms including additional information on surface characteristics, dominant and secondary erosion and deposition processes, process activity and sediment storage coupling. We develop the working hypothesis that the present-day surface area ratio between rockfall talus (area as a proxy for volume, backed by geophysical analysis of selected talus cones) and corresponding rockwall source area is a measure of rockfall activity since deglaciation; large talus cones derived from small rockwall catchments indicate high activity, while low activity can be inferred where rockfall from large rock faces has created only small deposits. The surface area ratio of talus and corresponding rockwalls is analysed using a landform-based and a process-based approach. For the landform-based approach, we designed a GIS procedure which derives the (hydrological) catchment area of the contact lines of talus and rockwall landforms in the geomorphological map. The process-based approach simulates rockfall trajectories from steep (>45°) portions of a DEM generated by a random-walk rockfall model. By back-tracing those trajectories that

Modelling metaldehyde in catchments: a River Thames case-study.

PubMed

Lu, Q; Whitehead, P G; Bussi, G; Futter, M N; Nizzetto, L

2017-04-19

The application of metaldehyde to agricultural catchment areas to control slugs and snails has caused severe problems for drinking water supply in recent years. In the River Thames catchment, metaldehyde has been detected at levels well above the EU and UK drinking water standards of 0.1 μg l -1 at many sites across the catchment between 2008 and 2015. Metaldehyde is applied in autumn and winter, leading to its increased concentrations in surface waters. It is shown that a process-based hydro-biogeochemical transport model (INCA-contaminants) can be used to simulate metaldehyde transport in catchments from areas of application to the aquatic environment. Simulations indicate that high concentrations in the river system are a direct consequence of excessive application rates. A simple application control strategy for metaldehyde in the Thames catchment based on model results is presented.

Comorbid mental disorders in substance users from a single catchment area - a clinical study

PubMed Central

2011-01-01

Background The optimal treatment of patients with substance use disorders (SUDs) requires an awareness of their comorbid mental disorders and vice versa. The prevalence of comorbidity in first-time-admitted SUD patients has been insufficiently studied. Diagnosing comorbidity in substance users is complicated by symptom overlap, symptom fluctuations, and the limitations of the assessment methods. The aim of this study was to diagnose all mental disorders in substance users living in a single catchment area, without any history of treatment for addiction or psychiatric disorders, admitted consecutively to the specialist health services. The prevalence of substance-induced versus substance-independent disorders according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), in SUD patients will be described. Methods First-time consecutively admitted patients from a single catchment area, aged 16 years or older, admitted to addiction clinics or departments of psychiatry as outpatients or inpatients will be screened for substance-related problems using the Alcohol Use Disorder Identification Test and the Drug Use Disorder Identification Test. All patients with scores above the cutoff value will be asked to participate in the study. The patients included will be diagnosed for SUD and other axis I disorders by a psychiatrist using the Psychiatric Research Interview for Substance and Mental Disorders. This interview was designed for the diagnosis of primary and substance-induced disorders in substance users. Personality disorders will be assessed according to the Structured Clinical Interview for DSM-IV axis II disorders. The Symptom Checklist-90-Revised, the Inventory of Depressive Symptoms, the Montgomery Asberg Depression Rating Scale, the Young Mania Rating Scale, and the Angst Hypomania Check List will be used for additional diagnostic assessments. The sociodemographic data will be recorded with the Stanley Foundation's Network Entry

Nine steps to risk-informed wellhead protection and management: Methods and application to the Burgberg Catchment

NASA Astrophysics Data System (ADS)

Nowak, W.; Enzenhoefer, R.; Bunk, T.

2013-12-01

Wellhead protection zones are commonly delineated via advective travel time analysis without considering any aspects of model uncertainty. In the past decade, research efforts produced quantifiable risk-based safety margins for protection zones. They are based on well vulnerability criteria (e.g., travel times, exposure times, peak concentrations) cast into a probabilistic setting, i.e., they consider model and parameter uncertainty. Practitioners still refrain from applying these new techniques for mainly three reasons. (1) They fear the possibly cost-intensive additional areal demand of probabilistic safety margins, (2) probabilistic approaches are allegedly complex, not readily available, and consume huge computing resources, and (3) uncertainty bounds are fuzzy, whereas final decisions are binary. The primary goal of this study is to show that these reservations are unjustified. We present a straightforward and computationally affordable framework based on a novel combination of well-known tools (e.g., MODFLOW, PEST, Monte Carlo). This framework provides risk-informed decision support for robust and transparent wellhead delineation under uncertainty. Thus, probabilistic risk-informed wellhead protection is possible with methods readily available for practitioners. As vivid proof of concept, we illustrate our key points on a pumped karstic well catchment, located in Germany. In the case study, we show that reliability levels can be increased by re-allocating the existing delineated area at no increase in delineated area. This is achieved by simply swapping delineated low-risk areas against previously non-delineated high-risk areas. Also, we show that further improvements may often be available at only low additional delineation area. Depending on the context, increases or reductions of delineated area directly translate to costs and benefits, if the land is priced, or if land owners need to be compensated for land use restrictions.

Modeling pluvial flooding damage in urban environments: spatial relationships between citizens' complaints and overland catchment areas

NASA Astrophysics Data System (ADS)

Gaitan, Santiago; ten Veldhuis, Marie-Claire; van de Giesen, Nick

2013-04-01

Extreme weather events such as floods and storms are expected to cause severe economic losses in The Netherlands. Cumulative damage due to pluvial flooding can be considerable, especially in lowland areas where this type of floods occurs relatively frequently. Currently, in The Netherlands, water-related damages to property and contents are covered through private insurance. As pluvial flooding is becoming heavier and more likely to occur, sound modelling of damages is required to ensure that insurance systems are able to stand as an adaptation measure. Current damage models based on rainfall intensity, registries of insurance claims, and classifications of building types are unable to fully explain damage variability. Further developments assessing additional explanatory factors and reducing uncertainties, are required in order to significantly explain damage. In this study, urban topography is used as an explanatory factor for modelling of urban pluvial flooding. Flood damage is evaluated based on complaints data, a valuable resource for assessing vulnerability to urban pluvial flooding. Though previous research has shown coincidences between the localization of high complaint counts and large size catchments areas in Rotterdam, additional research is needed to establish the precise spatial relationship of those two variables. This additional task is the focus of the presented work. To that end a data base of complaints, that was made available by the Municipality Administration of the City, will be analysed. It comprises close to 36800 complaints from 2004 to 2011. The geographical position of the registries is aggregated into 4 to 6-digit Postal Code zones, which represents entire streets or relative positions along a street, respectively. The Municipality also provided the DEM, characterized by a spatial resolution of 0.5 m × 0.5 m, a vertical precision of 5 cm, and an accuracy better than two standard deviations of 15 cm. First the localization of complaints

Karstic water storage response to the recent droughts in Southwest China estimated from satellite gravimetry

NASA Astrophysics Data System (ADS)

Yao, Chaolong; Luo, Zhicai

2015-12-01

The water resources crisis is intensifying in Southwest China (SWC), which includes the world's largest continuous coverage of karst landforms, due to recent severe drought events. However, because of the special properties of karstic water system, such as strong heterogeneity, monitoring the variation of karstic water resources at large scales remains still difficult. Satellite gravimetry has emerged as an effective tool for investigating the global and regional water cycles. In this study, we used GRACE (Gravity Recovery and Climate Experiment) data from January 2003 to January 2013 to investigate karstic water storage variability over the karst region of SWC. We assessed the impacts of the recent severe droughts on karst water resources, including two heavy droughts in September 2010 to May 2010 and August 2011 to January 2012. Results show a slightly water increase tend during the studied period, but these two severe droughts have resulted in significant water depletion in the studied karst region. The latter drought during 2011 and 2012 caused more water deficits than that of the drought in 2010. Strong correlation between the variations of GRACE-based total water storage and precipitation suggests that climate change is the main driving force for the significant water absent over the studied karst region. As the world's largest continuous coverage karst aquifer, the karst region of SWC offers an example of GRACE applications to a karst system incisively and will benefit for water management from a long-term perspective in karst systems throughout the world.

Airport Catchment Area- Example Warsaw Modlin Airport

NASA Astrophysics Data System (ADS)

Błachut, Jakub

2017-10-01

The form and functions of airports change over time, just like the form and function of cities. Historically, airports are understood as places of aircraft landing, control towers operation and location of other facilities used for communication and transport. This traditional model is giving way to the concept of so-called Airport Cities, based on the assumption that, in addition to its infrastructure and air services, also non-air services are performed, constituting a source of income. At the same time, their reach and impact on the economy of the areas around the airport are expanding. Idea City Airport appeared in the United States in the late twentieth century. The author is J. D. Kasarda, he believes that it is around these big air ports that airport cities develop. In the world, there are currently 45 areas which can be classified in this category, out of which 12 are located in Europe. Main air traffic hubs in Europe are not only the most important passenger traffic junctions, but also largest centres dispatching goods (cargo). It can be said that, among the 30 largest airports, 24 are the largest in terms of both passenger and freight traffic. These airports cover up to 89.9% of the total freight transport of all European airports. At the same time, they serve 56.9% of all passengers in Europe. Based on the concept of Airport City was developed document THE INTEGRATED REGIONAL POLYCENTRIC DEVELOPMENT PLANS FOR THE WARSAW MODLIN AIRPORT CATCHMENT AREA. The plan developed takes into account the findings of the Mazovian voivodeship spatial development plan, specifying the details of its provisions where possible. The development is the first step for the implementation of the concept of the Modlin Airport City. The accomplishment of this ambitious vision will only be possible with hard work of a number of entities, as well as taking into account the former Modlin Fortress, currently under revitalisation, in concepts and plans.

Application of the Soil and Water Assessment Tool (SWAT) to predict the impact of best management practices in Jatigede Catchment Area

NASA Astrophysics Data System (ADS)

Ridwansyah, Iwan; Fakhrudin, M.; Wibowo, Hendro; Yulianti, Meti

2018-02-01

Cimanuk watershed is one of the national priority watersheds for rehabilitation considering its critical condition. In this area, Jatigede Reservoir operates, which is the second largest reservoir in Indonesia, after Jatiluhur Reservoir. The reservoir performs several functions, including flood control, irrigation for 90.000 ha of rice fields, water supply of 3.500 litres per second, and power generation of 110 MW. In 2004 the Jatigede Reservoir catchment area had a critical land area of 40.875 ha (28% of the catchment area). The sedimentation rate in Cimanuk River at Eretan station shows a high rate (5.32 mm/year), which potentially decreases the function of Jatigede Reservoir. Therefore, a strategy of Best Management Practice’s (BMP’s) is required to mitigate the problem by using SWAT hydrology modelling. The aim of this study is to examine the impact of BMP’s on surface runoff and sediment yield in Jatigede Reservoir Catchment Area. Simulations were conducted using land use in 2011. The results of this study suggest that SWAT model is considered as a reasonable modelling of BMP’s simulation concerning Nash-Sutcliffe Coefficients (0.71). The simulation is using terraces, silt pit, and dam trenches as BMP’s techniques. The BMP’s application can reduce surface runoff from 99.7 mm to 75.8 mm, and decrease sediment yield from 61.9 ton/ha/year to 40.8 ton/ha/year.

Catchment land use predicts benthic vegetation in small estuaries

PubMed Central

Warry, Fiona Y.; Reich, Paul; Mac Nally, Ralph; Woodland, Ryan J.

2018-01-01

Many estuaries are becoming increasingly eutrophic from human activities within their catchments. Nutrient loads often are used to assess risk of eutrophication to estuaries, but such data are expensive and time consuming to obtain. We compared the percent of fertilized land within a catchment, dissolved inorganic nitrogen loads, catchment to estuary area ratio and flushing time as predictors of the proportion of macroalgae to total vegetation within 14 estuaries in south-eastern Australia. The percent of fertilized land within the catchment was the best predictor of the proportion of macroalgae within the estuaries studied. There was a transition to a dominance of macroalgae once the proportion of fertilized land in the catchment exceeded 24%, highlighting the sensitivity of estuaries to catchment land use. PMID:29473004

Geological modeling and infiltration pattern of a karstic system based upon crossed geophysical methods and image-guided inversion

NASA Astrophysics Data System (ADS)

Duran, Lea; Jardani, Abderrahim; Fournier, Matthieu; Massei, Nicolas

2015-04-01

Karstic aquifers represent an important part of the water resources worldwide. Though they have been widely studied on many aspects, their geological and hydrogeological modeling is still complex. Geophysical methods can provide useful subsurface information for the characterization and mapping of karstic systems, especially when not accessible by speleology. The site investigated in this study is a sinkhole-spring system, with small diameter conduits that run within a chalk aquifer (Norville, in Upper Normandy, France). This site was investigated using several geophysical methods: electrical tomography, self-potential, mise-à-la-masse methods, and electromagnetic method (EM34). Coupling those results with boreholes data, a 3D geological model of the hydrogeological basin was established, including tectonic features as well as infiltration structures (sinkhole, covered dolines). The direction of the karstic conduits near the main sinkhole could be established, and the major fault was shown to be a hydraulic barrier. Also the average concentration of dolines on the basin could be estimated, as well as their depth. At last, several hypotheses could be made concerning the location of the main conduit network between the sinkhole and the spring, using previous hydrodynamic study of the site along with geophysical data. In order to validate the 3D geological model, an image-guided inversion of the apparent resistivity data was used. With this approach it is possible to use geological cross sections to constrain the inversion of apparent resistivity data, preserving both discontinuities and coherences in the inversion of the resistivity data. This method was used on the major fault, enabling to choose one geological interpretation over another (fault block structure near the fault, rather than important folding). The constrained inversion was also applied on covered dolines, to validate the interpretation of their shape and depth. Key words: Magnetic and electrical

A simple distributed sediment delivery approach for rural catchments

NASA Astrophysics Data System (ADS)

Reid, Lucas; Scherer, Ulrike

2014-05-01

The transfer of sediments from source areas to surface waters is a complex process. In process based erosion models sediment input is thus quantified by representing all relevant sub processes such as detachment, transport and deposition of sediment particles along the flow path to the river. A successful application of these models requires, however, a large amount of spatially highly resolved data on physical catchment characteristics, which is only available for a few, well examined small catchments. For the lack of appropriate models, the empirical Universal Soil Loss Equation (USLE) is widely applied to quantify the sediment production in meso to large scale basins. As the USLE provides long-term mean soil loss rates, it is often combined with spatially lumped models to estimate the sediment delivery ratio (SDR). In these models, the SDR is related to data on morphological characteristics of the catchment such as average local relief, drainage density, proportion of depressions or soil texture. Some approaches include the relative distance between sediment source areas and the river channels. However, several studies showed that spatially lumped parameters describing the morphological characteristics are only of limited value to represent the factors of influence on sediment transport at the catchment scale. Sediment delivery is controlled by the location of the sediment source areas in the catchment and the morphology along the flow path to the surface water bodies. This complex interaction of spatially varied physiographic characteristics cannot be adequately represented by lumped morphological parameters. The objective of this study is to develop a simple but spatially distributed approach to quantify the sediment delivery ratio by considering the characteristics of the flow paths in a catchment. We selected a small catchment located in in an intensively cultivated loess region in Southwest Germany as study area for the development of the SDR approach. The

Measuring Spatial Accessibility of Health Care Providers – Introduction of a Variable Distance Decay Function within the Floating Catchment Area (FCA) Method

PubMed Central

Groneberg, David A.

2016-01-01

We integrated recent improvements within the floating catchment area (FCA) method family into an integrated ‘iFCA`method. Within this method we focused on the distance decay function and its parameter. So far only distance decay functions with constant parameters have been applied. Therefore, we developed a variable distance decay function to be used within the FCA method. We were able to replace the impedance coefficient β by readily available distribution parameter (i.e. median and standard deviation (SD)) within a logistic based distance decay function. Hence, the function is shaped individually for every single population location by the median and SD of all population-to-provider distances within a global catchment size. Theoretical application of the variable distance decay function showed conceptually sound results. Furthermore, the existence of effective variable catchment sizes defined by the asymptotic approach to zero of the distance decay function was revealed, satisfying the need for variable catchment sizes. The application of the iFCA method within an urban case study in Berlin (Germany) confirmed the theoretical fit of the suggested method. In summary, we introduced for the first time, a variable distance decay function within an integrated FCA method. This function accounts for individual travel behaviors determined by the distribution of providers. Additionally, the function inherits effective variable catchment sizes and therefore obviates the need for determining variable catchment sizes separately. PMID:27391649

Catchment scale multi-objective flood management

NASA Astrophysics Data System (ADS)

Rose, Steve; Worrall, Peter; Rosolova, Zdenka; Hammond, Gene

2010-05-01

techniques will include: controlling headwater drainage, increasing evapotranspiration and interception by creating new woodlands in the upper catchment areas, enabling coarse woody debris dams to slow down water flows through steep valleys, improving soil water storage potential by appropriate soil and crop management, retaining water on lowland flood meadows and wet woodland creation within the floodplain. The project, due to run from 2009 until 2013, incorporates hydrometric and water quality monitoring, together with hydrologic and hydraulic modelling in order to attempt to demonstrate the effect of land management changes on flood dynamics and flood risk management. To date, the project team have undertaken the fundamental catchment characterisation work to understand its physical setting and the interaction of the physical processes that influence the hydrological response of the catchment to incident precipitation. The results of this initial work has led to the identification of a suitably robust hydrometric monitoring network within the catchments to meet the needs of providing both quantitative evidence of the impacts of land management change on flood risk, together with generating good quality datasets for the validation and testing of the new hydrologic models. As the project aims to demonstrate ‘best practice' in all areas, the opportunity has been taken to install a network of automatic hydrometric monitoring equipment, together with an associated telemetry system, in order to maximise data coverage, accuracy and reliability. Good quality datasets are a critical requirement for reliable modelling. The modelling will also be expanded to incorporate climate change scenarios. This paper will describe the catchment characterisation work undertaken to date, the proposed land management changes in relation to flood risk management, the initial catchment hydraulic modelling work and the implementation of the new hydrometric monitoring network within the study area.

Future Availability of Water Supply from Karstic Springs under Probable Climate Change. The case of Aravissos, Central Macedonia, Greece.

NASA Astrophysics Data System (ADS)

Vafeiadis, M.; Spachos, Th.; Zampetoglou, K.; Soupilas, Th.

2012-04-01

The test site of Aravissos is located at 70 Km to the West (W-NW) of Thessaloniki at the south banks of mount Païko, in the north part of Central Macedonia The karstic Aravissos springs supply 40% of total volume needed for the water supply of Thessaloniki, Greece. As the water is of excellent quality, it is feed directly in the distribution network without any previous treatment. The availability of this source is therefore of high importance for the sustainable water supply of this area with almost 1000000 inhabitants. The water system of Aravissos is developed in a karstic limestone with an age of about Late Cretaceous that covers almost the entire western part of the big-anticline of Païko Mountain. The climate in this area and the water consumption area, Thessaloniki, is a typical Mediterranean climate with mild and humid winters and hot and dry summers. The total annual number of rainy days is around 110. The production of the Aravissos springs depends mostly from the annual precipitations. As the feeding catchement and the karst aquifer are not well defined, a practical empirical balance model, that contains only well known relevant terms, is applied for the simulation of the operation of the springs under normal water extraction for water supply in present time. The estimation of future weather conditions are based on GCM and RCM simulation data and the extension of trend lines of the actual data. The future evolution of the availability of adequate water quantities from the springs is finally estimated from the balance model and the simulated future climatic data. This study has been realised within the project CC-WaterS, funded by the SEE program of the European Regional Development Fund (http://www.ccwaters.eu/).

Variability of atmospheric greenhouse gases as a biogeochemical processing signal at regional scale in a karstic ecosystem

NASA Astrophysics Data System (ADS)

Borràs, Sílvia; Vazquez, Eusebi; Morguí, Josep-Anton; Àgueda, Alba; Batet, Oscar; Cañas, Lídia; Curcoll, Roger; Grossi, Claudia; Nofuentes, Manel; Occhipinti, Paola; Rodó, Xavier

2015-04-01

The South-eastern area of the Iberian Peninsula is an area where climatic conditions reach extreme climatic conditions during the year, and is also heavily affected by the ENSO and NAO. The Natural Park of Cazorla, Segura de la Sierra and Las Villas is located in this region, and it is the largest protected natural area in Spain (209920 Ha). This area is characterized by important climatic and hydrologic contrasts: although the mean annual precipitation is 770 nm, the karstic soils are the main cause for water scarcity during the summer months, while on the other hand it is in this area where the two main rivers of Southern Spain, the Segura and the Guadalquivir, are born. The protected area comprises many forested landscapes, karstic areas and reservoirs like Tranco de Beas. The temperatures during summer are high, with over 40°C heatwaves occurring each year. But during the winter months, the land surface can be covered by snow for periods of time up until 30 days. The ENSO and NAO influences cause also an important inter annual climatic variability in this area. Under the ENSO, autumnal periods are more humid while the following spring is drier. In this area vegetal Mediterranean communities are dominant. But there are also a high number of endemic species and derelict species typical of temperate climate. Therefore it is a protected area with high specific diversity. Additionally, there is an important agricultural activity in the fringe areas of the Natural Park, mainly for olive production, while inside the Park this activity is focused on mountain wheat production. Therefore the diverse vegetal communities and landscapes can easily be under extreme climatic pressures, affecting in turn the biogeochemical processes at the regional scale. The constant, high-frequency monitoring of greenhouse gases (GHG) (CO2 and CH4) integrates the biogeochemical signal of changes in this area related to the carbon cycle at the regional scale, capturing the high diversity of

Towards a catchment-scale macro-ecological model to support integrated catchment management in Europe

NASA Astrophysics Data System (ADS)

Lerner, R. N.; Lerner, D. N.; Surridge, B.; Paetzold, A.; Harris, B.; Anderson, C. W.

2005-12-01

In Europe, the Water Framework Directive (WFD) is providing a powerful regulatory driver to adopt integrated catchment management, and so pressurizing researchers to build suitable supporting tools. The WFD requires agencies to drive towards `good ecological quality' by 2015. After the initial step of characterising water bodies and the pressures on them, the next substantive step is the preparation of river basin management plans and proposed programmes of measures by 2009. Ecological quality is a complex concept and poorly defined, unless it is taken as a simple measure such as the abundance of a particular species of organism. There is clearly substantial work to do to build a practical but sound definition of ecological quality; practical in the sense of being easy to measure and explain to stakeholders, and sound in the sense that it reflects ecological complexity within catchments, the variability between catchments, and the conflicts demands for goods and services that human society places upon the ecological system. However ecological quality is defined, it will be driven by four interacting groups of factors. These represent the physical, chemical, ecological and socio-economic environments within and encompassing the catchment. Some of these groupings are better understood than others, for example hydrological processes and the transport of solutes are reasonably understood, even though they remain research areas in their own right. There are much larger gaps in our understanding at the interfaces, i.e. predicting how, for example, hydrological processes such as flow and river morphology influence ecological quality. Overall, it is clear we are not yet in a position to build deterministic models of the overall ecological behaviour of catchment. But we need predictive tools to support catchment management agencies in preparing robust plans. This poster describes our current exploration of soft modelling options to build a comprehensive macro

Two dimensions of nitrate pollution management in an agricultural catchment

NASA Astrophysics Data System (ADS)

Wachniew, Przemysław; Martinez, Grit; Bar-Michalczyk, Dominika; Kania, Jarosław; Malina, Grzegorz; Michalczyk, Tomasz; Różański, Kazimierz; Witczak, Stanisław; Zięba, Damian; Żurek, Anna J.; Berrini, Anne

2017-04-01

The Kocinka River catchment underlain by the karstic-fissured upper Jurrasic Częstochowa aquifer in Southern Poland is the site of an interdisciplinary research aimed at finding solutions to pollution of water resources with nutrients. These efforts are conducted in the framework of the BONUS Soils2Sea project that deals with the development of differentiated environmental management measures based on utilization of the natural ability of soils, groundwater and surface water to remove surplus nutrients. Implementation of these or any other measures for the improvement of water quality depends primarily on the perceptions and attitudes of the major actors, which in turn are a product of the socio-economic, cultural-historical and political development spanning many generations. The problem of the deteriorating water quality is therefore twofold. Understanding the complex natural system consisting of the coupled groundwater and surface water component with a wide spectrum of time lags of pollution transport is only the beginning of the solution. The mitigation policies and measures based on this scientific knowledge have to recognize the equally complex nature of social factors and interactions. Implementation of the European and national policies and legislations has to take into account the regional perspective. Identification of the key stakeholders is in this regard a first step followed by an inquiry into their values, perceptions and motivations through interviews, workshops, etc. Understanding of the socio-cultural, historical, economic and political factors that shape stakeholder actions is a prerequisite for the development of the successful management and mitigation schemes. The process of gaining insights into the environmental and social aspects of nutrient pollution in the Kocinka catchment is partly presented by the documentary film "Soils2Sea: Reducing nutrient loadings into the Baltic Sea" (https://www.youtube.com/watch?v=LUouES4SeJk).

Modeling relationships between catchment attributes and river water quality in southern catchments of the Caspian Sea.

PubMed

Hasani Sangani, Mohammad; Jabbarian Amiri, Bahman; Alizadeh Shabani, Afshin; Sakieh, Yousef; Ashrafi, Sohrab

2015-04-01

Increasing land utilization through diverse forms of human activities, such as agriculture, forestry, urban growth, and industrial development, has led to negative impacts on the water quality of rivers. To find out how catchment attributes, such as land use, hydrologic soil groups, and lithology, can affect water quality variables (Ca(2+), Mg(2+), Na(+), Cl(-), HCO 3 (-) , pH, TDS, EC, SAR), a spatio-statistical approach was applied to 23 catchments in southern basins of the Caspian Sea. All input data layers (digital maps of land use, soil, and lithology) were prepared using geographic information system (GIS) and spatial analysis. Relationships between water quality variables and catchment attributes were then examined by Spearman rank correlation tests and multiple linear regression. Stepwise approach-based multiple linear regressions were developed to examine the relationship between catchment attributes and water quality variables. The areas (%) of marl, tuff, or diorite, as well as those of good-quality rangeland and bare land had negative effects on all water quality variables, while those of basalt, forest land cover were found to contribute to improved river water quality. Moreover, lithological variables showed the greatest most potential for predicting the mean concentration values of water quality variables, and noting that measure of EC and TDS have inversely associated with area (%) of urban land use.

Analysing Submarine Groundwater Discharge (SGD)-borne Dissolved Organic Matter (DOM) in a karstic aquifer, Co. Galway, Ireland.

NASA Astrophysics Data System (ADS)

Kelly, Tara; Rocha, Carlos

2014-05-01

Submarine Groundwater Discharge (SGD) constitutes an "invisible" link between land and sea, transporting allochthonous and autochthonous dissolved organic matter (DOM), nutrients and metals to the ocean via the subterranean estuary. The latter acts as a powerful bioreactor where groundwater, in transit from land to sea, mixes with seawater leading to active modulation of both DOM content and chemical makeup of SGD. DOM in freshwater systems is a key component of the global carbon cycle. Climate change may hence increase the concentration of allochthonous carbon entering the oceans as terrestrial DOC is released from soils at higher temperatures, and transported via SGD. Presently, little is known about the effects of SGD-borne DOM on coastal carbon cycling. SGD therefore represents a dynamic reservoir and analysis is critical to forecast future environmental management programmes, both on a local and global scale. Labile DOM plays a crucial role in microbial remineralisation processes, and as it breaks down it contributes to the groundwater nutrient pool. Locally, this could add to eutrophication. However, if refractory carbon is present, it will be recalcitrant to mineralisation in transit and at the subterranean estuary. This putative additional input will thus imply the contribution of SGD to oceanic carbon storage. This study is focused on Kinvara Bay (Galway, western Ireland), the focal point for waters discharging from the Gort-Kinvara karstic aquifer. This aquifer represents the ideal study location for evaluation of SGD contribution to the coastal DOM pool, as SGD is focused in the bay, surface drainage is very limited, and groundwater travels across a large catchment area with a short residence time, minimising DOM modification in transit. DOM samples collected in the field have been analysed using Three-Dimensional Excitation Emission Matrix Fluorescence (3D-EEMF) and High Temperature Catalytic Oxidation. PARAFAC is subsequently used as a tool to

Development of catchment research, with particular attention to Plynlimon and its forerunner, the East African catchments

NASA Astrophysics Data System (ADS)

Blackie, J. R.; Robinson, M.

2007-01-01

Dr J.S.G. McCulloch was deeply involved in the establishment of research catchments in East Africa and subsequently in the UK to investigate the hydrological consequences of changes in land use. Comparison of these studies provides an insight into how influential his inputs and direction have been in the progressive development of the philosophy, the instrumentation and the analytical techniques now employed in catchment research. There were great contrasts in the environments: tropical highland (high radiation, intense rainfall) vs. temperate maritime (low radiation and frontal storms), contrasting soils and vegetation types, as well as the differing social and economic pressures in developing and developed nations. Nevertheless, the underlying scientific philosophy was common to both, although techniques had to be modified according to local conditions. As specialised instrumentation and analytical techniques were developed for the UK catchments many were also integrated into the East African studies. Many lessons were learned in the course of these studies and from the experiences of other studies around the world. Overall, a rigorous scientific approach was developed with widespread applicability. Beyond the basics of catchment selection and the quantification of the main components of the catchment water balance, this involved initiating parallel process studies to provide information on specific aspects of catchment behaviour. This information could then form the basis for models capable of extrapolation from the observed time series to other periods/hydrological events and, ultimately, the capability of predicting the consequences of changes in catchment land management to other areas in a range of climates.

Hydrological Dynamics In High Mountain Catchment Areas of Central Norway

NASA Astrophysics Data System (ADS)

Löffler, Jörg; Rößler, Ole

Large-scaled landscape structure is regarded as a mosaic of ecotopes where process dynamics of water and energy fluxes are analysed due to its effects on ecosystem functioning. The investigations have been carried out in the continental most Vågå/Oppland high mountains in central Norway since 1994 (LÖFFLER &WUNDRAM 1999, 2000, 2001). Additionally, comparable investigations started in 2000 dealing with the oceanic high mountain landscapes on same latitudes (LÖFFLER et al. 2001). The theoretical and methodological framework of the project is given by the Landscape-Ecological Complex Analysis (MOSIMANN 1984, 1985) and its variations due to technical and principle methodical challenges in this high mountain landscape (KÖHLER et al. 1994, LÖFFLER 1998). The aim of the project is to characterize high mountain ecosystem structure, functioning and dynamics within small catchment areas, that are chosen in two different altitudinal belts each in the eastern continental and the western oceanic region of central Norway. In the frame of this research project hydrological and meteorological measurements on ground water, percolation and soil moisture dynamics as well as on evaporation, air humidity and air-, surface- and soil-temperatures have been conducted. On the basis of large-scaled landscape-ecological mappings (LÖFFLER 1997) one basic meteorological station and several major data logger run stations have been installed in representative sites of each two catchment areas in the low and mid alpine belts of the investigation regions ( JUNGet al. 1997, LÖFFLER &WUNDRAM 1997). Moreover, spatial differentiations of groundwater level, soil moisture and temperature profiles have been investigated by means of hand held measurements at different times of the day, during different climatic situations and different seasons. Daily and annual air-, surface- and soil-temperature dynamics are demonstrated by means of thermoisopleth-diagrams for different types of ecotopes of the

Customization of a hydrological model for the estimation of water resources in an alpine karstified catchment with sparse data

NASA Astrophysics Data System (ADS)

Kauzlaric, Martina; Schädler, Bruno; Weingartner, Rolf

2014-05-01

The main objective of the MontanAqua transdisciplinary project is to develop strategies moving towards a more sustainable water resources management in the Crans-Montana-Sierre region (Valais, Switzerland) in view of global change. Therefore, a detailed assessment of the available water resources in the study area today and in the future is needed. The study region is situated in the inner alpine zone, with strong altitudinal precipitation gradients: from the precipitation rich alpine ridge down to the dry Rhône plain. A typical plateau glacier on top of the ridge is partly drained through the karstic underground formations and linked to various springs to either side of the water divide. The main anthropogenic influences on the system are reservoirs and diversions to the irrigation channels. Thus, the study area does not cover a classical hydrological basin as the water flows frequently across natural hydrographic boundaries. This is a big challenge from a hydrological point of view, as we cannot easily achieve a closed, measured water balance. Over and above, a lack of comprehensive historical data in the catchment reduces the degree of process conceptualization possible, as well as prohibits usual parameter estimation procedures. The Penn State Integrated Hydrologic Model (PIHM) (Kumar, 2009) has been selected to estimate the available natural water resource for the whole study area. It is a semi-discrete, physically-based model which includes: channel routing, overland flow, subsurface saturated and unsaturated flow, rainfall interception, snow melting and evapotranspiration. Its unstructured mesh decomposition offers a flexible domain decomposition strategy for efficient and accurate integration of the physiographic, climatic and hydrographic watershed. The model was modified in order to be more suitable for a karstified mountainous catchment: it now includes the possibility to punctually add external sources, and the temperature-index approach for estimating

Understanding catchment scale sediment sources using geochemical tracers

NASA Astrophysics Data System (ADS)

Ferreira, Carla S. S.; Walsh, Rory P. D.; Shakesby, Richard A.; Steenhuis, Tammo S.; Ferreira, António J. D.; Coelho, Celeste O. A.

2013-04-01

It is well-established that urbanization leads to increased erosion (at least locally) as well as enhanced overland flow and streamflow peaks. Less is known about how the spatial distribution of erosion sources and scale of increases in erosion vary with the nature of urbanization in different climatic and socio-economic settings. This is important in order to prevent or reduce adverse impacts of erosion on downstream sedimentation, channel siltation and shifting, and river pollution. This paper adopts a sediment fingerprinting approach to assess the impact of partial urbanization and associated land-use change on sediment sources within a peri-urban catchment (6 km2), Ribeira dos Covões on the outskirts of the city of Coimbra in central Portugal. Urban land-use has increased from just 6% in 1958 to 30% in 2009. The urban pattern includes some well-defined urban residential centres, but also areas of discontinuous urban sprawl, including educational, health and small industrial facilities, numerous new roads and an enterprise park is under construction on the upper part of the catchment. The catchment has a wet Mediterranean climate and the lithology comprises sandstone in the west and limestone in the east. Soil depth is generally >40cm. The average slope angle is 8° (maximum 47°). Altitude ranges from 30m to 205m. A sediment fingerprinting approach was adopted to help establish the relative importance of sediment inputs from different urban areas. During September 2012 current bed-sediment samples (0-3 cm depth) were collected from 11 channel sites along the main stream and in different tributaries. At sites where bed-sediment was deeper, additional samples were taken at 3cm intervals to a maximum depth of around 42cm. In addition, overbank sediment samples (0-3cm depth) were collected at 11 locations around the catchment. All samples were oven-dried (at 38°C) and different particle size fractions (0.125-2mm, 0.063-0.125mm and <0.063mm) obtained, where the <0

Influence of catchment-scale military land use on stream physical and organic matter variables in small Southeaster Plains Catchments (USA)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maloney, Kelly

2005-01-01

We conducted a 3-year study designed to examine the relationship between disturbance from military land use and stream physical and organic matter variables within 12 small (<5.5 km2) Southeastern Plains catchments at the Fort Benning Military Installation, Georgia, USA. Primary land-use categories were based on percentages of bare ground and road cover and nonforested land (grasslands, sparse vegetation, shrublands, fields) in catchments and natural catchments features, including soils (% sandy soils) and catchment size (area). We quantified stream flashiness (determined by slope of recession limbs of storm hydrographs), streambed instability (measured by relative changes in bed height over time), organicmore » matter storage [coarse wood debris (CWD) relative abundance, benthic particulate organic matter (BPOM)] and stream-water dissolved organic carbon concentration (DOC). Stream flashiness was positively correlated with average storm magnitude and percent of the catchment with sandy soil, whereas streambed instability was related to percent of the catchment containing nonforested (disturbed) land. The proportions of in-stream CWD and sediment BPOM, and stream-water DOC were negatively related to the percent of bare ground and road cover in catchments. Collectively, our results suggest that the amount of catchment disturbance causing denuded vegetation and exposed, mobile soil is (1) a key terrestrial influence on stream geomorphology and hydrology and (2) a greater determinant of in-stream organic matter conditions than is natural geomorphic or topographic variation (catchment size, soil type) in these systems.« less

Catchments of general practice in different countries– a literature review

PubMed Central

2014-01-01

The purpose of this paper is to review the current research on catchment areas of private general practices in different developed countries because healthcare reform, including primary health care, has featured prominently as an important political issue in a number of developed countries. The debates around health reform have had a significant health geographic focus. Conceptually, GP catchments describe the distribution, composition and profile of patients who access a general practitioner or a general practice (i.e. a site or facility comprising one or more general practitioners). Therefore, GP catchments provide important information into the geographic variation of access rates, utilisation of services and health outcomes by all of the population or different population groups in a defined area or aggregated area. This review highlights a wide range of diversity in the literature as to how GP catchments can be described, the indicators and measures used to frame the scale of catchments. Patient access to general practice health care services should be considered from a range of locational concepts, and not necessarily constrained by their place of residence. An analysis of catchment patterns of general practitioners should be considered as dynamic and multi-perspective. Geographic information systems provide opportunities to contribute valuable methodologies to study these relationships. However, researchers acknowledge that a conceptual framework for the analysis of GP catchments requires access to real world data. Recent studies have shown promising developments in the use of real world data, especially from studies in the UK. Understanding the catchment profiles of individual GP surgeries is important if governments are serious about patient choice being a key part of proposed primary health reforms. Future health planning should incorporate models of GP catchments as planning tools, at the micro level as well as the macro level, to assist policies on the

The catchment based approach using catchment system engineering

NASA Astrophysics Data System (ADS)

Jonczyk, Jennine; Quinn, Paul; Barber, Nicholas; Wilkinson, Mark

2015-04-01

The catchment based approach (CaBa) has been championed as a potential mechanism for delivery of environmental directives such as the Water Framework Directive in the UK. However, since its launch in 2013, there has been only limited progress towards achieving sustainable, holistic management, with only a few of examples of good practice ( e.g. from the Tyne Rivers trust). Common issues with developing catchment plans over a national scale include limited data and resources to identify issues and source of those issues, how to systematically identify suitable locations for measures or suites of measures that will have the biggest downstream impact and how to overcome barriers for implementing solutions. Catchment System Engineering (CSE) is an interventionist approach to altering the catchment scale runoff regime through the manipulation of hydrological flow pathways throughout the catchment. A significant component of the runoff generation can be managed by targeting hydrological flow pathways at source, such as overland flow, field drain and ditch function, greatly reducing erosive soil losses. Coupled with management of farm nutrients at source, many runoff attenuation features or measures can be co-located to achieve benefits for water quality and biodiversity. A catchment, community-led mitigation measures plan using the CSE approach will be presented from a catchment in Northumberland, Northern England that demonstrate a generic framework for identification of multi-purpose features that slow, store and filter runoff at strategic locations in the landscape. Measures include within-field barriers, edge of field traps and within-ditch measures. Progress on the implementation of measures will be reported alongside potential impacts on the runoff regime at both local and catchment scale and costs.

Coupling of Markov chains and cellular automata spatial models to predict land cover changes (case study: upper Ci Leungsi catchment area)

NASA Astrophysics Data System (ADS)

Marko, K.; Zulkarnain, F.; Kusratmoko, E.

2016-11-01

Land cover changes particular in urban catchment area has been rapidly occur. Land cover changes occur as a result of increasing demand for built-up area. Various kinds of environmental and hydrological problems e.g. floods and urban heat island can happen if the changes are uncontrolled. This study aims to predict land cover changes using coupling of Markov chains and cellular automata. One of the most rapid land cover changes is occurs at upper Ci Leungsi catchment area that located near Bekasi City and Jakarta Metropolitan Area. Markov chains has a good ability to predict the probability of change statistically while cellular automata believed as a powerful method in reading the spatial patterns of change. Temporal land cover data was obtained by remote sensing satellite imageries. In addition, this study also used multi-criteria analysis to determine which driving factor that could stimulate the changes such as proximity, elevation, and slope. Coupling of these two methods could give better prediction model rather than just using it separately. The prediction model was validated using existing 2015 land cover data and shown a satisfactory kappa coefficient. The most significant increasing land cover is built-up area from 24% to 53%.

Representing macropore flow at the catchment scale: a comparative modeling study

NASA Astrophysics Data System (ADS)

Liu, D.; Li, H. Y.; Tian, F.; Leung, L. R.

2017-12-01

Macropore flow is an important hydrological process that generally enhances the soil infiltration capacity and velocity of subsurface water. Up till now, macropore flow is mostly simulated with high-resolution models. One possible drawback of this modeling approach is the difficulty to effectively represent the overall typology and connectivity of the macropore networks. We hypothesize that modeling macropore flow directly at the catchment scale may be complementary to the existing modeling strategy and offer some new insights. Tsinghua Representative Elementary Watershed model (THREW model) is a semi-distributed hydrology model, where the fundamental building blocks are representative elementary watersheds (REW) linked by the river channel network. In THREW, all the hydrological processes are described with constitutive relationships established directly at the REW level, i.e., catchment scale. In this study, the constitutive relationship of macropore flow drainage is established as part of THREW. The enhanced THREW model is then applied at two catchments with deep soils but distinct climates, the humid Asu catchment in the Amazon River basin, and the arid Wei catchment in the Yellow River basin. The Asu catchment has an area of 12.43km2 with mean annual precipitation of 2442mm. The larger Wei catchment has an area of 24800km2 but with mean annual precipitation of only 512mm. The rainfall-runoff processes are simulated at a hourly time step from 2002 to 2005 in the Asu catchment and from 2001 to 2012 in the Wei catchment. The role of macropore flow on the catchment hydrology will be analyzed comparatively over the Asu and Wei catchments against the observed streamflow, evapotranspiration and other auxiliary data.

Influence of Coastal Submarine Groundwater Discharges on Seagrass Communities in a Subtropical Karstic Environment.

PubMed

Kantún-Manzano, C A; Herrera-Silveira, J A; Arcega-Cabrera, F

2018-01-01

The influence of coastal submarine groundwater discharges (SGD) on the distribution and abundance of seagrass meadows was investigated. In 2012, hydrological variability, nutrient variability in sediments and the biotic characteristics of two seagrass beds, one with SGD present and one without, were studied. Findings showed that SGD inputs were related with one dominant seagrass species. To further understand this, a generalized additive model (GAM) was used to explore the relationship between seagrass biomass and environment conditions (water and sediment variables). Salinity range (21-35.5 PSU) was the most influential variable (85%), explaining why H. wrightii was the sole plant species present at the SGD site. At the site without SGD, GAM could not be performed since environmental variables could not explain a total variance of > 60%. This research shows the relevance of monitoring SGD inputs in coastal karstic areas since they significantly affect biotic characteristics of seagrass beds.

Hydro-economic modelling in mining catchments

NASA Astrophysics Data System (ADS)

Ossa Moreno, J. S.; McIntyre, N.; Rivera, D.; Smart, J. C. R.

2017-12-01

Hydro-economic models are gaining momentum because of their capacity to model both the physical processes related to water supply, and socio-economic factors determining water demand. This is particularly valuable in the midst of the large uncertainty upon future climate conditions and social trends. Agriculture, urban uses and environmental flows have received a lot of attention from researchers, as these tend to be the main consumers of water in most catchments. Mine water demand, although very important in several small and medium-sized catchments worldwide, has received less attention and only few models have attempted to reproduce its dynamics with other users. This paper describes an on-going project that addresses this gap, by developing a hydro-economic model in the upper Aconcagua River in Chile. This is a mountain catchment with large scale mining and hydro-power users at high altitudes, and irrigation areas in a downstream valley. Relevant obstacles to the model included the lack of input climate data, which is a common feature in several mining areas, the complex hydrological processes in the area and the difficulty of quantifying the value of water used by mines. A semi-distributed model developed within the Water Evaluation and Planning System (WEAP), was calibrated to reproduce water supply, and this was complemented with an analysis of the value of water for mining based on two methods; water markets and an analysis of its production processes. Agriculture and other users were included through methods commonly used in similar models. The outputs help understanding the value of water in the catchment, and its sensitivity to changes in climate variables, market prices, environmental regulations and changes in the production of minerals, crops and energy. The results of the project highlight the importance of merging hydrology and socio-economic calculations in mining regions, in order to better understand trade-offs and cost of opportunity of using

Morphology, geology and water quality assessment of former tin mining catchment.

PubMed

Ashraf, Muhammad Aqeel; Maah, Mohd Jamil; Yusoff, Ismail

2012-01-01

Bestari Jaya, former tin mining catchment covers an area of 2656.31 hectares comprised of four hundred and forty-two different-size lakes and ponds. The present study area comprise of 92 hectares of the catchment that include four large size lakes. Arc GIS version 9.2 used to develop bathymetric map, Global Positioning System (GPS) for hydrographical survey and flow meter was utilized for water discharge analysis (flow routing) of the catchment. The water quality parameters (pH, temperature, electric conductivity, dissolved oxygen DO, total dissolved solids TDS, chlorides, ammonium, nitrates) were analyzed by using Hydrolab. Quality assurance (QA) and quality control (QC) procedures were strictly followed throughout the field work and data analysis. Different procedures were employed to evaluate the analytical data and to check for possible transcription or dilution errors, changes during analysis, or unusual or unlikely values. The results obtained are compared with interim national water quality standards for Malaysia indicates that water quality of area is highly degraded. It is concluded that Bestri Jaya ex-mining catchment has a high pollution potential due to mining activities and River Ayer Hitam, recipient of catchment water, is a highly polluted river.

Morphology, Geology and Water Quality Assessment of Former Tin Mining Catchment

PubMed Central

Ashraf, Muhammad Aqeel; Maah, Mohd. Jamil; Yusoff, Ismail

2012-01-01

Bestari Jaya, former tin mining catchment covers an area of 2656.31 hectares comprised of four hundred and forty-two different-size lakes and ponds. The present study area comprise of 92 hectares of the catchment that include four large size lakes. Arc GIS version 9.2 used to develop bathymetric map, Global Positioning System (GPS) for hydrographical survey and flow meter was utilized for water discharge analysis (flow routing) of the catchment. The water quality parameters (pH, temperature, electric conductivity, dissolved oxygen DO, total dissolved solids TDS, chlorides, ammonium, nitrates) were analyzed by using Hydrolab. Quality assurance (QA) and quality control (QC) procedures were strictly followed throughout the field work and data analysis. Different procedures were employed to evaluate the analytical data and to check for possible transcription or dilution errors, changes during analysis, or unusual or unlikely values. The results obtained are compared with interim national water quality standards for Malaysia indicates that water quality of area is highly degraded. It is concluded that Bestri Jaya ex-mining catchment has a high pollution potential due to mining activities and River Ayer Hitam, recipient of catchment water, is a highly polluted river. PMID:22761549

Water and salt balance modelling to predict the effects of land-use changes in forested catchments. 3. The large catchment model

NASA Astrophysics Data System (ADS)

Sivapalan, Murugesu; Viney, Neil R.; Jeevaraj, Charles G.

1996-03-01

This paper presents an application of a long-term, large catchment-scale, water balance model developed to predict the effects of forest clearing in the south-west of Western Australia. The conceptual model simulates the basic daily water balance fluxes in forested catchments before and after clearing. The large catchment is divided into a number of sub-catchments (1-5 km2 in area), which are taken as the fundamental building blocks of the large catchment model. The responses of the individual subcatchments to rainfall and pan evaporation are conceptualized in terms of three inter-dependent subsurface stores A, B and F, which are considered to represent the moisture states of the subcatchments. Details of the subcatchment-scale water balance model have been presented earlier in Part 1 of this series of papers. The response of any subcatchment is a function of its local moisture state, as measured by the local values of the stores. The variations of the initial values of the stores among the subcatchments are described in the large catchment model through simple, linear equations involving a number of similarity indices representing topography, mean annual rainfall and level of forest clearing.The model is applied to the Conjurunup catchment, a medium-sized (39·6 km2) catchment in the south-west of Western Australia. The catchment has been heterogeneously (in space and time) cleared for bauxite mining and subsequently rehabilitated. For this application, the catchment is divided into 11 subcatchments. The model parameters are estimated by calibration, by comparing observed and predicted runoff values, over a 18 year period, for the large catchment and two of the subcatchments. Excellent fits are obtained.

DEM-based analysis of landscape organization: 2) Application to catchment comparison

NASA Astrophysics Data System (ADS)

Seibert, J.; McGlynn, B.

2003-04-01

The delineation of homogeneous landscape elements (or "hydrologic response units") is often a prerequisite in field investigations and the application of semi-distributed hydrologic (or coupled hydrologic and biogeochemical) models. Delineation and quantification of dominant landscape elements requires methods to extract the features from digital elevation data or other readily available information. It is often assumed that hillslope and riparian areas constitute the two most important and identifiable landscape units contributing to catchment runoff in upland humid catchments. In addition, we have found that that the degree of hillslope water expression in stormflow is partially a function of riparian to hillslope reservoir ratios and landscape organization. Therefore, we developed a simple approach for quantifying landscape organization and distributed riparian to hillslope area ratios (riparian buffer ratios), as described in the accompanying contribution. Here we use this method as a framework for comparing and classifying diverse catchments located in Europe, the U.S., and New Zealand. Based on the three catchments Maimai (New Zealand), Panola (Georgia) and Sleepers (Vermont) we obtained the following preliminary results: (1) Local area entering the stream channels was most variable at Maimai and consistently diffuse at Sleepers and Panola. Also the median local area entering the channel network was largest at Maimai and smallest at Sleepers and Panola. This demonstrates the degree of landscape dissection (highest for Maimai) and the concentration of hillslope inputs along the stream network. (2) Riparian areas were smallest at Maimai, larger at Sleepers, and largest at Panola. The combination of riparian zone extent and focused (Maimai) versus diffuse (Sleepers and Panola) hillslope inputs to riparian zones controls local riparian to hillslope area ratios (riparian buffer capacities). (3) Area was accumulated to a large extend in the channel heads in all

Emergent Archetype Hydrological-Biogeochemical Response Patterns in Heterogeneous Catchments

NASA Astrophysics Data System (ADS)

Jawitz, J. W.; Gall, H. E.; Rao, P.

2013-12-01

What can spatiotemporally integrated patterns observed in stream hydrologic and biogeochemical signals generated in response to transient hydro-climatic and anthropogenic forcing tell us about the interactions between spatially heterogeneous soil-mediated hydrological and biogeochemical processes? We seek to understand how the spatial structure of solute sources coupled with hydrologic responses affect observed concentration-discharge (C-Q) patterns. These patterns are expressions of the spatiotemporal structure of solute loads exported from managed catchments, and their likely ecological consequences manifested in receiving water bodies (e.g., wetlands, rivers, lakes, and coastal waters). We investigated the following broad questions: (1) How does the correlation between flow-generating areas and biogeochemical source areas across a catchment evolve under stochastic hydro-climatic forcing? (2) What are the feasible hydrologic and biogeochemical responses that lead to the emergence of the observed archetype C-Q patterns? and; (3) What implications do these coupled dynamics have for catchment monitoring and implementation of management practices? We categorize the observed temporal signals into three archetypical C-Q patterns: dilution; accretion, and constant concentration. We introduce a parsimonious stochastic model of heterogeneous catchments, which act as hydrologic and biogeochemical filters, to examine the relationship between spatial heterogeneity and temporal history of solute export signals. The core concept of the modeling framework is considering the types and degree of spatial correlation between solute source zones and flow generating zones, and activation of different portions of the catchments during rainfall events. Our overarching hypothesis is that each of the archetype C-Q patterns can be generated by explicitly linking landscape-scale hydrologic responses and spatial distributions of solute source properties within a catchment. The model

Modelling remediation scenarios in historical mining catchments.

PubMed

Gamarra, Javier G P; Brewer, Paul A; Macklin, Mark G; Martin, Katherine

2014-01-01

Local remediation measures, particularly those undertaken in historical mining areas, can often be ineffective or even deleterious because erosion and sedimentation processes operate at spatial scales beyond those typically used in point-source remediation. Based on realistic simulations of a hybrid landscape evolution model combined with stochastic rainfall generation, we demonstrate that similar remediation strategies may result in differing effects across three contrasting European catchments depending on their topographic and hydrologic regimes. Based on these results, we propose a conceptual model of catchment-scale remediation effectiveness based on three basic catchment characteristics: the degree of contaminant source coupling, the ratio of contaminated to non-contaminated sediment delivery, and the frequency of sediment transport events.

Applying Thiessen Polygon Catchment Areas and Gridded Population Weights to Estimate Conflict-Driven Population Changes in South Sudan

NASA Astrophysics Data System (ADS)

Jordan, L.

2017-10-01

Recent violence in South Sudan produced significant levels of conflict-driven migration undermining the accuracy and utility of both national and local level population forecasts commonly used in demographic estimates, public health metrics and food security proxies. This article explores the use of Thiessen Polygons and population grids (Gridded Population of the World, WorldPop and LandScan) as weights for estimating the catchment areas for settlement locations that serve large populations of internally displaced persons (IDP), in order to estimate the county-level in- and out-migration attributable to conflict-driven displacement between 2014-2015. Acknowledging IDP totals improves internal population estimates presented by global population databases. Unlike other forecasts, which produce spatially uniform increases in population, accounting for displaced population reveals that 15 percent of counties (n = 12) increased in population over 20 percent, and 30 percent of counties (n = 24) experienced zero or declining population growth, due to internal displacement and refugee out-migration. Adopting Thiessen Polygon catchment zones for internal migration estimation can be applied to other areas with United Nations IDP settlement data, such as Yemen, Somalia, and Nigeria.

Changes in catchment hydrology in relation to vegetation recovery: a comparative modelling experiment

NASA Astrophysics Data System (ADS)

Lana-Renault, Noemí; Karssenberg, Derek; Latron, Jérôme; Serrano, Mā Pilar; Regüés, David; Bierkens, Marc F. P.

2010-05-01

Mediterranean mountains have been largely affected by land abandonment and subsequent vegetation recovery, with a general expansion of shrubs and forests. Such a large scale land-cover change has modified the hydrological behavior of these areas, with significant impact on runoff production. Forecasting the trend of water resources under future re-vegetation scenarios is of paramount importance in Mediterranean basins, where water management relies on runoff generated in these areas. With this purpose, a modelling experiment was designed based on the information collected in two neighbouring research catchments with a different history of land use in the central Spanish Pyrenees. One (2.84 km2) is an abandoned agricultural catchment subjected to plant colonization and at present mainly covered by shrubs. The other (0.92 km2) is a catchment covered by dense natural forest, representative of undisturbed environments. Here we present the results of the analysis of the hydrological differences between the two catchments, and a description of the approach and results of the modelling experiment. In a statistical analysis of the field data, significant differences were observed in the streamflow response of the two catchments. The forested catchment recorded fewer floods per year compared to the old agricultural catchment, and its hydrological response was characterised by a marked seasonality, with autumn and spring as the only high flow periods. Stormflow was generally higher in the old agricultural catchment, especially for low to intermediate size events; only for large events the stormflow in the forested catchment was sometimes greater. Under drier conditions, the relative differences in the stormflow between the two catchments tended to increase whereas under wet conditions they tended to be similar. The forested catchment always reacted more slowly to rainfall, with lower peakflows (generally one order of magnitude lower) and longer recession limbs. The modelling

Understanding fine sediment and phosphorous delivery in upland catchments

NASA Astrophysics Data System (ADS)

Perks, M. T.; Reaney, S. M.

2013-12-01

The uplands of UK are heavily impacted by land management including; farming and forestry operations, moorland burning, peat extraction, metal mining, artificial drainage and channelisation. It has been demonstrated that such land management activity may modify hillslope processes, resulting in enhanced runoff generation and changing the spatial distribution and magnitude of erosion. Resultantly, few upland river systems of the UK are operating in a natural state, with land management activity often resulting in increased fluxes of suspended sediment (< 2 mm) and associated pollutants (such as phosphorous). Most recent Environment Agency (EA) data reveals that 60% of monitored water bodies within upland areas of the UK are currently at risk of failing the Water Framework Directive (WFD) due to poor ecological status. In order to prevent the continual degradation of many upland catchments, riverine systems and their diverse ecosystems, a range of measures to control diffuse pollution will need to be implemented. Future mitigation options and measures in the UK may be tested and targeted through the EA's catchment pilot scheme; DEFRA's Demonstration Test Catchment (DTC) programmes and through the catchment restoration fund. However, restoring the physical and biological processes of past conditions in inherently sensitive upland environments is extremely challenging requiring the development of a solid evidence base to determine the effectiveness of resource allocation and to enable reliable and transparent decisions to be made about future catchment operations. Such evidence is rarely collected, with post-implementation assessments often neglected. This paper presents research conducted in the Morland sub-catchment of the River Eden within Cumbria; UK. 80% of this headwater catchment is in upland areas and is dominated by improved grassland and rough grazing. The catchment is heavily instrumented with a range of hydro-meteorological equipment. A high-tech monitoring

Hydrological Dynamics In High Mountain Catchment Areas of Central Norway

NASA Astrophysics Data System (ADS)

Löffler, J.; Rössler, O.

Large-scaled landscape structure is regarded as a mosaic of ecotopes where pro- cess dynamics of water and energy fluxes are analysed due to its effects on ecosys- tem functioning. The investigations have been carried out in the continental most Vågå/Oppland high mountains in central Norway since 1994 (LÖFFLER WUN- DRAM 1999, 2000, 2001). Additionally, comparable investigations started in 2000 dealing with the oceanic high mountain landscapes on same latitudes (LÖFFLER et al. 2001). The theoretical and methodological framework of the project is given by the Landscape-Ecological Complex Analysis (MOSIMANN 1984, 1985) and its variations due to technical and principle methodical challenges in this high moun- tain landscape (KÖHLER et al. 1994, LÖFFLER 1998). The aim of the project is to characterize high mountain ecosystem structure, functioning and dynamics within small catchment areas, that are chosen in two different altitudinal belts each in the eastern continental and the western oceanic region of central Norway. In the frame of this research project hydrological and meteorological measurements on ground water, percolation and soil moisture dynamics as well as on evaporation, air humidity and air-, surface- and soil-temperatures have been conducted. On the basis of large-scaled landscape-ecological mappings (LÖFFLER 1997) one basic meteorological station and several major data logger run stations have been installed in representative sites of each two catchment areas in the low and mid alpine belts of the investigation re- gions (JUNG et al. 1997, LÖFFLER WUNDRAM 1997). Moreover, spatial differ- entiations of groundwater level, soil moisture and temperature profiles have been in- vestigated by means of hand held measurements at different times of the day, during different climatic situations and different seasons. Daily and annual air-, surface- and soil-temperature dynamics are demonstrated by means of thermoisopleth-diagrams for different types of

A synoptic survey of ecosystem services from headwater catchments in the United States

Treesearch

Brian H. Hill; Randall K. Kolka; Frank H. McCormick; Matthew A. Starry

2014-01-01

Ecosystem production functions for water supply, climate regulation, and water purification were estimated for 568 headwater streams and their catchments. Results are reported for nine USA ecoregions. Headwater streams represented 74-80% of total catchment stream length. Water supply per unit catchment area was highest in the Northern Appalachian Mountains ecoregion...

Influence of hydroclimatic variations on solute concentration dynamics in nested subtropical catchments with heterogeneous landscapes.

PubMed

Piazza, Gustavo Antonio; Dupas, Rémi; Gascuel-Odoux, Chantal; Grimaldi, Catherine; Pinheiro, Adilson; Kaufmann, Vander

2018-04-20

Despite global efforts to monitor water quality in catchments worldwide, tropical and subtropical zones still lack data to study the influence of human activities and climate variations on solute dynamics. In this study, we monitored ten solutes every two weeks for six years (2010-2015) in three nested catchments (2 to30 km 2 ), which contained heterogeneous landscapes composed of forests and agricultural land, and one small neighboring forested catchment (0.4 km 2 ). Data analysis revealed that i) rainfall, discharge and solute concentrations displayed no clear seasonal patterns, unlike many catchments of the temperate zone; ii) solute concentrations in the agricultural area were higher than those in the forested area, but both areas displayed similar temporal patterns due to a common hydroclimatic driver; iii) all four catchments displayed a chemostatic export regime for most of the solutes, similar to catchments of the temperate zone; and iv) a positive correlation was observed between anion concentrations and ENSO (El Niño-Southern Oscillation) index. ENSO appeared to influence both hydroclimatic and anion dynamics in these subtropical catchments. Copyright © 2018 Elsevier B.V. All rights reserved.

Modeling nonlinear responses of DOC transport in boreal catchments in Sweden

NASA Astrophysics Data System (ADS)

Kasurinen, Ville; Alfredsen, Knut; Ojala, Anne; Pumpanen, Jukka; Weyhenmeyer, Gesa A.; Futter, Martyn N.; Laudon, Hjalmar; Berninger, Frank

2016-07-01

Stream water dissolved organic carbon (DOC) concentrations display high spatial and temporal variation in boreal catchments. Understanding and predicting these patterns is a challenge with great implications for water quality projections and carbon balance estimates. Although several biogeochemical models have been used to estimate stream water DOC dynamics, model biases common during both rain and snow melt-driven events. The parsimonious DOC-model, K-DOC, with 10 calibrated parameters, uses a nonlinear discharge and catchment water storage relationship including soil temperature dependencies of DOC release and consumption. K-DOC was used to estimate the stream water DOC concentrations over 5 years for eighteen nested boreal catchments having total area of 68 km2 (varying from 0.04 to 67.9 km2). The model successfully simulated DOC concentrations during base flow conditions, as well as, hydrological events in catchments dominated by organic and mineral soils reaching NSEs from 0.46 to 0.76. Our semimechanistic model was parsimonious enough to have all parameters estimated using statistical methods. We did not find any clear differences between forest and mire-dominated catchments that could be explained by soil type or tree species composition. However, parameters controlling slow release and consumption of DOC from soil water behaved differently for small headwater catchments (less than 2 km2) than for those that integrate larger areas of different ecosystem types (10-68 km2). Our results emphasize that it is important to account for nonlinear dependencies of both, soil temperature, and catchment water storage, when simulating DOC dynamics of boreal catchments.

Environmental care in agricultural catchments: Toward the communicative catchment

NASA Astrophysics Data System (ADS)

Martin, Peter

1991-11-01

Substantial land degradation of agricultural catchments in Australia has resulted from the importation of European farming methods and the large-scale clearing of land. Rural communities are now being encouraged by government to take responsibility for environmental care. The importance of community involvement is supported by the view that environmental problems are a function of interactions between people and their environment. It is suggested that the commonly held view that community groups cannot care for their resources is due to inappropriate social institutions rather that any inherent disability in people. The communicative catchment is developed as a vision for environmental care into the future. This concept emerges from a critique of resource management through the catchment metaphors of the reduced, mechanical, and the complex, evolving catchment, which reflect the development of systemic and people-centered approaches to environmental care. The communicative catchment is one where both community and resource managers participate collaboratively in environmental care. A methodology based on action research and systemic thinking (systemic action research) is proposed as a way of moving towards the communicative catchment of the future. Action research is a way of taking action in organizations and communities that is participative and informed by theory, while systemic thinking takes into account the interconnections and relationships between social and natural worlds. The proposed vision, methodology, and practical operating principles stem from involvement in an action research project looking at extension strategies for the implementation of total catchment management in the Hunter Valley, New South Wales.

Influence of landscape mosaic on streamflow of a peri-urban catchment under Mediterranean climate

NASA Astrophysics Data System (ADS)

Ferreira, Carla; Walsh, Rory; Ferreira, António

2017-04-01

Peri-urban areas tend to be characterized by patchy landscape mosaics of different land-uses. Although the impact of land-use changes on catchment hydrology have been widely investigated, the impact of mixed land-use patterns on the streamflow of peri-urban areas is still poorly understood. This study aims to (i) explore and quantify streamflow delivery from sub-catchments characterized by distinct landscape mosaics; (ii) assess the impact of different urbanization styles on hydrograph properties; and (iii) explore the influence of urbanization type on flow connectivity and stream discharge. The study was carried out in Ribeira dos Covões, a small (6.2km2) peri-urban catchment in central Portugal. The climate is Mediterranean, with a mean annual rainfall of 892mm. Catchment geology comprises sandstone (56%), limestone (41%) and alluvial deposits (3%). Soils developed on sandstone are generally deep (>3m) Fluvisols and Podsols, whereas on limestone the Leptic Cambisols are typically shallow (<0.4m). Forest is the dominant land-use (56%), but urban areas cover an extensive area (40%), whereas agricultural land has declined to a very small area (4%). The urban area comprises contrasting urban styles, notably older discontinuous urban areas with buildings separated by gardens of low population density (<25 inhabitants km-2), and recent well-defined continuous urban cores dominated by apartment blocks and of high population density (9900 inhabitants km-2). The study uses hydrological data recorded over three hydrological years, starting in November 2010, in a monitoring network comprising eight streamflow gauging stations (instrumented with water level recorders) and five rainfall gauges. The gauging stations provide information on the discharge response to rainstorms of the catchment outlet and upstream sub-catchments of different size, urban pattern (in terms of percentage urban land-use and impervious area, distance to the stream network, and storm water management

Drought propagation and its relation with catchment biophysical characteristics

NASA Astrophysics Data System (ADS)

Alvarez-Garreton, C. D.; Lara, A.; Garreaud, R. D.

2016-12-01

Droughts propagate in the hydrological cycle from meteorological to soil moisture to hydrological droughts. To understand the drivers of this process is of paramount importance since the economic and societal impacts in water resources are directly related with hydrological droughts (and not with meteorological droughts, which have been most studied). This research analyses drought characteristics over a large region and identify its main exogenous (climate forcing) and endogenous (biophysical characteristics such as land cover type and topography) explanatory factors. The study region is Chile, which covers seven major climatic subtypes according to Köppen system, it has unique geographic characteristics, very sharp topography and a wide range of landscapes and vegetation conditions. Meteorological and hydrological droughts (deficit in precipitation and streamflow, respectively) are characterized by their durations and standardized deficit volumes using a variable threshold method, over 300 representative catchments (located between 27°S and 50°S). To quantify the propagation from meteorological to hydrological drought, we propose a novel drought attenuation index (DAI), calculated as the ratio between the meteorological drought severity slope and the hydrological drought severity slope. DAI varies from zero (catchment that attenuates completely a meteorological drought) to one (the meteorological drought is fully propagated through the hydrological cycle). This novel index provides key (and comparable) information about drought propagation over a wide range of different catchments, which has been highlighted as a major research gap. Similar drought indicators across the wide range of catchments are then linked with catchment biophysical characteristics. A thorough compilation of land cover information (including the percentage of native forests, grass land, urban and industrial areas, glaciers, water bodies and no vegetated areas), catchment physical

Can spatial statistical river temperature models be transferred between catchments?

NASA Astrophysics Data System (ADS)

Jackson, Faye L.; Fryer, Robert J.; Hannah, David M.; Malcolm, Iain A.

2017-09-01

There has been increasing use of spatial statistical models to understand and predict river temperature (Tw) from landscape covariates. However, it is not financially or logistically feasible to monitor all rivers and the transferability of such models has not been explored. This paper uses Tw data from four river catchments collected in August 2015 to assess how well spatial regression models predict the maximum 7-day rolling mean of daily maximum Tw (Twmax) within and between catchments. Models were fitted for each catchment separately using (1) landscape covariates only (LS models) and (2) landscape covariates and an air temperature (Ta) metric (LS_Ta models). All the LS models included upstream catchment area and three included a river network smoother (RNS) that accounted for unexplained spatial structure. The LS models transferred reasonably to other catchments, at least when predicting relative levels of Twmax. However, the predictions were biased when mean Twmax differed between catchments. The RNS was needed to characterise and predict finer-scale spatially correlated variation. Because the RNS was unique to each catchment and thus non-transferable, predictions were better within catchments than between catchments. A single model fitted to all catchments found no interactions between the landscape covariates and catchment, suggesting that the landscape relationships were transferable. The LS_Ta models transferred less well, with particularly poor performance when the relationship with the Ta metric was physically implausible or required extrapolation outside the range of the data. A single model fitted to all catchments found catchment-specific relationships between Twmax and the Ta metric, indicating that the Ta metric was not transferable. These findings improve our understanding of the transferability of spatial statistical river temperature models and provide a foundation for developing new approaches for predicting Tw at unmonitored locations across

Methodological study of submarine groundwater discharge from a karstic aquifer in the Western Mediterranean Sea

NASA Astrophysics Data System (ADS)

Mejías, Miguel; Ballesteros, Bruno J.; Antón-Pacheco, Carmen; Domínguez, José A.; Garcia-Orellana, Jordi; Garcia-Solsona, Ester; Masqué, Pere

2012-09-01

SummaryA multiproxy approach of complementary techniques is applied to localise and quantify submarine groundwater discharge (SGD) from El Maestrazgo Jurassic aquifer, an example of widespread carbonate coastal aquifer of the Western Mediterranean Sea (Castellón, Spain). Unconventional water resources are critical in this area where highly populated resorts have been developed. The aquifer has two main features of particular interest: a karstic system with a deep saturated zone reaching 450 m and with no significant surface discharge occurring within the continental area. On the other hand, SGD can alter the condition of coastal marine environments, reducing salinities and providing nutrients that can cause eutrophication and algal blooms. The applied combined techniques make it possible to detect groundwater outflows using airborne thermal infrared (TIR) images to monitor physico-chemical anomalies in the sea and to quantify the submarine groundwater discharges by means of direct measurements and radium isotopic analyses. Three main coastal areas affected by SGD and a submarine spring located at 3 km from the coast, which seems to be associated with tectonic discontinuities, were localised. The calculated fresh SGD from Ra isotopes, 375 Mm3 y-1, is in agreement with the mean aquifer recharge obtained by hydrogeological methods, 394 Mm3 y-1.

Hydrological impacts of urbanization at the catchment scale

NASA Astrophysics Data System (ADS)

Oudin, Ludovic; Salavati, Bahar; Furusho-Percot, Carina; Ribstein, Pierre; Saadi, Mohamed

2018-04-01

The impacts of urbanization on floods, droughts and the overall river regime have been largely investigated in the past few decades, but the quantification and the prediction of such impacts still remain a challenge in hydrology. We gathered a sample of 142 catchments that have a documented increase in urban areas over the hydrometeorological record period in the United States. The changes in river flow regimes due to urban spread were differentiated from climate variability using the GR4J conceptual hydrological model. High, low and mean flows were impacted at a threshold of a 10% total impervious area. Moreover, the historical evolution of urban landscape spatial patterns was used to further detail the urbanization process in terms of extent and fragmentation of urban areas throughout the catchment and to help interpret the divergent impacts observed in streamflow behaviors. Regression analysis pointed out the importance of major wastewater treatment facilities that might overpass the effects of imperviousness, and therefore further research should either take them explicitly into account or select a wastewater facility-free catchment sample to clearly evaluate the impacts of urban landscape on low flows.

Catchment Dispersion Mechanisms in an Urban Context

NASA Astrophysics Data System (ADS)

Gironas, J. A.; Mejia, A.; Rossel, F.; Rinaldo, A.; Rodriguez, F.

2014-12-01

Dispersion mechanisms have been examined in-depth in natural catchments in previous studies. However, these dispersion mechanisms have been studied little in urban catchments, where artificial transport elements and morphological arrangements are expected to modify travel times and mobilize excess rainfall from spatially distributed impervious sites. Thus, these features can modify the variance of the catchment's travel times and hence the total dispersion. This work quantifies the dispersion mechanisms in an urban catchment using the theory of transport by travel times as represented by the Urban Morpho-climatic Instantaneous Unit Hydrograph (U-McIUH) model. This model computes travel times based on kinematic wave theory and accounts explicitly for the path heterogeneities and altered connectivity patterns characteristic of an urban drainage network. The analysis is illustrated using the Aubinière urban catchment (France) as a case study. We found that kinematic dispersion is dominant for small rainfall intensities, whereas geomorphologic dispersion becomes more dominant for larger intensities. The total dispersion scales with the drainage area in a power law fashion. The kinematic dispersion is dominant across spatial scales up to a threshold of approximately 2-3 km2, after which the geomorphologic dispersion becomes more dominant. Overall, overland flow is responsible for most of the dispersion, while conduits tend to counteract the increase of the geomorphologic dispersion with a negative kinematic dispersion. Further studies with other catchments are needed to assess whether the latter is a general feature of urban drainage networks.

Carbon redistribution by erosion processes in an intensively disturbed catchment

NASA Astrophysics Data System (ADS)

Boix-Fayos, Carolina; Martínez-Mena, María; Pérez Cutillas, Pedro; de Vente, Joris; Barberá, Gonzalo G.; Mosch, Wouter; Navarro Cano, Jose Antonio; Gaspar, Leticia; Navas, Ana

2016-04-01

Understanding how organic carbon moves with sediments along the fluvial system is crucial to close catchment scale carbon budgets. Especially challenging is the analysis of organic carbon dynamics during fluvial transport in heterogeneous, fragile and disturbed environments with ephemeral and intense hydrological pulses, typical of Mediterranean conditions. This paper explores the catchment scale organic carbon redistribution by lateral flows in extreme Mediterranean environmental conditions from a geomorphological perspective. The study area is a catchment (Cárcavo) in SE Spain with a semiarid climate, erodible lithologies, shallow soils, and highly disturbed by agricultural terraces, land levelling, reforestations and construction of check-dams. To increase understanding of erosion induced catchment scale organic carbon redistribution, we studied the subcatchments of 8 check-dams distributed along the catchment main channel in detail. We determined 137Cs, physicochemical characteristics and organic carbon pools of soils and sediments deposited behind each check-dam, performed spatial analysis of properties of the catchment and buffer areas around check-dams, and carried out geomorphological analysis of the slope-channel connections. Soils showed very low Total Organic Carbon (TOC) values oscillating between 15.2 and 4.4 g Kg-1 for forest and agricultural soils, respectively. Sediments mobilized by erosion were poor in TOC compared to the eroded (forest) soils (6.6±0.7 g Kg-1), and the redistribution of organic carbon through the catchment, especially of the Mineral Associated Organic Carbon (MAC) pool, showed the same pattern as clay particles and 137Cs. The TOC erosion rates (0.031±0.03 Mg ha-1 y-1) were comparable to others reported for subhumid Mediterranean catchments and to those modelled worldwide for pasture land. Those lateral fluxes were equivalent to 10.4 % of the TOC stock from the topsoil at the moment of the check-dam construction and

Geophysical and geomorphological investigations of a Quaternary karstic paleolake and its underground marine connection in Cassis (Bestouan, Cassis, SE France)

NASA Astrophysics Data System (ADS)

Romey, Carole; Rochette, Pierre; Vella, Claude; Arfib, Bruno; Andrieu-Ponel, Valérie; Braucher, Régis; Champollion, Cédric; Douchet, Marc; Dussouillez, Philippe; Hermitte, Daniel; Mattioli, Emanuela; Parisot, Jean-Claude; Schwenninger, Jean-Luc

2014-06-01

An original karstic system in a coastal alluvial plain located in a carbonate environment (Cassis, Provence - SE France) was studied using a multi-method approach (electrical resistivity tomography, gravimetric, passive seismic survey), combined with geomorphologic methods, surface observations and drilling. Limestone dissolution and/or cavity collapse led to the development of a polje, which was filled rapidly by erosion of Aptian marls. The combination of several dating and paleoenvironmental proxies indicates that the polje was filled during a glacial period (MIS 6, 8 or 10, i.e. in the 130-360 ka age range). This discovery has implications for the understanding of karst processes. The connection between the polje and the three km-long Bestouan underwater karstic conduit with submarine outlet is strongly suggested by sedimentological studies and geophysical prospections.

Catchment management and the Great Barrier Reef.

PubMed

Brodie, J; Christie, C; Devlin, M; Haynes, D; Morris, S; Ramsay, M; Waterhouse, J; Yorkston, H

2001-01-01

Pollution of coastal regions of the Great Barrier Reef is dominated by runoff from the adjacent catchment. Catchment land-use is dominated by beef grazing and cropping, largely sugarcane cultivation, with relatively minor urban development. Runoff of sediment, nutrients and pesticides is increasing and for nitrogen is now four times the natural amount discharged 150 years ago. Significant effects and potential threats are now evident on inshore reefs, seagrasses and marine animals. There is no effective legislation or processes in place to manage agricultural pollution. The Great Barrier Reef Marine Park Act does not provide effective jurisdiction on the catchment. Queensland legislation relies on voluntary codes and there is no assessment of the effectiveness of the codes. Integrated catchment management strategies, also voluntary, provide some positive outcomes but are of limited success. Pollutant loads are predicted to continue to increase and it is unlikely that current management regimes will prevent this. New mechanisms to prevent continued degradation of inshore ecosystems of the Great Barrier Reef World Heritage Area are urgently needed.

A plot tree structure to represent surface flow connectivity in rural catchments: definition and application for mining critical source areas and temporal conditions

NASA Astrophysics Data System (ADS)

Gascuel-Odoux, Chantal; Cordier, Marie-Odile; Grimaldi, Catherine; Salmon-Monviola, Jordy; Masson, Veronique; Squividant, Herve; Trepos, Ronan

2013-04-01

Agricultural landscapes are structured by a mosaic of farmers'fields whose boundaries and land use change over time, and by linear elements such as hedgerows, ditches and roads, which are more or less connected to each other. Such man-made features are now well known to have an effect on catchment hydrology, erosion and water quality. In such agricultural landscapes, it is crucial to have an adequate functional representation of the flow pathways and define relevant indicators of surface flow connectivity over the catchment towards the stream, as a necessary step for improving landscape design and water protection. A new conceptual object oriented approach has been proposed by building the drainage network on the identification of the inlets and outlets for surface water flow on each farmers' field and surrounding landscape elements (Aurousseau et al., 2009 ; Gascuel-Odoux et al., 2011), then on delineating a set of elementary plot outlet trees labelled by attributes which feed the stream. This drainage network is therefore represented as a global plot outlet tree which conceptualizes the connectivity of the surface flow patterns over the catchment. This approach has been applied to different catchment areas, integrated in modelling (Gascuel-Odoux et al., 2009) and decision support tools. It provides a functional display of data for decision support which can highlight the plots of potential risk regarding the surface runoff, areas which are often shortly extended over catchments (suspended sediment application). Integrated in modelling and mining tools, it allows to catch typologies of the most spatial pattern involved in water quality degradation (herbicides transport model) (Trepos et al., 2012) and test their permanency in time regarding the variations of climate conditions and agricultural practices (Salmon-Monviola et al., 2011). This set of works joins skills in hydrology, agronomy and computer sciences. Aurousseau P., Gascuel-Odoux C., Squividant H

Impact of land-use on water pollution in a rapidly urbanizing catchment in China

NASA Astrophysics Data System (ADS)

Khu, Soon-Thiam; Qin, Huapeng

2010-05-01

Many catchments in developing countries are undergoing fast urbanization which is usually characterized by population increase, economic growth as well as drastic changes of land-use from natural/rural to urban area. During the urbanization process, some catchments experience water quality deterioration due to rapid increase of pollution loads. Nonpoint source pollution resulting from storm water runoff has been recognized as one of the major causes of pollutants in many cities in developing countries. The composition of land-use for a rapidly urbanizing catchment is usually heterogeneous, and this may result in significant spatial variations of storm runoff pollution and increase the difficulties of water quality management in the catchment. The Shiyan Reservoir catchment, a typical rapidly urbanizing area in China, is chosen as the study area, and temporary monitoring sites were set at the outlets of its 6 sub-catchments to synchronously measured rainfall, runoff and water quality during 4 storm events. Three indicators, event pollutant loads per unit area (EPL), event mean concentration (EMC) and pollutant loads transported by the first 50% of runoff volume (FF50), were used to describe the runoff pollution for different pollutants (such as COD, BOD, NH3-N, TN, TP and SS) in each sub-catchment during the storm events; and the correlations between runoff pollution spatial variations and land-use patterns were tested by Spearman's rank correlation analysis. The results indicated that similar spatial variation trends were found for different pollutants (EPL or EMC) in light storm events, which strongly correlate with the proportion of residential land-use; however, they have different trends in heavy storm events, which correlate with the different proportional combination of residential, industrial, agricultural and bare land-use. It is also shown that it is necessary to consider some pervious land-use types in runoff pollution monitoring or management for a

Spatial Connectivity and Temporal Response of Variable Source Areas (VSAs): Implications for Catchment Scale Water and Solute Mixing

NASA Astrophysics Data System (ADS)

Inamdar, S.; Mitchell, M.; McDonnell, J.; McGlynn, B.; Shanley, J.

2001-05-01

The significance of variable source areas (VSAs) in storm runoff generation and as loci for mixing of event and pre-event waters has long been recognized. Recent research suggests that VSAs may also play an important role in regulating the export of C and N solutes from catchments. We hypothesize that the spatial distribution of VSAs in the catchment and their connectedness with the stream network is a first order control on the temporal dynamics and expression of water and solutes from the catchment. We examined two contrasting scenarios of VSA distribution: (1) VSAs located lower in the catchment and well connected to the stream network, versus, (2) discrete VSAs located in the upper portions of the catchment and disconnected from the stream network. We evaluated the potential impact of these scenarios on: (a) the timing and peak of event water contributions, and (b) the timing and peak of solute signatures. We hypothesized that if VSAs are well connected to the stream network (Scenario 1), then event water contributions would be distinct and would predominate early on during the rising limb of the hydrograph of stream discharge. In contrast, if VSAs are isolated and disconnected (Scenario 2), then event water contributions would be damped and delayed and possibly continue to be observed through hydrograph recession. We believe solutes such as dissolved organic carbon (DOC), which are primarily flushed from near surface soil horizons, will follow an event water trajectory. We tested these hypotheses for a 135 ha forested headwater catchment in the Adirondack Mountains of New York. Detailed storm runoff and solute data for the catchment are available since 1994. A two-component separation model using base cations (Na, Mg, Ca, and K) was used to partition stormflow discharge into pre-event and event components. Event water contributions were small on the rising limb of the hydrograph, reached their maximum just after the discharge peak, and continued through the

Spatio-temporal dynamics of sediment sources in a peri-urban Mediterranean catchment

NASA Astrophysics Data System (ADS)

Ferreira, Carla; Walsh, Rory; Blake, William; Kikuchi, Ryunosuke; Ferreira, António

2017-04-01

Sediment fluxes driven by hydrological processes lead to natural soil losses, but human activities, such as urbanization, influence hydrology and promote erosion, altering the landscape and sediment fluxes. In peri-urban areas, comprising a mixture of semi-natural and man-made land-uses, understanding sediment fluxes is still a research challenge. This study investigates spatial and temporal dynamics of fluvial sediments in a rapidly urbanizing catchment. Specific objectives are to understand the main sources of sediments relating to different types of urban land disturbance, and their variability driven by (i) weather, season and land-use changes through time, and (ii) sediment particle size. The study was carried out Ribeira dos Covões, a peri-urban catchment (6.2km2) in central Portugal. The climate is humid Mediterranean, with mean annual temperature and rainfall of 15˚ C and 892 mm, respectively. The geology comprises sandstone (56%), limestone (41%) and alluvial deposits (3%). The catchment has an average slope of 9˚ , but includes steep slopes of up to 46˚ . The land-use is a complex mosaic of woodland (56%), urban (40%) and agricultural (4%) land parcels, resulting from urbanization occurring progressively since 1973. Urbanization since 2010 has mainly comprised the building of a major road, covering 1% of the catchment area, and the ongoing construction of an enterprise park, occupying 5% of the catchment. This study uses a multi-proxy sediment fingerprinting approach, based on X-Ray Fluorescence (XRF) analyses to characterize the elemental geochemistry of sediments collected within the stream network after three storm events in 2012 and 2015. A range of statistical techniques, including hierarchical cluster analysis, was used to identify discriminant sediment properties and similarities between fine bed-sediment samples of tributaries and downstream sites. Quantification of sediment supply from upstream sub-catchments was undertaken using a Bayesian

Determination of The Water Catchment Area in Semarang City Using a Combination of Object Based Image Analysis (OBIA) Classification, InSAR and Geographic Information System (GIS) Methods Based On a High-Resolution SPOT 6 Image and Radar Imagery

NASA Astrophysics Data System (ADS)

Prasetyo, Yudo; Ardi Gunawan, Setyo; Maksum, Zia Ul

2016-11-01

Semarang is the biggest city in central Java-Indonesia which has a rapid and massive infrastructure development nowadays. In order to control water resources and flood, the local goverment has been built east and west flood canal in Kaligarang and West Semarang River. One of main problem in Semarang city is the lack of fresh water in dry season because ground water is not rechargeable well. Rechargeable groundwater ability depends on underground water recharge rate and catchment area condition. The objective of the study is to determine condition and classification of water catchment area in Semarang city. The catchment area conditions will be determine by five parameters as follows soil type, land use, slope, ground water potential and rainfall intensity. In this study, we use three methods approach to solve the problem which is segmentation classification to acquire land use classification from high resolution imagery using nearest neighborhood algorithm, Interferometric Synthetic Aperture Radar (SAR) to derive DTM from SAR Imagery and multi criteria weighting and spatial analysis using GIS method. There are three types optical image (ALOS PRISM, SPOT-6 and ALOS PALSAR) to calculate water catchment area condition in Semarang city. For final result, this research will divide the water catchment into six criteria as follows good, naturally normal, early critical, a little bit critical, critical and very critical condition. The result shows that water catchment area condition is in an early critical condition around 2607,523 Ha (33,17 %), naturally normal condition around 1507,674 Ha (19,18 %), a little bit critical condition around 1452,931 Ha (18,48 %), good with 1157,04 Ha (14,72 %), critical with 1058,639 Ha (13,47 %) and very critical with 75,0387 Ha (0,95 %). The distribution of water catchment area conditions in West and East Flood Canal have an irreguler pattern. In northern area of watershed consists of begin to critical, naturally normal and good condition

Stormflow generation: a meta-analysis of field studies and research catchments

NASA Astrophysics Data System (ADS)

Barthold, Frauke; Elsenbeer, Helmut

2014-05-01

Runoff characteristics are expressions of runoff generation mechanisms. In this study, we want to test the hypothesis if storm hydrographs of catchments with prevailing near-surface flow paths are dominated by new water. We aim to test this hypothesis using published data from the scientific literature. We developed a classification system based on three runoff characteristics: (1) hydrograph response (HR: slowly or quickly), (2) the temporal source of water that dominates the hydrograph (TS: pre-event vs. event water) and (3) the flow paths that the water takes until it is released to the stream (FP: subsurface vs. surface flow paths). We then performed a literature survey to collect information on these runoff characteristics for small, forested headwater catchments that served as study areas in runoff generation studies and assigned each study catchment to one of the 8 classes. For this purpose, we designed a procedure to objectively diagnose the predominant conceptual model of storm flow generation in each catchment and assess its temporal and spatial relevance for the catchment. Finally, we performed an explorative analysis of the classified research catchments and summarized field evidence. Our literature survey yielded a sample of 22 research catchments that fell within our defined criteria (small, naturally forested catchments which served as study areas in stormflow generation studies). We applied our classification procedure to all of these catchments. Among them were 14 catchments for which our meta-analysis yielded a complete set of stormflow characteristics resulting in one of the 8 model concepts and were assigned into our classification scheme. Of the 14 classified research catchments, 10 were dominated by subsurface flow paths while 4 were dominated by overland flow. The data also indicate that the spatial and temporal relevance is high for catchments with subsurface flow paths while often weak for surface flow paths dominated catchments. The

Water quality assessment of the Asata River catchment area in Enugu Metropolis, Southeast Nigeria

NASA Astrophysics Data System (ADS)

Osinowo, Olawale Olakunle

2016-09-01

Hydrogeochemical mapping of the Asata River Catchment area in the Enugu metropolis, southeast Nigeria was carried out in order to assess the quality of the surface and groundwater and based on the analyses of the hydrogeochemical data, establish the level of chemical contaminations which inhibit the availability of potable water in the area. Forty (40) water samples comprising five (5) springs, nineteen (19) surface (streams/rivers) and sixteen (16) groundwater (well/borehole) samples were collected and analysed for the presence and degree of contamination of nine (9) major chemical contaminants. Hydrochemical analyses indicate that Electrical Conductivity (EC) which has a linear relationship with Total Dissolved Solid (TDS) ranges between 015 and 887 μS/cm, pH between 4.4 and 8.3, nitrate (NO3-) ranges between 40 and 130 mg/l and chloride (Cl-) between 7 and 130 mg/l. The concentrations of the dissolved chemical constituents defined the pollution trend and the rate of dispersion of contaminants. The degree of contaminants followed a simple trend, where the level of contamination of the dissolved chemical constituents is least in sampled spring water, with measured chemical constituents of EC, pH, NO3- and Cl- range from 15 to 354 μS/cm; 6.4-6.5; 4.0-70 mg/l and 8-36 mg/l, respectively. However, the value of the measured chemical constituent of EC, pH, NO3- and Cl- gradually increases down the stream in both the surface (63-354 μS/cm; 4.5-7.7; 7.1-110 mg/l; 8-41 mg/l) and groundwater (56-531 μS/cm; 4.5-7.5; 40-130 mg/l; 7-130 mg/l), respectively. Noticeable peaks in contamination levels characterised sections of the study area where human population or their activities is highest. The result of the hydrogeochemical mapping indicate that Enugu coal mine operation, the industrial activities, fertilizer applied to plants cultivated on river banks and domestic human wastes which are indiscriminately dumped along river channels are the major sources of chemical

Calcite Biomineralization by Bacterial Isolates from the Recently Discovered Pristine Karstic Herrenberg Cave

PubMed Central

Rusznyák, Anna; Akob, Denise M.; Nietzsche, Sándor; Eusterhues, Karin; Totsche, Kai Uwe; Neu, Thomas R.; Frosch, Torsten; Popp, Jürgen; Keiner, Robert; Geletneky, Jörn; Katzschmann, Lutz; Schulze, Ernst-Detlef

2012-01-01

Karstic caves represent one of the most important subterranean carbon storages on Earth and provide windows into the subsurface. The recent discovery of the Herrenberg Cave, Germany, gave us the opportunity to investigate the diversity and potential role of bacteria in carbonate mineral formation. Calcite was the only mineral observed by Raman spectroscopy to precipitate as stalactites from seepage water. Bacterial cells were found on the surface and interior of stalactites by confocal laser scanning microscopy. Proteobacteria dominated the microbial communities inhabiting stalactites, representing more than 70% of total 16S rRNA gene clones. Proteobacteria formed 22 to 34% of the detected communities in fluvial sediments, and a large fraction of these bacteria were also metabolically active. A total of 9 isolates, belonging to the genera Arthrobacter, Flavobacterium, Pseudomonas, Rhodococcus, Serratia, and Stenotrophomonas, grew on alkaline carbonate-precipitating medium. Two cultures with the most intense precipitate formation, Arthrobacter sulfonivorans and Rhodococcus globerulus, grew as aggregates, produced extracellular polymeric substances (EPS), and formed mixtures of calcite, vaterite, and monohydrocalcite. R. globerulus formed idiomorphous crystals with rhombohedral morphology, whereas A. sulfonivorans formed xenomorphous globular crystals, evidence for taxon-specific crystal morphologies. The results of this study highlighted the importance of combining various techniques in order to understand the geomicrobiology of karstic caves, but further studies are needed to determine whether the mineralogical biosignatures found in nutrient-rich media can also be found in oligotrophic caves. PMID:22179248

Calcite biomineralization by bacterial isolates from the recently discovered pristine karstic herrenberg cave.

PubMed

Rusznyák, Anna; Akob, Denise M; Nietzsche, Sándor; Eusterhues, Karin; Totsche, Kai Uwe; Neu, Thomas R; Frosch, Torsten; Popp, Jürgen; Keiner, Robert; Geletneky, Jörn; Katzschmann, Lutz; Schulze, Ernst-Detlef; Küsel, Kirsten

2012-02-01

Karstic caves represent one of the most important subterranean carbon storages on Earth and provide windows into the subsurface. The recent discovery of the Herrenberg Cave, Germany, gave us the opportunity to investigate the diversity and potential role of bacteria in carbonate mineral formation. Calcite was the only mineral observed by Raman spectroscopy to precipitate as stalactites from seepage water. Bacterial cells were found on the surface and interior of stalactites by confocal laser scanning microscopy. Proteobacteria dominated the microbial communities inhabiting stalactites, representing more than 70% of total 16S rRNA gene clones. Proteobacteria formed 22 to 34% of the detected communities in fluvial sediments, and a large fraction of these bacteria were also metabolically active. A total of 9 isolates, belonging to the genera Arthrobacter, Flavobacterium, Pseudomonas, Rhodococcus, Serratia, and Stenotrophomonas, grew on alkaline carbonate-precipitating medium. Two cultures with the most intense precipitate formation, Arthrobacter sulfonivorans and Rhodococcus globerulus, grew as aggregates, produced extracellular polymeric substances (EPS), and formed mixtures of calcite, vaterite, and monohydrocalcite. R. globerulus formed idiomorphous crystals with rhombohedral morphology, whereas A. sulfonivorans formed xenomorphous globular crystals, evidence for taxon-specific crystal morphologies. The results of this study highlighted the importance of combining various techniques in order to understand the geomicrobiology of karstic caves, but further studies are needed to determine whether the mineralogical biosignatures found in nutrient-rich media can also be found in oligotrophic caves.

Simulation of irrigation effect on water cycle in Yellow River catchment, China

NASA Astrophysics Data System (ADS)

Nakayama, T.; Watanabe, M.

2006-12-01

The Yellow River is 5,464 km long with a catchment area of 794,712 km2 if the Erdos inner flow area is included. This river catchment is divided between the upper region (length: 3472 km, area: 428,235 km2) from the headwater to Lanzhou in Gansu province, the middle region (length: 1,206 km, area: 343,751 km2) from Lanzhou to Huayuankou in Henan province, and the lower region (length: 786 km, area: 22,726 km2) from Huayuankou to the estuary. This river is well known for high sand content, frequent floods, unique channel characteristics in the lower reach (the river bed is higher than the land outside the banks), and the limited water resources. Since the competition of a large-scale irrigation project in 1969, noticeable river drying has been observed in the Yellow River. This flow dry-up phenomena, i.e., zero-flow in sections of the river channel, resulting from the intense competition between water supply and water demand, has occurred more and more often during the last 30 years. It is very important for decision making to ensure sustainable water resource utilization whether human activities were the only cause of the water shortage, the climate has changed during the last several decades in this catchment, and the water shortage has anything to do with climatic warming. The present research focuses on simulating the groundwater/river irrigation-effects on the water/heat dynamics in the Yellow River catchment. We combined the NIES Integrated Catchment-based Eco-hydrology (NICE) model (Nakayama and Watanabe, 2004, 2006; Nakayama et al., 2006) with the agricultural model in order to evaluate river drying in the Yellow River (NICE-DRY). We simulated the water/heat dynamics in the entire catchment with a resolution of 10 km mesh by using the NICE-DRY. The model reproduced excellently the river discharge, soil moisture, evapotranspiration, groundwater level, crop water use, crop productivity, et al. Furthermore, we evaluated the role of irrigation on the water

Developing a playground as catchment area in effort to maintaining groundwater in Jaten village of Karanganyar district of Central Java, Indonesia

NASA Astrophysics Data System (ADS)

Legowo, Budi; Darsono; Wahyuningsih, Daru

2016-11-01

Changes in land use for housing indirectly disturb the hydrology balance of the area. Groundwater conservation efforts can be done by keeping the function the catchment area. One of the housing developer's obligations is providing open spaces (the playground) to play or activity of the residents. Playground in Bumi Graha Indah Housing, Jaten village, Karanganyar district, Central Java, Indonesia has a fundamental issue, that is, in the rainy season the water is difficult to seep due landfill process are not well planned. It causes the playground become in muddy conditions with tall grass, so that reduces the function as a playground and or activity the residents. In the dry season, the soil dry of landfill caused dust scattering and disrupt the activities of people around the playground. Lack of water resources lead watering process for solving the problem of dust during the dry season was considered ineffective. Structuring drainage combined with modified recharge wells can be used to catch water runoff housing. This modification of water catchment areas can make playground dry quickly after rain so the activities of people are not bothered when utilizing the open space provided. Surface runoff water absorbed in open aquifer so that the hydrological balance always be maintained. Adequacy groundwater in the area playground can be used to sprinkler dust and backup needs clean water residents by creating wells and reservoir stocks.

Nested Tracer Studies In Catchment Hydrology: Towards A Multiscale Understanding of Runoff Generation and Catchment Funtioning

NASA Astrophysics Data System (ADS)

Soulsby, C.; Rodgers, P.; Malcolm, I. A.; Dunn, S.

Geochemical and isotopic tracers have been shown to have widespread utility in catch- ment hydrology in terms of identifying hydrological source areas and characterising residence time distributions. In many cases application of tracer techniques has pro- vided insights into catchment functioning that could not be obtained from hydromet- ric and/or modelling studies alone. This paper will show how the use of tracers has contributed to an evolving perceptual model of hydrological pathways and runoff gen- eration processes in catchments in the Scottish highlands. In particular the paper will focus on the different insights that are gained at three different scales of analysis; (a) nested sub-catchments within a mesoscale (ca. 200 square kilometers) experimen- tal catchment; (b) hillslope-riparian interactions and (c) stream bed fluxes. Nested hydrometric and hydrochemical monitoring within the mesoscale Feugh catchment identified three main hydrological response units: (i) plateau peatlands which gener- ated saturation overland flow in the catchment headwaters, (ii) steep valley hillslopes which drain from the plateaux into (iii) alluvial and drift aquifers in the valley bottoms. End Member Mixing Analysis (EMMA) in 8 nested sub-catchments indicated that that stream water tracer concentrations can be modelled in terms of 2 dominant runoff pro- cesses; overland flow from the peat and groundwater from the drift aquifers. Ground- water contributions generally increased with catchment size, though this was moder- ated by the characteristics of individual sub-basins, with drift cover being particularly important. Hillslope riparian interactions were also examined using tracers, hydromet- ric data and a semi-distributed hydrological model. This revealed that in the glaciated, drift covered terrain of the Scottish highlands, extensive valley bottom aquifers effec- tively de-couple hillslope waters from the river channel. Thus, riparian groundwater appears to significantly

Modeling and evaluation of compliance to water quality regulations in bathing areas on the Daoulas catchment and estuary (France).

PubMed

Bougeard, M; Le Saux, J C; Jouan, M; Durand, G; Pommepuy, M

2010-01-01

The microbiological quality of waters in estuaries determines their acceptability for recreational uses. Microbiological contamination often results from urban wastewater discharges or non-point source pollution (manure spreading), and can cause bathing zones to be closed. European regulations (EC/7/2006) have proposed standards (500 E. coli/100 ml) for the acceptability areas for bathing. In this study, two models were associated to simulate contamination: SWAT on a catchment and MARS 2D in the downstream estuary. After river flow calibration and validation, two scenarios were simulated in SWAT, and E. coli fluxes obtained at the main outlet of the catchment were then introduced into MARS 2D to follow E. coli concentrations in the estuary. An annual evaluation of compliance to bathing area water quality standards was then calculated, linked with daily rainfall classes. Water quality in the estuary was below the standard on 13 days, including 5 days with rainfall superior to 10 mm, due to faecal contamination from soil leaching by rain, and 5 days with rainfall ranging from 0.1 to 5 mm/day, due to the high frequency of this level of rainfall. To conclude, this study allowed us to demonstrate the efficiency of models to gain a better understanding on water quality degradation factors.

[Decentralized outpatient teams in community-based psychiatric care: comparison of two Bavarian rural catchment areas].

PubMed

Valdes-Stauber, J; Putzhammer, A; Kilian, R

2014-05-01

Psychiatric outpatient clinics (PIAs) are an indispensable care service for crisis intervention and multidisciplinary treatment of people suffering from severe and persistent mental disorders. The decentralization of outpatient clinics can be understood as a further step in the deinstitutionalization process. This cross-sectional study (n=1,663) compared the central outpatient clinic with the decentralized teams for the year 2010 by means of analyses of variance, χ(2)-tests and robust multivariate regression models. The longitudinal assessment (descriptively and by means of Prais-Winsten regression models for time series) was based on all hospitalizations for the two decentralized teams (n = 6,693) according to partial catchment areas for the time period 2002-2010 in order to examine trends after their installation in the year 2007. Decentralized teams were found to be similar with respect to the care profile but cared for relatively more patients suffering from dementia, addictive and mood disorders but not for those suffering from schizophrenia and personality disorders. Decentralized teams showed less outpatient care costs as well as psychopharmacological expenses but a lower contact frequency than the central outpatient clinic. Total expenses for psychiatric care were not significantly different and assessed hospitalization variables (e.g. total number of annual admissions, cumulative length of inpatient-stay and annual hospitalizations per patient) changed slightly 3 years after installation of the decentralized teams. The number of admissions of people suffering from schizophrenia decreased whereas those for mood and stress disorders increased. Decentralized outpatient teams seemed to reach patients in rural regions who previously were not reached by the central outpatient clinic. Economic figures indicate advantages for the installation of such teams because care expenses are not higher than for patients treated in centralized outpatient clinics and

River-groundwater connectivity and nutrient dynamics in a mesoscale catchment

NASA Astrophysics Data System (ADS)

Fleckenstein, Jan H.; Musolff, Andreas; Gilfedder, Benjamin; Frei, Sven; Wankmüller, Fabian; Trauth, Nico

2017-04-01

gains were observed downstream of where the Selke River leaves the Harz Mountains and enters the alluvial plains. At this location, land use, hydrogeological setup and river slope as well as average slope of the contributing catchment area change significantly. Downstream of this point 15N isotope values were also significantly higher, suggesting higher denitrification activity in the deeper aquifers of lower catchment. While specific discharge (discharge per catchment area) was 3 times higher in the upper catchment, nitrate mass flux per area was more than 3 times higher in lower catchment compared to the respective other part of the catchment. We conclude that catchment morphology, (hydro)geology and hydrology control river-groundwater connectivity while the interplay with land use controls in stream nitrate concentrations. Repeated sampling campaigns will allow assessing seasonal changes in solute inputs and turnover. References Frei, S. & Gilfedder, B.S. (2015): FINIFLUX: An implicit finite element model for quantification of groundwater fluxes and hyporheic exchange in streams and rivers using radon. Water Resources Research, DOI: 10.1002/2015WR017212.

The Qtracer2 Program for Tracer-Breakthrough Curve Analysis for Tracer Tests in Karstic Aquifers and Other Hydrologic Systems (2002)

EPA Science Inventory

Tracer testing is generally regarded as the most reliable and efficient method of gathering surface and subsurface hydraulic information. This is especially true for karstic and fractured-rock aquifers. Qualitative tracing tests have been conventionally employed in most karst s...

River recharge sources and the partitioning of catchment evapotranspiration fluxes as revealed by stable isotope signals in a typical high-elevation arid catchment

NASA Astrophysics Data System (ADS)

Guo, Xiaoyu; Tian, Lide; Wang, Lei; Yu, Wusheng; Qu, Dongmei

2017-06-01

Catchment-scale hydrological cycles are expected to suffer more extremes under a background of climate change. Quantifying hydrological changes in high and remote areas is practically challenging. However, stable isotopes in river water can be seen to vary, dependent upon the combined influence exerted by recharge sources and local climatic conditions; the study of river water stable isotopes can therefore provide a meaningful method for delineating catchment-scale hydrological studies. In this study, we present high-resolution time series of river δ18O and d-excess values; additionally, we identify the seasonal dynamics of river recharge sources and major components of the catchment-scale water balance, together with precipitation and groundwater isotopes, and concurrent meteorological data recorded in Magazangbu catchment on the northwestern Tibetan Plateau (TP). Using isotopic analysis, and within a proportional framework, we partitioned the isotopic fractionation (E1) or non-fractionation (E2) from soil evaporation fluxes (Esoil) apparent in different processes, using NDVI (Normal Differential Vegetation Index) data collected by MODIS satellites to calculate the vegetation fractional coverage (VFC), and Global Land Data Assimilation System (GLDAS) records to determine evapotranspiration data (ET). Finally, the contributions made by each ET component (Esoil and plant transpiration) to total catchment ET were computed for the high and remote northwestern TP. Our results show that: (1) river δ18O values were high in summer and low in winter, while d-excess values displayed a contrary seasonal cycle; (2) for the monsoon period, precipitation contributed 60.6% to Magazangbu catchment runoff. Deeper groundwater was the main water source for the winter low base flow, and shallow groundwater or high elevation snowmelt was the principal component of the spring thaw and autumn freezing periods; and (3) a substantial proportion of Esoil (96.4% annually; 92.2% during

Modeling suspended sediment transport and assessing the impacts of climate change in a karstic Mediterranean watershed.

PubMed

Nerantzaki, S D; Giannakis, G V; Efstathiou, D; Nikolaidis, N P; Sibetheros, I Α; Karatzas, G P; Zacharias, I

2015-12-15

Mediterranean semi-arid watersheds are characterized by a climate type with long periods of drought and infrequent but high-intensity rainfalls. These factors lead to the formation of temporary flow tributaries which present flashy hydrographs with response times ranging from minutes to hours and high erosion rates with significant sediment transport. Modeling of suspended sediment concentration in such watersheds is of utmost importance due to flash flood phenomena, during which, large quantities of sediments and pollutants are carried downstream. The aim of this study is to develop a modeling framework for suspended sediment transport in a karstic watershed and assess the impact of climate change on flow, soil erosion and sediment transport in a hydrologically complex and intensively managed Mediterranean watershed. The Soil and Water Assessment Tool (SWAT) model was coupled with a karstic flow and suspended sediment model in order to simulate the hydrology and sediment yield of the karstic springs and the whole watershed. Both daily flow data (2005-2014) and monthly sediment concentration data (2011-2014) were used for model calibration. The results showed good agreement between observed and modeled values for both flow and sediment concentration. Flash flood events account for 63-70% of the annual sediment export depending on a wet or dry year. Simulation results for a set of IPCC "A1B" climate change scenarios suggested that major decreases in surface flow (69.6%) and in the flow of the springs (76.5%) take place between the 2010-2049 and 2050-2090 time periods. An assessment of the future ecological flows revealed that the frequency of minimum flow events increases over the years. The trend of surface sediment export during these periods is also decreasing (54.5%) but the difference is not statistically significant due to the variability of the sediment. On the other hand, sediment originating from the springs is not affected significantly by climate change

Quantifying the impacts of vegetation changes on catchment storage-discharge dynamics using paired-catchment data

NASA Astrophysics Data System (ADS)

Cheng, Lei; Zhang, Lu; Chiew, Francis H. S.; Canadell, Josep G.; Zhao, Fangfang; Wang, Ying-Ping; Hu, Xianqun; Lin, Kairong

2017-07-01

It is widely recognized that vegetation changes can significantly affect the local water availability. Methods have been developed to predict the effects of vegetation change on water yield or total streamflow. However, it is still a challenge to predict changes in base flow following vegetation change due to limited understanding of catchment storage-discharge dynamics. In this study, the power law relationship for describing catchment storage-discharge dynamics is reformulated to quantify the changes in storage-discharge relationship resulting from vegetation changes using streamflow data from six paired-catchment experiments, of which two are deforestation catchments and four are afforestation catchments. Streamflow observations from the paired-catchment experiments clearly demonstrate that vegetation changes have led to significant changes in catchment storage-discharge relationships, accounting for about 83-128% of the changes in groundwater discharge in the treated catchments. Deforestation has led to increases in groundwater discharge (or base flow) but afforestation has resulted in decreases in groundwater discharge. Further analysis shows that the contribution of changes in groundwater discharge to the total changes in streamflow varies greatly among experimental catchments ranging from 12% to 80% with a mean of 38 ± 22% (μ ± σ). This study proposed a new method to quantify the effects of vegetation changes on groundwater discharge from catchment storage and will improve our predictability about the impacts of vegetation changes on catchment water yields.

Exploring the Linkage between Urban Flood Risk and Spatial Patterns in Small Urbanized Catchments of Beijing, China

PubMed Central

Yao, Lei; Chen, Liding; Wei, Wei

2017-01-01

In the context of global urbanization, urban flood risk in many cities has become a serious environmental issue, threatening the health of residents and the environment. A number of hydrological studies have linked urban flooding issues closely to the spectrum of spatial patterns of urbanization, but relatively little attention has been given to small-scale catchments within the realm of urban systems. This study aims to explore the hydrological effects of small-scaled urbanized catchments assigned with various landscape patterns. Twelve typical residential catchments in Beijing were selected as the study areas. Total Impervious Area (TIA), Directly Connected Impervious Area (DCIA), and a drainage index were used as the catchment spatial metrics. Three scenarios were designed as different spatial arrangement of catchment imperviousness. Runoff variables including total and peak runoff depth (Qt and Qp) were simulated by using Strom Water Management Model (SWMM). The relationship between catchment spatial patterns and runoff variables were determined, and the results demonstrated that, spatial patterns have inherent influences on flood risks in small urbanized catchments. Specifically: (1) imperviousness acts as an effective indicator in affecting both Qt and Qp; (2) reducing the number of rainwater inlets appropriately will benefit the catchment peak flow mitigation; (3) different spatial concentrations of impervious surfaces have inherent influences on Qp. These findings provide insights into the role of urban spatial patterns in driving rainfall-runoff processes in small urbanized catchments, which is essential for urban planning and flood management. PMID:28264521

Exploring the Linkage between Urban Flood Risk and Spatial Patterns in Small Urbanized Catchments of Beijing, China.

PubMed

Yao, Lei; Chen, Liding; Wei, Wei

2017-02-28

In the context of global urbanization, urban flood risk in many cities has become a serious environmental issue, threatening the health of residents and the environment. A number of hydrological studies have linked urban flooding issues closely to the spectrum of spatial patterns of urbanization, but relatively little attention has been given to small-scale catchments within the realm of urban systems. This study aims to explore the hydrological effects of small-scaled urbanized catchments assigned with various landscape patterns. Twelve typical residential catchments in Beijing were selected as the study areas. Total Impervious Area ( TIA ), Directly Connected Impervious Area ( DCIA ), and a drainage index were used as the catchment spatial metrics. Three scenarios were designed as different spatial arrangement of catchment imperviousness. Runoff variables including total and peak runoff depth ( Q t and Q p ) were simulated by using Strom Water Management Model (SWMM). The relationship between catchment spatial patterns and runoff variables were determined, and the results demonstrated that, spatial patterns have inherent influences on flood risks in small urbanized catchments. Specifically: (1) imperviousness acts as an effective indicator in affecting both Q t and Q p ; (2) reducing the number of rainwater inlets appropriately will benefit the catchment peak flow mitigation; (3) different spatial concentrations of impervious surfaces have inherent influences on Q p . These findings provide insights into the role of urban spatial patterns in driving rainfall-runoff processes in small urbanized catchments, which is essential for urban planning and flood management.

Probability based hydrologic catchments of the Greenland Ice Sheet

NASA Astrophysics Data System (ADS)

Hudson, B. D.

2015-12-01

Greenland Ice Sheet melt water impacts ice sheet flow dynamics, fjord and coastal circulation, and sediment and biogeochemical fluxes. Melt water exiting the ice sheet also is a key term in its mass balance. Because of this, knowledge of the area of the ice sheet that contributes melt water to a given outlet (its hydrologic catchment) is important to many ice sheet studies and is especially critical to methods using river runoff to assess ice sheet mass balance. Yet uncertainty in delineating ice sheet hydrologic catchments is a problem that is rarely acknowledged. Ice sheet catchments are delineated as a function of both basal and surface topography. While surface topography is well known, basal topography is less certain because it is dependent on radar surveys. Here, I a present a Monte Carlo based approach to delineating ice sheet catchments that quantifies the impact of uncertain basal topography. In this scheme, over many iterations I randomly vary the ice sheet bed elevation within published error bounds (using Morlighem et al., 2014 bed and bed error datasets). For each iteration of ice sheet bed elevation, I calculate the hydraulic potentiometric surface and route water over its path of 'steepest' descent to delineate the catchment. I then use all realizations of the catchment to arrive at a probability map of all major melt water outlets in Greenland. I often find that catchment size is uncertain, with small, random perturbations in basal topography leading to large variations in catchments size. While some catchments are well defined, others can double or halve in size within published basal topography error bars. While some uncertainty will likely always remain, this work points to locations where studies of ice sheet hydrology would be the most successful, allows reinterpretation of past results, and points to where future radar surveys would be most advantageous.

[Comparison of nitrogen loss via surface runoff from two agricultural catchments in semi-arid North China].

PubMed

Lu, Hai-Ming; Yin, Cheng-Qing; Wang, Xia-Hui; Zou, Ying

2008-10-01

Nitrogen loss characteristics via surface runoff from two typical agricultural catchments into Yuqiao Reservoir--the important drinking water source area for Tianjin city in semi-arid North China were investigated through two-year in-situ monitoring and indoor chemical analysis. The results showed that annual nitrogen export mainly concentrated in the rainy period between June to September. About 41% of the annual water output and 52% of the annual total nitrogen output took place in two rainfall events with rainfall> 60 mm in Taohuasi catchment (T catchment), while the distribution of water and nitrogen export among various rainfalls in Caogezhuang catchment (C catchment) was smooth. The rainfall thresholds for the appearance of water and nitrogen export from the outlet of T catchment and C catchment were 20 mm and 10 mm. The mean annual runoff coefficients of C and T catchments were 0.013 2 and 0.001 6, respectively. The mean annual total nitrogen exports from C catchment and T catchment were 1.048 kg x (hm2 x a)(-1) and 0.158 kg x (hm2 x a)(-1) respectively. The difference of micro-topography, landscape pattern and hydrological pathway between two catchments could explain the nitrogen export gap. Micro-topographical features created by long-term anthropological disturbance decrease the runoff generation ability. The distance between nitrogen source area and the outlet in T catchment was around 1 500 m, while such distance in C catchment was just around 200 m. The short distance added the nitrogen export risk via surface runoff. Road-type hydrological pathway in C catchment could transfer nitrogen into the receiving water via surface runoff directly, while nitrogen could be detained within the pathway by many sink structures such as small stones, vegetated buffer strip and dry ponds in T catchment.

Influence of urbanization pattern on stream flow of a peri-urban catchment under Mediterranean climate

NASA Astrophysics Data System (ADS)

Ferreira, Carla S. S.; Walsh, Rory P. D.; Ferreira, António J. D.; Steenhuis, Tammo S.; Coelho, Celeste A. O.

2015-04-01

The demand for better life quality and lower living costs created a great pressure on peri-urban areas, leading to significant land-use changes. The complexity of mixed land-use patterns, however, presents a challenge to understand the hydrological pathways and streamflow response involved in such changes. This study assesses the impact of a actively changing Portuguese peri-urban area on catchment hydrology. It focuses on quantifying streamflow delivery from contributing areas, of different land-use arrangement and the seasonal influence of the Mediterranean climate on stream discharge. The study focuses on Ribeira dos Covões a small (6 km2) peri-urban catchment on the outskirts of Coimbra, one of the main cities in central Portugal. Between 1958 and 2012 the urban area of the catchment expanded from 8% to 40%, mostly at the expense of agriculture (down from 48% to 4%), with woodland now accounting for the remaining 56% of the catchment area. The urban area comprises contrasting urban settings, associated with older discontinuous arrangement of buildings and urban structures and low population density (<25 inhabitants/km), and recent well-defined urban cores dominated by apartment blocks and high population density (9900 inhabitants/km). The hydrological response of the catchment has been monitored since 2007 by a flume installed at the outlet. In 2009, five rainfall gauges and eight additional water level recorders were installed upstream, to assess the hydrological response of different sub-catchments, characterized by distinct urban patterns and either limestone or sandstone lithologies. Annual runoff coefficients range between 14% and 22%. Changes in annual baseflow index (36-39% of annual rainfall) have been small with urbanization (from 34% to 40%) during the monitoring period itself. Annual runoff coefficients were lowest (14-7%) on catchments >80% woodland and highest (29% on sandstone; 18% on limestone) in the most urbanized (49-53% urban) sub-catchments

A sediment budget from a glaciated catchment: reconciling subglacial and periglacial erosion on short timescales

NASA Astrophysics Data System (ADS)

Delaney, Ian; Gindraux, Saskia; Weidmann, Yvo; Bauder, Andreas

2017-04-01

Glaciated catchments are known to expel great amounts of sediment, particularly during periods of climatic perturbation. Sediment in these catchments either originates subglacially, where it is eroded by pressurized water below the glacier, or from periglacial areas, which are commonly comprised of easily erodible, unconsolidated material no longer buttressed and held in place by ice. To better forecast sediment dynamics and erosion rates in to the future, contributions of subglacial and periglacial sediment must be quantified, and the processes controlling erosion in these respective sources described. To determine the relative contributions of these sources, we examine the Griesgletscher catchment in the Swiss Alps. Its rather simplistic geometry, as well as, the presence of a proglacial reservoir that serves as a sediment trap, provides an unusually constrained environment to directly measure sediment sources and sinks in the catchment. Subtraction of three digital elevation models created from structure-from-motion and photogrammetric techniques over a one year period, from October 2015 to October 2016, were used to measured sediment flux from the proglacial area. Furthermore, comparison of bathymetries collected from the proglacial reservoir in fall of 2015 and 2016 determined total sediment flux from the entire catchment over this 10 km2time period. Data from a turbidity meter, installed below the reservoir outflow, suggest that negligible amounts of sediment leave the reservoir. Thus comparison of reservoir bathymetry and sediment fluxes from the proglacial area give estimates of the relative contribution of proglacial and subglacial sediment erosion to total catchment sedimentation. Analysis of this data suggest that while the proglacial area experiences a greater erosion rate, it is likely more sediment originates subglacially. As proglacial areas are expected to grow in area and partially stabilize, and glacial areas are predicted to shrink and possibly

Pollution indicators in groundwater of two agricultural catchments in Lower Silesia (Poland)

NASA Astrophysics Data System (ADS)

Kasperczyk, Lidia; Modelska, Magdalena; Staśko, Stanisław

2016-12-01

The article discusses the content and source of mineral nitrogen compounds in groundwater, based on the data collected in two river catchments in two series (spring and autumn 2014). The study area comprises two catchments located in Lower Silesia, Poland - Cicha Woda and Sąsiecznica. Both catchments are characterised agricultural character of development. In the both researched areas, the points of State Environmental Monitoring (SEM) are located but only the Cicha Woda area is classified as nitrate vulnerable zone (NVZ). To analyse and compare the contamination of Quaternary and Neogene aquifers, the concentration of nitrates, nitrites, ammonium and potassium ions was measured primarily. Results showed the exceedance of nitrogen mineral forms of shallow groundwater Quaternary aquifer in both basins. The concentration of nitrates range from 0.08 to 142.12 mgNO3 -/dm3 (Cicha Woda) and from 2.6 to 137.65 mg NO3 -/dm3 (Sąsiecznica). The major source of pollution is probably the intensive agriculture activity. It causes a degradation of the shallow groundwater because of nitrate, nitrite, potassium, phosphates and ammonium contents. There was no observed contamination of anthropogenic origin in the deeper Neogene aquifer of Cicha Woda catchment.

Approaches to the implementation of the Water Framework Directive: targeting mitigation measures at critical source areas of diffuse phosphorus in Irish catchments.

PubMed

Doody, D G; Archbold, M; Foy, R H; Flynn, R

2012-01-01

The Water Framework Directive (WFD) has initiated a shift towards a targeted approach to implementation through its focus on river basin districts as management units and the natural ecological characteristics of waterbodies. Due to its role in eutrophication, phosphorus (P) has received considerable attention, resulting in a significant body of research, which now forms the evidence base for the programme of measures (POMs) adopted in WFD River Basin Management Plans (RBMP). Targeting POMs at critical sources areas (CSAs) of P could significantly improve environmental efficiency and cost effectiveness of proposed mitigation strategies. This paper summarises the progress made towards targeting mitigation measures at CSAs in Irish catchments. A review of current research highlights that knowledge related to P export at field scale is relatively comprehensive however; the availability of site-specific data and tools limits widespread identification of CSA at this scale. Increasing complexity of hydrological processes at larger scales limits accurate identification of CSA at catchment scale. Implementation of a tiered approach, using catchment scale tools in conjunction with field-by-field surveys could decrease uncertainty and provide a more practical and cost effective method of delineating CSA in a range of catchments. Despite scientific and practical uncertainties, development of a tiered CSA-based approach to assist in the development of supplementary measures would provide a means of developing catchment-specific and cost-effective programmes of measures for diffuse P. The paper presents a conceptual framework for such an approach, which would have particular relevance for the development of supplementary measures in High Status Waterbodies (HSW). The cost and resources necessary for implementation are justified based on HSWs' value as undisturbed reference condition ecosystems. Copyright © 2011 Elsevier Ltd. All rights reserved.

Assessing catchment connectivity using hysteretic loops

NASA Astrophysics Data System (ADS)

Davis, Jason; Masselink, Rens; Goni, Mikel; Gimenez, Rafael; Casali, Javier; Seeger, Manuel; Keesstra, Saskia

2017-04-01

Storm events mobilize large proportions of sediments in catchment systems. Therefore understanding catchment sediment dynamics throughout the continuity of storms and how initial catchment states act as controls on the transport of sediment to catchment outlets is important for effective catchment management. Sediment connectivity is a concept which can explain the origin, pathways and sinks of sediments within catchments (Baartman et al., 2013; Parsons et al., 2015; Masselink et al., 2016a,b; Mekonnen et al., 2016). However, sediment connectivity alone does not provide a practicable mechanism by which the catchment's initial state - and thus the location of entrained sediment in the sediment transport cascade - can be characterized. Studying the dynamic relationship between water discharge (Q) and suspended sediment (SS) at the catchment outlet can provide a valuable research tool to infer the likely source areas and flow pathways contributing to sediment transport because the relationship can be characterized by predictable hysteresis patterns. Hysteresis is observed when the sediment concentration associated with a certain flow rate is different depending on the direction in which the analysis is performed - towards the increase or towards the diminution of the flow. However, the complexity of the phenomena and factors which determine the hysteresis make its interpretation ambiguous. Previous work has described various types of hysteretic loops as well as the cause for the shape of the loop, mainly pointing to the origin of the sediments. The data set for this study comes from four experimental watersheds in Navarre (Spain), owned and maintained by the Government of Navarre. These experimental watersheds have been monitored and studied since 1996 (La Tejería and Latxaga) and 2001 (Oskotz principal and Oskotz woodland). La Tejería and Latxaga watersheds are similar to each other regarding size (approximately 200 ha), geology (marls and sandstones), soils (fine

Adaptations of a physical-based hydrological model for alpine catchments. Application to the upper Durance catchment.

NASA Astrophysics Data System (ADS)

Lafaysse, Matthieu; Hingray, Benoit

2010-05-01

The impact of global change on water resources is expected to be especially pronounced in mountainous areas. Future hydrological scenarios required for impact studies are classically simulated with hydrological models from future meteorological scenarios based on GCMs outputs. Future hydrological regimes of French rivers were estimated following this methodology by Boé et al. (2009) with the physical-based hydrological model SAFRAN-ISBA-MODCOU (SIM), developed by Météo-France. Scenarios obtained for the Alps seem however not very reliable due to the poor performance achieved by the model for the present climate over this region. This work presents possible improvements of SIM for a more relevant simulation of alpine catchments hydrological behavior. Results obtained for the upper Durance catchment (3580 km2) are given for illustration. This catchment is located in Southern French Alps. Its outlet is the Serre-Ponçon lake, a large dam operated for hydropower production, with a key role for water supply in southeastern France. With altitudes ranging from 700 to 4100 meters, the catchment presents highly seasonal flows: minimum and maximum discharges are observed in winter and spring respectively due to snow accumulation and melt, low flows are sustained by glacier melt in late summer (39 km2 are covered by glaciers), major floods can be observed in fall due to large liquid precipitation amounts. Two main limitations of SIM were identified for this catchment. First the 8km-side grid discretization gives a bad representation of the spatial variability of hydrological processes induced by elevation and orientation. Then, low flows are not well represented because the model doesn't include deep storage in aquifers nor ice melt from glaciers. We modified SIM accordingly. For the first point, we applied a discretization based on topography : we divided the catchment in 9 sub-catchments and further 300 meters elevation bands. The vertical variability of meteorological

Fish community structure in freshwater karstic water bodies of the Sian Ka'an Reserve in the Yucatan peninsula, Mexico

USGS Publications Warehouse

Zambrano, L.; Vazquez-Dominguez, E.; Garcia-Bedoya, D.; Loftus, W.F.; Trexler, J.C.

2006-01-01

We evaluated the relationship between limnetic characteristics and fish community structure (based on species richness, abundance and individual size) in contrasting but interconnected inland aquatic habitats of freshwater karstic wetlands in the Yucatan peninsula, Mexico. In the western hemisphere, freshwater karstic wetlands are found in south-eastern Mexico, northern Belize, western Cuba, Andros Island, Bahamas and the Everglades of southern Florida. Only in the Everglades have fish communities been well described. Karstic wetlands are typically oligotrophic because calcium carbonate binds phosphorus, making it relatively unavailable for plants. Fourteen permanent and seasonally flooded water bodies were sampled in both wet and dry seasons in Sian Ka'an Biosphere Reserve, in the Mexican state of Quintana Roo. Water systems were divided by morphology in four groups: cenotes with vegetation (CWV), cenotes without vegetation (CNV), wetlands (WTL), and temporal cenotes (TPC). Discriminant analysis based on physical characteristics such as turbidity, temperature, depth and oxygen confirmed that these habitats differed in characteristics known to influence fish communities. A sample-based rarefaction test showed that species richness was significantly different between water systems groups, showing that WTL and CWV had higher richness values than CNV and TPC. The most abundant fish families, Poeciliidae, Cichlidae and Characidae, differed significantly in average size among habitats and seasons. Seasonal and inter-annual variation, reflecting temporal variation in rainfall, strongly influenced the environmental differences between shallow and deep habitats, which could be linked to fish size and life cycles. Five new records of species were found for the reserve, and one new record for Quintana Roo state. ?? 2006 by Verlag Dr. Friedrich Pfeil.

The water quality of the LOCAR Pang and Lambourn catchments

NASA Astrophysics Data System (ADS)

Neal, C.; Jarvie, H. P.; Wade, A. J.; Neal, M.; Wyatt, R.; Wickham, H.; Hill, L.; Hewitt, N.

The water quality of the Pang and Lambourn, tributaries of the River Thames, in south-eastern England, is described in relation to spatial and temporal dimensions. The river waters are supplied mainly from Chalk-fed aquifer sources and are, therefore, of a calcium-bicarbonate type. The major, minor and trace element chemistry of the rivers is controlled by a combination of atmospheric and pollutant inputs from agriculture and sewage sources superimposed on a background water quality signal linked to geological sources. Water quality does not vary greatly over time or space. However, in detail, there are differences in water quality between the Pang and Lambourn and between sites along the Pang and the Lambourn. These differences reflect hydrological processes, water flow pathways and water quality input fluxes. The Pang’s pattern of water quality change is more variable than that of the Lambourn. The flow hydrograph also shows both a cyclical and "uniform pattern" characteristic of aquifer drainage with, superimposed, a series of "flashier" spiked responses characteristic of karstic systems. The Lambourn, in contrast, shows simpler features without the "flashier" responses. The results are discussed in relation to the newly developed UK community programme LOCAR dealing with Lowland Catchment Research. A descriptive and box model structure is provided to describe the key features of water quality variations in relation to soil, unsaturated and groundwater flows and storage both away from and close to the river.

Flash floods and debris flow in the city area of Messina, North-East part of Sicily, Italy in October 2009: the case of the Giampilieri catchment

NASA Astrophysics Data System (ADS)

Aronica, G. T.; Brigandi, G.; Morey, N.

2010-09-01

Flash floods are phenomena in which the important hydrologic processes are occurring on the same spatial and temporal scales as the intense precipitation. Most of the catchment in the North-East part of Sicily (Italy) are small, with a steep slope, and characterized by short concentration times. These characteristics make those catchment prone to flash flood formation, as demonstrated by events that occurred in the area around Messina in the North-East part of Sicily, Italy in the last recent years. The events occurred on 25th October 2007 in the Mastroguglielmo torrent on the ionic sea coast, on 11th December 2008 in the Elicona catchment on the Tyrrhenian sea coast and on 1st October 2009 in Racinazzi and Giampilieri torrents on the ionic sea coast are an example of flash floods and debris flow events that caused not only significant economic damages to property, buildings, roads and bridges but also, for this that concern the 1st October 2009 flash flood event, loss of human life. This work is aimed by the 1st October 2009 flash flood and debris flow event where a devastating flooding was caused by a very intense rainfall concentrated over the Messina area. The storm caused severe flash floods in many villages around the city of Messina, such as Giampilieri, Scaletta Zanclea, Altolia Superiore and Molino with forty casualties and significant damage to property, buildings, roads and bridges estimated close to 200 million Euro. Main focus of this work is to perform a post event analysis of the 2009 flash flood event, putting together available meteorological and hydrological data in order to get better insight into temporal and spatial variability of the rain storm, the soil moisture condition and the consequent flash floods in the catchment of the Giampilieri catchment. Starting from these information another objective has been, then, to document the post-failure stage of event concerning slid materials. With the help of GIS technology and particularly spatial

Grey water on three agricultural catchments in the Czech Republic

NASA Astrophysics Data System (ADS)

Blazkova, Sarka D.; Kulasova, Alena

2014-05-01

The COST project EU EURO-AGRIWAT focuses apart from other problems on the assessment of water footprint (WF). WF is defined as the quantity of water used to produce some goods or a service. In particular, the WF of an agricultural product is the volume of water used during the crop growing period. It has three components: the green water which is rain or soil moisture transpired by a crop, the blue water which is the amount of irrigation water transpired and the grey water which is the volume of water required to dilute pollutants and to restore the quality standards of the water body. We have been observing three different agricultural catchments. The first of them is Smrzovka Brook, located in the protected nature area in the south part of the Jizerske Mountains. An ecological farming has been carried out there. The second agricultural catchment area is the Kralovsky Creek, which lies in the foothills of the Krkonose Mountains and is a part of an agricultural cooperative. The last agricultural catchment is the Klejnarka stream, located on the outskirts of the fertile Elbe lowlands near Caslav. Catchments Kralovsky Brook and Klejnarka carry out usual agricultural activities. On all three catchments, however, recreational cottages or houses not connected to the sewerage system and/or with inefficient septic tanks occur. The contribution shows our approach to trying to quantify the real grey water from agriculture, i.e. the grey water caused by nutrients not utilised by the crops.

Remote sensing of surface water quality in relation to catchment condition in Zimbabwe

NASA Astrophysics Data System (ADS)

Masocha, Mhosisi; Murwira, Amon; Magadza, Christopher H. D.; Hirji, Rafik; Dube, Timothy

2017-08-01

The degradation of river catchments is one of the most important contemporary environmental problems affecting water quality in tropical countries. In this study, we used remotely sensed Normalised Difference Vegetation Index (NDVI) to assess how catchment condition varies within and across river catchments in Zimbabwe. We then used non-linear regression to test whether catchment condition assessed using the NDVI is significantly (α = 0.05) related with levels of Total Suspended Solids (TSS) measured at different sampling points in thirty-two sub-catchments in Zimbabwe. The results showed a consistent negative curvilinear relationship between Landsat 8 derived NDVI and TSS measured across the catchments under study. In the drier catchments of the country, 98% of the variation in TSS is explained by NDVI, while in wetter catchments, 64% of the variation in TSS is explained by NDVI. Our results suggest that NDVI derived from free and readily available multispectral Landsat series data (Landsat 8) is a potential valuable tool for the rapid assessment of physical water quality in data poor catchments. Overall, the finding of this study underscores the usefulness of readily available satellite data for near-real time monitoring of the physical water quality at river catchment scale, especially in resource-constrained areas, such as the sub-Saharan Africa.

Urban flood simulation and prioritization of critical urban sub-catchments using SWMM model and PROMETHEE II approach

NASA Astrophysics Data System (ADS)

Babaei, Sahar; Ghazavi, Reza; Erfanian, Mahdi

2018-06-01

Urban runoff increased due to augment of impervious surfaces. In order to flood mitigation during rainy season, determination of critical urban sub-catchments is very important for urban planners. Due to lack of information, adopting a simulation approach is one of the practical ways to identify the surcharged junctions and critical sub-catchments. Occurrence of destructive floods in the rainy seasons indicates the inappropriateness of the urban drainage system in Urmia. The main aims of this study were to estimate the surface runoff of urban sub-catchments using SWMM, to evaluate the accuracy of the drainage system of the study urban area and to prioritize sub-catchments using PROMETHEE II approach and SWMM. In the present study, the occurrence of rainfall event of the Urmia city (West Azerbaijan province, Iran) used for estimation of runoff depth. The study area was divided into 22 sub-catchments. For calibration and validation of model parameters, 3 rainfall events and their related runoff were measured. According to sensitivity analysis CN was the most sensitive parameter for model calibration. Amount of surcharged conduits and junctions indicates that the drainage system of the study area has not enough capacity for converting of the runoff and. For 10 year return period, depth of channels should increase by 20% for prevention of flooding in these sub-catchments. Sub-catchments were prioritized using PROMETHEE II approach and its results were compared with SWMM simulation outcomes. Based on SWMM simulation, S11, S7, S18, S16 and S1 sub-catchments are more critical sub-catchments respectively, while according to PROMETHEE method, S1, S11, S16, S14 and S18 are determined as the critical areas.

Similarity and scale in catchment storm response

NASA Technical Reports Server (NTRS)

Wood, Eric F.; Sivapalan, Murugesu; Beven, Keith

1993-01-01

Until recently, very little progress had been made in understanding the relationship between small-scale variability of topography, soil, and rainfalls and the storm response seen at the catchment scale. The work reviewed here represents the first attempt at a systematic theoretical framework for such understanding in the context of surface runoff generation by different processes. The parameterization of hydrological processes over a range of scales is examined, and the concept of the 'representative elementary area' (REA) is introduced. The REA is a fundamental scale for catchment modeling at which continuum assumptions can be applied for the spatially variable controls and parameters, and spatial patterns no longer have to be considered explicitly. The investigation of scale leads into the concept of hydrologic similarity in which the effects of the environmental controls on runoff generation and flood frequency response be investigated independently of catchment scale. The paper reviews the authors' initial results and hopefully will motivate others to also investigate the issues of hydrologic scale and similarity.

Assessment of Useful Plants in the Catchment Area of the Proposed Ntabelanga Dam in the Eastern Cape Province, South Africa

PubMed Central

2017-01-01

Background The developmental projects, particularly construction of dams, result in permanent changes of terrestrial ecosystems through inundation. Objective The present study was undertaken aiming at documenting useful plant species in Ntabelanga dam catchment area that will be impacted by the construction of the proposed dam. Methods A total of 55 randomly selected quadrats were used to assess plant species diversity and composition. Participatory rural appraisal (PRA) methods were used to identify useful plant species growing in the catchment area through interviews with 108 randomly selected participants. Results A total of 197 plant species were recorded with 95 species (48.2%) utilized for various purposes. Use categories included ethnoveterinary and herbal medicines (46 species), food plants (37 species), construction timber and thatching (14 species), firewood (five species), browse, live fence, and ornamental (four species each), and brooms and crafts (two species). Conclusion This study showed that plant species play an important role in the daily life and culture of local people. The construction of Ntabelanga dam is, therefore, associated with several positive and negative impacts on plant resources which are not fully integrated into current decision-making, largely because of lack of multistakeholder dialogue on the socioeconomic issues of such an important project. PMID:28828397

Vulnerability of European freshwater catchments to climate change.

PubMed

Markovic, Danijela; Carrizo, Savrina F; Kärcher, Oskar; Walz, Ariane; David, Jonathan N W

2017-09-01

Climate change is expected to exacerbate the current threats to freshwater ecosystems, yet multifaceted studies on the potential impacts of climate change on freshwater biodiversity at scales that inform management planning are lacking. The aim of this study was to fill this void through the development of a novel framework for assessing climate change vulnerability tailored to freshwater ecosystems. The three dimensions of climate change vulnerability are as follows: (i) exposure to climate change, (ii) sensitivity to altered environmental conditions and (iii) resilience potential. Our vulnerability framework includes 1685 freshwater species of plants, fishes, molluscs, odonates, amphibians, crayfish and turtles alongside key features within and between catchments, such as topography and connectivity. Several methodologies were used to combine these dimensions across a variety of future climate change models and scenarios. The resulting indices were overlaid to assess the vulnerability of European freshwater ecosystems at the catchment scale (18 783 catchments). The Balkan Lakes Ohrid and Prespa and Mediterranean islands emerge as most vulnerable to climate change. For the 2030s, we showed a consensus among the applied methods whereby up to 573 lake and river catchments are highly vulnerable to climate change. The anthropogenic disruption of hydrological habitat connectivity by dams is the major factor reducing climate change resilience. A gap analysis demonstrated that the current European protected area network covers <25% of the most vulnerable catchments. Practical steps need to be taken to ensure the persistence of freshwater biodiversity under climate change. Priority should be placed on enhancing stakeholder cooperation at the major basin scale towards preventing further degradation of freshwater ecosystems and maintaining connectivity among catchments. The catchments identified as most vulnerable to climate change provide preliminary targets for

On the forecast of runoff based on the harmonic analysis of time series of precipitation in the catchment area

NASA Astrophysics Data System (ADS)

Cherednichenko, A. V.; Cherednichenko, A. V.; Cherednichenko, V. S.

2018-01-01

It is shown that a significant connection exists between the most important harmonics, extracted in the process of harmonic analysis of time series of precipitation in the catchment area of rivers and the amount of runoff. This allowed us to predict the size of the flow for a period of up to 20 years, assuming that the main parameters of the harmonics are preserved at the predicted time interval. The results of such a forecast for three river basins of Kazakhstan are presented.

A synoptic survey of ecosystem services from headwater catchments in the United States (presentation)

EPA Science Inventory

Ecosystem production functions for water supply, climate regulation, and water purification were estimated for 568 headwater streams and their catchments. Water supply per unit catchment area was highest in the Northern Appalachian Mountains and lowest in the Northern Plains. C, ...

A synoptic survey of ecosystem services from headwater catchments in the United States- webinar

EPA Science Inventory

Ecosystem production functions for water supply, climate regulation, and water purification were estimated for 568 headwater streams and their catchments. Water supply per unit catchment area was highest in the Northern Appalachian Mountains and lowest in the Northern Plains. C, ...

Using the Spatial Persistence of Soil Moisture Patterns to Estimate Catchment Soil Moisture in Semi-arid Areas

NASA Astrophysics Data System (ADS)

Willgoose, G. R.

2006-12-01

In humid catchments the spatial distribution of soil water is dominated by subsurface lateral fluxes, which leads to a persistent spatial pattern of soil moisture principally described by the topographic index. In contrast, semi-arid, and dryer, catchments are dominated by vertical fluxes (infiltration and evapotranspiration) and persistent spatial patterns, if they exist, are subtler. In the first part of this presentation the results of a reanalysis of a number of catchment-scale long-term spatially-distributed soil moisture data sets are presented. We concentrate on Tarrawarra and SASMAS, both catchments in Australia that are water-limited for at least part of the year and which have been monitored using a variety of technologies. Using the data from permanently installed instruments (neutron probe and reflectometry) both catchments show persistent patterns at the 1-3 year timescale. This persistent pattern is not evident in the field campaign data where field portable instruments (reflectometry) instruments were used. We argue, based on high-resolution soil moisture semivariograms, that high short-distance variability (100mm scale) means that field portable instrument cannot be replaced at the same location with sufficient accuracy to ensure deterministic repeatability of soil moisture measurements from campaign to campaign. The observed temporal persistence of the spatial pattern can be caused by; (1) permanent features of the landscape (e.g. vegetation, soils), or (2) long term memory in the soil moisture store. We argue that it is permanent in which case it is possible to monitor the soil moisture status of a catchment using a single location measurement (continuous in time) of soil moisture using a permanently installed reflectometry instrument. This instrument will need to be calibrated to the catchment averaged soil moisture but the temporal persistence of the spatial pattern of soil moisture will mean that this calibration will be deterministically

Modelling Pesticide Leaching At Column, Field and Catchment Scales I. Analysis of Soil Variability At Field and Catchment Scales

NASA Astrophysics Data System (ADS)

Gärdenäs, A.; Jarvis, N.; Alavi, G.

The spatial variability of soil characteristics was studied in a small agricultural catch- ment (Vemmenhög, 9 km2) at the field and catchment scales. This analysis serves as a basis for assumptions concerning upscaling approaches used to model pesticide leaching from the catchment with the MACRO model (Jarvis et al., this meeting). The work focused on the spatial variability of two key soil properties for pesticide fate in soil, organic carbon and clay content. The Vemmenhög catchment (9 km2) is formed in a glacial till deposit in southernmost Sweden. The landscape is undulating (30 - 65 m a.s.l.) and 95 % of the area is used for crop production (winter rape, winter wheat, sugar beet and spring barley). The climate is warm temperate. Soil samples for or- ganic C and texture were taken on a small regular grid at Näsby Farm, (144 m x 144 m, sampling distance: 6-24 m, 77 points) and on an irregular large grid covering the whole catchment (sampling distance: 333 m, 46 points). At the field scale, it could be shown that the organic C content was strongly related to landscape position and height (R2= 73 %, p < 0.001, n=50). The organic C content of hollows in the landscape is so high that they contribute little to the total loss of pesticides (Jarvis et al., this meeting). Clay content is also related to landscape position, being larger at the hilltop locations resulting in lower near-saturated hydraulic conductivity. Hence, macropore flow can be expected to be more pronounced (see also Roulier & Jarvis, this meeting). The variability in organic C was similar for the field and catchment grids, which made it possible to krige the organic C content of the whole catchment using data from both grids and an uneven lag distance.

Iron, cadmium, and chromium in seagrass (Thalassia testudinum) from a coastal nature reserve in karstic Yucatán.

PubMed

Avelar, Mayra; Bonilla-Heredia, Blanca; Merino-Ibarra, Martín; Herrera-Silveira, Jorge A; Ramirez, Javier; Rosas, Humberto; Valdespino, Job; Carricart-Ganivet, Juan P; Martínez, Ana

2013-09-01

The management of protected areas in karstic regions is a challenge because flooded cave systems form there and provide underground hydrological conducts that may link different zones. As a consequence, affectations to the protected areas can possibly occur as a consequence of human activities in remote areas and may therefore pass undetected. Thus, the monitoring of possible contaminants in these regions is becoming imperative. In this work, we analyze the concentration of essential (iron) and non-essential metals (cadmium and chromium) in the seagrass Thalassia testudinum that grows in Yalahau Lagoon, located in a near-to-pristine protected area of the Yucatán Peninsula, close to the rapidly developing touristic belt of the Mexican Caribbean. Salinity and silicate patterns show that Yalahau is an evaporation lagoon, where groundwater discharge is important. High iron (> 400 μg/g), cadmium (>4 μg/g), and chromium (≈ 1 μg/g) concentrations were found in the area of highest groundwater input of the lagoon. High levels (5.1 μg/g) were also found near the town dump. In the rest of the sampling sites, metal concentrations remained near to background levels as estimated from other works. Temporal changes of concentrations in the seagrass tissues show also a local input and an input from the groundwater that could provoke an environmental problem in the Yalahau Lagoon in the near future.

Exploring the Recurrence of Contributing Area Dynamics

NASA Astrophysics Data System (ADS)

Spence, C.; Mengistu, S. G.

2015-12-01

Recent years have witnessed a progression towards using models as a tool for predicting high frequency contributing area dynamics in catchments. High frequency contributing area modeling can become a viable alternative to the current approach for estimating contributing area in Canadian catchments, which assumes a static portion of the catchment's gross drainage area. The current approach does not consider the spatiotemporal variability of contributing area dynamics, and therefore, represents an important challenge for characterizing the recurrence that saturated areas in the catchment can actively connect and contribute to the main channel in response to runoff producing snowmelt or storm events. Such characterizations are useful to assess the relative importance of different areas within a catchment for runoff generation, and nutrient production and transport. In this study, the PDMROF configuration of Environment Canada's MESH model has been applied to simulate areas actively contributing to daily streamflow from four nested catchments of the Qu'Appelle River basin. The return periods of annual maximum contributing areas were computed using Weibull's equation. The research also evaluates if runoff magnitude is always associated with the same extent and recurrence of contributing area and investigates how contributing area and streamflow return periods relate. This work provides the foundation for evaluating the effect of environmental changes (mainly land use and climate associated changes) on contributing area recurrence by conducting similar investigations under various environmental change scenarios.

Runoff Responses to Forest Thinning at Plot and Catchment Scales in a Headwater Catchment Draining Japanese Cypress Forest

EPA Science Inventory

We examined the effect of forest thinning on runoff generation at plot and catchment scales in headwater basins draining a Japanese cypress (Chamaecyparis obtusa) forest. We removed 58.3% of the stems (corresponding to 43.2% of the basal area) in the treated headwater basin (catc...

Dynamics of natural prokaryotes, viruses, and heterotrophic nanoflagellates in alpine karstic groundwater

PubMed Central

Wilhartitz, Inés C; Kirschner, Alexander K T; Brussaard, Corina P D; Fischer, Ulrike R; Wieltschnig, Claudia; Stadler, Hermann; Farnleitner, Andreas H

2013-01-01

Abstract Seasonal dynamics of naturally occurring prokaryotes, viruses, and heterotrophic nanoflagellates in two hydro-geologically contrasting alpine karst springs were monitored over three annual cycles. To our knowledge, this study is the first to shed light on the occurrence and possible interrelationships between these three groups in karstic groundwater. Hydrological and microbiological standard indicators were recovered simultaneously in order to estimate surface influence, especially during rainfall events. Data revealed a strong dependence of the microbial communities on the prevailing hydrological situation. Prokaryotic numbers averaged 5.1 × 107 and 1.3 × 107 cells L−1, and heterotrophic nanoflagellate abundance averaged 1.1 × 104 and 3 × 103 cells L−1 in the limestone spring type (LKAS2) and the dolomitic spring type (DKAS1), respectively. Viral abundance in LKAS2 and DKAS1 averaged 9.4 × 108 and 1.1 × 108 viruses L−1. Unlike in DKAS1, the dynamic spring type LKAS2 revealed a clear difference between base flow and high discharge conditions. The virus-to-prokaryotes ratio was generally lower by a factor of 2–3, at higher average water residence times. Furthermore, the high prokaryotes-to-heterotrophic nanoflagellate ratios, namely about 4700 and 5400 for LKAS2 and DKAS1, respectively, pointed toward an uncoupling of these two groups in the planktonic fraction of alpine karstic aquifers. Seasonal dynamics of naturally occurring prokaryotes, viruses and heterotrophic nanoflagellates in two hydro-geologically contrasting alpine karst springs were monitored over three annual cycles. Data revealed a strong dependence of the microbial communities on the prevailing hydrological situation. PMID:23828838

Lessons learned for applying a paired-catchment approach in drought analysis

NASA Astrophysics Data System (ADS)

Van Loon, Anne; Rangecroft, Sally; Coxon, Gemma; Agustín Breña Naranjo, José; Van Ogtrop, Floris; Croghan, Danny; Van Lanen, Henny

2017-04-01

Ongoing research is looking to quantify the human impact on hydrological drought using observed data. One potentially suitable method is the paired-catchment approach. Paired catchments have been successfully used for quantifying the impact of human actions (e.g. forest treatment and wildfires) on various components of a catchment's water balance. However, it is unclear whether this method could successfully be applied to drought. In this study, we used a paired-catchment approach to quantify the effects of reservoirs, groundwater abstraction and urbanisation on hydrological drought in the UK, Mexico, and Australia. Following recommendations in literature, we undertook a thorough catchment selection and identified catchments of similar size, climate, geology, and topography. One catchment of the pair was affected by either reservoirs, groundwater abstraction or urbanisation. For the selected catchment pairs, we standardised streamflow time series to catchment area, calculated a drought threshold from the natural catchment and applied it to the human-influenced catchment. The underlying assumption being that the differences in drought severity between catchments can then be attributed to the anthropogenic activity. In some catchments we had local knowledge about human influences, and therefore we could compare our paired-catchment results with hydrological model scenarios. However, we experienced that detailed data on human influences usually are not well recorded. The results showed us that it is important to account for variation in average annual precipitation between the paired catchments to be able to transfer the drought threshold of the natural catchment to the human-influenced catchment. This can be achieved by scaling the discharge by the difference in annual average precipitation. We also found that the temporal distribution of precipitation is important, because if meteorological droughts differ between the paired catchments, this may mask changes caused

Preliminary Map of Potentially Karstic Carbonate Rocks in the Central and Southern Appalachian States

USGS Publications Warehouse

Weary, David J.

2008-01-01

Karst is a landscape produced by dissolution of rocks and the development of integrated subterranean drainages dominated by the flow of ground water in solutionally enlarged conduits. Karst landscapes typically include cave entrances, sinkholes, blind valleys, losing streams, springs, and large and small-scale solution features on bedrock surfaces. Water-bearing rocks beneath the surface containing solutionally enlarged pores, fractures, or conduits are referred to as karst aquifers. About 40 percent of all ground water extracted in the United States comes from karst aquifers (Karst Waters Institute). Karst means many things to many people. To most cavers and many speleologists, karst means areas containing caves. To engineers, home builders, local governments, and insurance companies, karst is exemplified by the occurrence of sinkholes and subsidence hazard. To hydrologists, well drillers, and environmental consultants, the focus on karst may be more limited to karst aquifers and springs. Precise figures are not available, but ground collapses in karst areas in the United States require hundreds of millions of dollars in repair and mitigation costs each year. Most karst in the United States is formed in either carbonate or evaporite rocks. This map depicts only areas of carbonate rock outcrop, the chief host for karst formation in the eastern United States. The U.S. Geological Survey (USGS), in cooperation with the National Cave and Karst Research Institute (NCKRI), the National Speleological Society (NSS), and various State geological surveys, is working on a new national karst map that will delineate areas of karst and karst-like features nationwide. This product attempts to identify potentially karstic areas of the Appalachian states as defined by the Appalachian Regional Commission (ARC), with the addition of the state of Delaware. This map is labeled preliminary because there is an expectation that it will be revised and updated as part of a new national

The role of land use and soils in regulating water flow in small headwater catchments of the Andes

NASA Astrophysics Data System (ADS)

Roa-GarcíA, M. C.; Brown, S.; Schreier, H.; Lavkulich, L. M.

2011-05-01

Land use changes can have a significant impact on the terrestrial component of the water cycle. This study provides a comparison of three small headwater catchments in the Andean mountains of Colombia with different composition of land use. Several methods were used to quantify differences in the hydrological behavior of these catchments such as flow duration curves, stormflow analysis, and the linear reservoir concept. They were combined with an analysis of the characteristics of soils that contribute to understanding the aggregate catchment hydrological behavior. Andisols, which are soils formed in volcanic areas and with a large capacity to hold water, amplify differences in land use and limit the potential impact of land use management activities (conservation or restoration) on the water regulation function of catchments. Of the three studied catchments, less variability of flows was observed from the catchment with a larger percentage of area in forest, and a slower decrease of flows in the dry season was observed for the catchment with a relatively higher percentage of area in wetlands. Evidence is provided for the infiltration trade-off hypothesis for tropical environments, which states that after forest removal, soil infiltration rates are smaller and the water losses through quick flow are larger than the gains by reduced evapotranspiration; this is compatible with the results of the application of the linear reservoir concept showing a faster release of water for the least forested catchment.

Controls on Water Storage, Mixing and Release in a Nested Catchment Set-up with Clean and Mixed Physiographic Characteristics

NASA Astrophysics Data System (ADS)

Pfister, L.; McDonnell, J.; Hissler, C.; Martínez-Carreras, N.; Klaus, J.

2015-12-01

With catchment water storage being only rarely determined, storage dynamics remain largely unknown to date. However, storage bears considerable potential for catchment inter-comparison exercises, as well as it is likely to have an important role in regulating catchment functions. Catchment comparisons across a wide range of environments and scales will help to increase our understanding of relationships between storage dynamics and catchment processes. With respect to the potential of catchment storage for bringing new momentum to catchment classification and catchment processes understanding we currently investigate spatial and temporal variability of dynamic storage in a nested catchment set-up (16 catchments) of the Alzette River basin (Luxembourg, Europe), covering a wide range of geological settings, catchment areas, contrasted landuse, and hydro-meteorological and tracer series. We define catchment storage as the total amount of water stored in a control volume, delimited by the catchment's topographical boundaries and depth of saturated and unsaturated zones. Complementary storage assessments (via input-output dynamics of natural tracers, geographical sounding, groundwater level measurements, soil moisture measurements, hydrometry) are carried out for comparison purposes. In our nested catchment set-up we have (1) assessed dependencies between geology, catchment permeability and winter runoff coefficients, (2) calculated water balance derived catchment storage and mixing potential and quantified how dynamic storage differs between catchments and scales, and (3) examined how stream baseflow dD (as a proxy for baseflow transit time) and integrated flow measures (like the flow duration curve) relate to bedrock geology. Catchments with higher bedrock permeability exhibited larger storage capacities and eventually lower average winter runoff coefficients. Over a time-span of 11 years, all catchments re-produced the same winter runoff coefficients year after year

Mapping for the management of diffuse pollution risks related to agricultural plant protection practices: case of the Etang de l'Or catchment area in France.

PubMed

Mghirbi, Oussama; Bord, Jean-Paul; Le Grusse, Philippe; Mandart, Elisabeth; Fabre, Jacques

2018-03-08

Faced with health, environmental, and socio-economic issues related to the heavy use of pesticides, diffuse phytosanitary pollution becomes a major concern shared by all the field actors. These actors, namely the farmers and territorial managers, have expressed the need to implement decision support tools for the territorial management of diffuse pollution resulting from the plant protection practices and their impacts. To meet these steadily increasing requests, a cartographic analysis approach was implemented based on GIS which allows the spatialization of the diffuse pollution impacts related to plant protection practices on the Etang de l'Or catchment area in the South of France. Risk mapping represents a support-decision tool that enables the different field actors to identify and locate vulnerable areas, so as to determine action plans and agri-environmental measures depending on the context of the natural environment. This work shows that mapping is helpful for managing risks related to the use of pesticides in agriculture by employing indicators of pressure (TFI) and risk on the applicator's health (IRSA) and on the environment (IRTE). These indicators were designed to assess the impact of plant protection practices at various spatial scales (field, farm, etc.). The cartographic analysis of risks related to plant protection practices shows that diffuse pollution is unequally located in the North (known for its abundant garrigues and vineyards) and in the South of the Etang de l'Or catchment area (the Mauguio-Lunel agricultural plain known for its diversified cropping systems). This spatial inequity is essentially related to land use and agricultural production system. Indeed, the agricultural lands cover about 60% of the total catchment area. Consequently, this cartographic analysis helps the territorial actors with the implementation of strategies for managing risks of diffuse pollution related to pesticides use in agriculture, based on environmental and

Hydrologic connectivity between landscapes and streams: Transferring reach‐ and plot‐scale understanding to the catchment scale

USGS Publications Warehouse

Jencso, Kelsey G.; McGlynn, Brian L.; Gooseff, Michael N.; Wondzell, Steven M.; Bencala, Kenneth E.; Marshall, Lucy A.

2009-01-01

The relationship between catchment structure and runoff characteristics is poorly understood. In steep headwater catchments with shallow soils the accumulation of hillslope area (upslope accumulated area (UAA)) is a hypothesized first‐order control on the distribution of soil water and groundwater. Hillslope‐riparian water table connectivity represents the linkage between the dominant catchment landscape elements (hillslopes and riparian zones) and the channel network. Hydrologic connectivity between hillslope‐riparian‐stream (HRS) landscape elements is heterogeneous in space and often temporally transient. We sought to test the relationship between UAA and the existence and longevity of HRS shallow groundwater connectivity. We quantified water table connectivity based on 84 recording wells distributed across 24 HRS transects within the Tenderfoot Creek Experimental Forest (U.S. Forest Service), northern Rocky Mountains, Montana. Correlations were observed between the longevity of HRS water table connectivity and the size of each transect's UAA (r2 = 0.91). We applied this relationship to the entire stream network to quantify landscape‐scale connectivity through time and ascertain its relationship to catchment‐scale runoff dynamics. We found that the shape of the estimated annual landscape connectivity duration curve was highly related to the catchment flow duration curve (r2 = 0.95). This research suggests internal catchment landscape structure (topography and topology) as a first‐order control on runoff source area and whole catchment response characteristics.

Evaluation of catchment delineation methods for the medium-resolution National Hydrography Dataset

USGS Publications Warehouse

Johnston, Craig M.; Dewald, Thomas G.; Bondelid, Timothy R.; Worstell, Bruce B.; McKay, Lucinda D.; Rea, Alan; Moore, Richard B.; Goodall, Jonathan L.

2009-01-01

Different methods for determining catchments (incremental drainage areas) for stream segments of the medium-resolution (1:100,000-scale) National Hydrography Dataset (NHD) were evaluated by the U.S. Geological Survey (USGS), in cooperation with the U.S. Environmental Protection Agency (USEPA). The NHD is a comprehensive set of digital spatial data that contains information about surface-water features (such as lakes, ponds, streams, and rivers) of the United States. The need for NHD catchments was driven primarily by the goal to estimate NHD streamflow and velocity to support water-quality modeling. The application of catchments for this purpose also demonstrates the broader value of NHD catchments for supporting landscape characterization and analysis. Five catchment delineation methods were evaluated. Four of the methods use topographic information for the delineation of the NHD catchments. These methods include the Raster Seeding Method; two variants of a method first used in a USGS New England study-one used the Watershed Boundary Dataset (WBD) and the other did not-termed the 'New England Methods'; and the Outlet Matching Method. For these topographically based methods, the elevation data source was the 30-meter (m) resolution National Elevation Dataset (NED), as this was the highest resolution available for the conterminous United States and Hawaii. The fifth method evaluated, the Thiessen Polygon Method, uses distance to the nearest NHD stream segments to determine catchment boundaries. Catchments were generated using each method for NHD stream segments within six hydrologically and geographically distinct Subbasins to evaluate the applicability of the method across the United States. The five methods were evaluated by comparing the resulting catchments with the boundaries and the computed area measurements available from several verification datasets that were developed independently using manual methods. The results of the evaluation indicated that the two

Relationships between landscape pattern, wetland characteristics, and water quality in agricultural catchments.

PubMed

Moreno-Mateos, David; Mander, Ulo; Comín, Francisco A; Pedrocchi, César; Uuemaa, Evelyn

2008-01-01

Water quality in streams is dependent on landscape metrics at catchment and wetland scales. A study was undertaken to evaluate the correlation between landscape metrics, namely patch density and area, shape, heterogeneity, aggregation, connectivity, land-use ratio, and water quality variables (salinity, nutrients, sediments, alkalinity, other potential pollutants and pH) in the agricultural areas of a semiarid Mediterranean region dominated by irrigated farmlands (NE Spain). The study also aims to develop wetland construction criteria in agricultural catchments. The percentage of arable land and landscape homogeneity (low value of Simpson index) are significantly correlated with salinity (r(2) = 0.72) and NO(3)-N variables (r(2) = 0.49) at catchment scale. The number of stock farms was correlated (Spearman's corr. = 0.60; p < 0.01) with TP concentration in stream water. The relative abundance of wetlands and the aggregation of its patches influence salinity variables at wetland scale (r(2) = 0.59 for Na(+) and K(+) concentrations). The number and aggregation of wetland patches are closely correlated to the landscape complexity of catchments, measured as patch density (r(2) = 0.69), patch size (r(2) = 0.53), and landscape heterogeneity (r(2) = 0.62). These results suggest that more effective results in water quality improvement would be achieved if we acted at both catchment and wetland scales, especially reducing landscape homogeneity and creating numerous wetlands scattered throughout the catchment. A set of guidelines for planners and decision makers is provided for future agricultural developments or to improve existing ones.

Water exchange, mixing and transient storage between a saturated karstic conduit and the surrounding aquifer: Groundwater flow modeling and inputs from stable water isotopes

NASA Astrophysics Data System (ADS)

Binet, S.; Joigneaux, E.; Pauwels, H.; Albéric, P.; Fléhoc, Ch.; Bruand, A.

2017-01-01

Water exchanges between a karstic conduit and the surrounding aquifer are driven by hydraulic head gradient at the interface between these two domains. The case-study presented in this paper investigates the impact of the geometry and interface conditions around a conduit on the spatial distribution of these exchanges. Isotopic (δ18O and δD), discharge and water head measurements were conducted at the resurgences of a karst system with a strong allogenic recharge component (Val d'Orléans, France), to estimate the amounts of water exchanged and the mixings between a saturated karstic conduit and the surrounding aquifer. The spatio-temporal variability of the observed exchanges was explored using a 2D coupled continuum-conduit flow model under saturated conditions (Feflow®). The inputs from the water heads and stable water isotopes in the groundwater flow model suggest that the amounts of water flowing from the aquifer are significant if the conduit flow discharges are less than the conduit flow capacity. This condition creates a spatial distribution of exchanges from upstream where the aquifer feeds the conduit (recharge area) to downstream where the conduit reaches its maximum discharge capacity and can feed the aquifer (discharge area). In the intermediate transport zone no exchange between the two domains takes place that brings a new criterion to delineate the vulnerable zones to surface water. On average, 4% of the water comes from the local recharge, 80% is recent river water and 16% is old river water. During the November 2008 flood, both isotopic signatures and model suggest that exchanges fluctuate around this steady state, limited when the river water level increases and intensified when the river water level decreases. The existence of old water from the river suggests a transient storage at the aquifer/conduit interface that can be considered as an underground hyporheic zone.

Phase II modification of the Water Availability Tool for Environmental Resources (WATER) for Kentucky: The sinkhole-drainage process, point-and-click basin delineation, and results of karst test-basin simulations

USGS Publications Warehouse

Taylor, Charles J.; Williamson, Tanja N.; Newson, Jeremy K.; Ulery, Randy L.; Nelson, Hugh L.; Cinotto, Peter J.

2012-01-01

This report describes Phase II modifications made to the Water Availability Tool for Environmental Resources (WATER), which applies the process-based TOPMODEL approach to simulate or predict stream discharge in surface basins in the Commonwealth of Kentucky. The previous (Phase I) version of WATER did not provide a means of identifying sinkhole catchments or accounting for the effects of karst (internal) drainage in a TOPMODEL-simulated basin. In the Phase II version of WATER, sinkhole catchments are automatically identified and delineated as internally drained subbasins, and a modified TOPMODEL approach (called the sinkhole drainage process, or SDP-TOPMODEL) is applied that calculates mean daily discharges for the basin based on summed area-weighted contributions from sinkhole drain-age (SD) areas and non-karstic topographically drained (TD) areas. Results obtained using the SDP-TOPMODEL approach were evaluated for 12 karst test basins located in each of the major karst terrains in Kentucky. Visual comparison of simulated hydrographs and flow-duration curves, along with statistical measures applied to the simulated discharge data (bias, correlation, root mean square error, and Nash-Sutcliffe efficiency coefficients), indicate that the SDPOPMODEL approach provides acceptably accurate estimates of discharge for most flow conditions and typically provides more accurate simulation of stream discharge in karstic basins compared to the standard TOPMODEL approach. Additional programming modifications made to the Phase II version of WATER included implementation of a point-and-click graphical user interface (GUI), which fully automates the delineation of simulation-basin boundaries and improves the speed of input-data processing. The Phase II version of WATER enables the user to select a pour point anywhere on a stream reach of interest, and the program will automatically delineate all upstream areas that contribute drainage to that point. This capability enables

Sources and yields of dissolved carbon in northern Wisconsin stream catchments with differing amounts of Peatland

USGS Publications Warehouse

Elder, J.F.; Rybicki, N.B.; Carter, V.; Weintraub, V.

2000-01-01

In five tributary streams (four inflowing and one outflowing) of 1600-ha Trout Lake in northern Wisconsin, USA, we examined factors that can affect the magnitude of stream flow and transport of dissolved organic and inorganic carbon (DOC and DIC) through the streams to the lake. One catchment, the Allequash Creek basin, was investigated in more detail to describe the dynamics of carbon flow and to identify potential carbon sources. Stream flows and carbon loads showed little or no relation to surface-water catchment area. They were more closely related to ground-water watershed area because ground-water discharge, from both local and regional sources, is a major contributor to the hydrologic budgets of these catchments. An important factor in determining carbon influx to the stream is the area of peatland in the catchment. Peatland porewaters contain DOC concentrations up to 40 mg l-1 and are a significant potential carbon source. Ground-water discharge and lateral flow through peat are the suspected mechanisms for transport of that carbon to the streams. Carbon and nitrogen isotopes suggested that the sources of DOC in Allequash Creek above Allequash Lake were wetland vegetation and peat and that the sources below Allequash Lake were filamentous algae and wild rice. Catchments with high proportions of peatland, including the Allequash Creek catchment, tended to have elevated DOC loads in outflowing stream water. Respiration and carbon mineralization in lakes within the system tend to produce low DOC and low DOC/DIC in lake outflows, especially at Trout Lake. In Allequash Lake, however, the shallow peat island and vegetation-filled west end were sources of DOC. Despite the vast carbon reservoir in the peatlands, carbon yields were very low in these catchments. Maximum yields were on the order of 2.5 g m-2 y-1 DOC and 5.5 g m-2 y-1 DIC. The small yields were attributable to low stream flows due to lack of significant overland runoff and very limited stream channel

The influence of climate, topography and land-use on the hydrology of ephemeral upland catchments

NASA Astrophysics Data System (ADS)

Daly, E.; Webb, J.; Dresel, E.

2016-12-01

We report on an on-going project aimed at determining the effects of climate variability and land use change on water resources in ephemeral productive catchments. Meteorological data (including rainfall, solar radiation, air temperature, humidity and wind speed), streamflow and groundwater levels were collected continuously for over five years in seven ephemeral catchments in southeastern Australia. The catchments, dominated by either pasture for grazing (four) or Eucalyptus globulus (blue gum) plantations of different ages (three), were located in three different geological settings. Rainfall varied from higher than the long-term average of this area for the initial years of the study period to much drier than the long-term average for the last two years. Groundwater levels in the farm sites remained stable or slightly increased through the study period, while levels declined in all the plantation catchments, where evapotranspiration rates were greater than rainfall. The trees intercept groundwater recharge and in some areas of the catchments directly access groundwater. Streamflow occurred mainly during winter, with short-term flows in summer caused by sporadic large rainfall events. Despite the large annual rainfall variability, flow rates in each year were similar in most catchments, with the duration of flow being important in determining the annual flow. The frequency rather than the amount of rainfall events determines the generation of streamflow in the two catchments with steeper slopes. The effect of the tree plantations on streamflow varied from a substantial reduction in one catchment to no effect in another, where the tree rows are oriented predominantly downslope, allowing greater runoff. In the third plantation catchment, geology is the main driver of runoff due to capture into underlying karst conduits.

Process-based interpretation of conceptual hydrological model performance using a multinational catchment set

NASA Astrophysics Data System (ADS)

Poncelet, Carine; Merz, Ralf; Merz, Bruno; Parajka, Juraj; Oudin, Ludovic; Andréassian, Vazken; Perrin, Charles

2017-08-01

Most of previous assessments of hydrologic model performance are fragmented, based on small number of catchments, different methods or time periods and do not link the results to landscape or climate characteristics. This study uses large-sample hydrology to identify major catchment controls on daily runoff simulations. It is based on a conceptual lumped hydrological model (GR6J), a collection of 29 catchment characteristics, a multinational set of 1103 catchments located in Austria, France, and Germany and four runoff model efficiency criteria. Two analyses are conducted to assess how features and criteria are linked: (i) a one-dimensional analysis based on the Kruskal-Wallis test and (ii) a multidimensional analysis based on regression trees and investigating the interplay between features. The catchment features most affecting model performance are the flashiness of precipitation and streamflow (computed as the ratio of absolute day-to-day fluctuations by the total amount in a year), the seasonality of evaporation, the catchment area, and the catchment aridity. Nonflashy, nonseasonal, large, and nonarid catchments show the best performance for all the tested criteria. We argue that this higher performance is due to fewer nonlinear responses (higher correlation between precipitation and streamflow) and lower input and output variability for such catchments. Finally, we show that, compared to national sets, multinational sets increase results transferability because they explore a wider range of hydroclimatic conditions.

Identifying Catchment-Scale Predictors of Coal Mining Impacts on New Zealand Stream Communities.

PubMed

Clapcott, Joanne E; Goodwin, Eric O; Harding, Jon S

2016-03-01

Coal mining activities can have severe and long-term impacts on freshwater ecosystems. At the individual stream scale, these impacts have been well studied; however, few attempts have been made to determine the predictors of mine impacts at a regional scale. We investigated whether catchment-scale measures of mining impacts could be used to predict biological responses. We collated data from multiple studies and analyzed algae, benthic invertebrate, and fish community data from 186 stream sites, including un-mined streams, and those associated with 620 mines on the West Coast of the South Island, New Zealand. Algal, invertebrate, and fish richness responded to mine impacts and were significantly higher in un-mined compared to mine-impacted streams. Changes in community composition toward more acid- and metal-tolerant species were evident for algae and invertebrates, whereas changes in fish communities were significant and driven by a loss of nonmigratory native species. Consistent catchment-scale predictors of mining activities affecting biota included the time post mining (years), mining density (the number of mines upstream per catchment area), and mining intensity (tons of coal production per catchment area). Mining was associated with a decline in stream biodiversity irrespective of catchment size, and recovery was not evident until at least 30 years after mining activities have ceased. These catchment-scale predictors can provide managers and regulators with practical metrics to focus on management and remediation decisions.

Identifying Catchment-Scale Predictors of Coal Mining Impacts on New Zealand Stream Communities

NASA Astrophysics Data System (ADS)

Clapcott, Joanne E.; Goodwin, Eric O.; Harding, Jon S.

2016-03-01

Coal mining activities can have severe and long-term impacts on freshwater ecosystems. At the individual stream scale, these impacts have been well studied; however, few attempts have been made to determine the predictors of mine impacts at a regional scale. We investigated whether catchment-scale measures of mining impacts could be used to predict biological responses. We collated data from multiple studies and analyzed algae, benthic invertebrate, and fish community data from 186 stream sites, including un-mined streams, and those associated with 620 mines on the West Coast of the South Island, New Zealand. Algal, invertebrate, and fish richness responded to mine impacts and were significantly higher in un-mined compared to mine-impacted streams. Changes in community composition toward more acid- and metal-tolerant species were evident for algae and invertebrates, whereas changes in fish communities were significant and driven by a loss of nonmigratory native species. Consistent catchment-scale predictors of mining activities affecting biota included the time post mining (years), mining density (the number of mines upstream per catchment area), and mining intensity (tons of coal production per catchment area). Mining was associated with a decline in stream biodiversity irrespective of catchment size, and recovery was not evident until at least 30 years after mining activities have ceased. These catchment-scale predictors can provide managers and regulators with practical metrics to focus on management and remediation decisions.

Catchments network on badlands around Mediterranean area (RESOBAM)

NASA Astrophysics Data System (ADS)

Copard, Yoann; Lebouteiller, Caroline; Regues-Munoz, David; Latron, Jerome; Solé-Benet, Albert; Canton, Yolanda; Nadal-Romero, Estela; Della Seta, Marta; Rossi, Mauro; Capolongo, Domenico; Maquaire, Olivier; Forey, Estelle; Di-Giovanni, Christian; Gallart, Francesc; Delmonte, Maurizio; Vergari, Francesca; Massei, Nicolas; Torri, Dino

2016-04-01

Between 2013 and 2014, a network funded by MISTRALS-ENVIMED institution, was born around some instrumented catchments developing a badland-type morphology. This network has grouped 3 countries (France, Spain and Italy) with 12 scientific labs. RESOBAM has concerned two sites in France (Draix-Bléone and Vaches Noires), three in Spain (Vallcebre, Araguas and El Cautivo) and some sites in Italy (Tuscany, Basilicata). Main goal of this network was to federate the research around badlands at the European scale, by proposing some scientific topics as: sediment and water transports / budget, (bio)geochemical cycles, agricultural (farming), education, restoration, cultural heritage, soil conservation / biodiversity, climatic change etc. Other main interests were also to propose some common scientific projects and the development of students exchanges. This communication presents the synthesis of our four meetings held at Draix, Zaragoza, Almeriá and Rouen and some perspectives to continue this network.

Spatial characterization of catchment dispersion mechanisms in an urban context

NASA Astrophysics Data System (ADS)

Rossel, Florian; Gironás, Jorge; Mejía, Alfonso; Rinaldo, Andrea; Rodriguez, Fabrice

2014-12-01

Previous studies have examined in-depth the dispersion mechanisms in natural catchments. In contrast, these dispersion mechanisms have been studied little in urban catchments, where artificial transport elements and morphological arrangements are expected to modify travel times and mobilize excess rainfall from spatially distributed impervious sites. This has the ability to modify the variance of the catchment's travel times and hence the total dispersion. This work quantifies the dispersion mechanisms in an urban catchment using the theory of transport by travel times as represented by the Urban Morpho-climatic Instantaneous Unit Hydrograph (U-McIUH) model. The U-McIUH computes travel times based on kinematic wave theory and accounts explicitly for the path heterogeneities and altered connectivity patterns characteristic of an urban drainage network. The analysis is illustrated using the Aubinière urban catchment in France as a case study. We found that kinematic dispersion is dominant for small rainfall intensities, whereas geomorphologic dispersion becomes more dominant for larger intensities. The total dispersion scales with the drainage area in a power law fashion. The kinematic dispersion is dominant across spatial scales up to a threshold of approximately 2-3 km2, after which the geomorphologic dispersion becomes more dominant. Overall, overland flow is responsible for most of the dispersion in the catchment, while conduits tend to counteract the increase of the geomorphologic dispersion with a negative kinematic dispersion. Further study with other catchments is needed to asses if the latter is a general feature of urban drainage networks.

Hillslope versus riparian zone runoff contributions in headwater catchments: A multi-watershed comparison

NASA Astrophysics Data System (ADS)

McGlynn, B. L.; McGlynn, B. L.; McDonnell, J. J.; Hooper, R. P.; Shanley, J. B.; Hjerdt, K. N.; Hjerdt, K. N.

2001-12-01

It is often assumed that hillslope and riparian areas constitute the two most important and identifiable landscape units contributing to catchment runoff in upland humid catchments. Nevertheless, the relative amount and timing of hillslope versus riparian contributions to stormflow are poorly understood across different watersheds. We quantified the contributions of hillslopes and riparian zones to stormflow using physical, chemical, and isotopic techniques across 3 diverse ({ ~}15 ha) headwater catchments: a highly responsive steep wet watershed (Maimai, New Zealand), a moderately steep snowmelt dominated watershed (Sleepers, River, VT), and at a highly seasonal relatively low relief watershed (Panola Mt., Georgia). We monitored catchment runoff, internal hydrological response, and isotopic and solute dynamics for discrete riparian and hillslope zones within each catchment. Monitored catchment positions, including hillslope trenches at Maimai and Panola, were used to characterize directly, the hydrologic response and source water signatures for hillslope zones and riparian zones. We also examined the spatial and temporal source components of catchment stormflow using 3-component mass balance hydrograph separation techniques. At Maimai, NZ we found that hillslope runoff comprised 47-55% of total runoff during a 70 mm event. Despite the large amount of subsurface hillslope runoff in total catchment stormflow, riparian and channel zones accounted for 28% out of 29% of the total new water measured catchment runoff. Riparian water dominated the storm hydrograph composition early in the event, although hillslope water reached the catchment outlet soon after hillslope water tables were developed. Preliminary results for Sleepers River, VT and Panola Mountain, GA indicate that the timing and relative proportion of hillslope water in catchment runoff is later and smaller than at Maimai. Our multi-catchment comparison suggests that the ratio of the riparian reservoir to the

Spatiotemporal dynamics of suspended sediment within an actively urbanizing peri-urban catchment in Portugal

NASA Astrophysics Data System (ADS)

Walsh, Rory; Ferreira, Carla; Ferreira, Antonio

2016-04-01

Suspended sediment levels tend to be enhanced in urban catchments, but vary considerably with (amongst many other factors) the degree of active urban development or redevelopment within the catchment and 'urbanization style'. Relatively little, however, is known about the relationship between suspended solids and urbanization style in peri-urban Mediterranean environments. This paper focuses on spatiotemporal suspended sediment dynamics within a typical Portuguese peri-urban catchment, Ribeira dos Covoes, that is undergoing rapid urbanization. The catchment currently has a 40% urban cover, with 17% impervious surfaces, dispersed between woodland (56%) and agricultural areas (4%). The study uses suspended sediment concentration measurements made at the catchment outlet (ESAC) and in three upstream tributaries: (i) Espírito Santo, with a largest urban area (49%); (ii) Porto Bordalo, 39% urbanized; and (iii) Quinta, 22% urbanized, most of which (18%) being an enterprise park under construction. Water sampling was carried out manually during 10 storm hydrographs between October 2011 and March 2013. Suspended sediment concentrations (SSC) were derived by laboratory analysis of the filtered samples using the gravimetric method. In addition total dissolved solids concentrations (TDS) were estimated using conductivity readings. Greatest SSCs were recorded in the Quinta sub-catchment and at the catchment outlet at ESAC (113-4320 mg L-1 and 200-1656 mg L-1, respectively) than in the Espírito Santo and Porto Bordalo sub-catchments (183-852 mg L-1 and 47-598 mg L-1 respectively, despite their greater impervious cover. The greatest SSCs for Quinta result from it containing the construction site, but it showed lower TDS (56-4010 mg L-1), perhaps due to the coarse sandy nature of the construction site. Higher TDS concentrations, however, were displayed in Porto Bordalo (27-5400 mg L-1), possibly due to the loamy soil. Espírito Santo, comprising sandy-loam soils, displayed 27

Human impacts on river water quality- comparative research in the catchment areas of the Tone River and the Mur River-

NASA Astrophysics Data System (ADS)

Kogure, K.

2013-12-01

Human activities in river basin affect river water quality as water discharges into river with pollutant after we use it. By detecting pollutants source, pathway, and influential factor of human activities, it will be possible to consider proper river basin management. In this study, material flow analysis was done first and then nutrient emission modeling by MONERIS was conducted. So as to clarify land use contribution and climate condition, comparison of Japanese and European river basin area has been made. The model MONERIS (MOdelling Nutrient Emissions in RIver Systems; Behrendt et al., 2000) was applied to estimate the nutrient emissions in the Danube river basin by point sources and various diffuse pathways. Work for the Mur River Basin in Austria was already carried out by the Institute of Water Quality, Resources and Waste Management at the Vienna University of Technology. This study treats data collection, modelling for the Tone River in Japan, and comparative analysis for these two river basins. The estimation of the nutrient emissions was carried out for 11 different sub catchment areas covering the Tone River Basin for the time period 2000 to 2006. TN emissions into the Tone river basin were 51 kt/y. 67% was via ground water and dominant for all sub catchments. Urban area was also important emission pathway. Human effect is observed in urban structure and agricultural activity. Water supply and sewer system make urban water cycle with pipeline structure. Excess evapotranspiration in arable land is also influential in water cycle. As share of arable land is 37% and there provides agricultural products, it is thought that N emission from agricultural activity is main pollution source. Assumption case of 10% N surplus was simulated and the result was 99% identical to the actual. Even though N surplus reduction does not show drastic impact on N emission, it is of importance to reduce excess of fertilization and to encourage effective agricultural activity

Sediment tracing in the upper Hunter catchment using elemental and mineralogical compositions: Implications for catchment-scale suspended sediment (dis)connectivity and management

NASA Astrophysics Data System (ADS)

Fryirs, Kirstie; Gore, Damian

2013-07-01

River bed colmation layers clog the interstices of gravel-bed rivers, impeding the vertical exchange of water and nutrients that drives ecosystem function in the hyporheic zone. In catchments where fine-grained sediment supply has increased since human disturbance, understanding sediment provenance and the (dis)connectivity of supply allows practitioners to target sediment source problems and treat them within catchment management plans. Release of alluvial fine-grained sediment from channel bank erosion since European settlement has resulted in the formation of a colmation layer along the upper Hunter River at Muswellbrook, eastern Australia. X-ray fluorescence spectrometry (XRF) and X-ray diffractometry (XRD) are used to determine the elemental and mineralogical signatures of colmation layer and floodplain sediment sources across this 4480 km2 catchment. This sediment tracing technique is used to construct a picture of how suspended sediment supply and (dis)connectivity operates in this catchment. In this system, the primary source areas are subcatchments in which sediments are stored largely in partly confined floodplain pockets, but from which sediment supply is unimpeded and directly connected to the receiving reach. Subcatchments in which alluvial sediment storage is significant — and which contain large, laterally unconfined valleys — are essentially 'switched off' or disconnected from the receiving reach. This is because large sediment sinks act to trap fine-grained sediment before it reaches the receiving reach, forming a buffer along the sediment conveyor belt. Given the age structure of floodplains in the receiving reach, this pattern of source area contributions and (dis)connectivity must have occurred throughout the Holocene.

Sediment budgets of mountain catchments: Scale dependence and the influence of land-use

NASA Astrophysics Data System (ADS)

Förster, Helga; Dotterweich, Markus; Wunderlich, Jürgen

2010-05-01

Long-term sediment budgets of forested mountain catchments are scarcely investigated today. This is because they are traditionally expected to show few erosion features and low sediment delivery. This opinion originates from process-based hydrological studies proving the runoff preventing properties of trees and forest soils. In addition mountain areas have been colonized later and only sporadically compared to the fruitful loess-covered lowlands. On the other hand steep hillslopes, narrow valleys and the availability of regolith cause a high erosion potential. And there is evidence that historical floods and yearly occurring storms initiate intensive but local and sporadic erosion events. Sediment budgets from zero-order catchments of the Palatinate Forest in the south-western sandstone escarpment in Rhineland-Palatinate show spatially varying intensities of land use impact and relief conditions. The budgets are based on field data and a soilscape model of an upper periglacial cover bed with a homogenous thickness. OSL- and 14C-dates of colluvial deposits allow relating erosion events to land-use changes derived from historical maps and written archives. The presented case studies from the Palatinate Forest are of special interest as the high proximity to the loess-covered and intensively cultivated Rhine Graben effected settlement and land-use intensity in the mountain catchments. Clear cuts for settlements were joined by deforestation for agriculture and stretched mainly along the Haardtrand and high order valleys. Off these areas the strength of interference in the forest ecosystem depended on transport possibilities and distance to the Rhine Graben. In the vicinity strong devastation and clear cutting occurred. With increasing distance the felling intensity decreased and some parts seem to be nearly undisturbed until the 18th century. The needs for wood were controlled by the economical development as well as political decisions on local to European scale. The

RNICO: a new simple geometric index for assessing the impact of urban development pattern on peak flows in urban catchments

NASA Astrophysics Data System (ADS)

Kasaee Roodsari, B.; Chandler, D. G.

2016-12-01

Urban sprawl is widespread across the world and the associated hydrologic impacts are increasing in peri-urban catchments due to increased area of impervious. There is a strong agreement on the positive correlation between the fractional impervious area and peak flows in urban catchments. Nevertheless, the effect of land development pattern on peak flows is not well investigated. In this study, a new simple geometric index, Relative Nearness of Imperviousness to the Catchment Outlet (RNICO), is defined to correlate imperviousness distribution of peri-urban catchments to runoff peak flows. Results of applying RNICO to 20 sub-catchments in New York State showed a strong positive correlation (R2>0.97) between RNICO and runoff peak flows for small peri-urban catchments (A< 42 km2) indicating higher flood risk of downstream urbanization. For large catchments (A> 42 km2), no correlation was indicated between RNICO and peak flows. We highlight the necessity of a greater discharge monitoring network at small peri-urban catchments to support local urban flood forecast.

Fluoroquinolones in the Wenyu River catchment, China: Occurrence simulation and risk assessment.

PubMed

Hao, Xuewen; Cao, Yan; Zhang, Lai; Zhang, Yongyong; Liu, Jianguo

2015-12-01

Concern is increasing regarding the environmental impact of the high usage rate and intensive release of antibiotics used for human and animal therapy in major urban areas of China. In the present study, regional environmental distribution simulations and risk assessments for 3 commonly used fluoroquinolones in the Wenyu River catchment were conducted using a typical catchment model widely used in Europe. The fluoroquinolone antibiotics investigated (ofloxacin, norfloxacin, and ciprofloxacin) are consumed at high levels for personal health care in China. These antibiotics were simulated in the aquatic environment of the Wenyu River catchment across the Beijing City area for annual average concentrations, with regional predicted environmental concentrations (PECs) of approximately 711 ng/L, 55.3 ng/L, and 22.2 ng/L and local PECs up to 1.8 µg/L, 116 ng/L, and 43 ng/L, respectively. Apart from hydrological conditions, the concentrations of fluoroquinolones were associated closely with the sewage treatment plants (STPs) and their serving population, as well as hospital distributions. The presence of these fluoroquinolones in the catchment area of the present study showed significant characteristics of the occurrence of pharmaceuticals in the aquatic environment in an urban river, with typical "down-the-drain" chemicals. Significantly high concentrations of specific antibiotics indicated non-negligible risks caused by the intensive use in the local aquatic environment in a metropolitan area, particularly ofloxacin in upstream Shahe Reservoir, middle stream and downstream Qing River, and Liangma River to the Ba River segment. Specific treatment measures for these pharmaceuticals and personal care products in STPs are required for such metropolitan areas. © 2015 SETAC.

Estimating Catchment-Scale Snowpack Variability in Complex Forested Terrain, Valles Caldera National Preserve, NM

NASA Astrophysics Data System (ADS)

Harpold, A. A.; Brooks, P. D.; Biederman, J. A.; Swetnam, T.

2011-12-01

Difficulty estimating snowpack variability across complex forested terrain currently hinders the prediction of water resources in the semi-arid Southwestern U.S. Catchment-scale estimates of snowpack variability are necessary for addressing ecological, hydrological, and water resources issues, but are often interpolated from a small number of point-scale observations. In this study, we used LiDAR-derived distributed datasets to investigate how elevation, aspect, topography, and vegetation interact to control catchment-scale snowpack variability. The study area is the Redondo massif in the Valles Caldera National Preserve, NM, a resurgent dome that varies from 2500 to 3430 m and drains from all aspects. Mean LiDAR-derived snow depths from four catchments (2.2 to 3.4 km^2) draining different aspects of the Redondo massif varied by 30%, despite similar mean elevations and mixed conifer forest cover. To better quantify this variability in snow depths we performed a multiple linear regression (MLR) at a 7.3 by 7.3 km study area (5 x 106 snow depth measurements) comprising the four catchments. The MLR showed that elevation explained 45% of the variability in snow depths across the study area, aspect explained 18% (dominated by N-S aspect), and vegetation 2% (canopy density and height). This linear relationship was not transferable to the catchment-scale however, where additional MLR analyses showed the influence of aspect and elevation differed between the catchments. The strong influence of North-South aspect in most catchments indicated that the solar radiation is an important control on snow depth variability. To explore the role of solar radiation, a model was used to generate winter solar forcing index (SFI) values based on the local and remote topography. The SFI was able to explain a large amount of snow depth variability in areas with similar elevation and aspect. Finally, the SFI was modified to include the effects of shading from vegetation (in and out of

Structural and functional connectivity in the agricultural Can Revull catchment (Mallorca, Spain)

NASA Astrophysics Data System (ADS)

Calsamiglia, Aleix; García-Comendador, Julián; Fortesa, Josep; Crema, Stefano; Cavalli, Marco; Alorda, Bartomeu; Estrany, Joan

2017-04-01

Unravelling the spatio-temporal variability of the sediment transfer within a catchment represents a challenge of great importance to quantify erosion, soil redistribution and their impacts on agricultural landscape. Structural and functional connectivity have been identified as useful aspects of connectivity that may clarify how these processes are coupled or decoupled in various types of catchment sediment cascades. In this study, hydrological and sediment connectivity in a Mediterranean agricultural catchment (1.4 km2) modified through traditional drainage systems (i.e., ditches and subsurface tile drainages) was assessed during two contrasted rainfall events occurred in October 2016 (20 mm in 24 h -return period < 1 yr-, I30 6.6 mm h-1 with 32 mm accumulated in 14 days) and in December 2016 (99 mm in 24 h -return period ≈ 25 yr-, I30 23 mm h-1 with 39 mm accumulated in 14 days). A morphometric index of connectivity (IC) was calculated to study the spatial patterns of structural connectivity. The identification of the main sediment pathways -in terms of functional connectivity- was conducted by field mapping, whilst the estimation of erosion and deposition rates by the analysis of high resolution digital terrain models (i.e., 5 cm pix-1; RMSE < 0.05 m) obtained from automated digital photogrammetry and unmanned aerial vehicle (UAV). The IC estimations allowed the identification of the most (dis-)connected areas related with the anthropogenic control in the resisting forces of the catchment. On the one hand, in the upper part of the catchment, depositional compartments were created by dry-stone walls that separate agricultural properties laminating flash floods. On the other hand, in the lower part of the catchment these depositional compartments were generated by an orthogonal network of ditches situated topographically above the natural thalwegs. In its turn, the most connected areas are located in the steepest parts of the catchment under rainfed herbaceous

Gene Flow within and between Catchments in the Threatened Riparian Plant Myricaria germanica

PubMed Central

Werth, Silke; Scheidegger, Christoph

2014-01-01

One of the major distinctions of riparian habitats is their linearity. In linear habitats, gene flow is predicted to follow a one-dimensional stepping stone model, characterized by bidirectional gene flow between neighboring populations. Here, we studied the genetic structure of Myricaria germanica, a threatened riparian shrub which is capable of both wind and water dispersal. Our data led us to reject the ‘one catchment – one gene pool’ hypothesis as we found support for two gene pools, rather than four as expected in a study area including four catchments. This result also implies that in the history of the studied populations, dispersal across catchments has occurred. Two contemporary catchment-crossing migration events were detected, albeit between spatially proximate catchments. Allelic richness and inbreeding coefficients differed substantially between gene pools. There was significant isolation by distance, and our data confirmed the one-dimensional stepping-stone model of gene flow. Contemporary migration was bidirectional within the studied catchments, implying that dispersal vectors other than water are important for M. germanica. PMID:24932520

Defining the sources of low-flow phosphorus transfers in complex catchments.

PubMed

Arnscheidt, J; Jordan, P; Li, S; McCormick, S; McFaul, R; McGrogan, H J; Neal, M; Sims, J T

2007-08-15

Nutrient transfers from the land to rivers have the potential to cause persistent eutrophic impacts at low flows even though the transfers may constitute a minor percentage of total annual fluxes. In rural catchments, the contribution from agricultural soils during storm events can be particularly large and untangling the relative contributions from multiple sources that vary in time and space is especially problematic. In this study, the potential for domestic septic tank system pollution during low flows was investigated in 3 small catchments (3 to 5 km(2)) using an integrated series of methods. These included septic system surveys, continuous (10 min) total phosphorus (TP) monitoring at the outlet of each catchment, repeated low-flow water quality surveys in sub-catchments upstream of the catchment outlets and single day river-walk water quality surveys. A series of faecal matter and grey-water fingerprinting techniques were also employed. These included determining sterol ratios in stream sediments, monitoring the presence of proteins, E. coli and enterococci bacterial signatures and boron. The total density and density of poorly maintained septic systems mirrored the magnitude of frequent TP concentrations in the catchments although this relationship was less apparent in the nested sub-catchments. The exception was possibly related to the simple hydraulics in one particular catchment and indicated temporary effluent attenuation in the other catchments. Repeated low-flow and river-walk water quality surveys highlighted discrete areas and reaches where stepped changes in nutrient concentration occurred. Bio-chemical fingerprinting showed that between 7% and 27% of sediments were contaminated with human faecal material and correlation matrices indicated that, at least during low flows, P fractions were positively correlated with some markers of faecal and grey-water contamination.

The relationship between soil heterotrophic activity, soil dissolved organic carbon (DOC) leachate, and catchment-scale DOC export in headwater catchments

USGS Publications Warehouse

Brooks, P.D.; McKnight, Diane M.; Bencala, K.E.

1999-01-01

Dissolved organic carbon (DOC) from terrestrial sources forms the major component of the annual carbon budget in many headwater streams. In high-elevation catchments in the Rocky Mountains, DOC originates in the upper soil horizons and is flushed to the stream primarily during spring snowmelt. To identify controls on the size of the mobile soil DOC pool available to be transported during the annual melt event, we measured soil DOC production across a range of vegetation communities and soil types together with catchment DOC export in paired watersheds in Summit County, Colorado. Both surface water DOC concentrations and watershed DOC export were lower in areas where pyrite weathering resulted in lower soil pH. Similarly, the amount of DOC leached from organic soils was significantly smaller (p < 0.01) at sites having low soil pH. Scaling point source measurements of DOC production and leaching to the two basins and assuming only vegetated areas contribute to DOC production, we calculated that the amount of mobile DOC available to be leached to surface water during melt was 20.3 g C m−2 in the circumneutral basin and 17.8 g C m−2 in the catchment characterized by pyrite weathering. The significant (r2=0.91 and p < 0.05), linear relationship between over-winter CO2 flux and the amount of DOC leached from upper soil horizons during snowmelt suggests that the mechanism for the difference in production of mobile DOC was heterotrophic processing of soil carbon in snow-covered soil. Furthermore, this strong relationship between over-winter heterotrophic activity and the size of the mobile DOC pool present in a range of soil and vegetation types provides a likely mechanism for explaining the interannual variability of DOC export observed in high-elevation catchments.

Catchment virtual observatory for sharing flow and transport models outputs: using residence time distribution to compare contrasting catchments

NASA Astrophysics Data System (ADS)

Thomas, Zahra; Rousseau-Gueutin, Pauline; Kolbe, Tamara; Abbott, Ben; Marcais, Jean; Peiffer, Stefan; Frei, Sven; Bishop, Kevin; Le Henaff, Geneviève; Squividant, Hervé; Pichelin, Pascal; Pinay, Gilles; de Dreuzy, Jean-Raynald

2017-04-01

The distribution of groundwater residence time in a catchment provides synoptic information about catchment functioning (e.g. nutrient retention and removal, hydrograph flashiness). In contrast with interpreted model results, which are often not directly comparable between studies, residence time distribution is a general output that could be used to compare catchment behaviors and test hypotheses about landscape controls on catchment functioning. In this goal, we created a virtual observatory platform called Catchment Virtual Observatory for Sharing Flow and Transport Model Outputs (COnSOrT). The main goal of COnSOrT is to collect outputs from calibrated groundwater models from a wide range of environments. By comparing a wide variety of catchments from different climatic, topographic and hydrogeological contexts, we expect to enhance understanding of catchment connectivity, resilience to anthropogenic disturbance, and overall functioning. The web-based observatory will also provide software tools to analyze model outputs. The observatory will enable modelers to test their models in a wide range of catchment environments to evaluate the generality of their findings and robustness of their post-processing methods. Researchers with calibrated numerical models can benefit from observatory by using the post-processing methods to implement a new approach to analyzing their data. Field scientists interested in contributing data could invite modelers associated with the observatory to test their models against observed catchment behavior. COnSOrT will allow meta-analyses with community contributions to generate new understanding and identify promising pathways forward to moving beyond single catchment ecohydrology. Keywords: Residence time distribution, Models outputs, Catchment hydrology, Inter-catchment comparison

The Access Vermont Initiative: An Investigation of Team Development in Two Vermont Catchment Areas Providing Services to Children with Severe Emotional Disturbances and Their Families.

ERIC Educational Resources Information Center

Fox, Barbara J.; Wright, Leanne M.

This study was designed to document the processes and dynamics of two multidisciplinary teams under the Access Vermont program, which provides services for children and youth with serious emotional disabilities and their families. In both cases, local interagency teams in the largely rural catchment areas developed plans for an initiative focused…

Integrated assessment of land use and cover changes in the Malagarasi river catchment in Tanzania

NASA Astrophysics Data System (ADS)

Kashaigili, J. J.; Majaliwa, A. M.

Malagarasi river catchment represents one of the largest and most significant transboundary natural ecosystems in Africa. The catchment constitutes about one third of the catchment area of Lake Tanganyika and contains ecosystems of both national and international importance (i.e. Muyovozi Wetland Ramsar site). It has been increasingly said that increased anthropogenic activities have had negative impacts on the Muyovozi wetland in particular and other catchment resources. Nevertheless, these beliefs are little supported by quantitative data. A study on the dynamics of land use and cover in the Malagarasi river catchment therefore investigated long-term and seasonal changes that have occurred as a result of human activities in the area for the periods between 1984 and 2001. Landsat TM and ETM+ images were used to locate and quantify the changes. Perceptions of local people on historical changes and drivers for the changes were also collected and integrated in the assessment. The study revealed a significant change in land use and cover within a period of 18 year. Between 1984 and 2001, the woodland and wetland vegetation covers declined by 0.09% and 2.51% per year. Areas with settlements and cultivation increased by 1.05% annually while bushed grassland increased at 1.93% annually. The perceived principal drivers for the changes were found to include fire, cultivation along rivers and lake shores, overgrazing, poor law enforcement, insufficient knowledge on environmental issues, increasing poverty, deforestation and population growth. The human population growth rate stands at 4.8% against a national figure of 2.9%. The most perceived environmental problems include drying of streams and rivers, change in rainfall, loss of soil fertility, soil erosion and reduced crop yield. The study concludes that, there has been significant changes in land use and cover in the catchment and these require concerted actions to reverse the changes. The study highlights the importance

The artifcial catchment Chicken Creek as a tool to study initial ecosystem development

NASA Astrophysics Data System (ADS)

Schaaf, W.; Elmer, M.; Fischer, A.; Gerwin, W.; Nenov, R.

2011-12-01

The artificial catchment Chicken Creek was constructed in 2005 to study the increasingly complex interactions of processes and structures during initial development of ecosystems. The 6ha area serves as the central research site for the Transregional Collaborative Research Center 38. Both internal and external factors could be identified as driving forces for the formation of structures and patterns in the artificial catchment during the first five years of development. Initial structures formed by the construction process (e.g. catchment morphology, subsurface structures like clay dams and dumping cones, caterpillar tracks at the surface) and initial substrate characteristics (e.g. texture, geochemistry) were decisive both for the distribution and flow of precipitation water and for vegetation succession. External factors like episodic events (e.g. heavy thunderstorms) triggered erosion and dissection during this initial phase, promoted by the low vegetation cover and the unconsolidated sandy substrate. These processes resulted in transport and redistribution of water and sediment within the catchment, mainly along the main slope, and the formation of new structural elements like gullies and channels, a sedimentation fan above and sediments within the pond. As a result, we observed an overall differentiation of the site, e.g. with respect to water availability and texture redistribution, into areas with abrasion or accumulation processes dominating and areas with stable surfaces. During further development, both external factors and processes within the catchment continued to influence the site. For example, beside the initial soil seed bank, the surrounding environment of the catchment clearly affected species invasion. The dissection and stability of surfaces may be an important factor for the establishment of plants and habitats as well as for the formation of vegetation patterns and biological soil crusts. The transformation of the initial geo-system into

Multi-catchment rainfall-runoff simulation for extreme flood estimation

NASA Astrophysics Data System (ADS)

Paquet, Emmanuel

2017-04-01

The SCHADEX method (Paquet et al., 2013) is a reference method in France for the estimation of extreme flood for dam design. The method is based on a semi-continuous rainfall-runoff simulation process: hundreds of different rainy events, randomly drawn up to extreme values, are simulated independently in the hydrological conditions of each day when a rainy event has been actually observed. This allows generating an exhaustive set of crossings between precipitation and soil saturation hazards, and to build a complete distribution of flood discharges up to extreme quantiles. The hydrological model used within SCHADEX, the MORDOR model (Garçon, 1996), is a lumped model, which implies that hydrological processes, e.g. rainfall and soil saturation, are supposed to be homogeneous throughout the catchment. Snow processes are nevertheless represented in relation with altitude. This hypothesis of homogeneity is questionable especially as the size of the catchment increases, or in areas of highly contrasted climatology (like mountainous areas). Conversely, modeling the catchment with a fully distributed approach would cause different problems, in particular distributing the rainfall-runoff model parameters trough space, and within the SCHADEX stochastic framework, generating extreme rain fields with credible spatio-temporal features. An intermediate solution is presented here. It provides a better representation of the hydro-climatic diversity of the studied catchment (especially regarding flood processes) while keeping the SCHADEX simulation framework. It consists in dividing the catchment in several, more homogeneous sub-catchments. Rainfall-runoff models are parameterized individually for each of them, using local discharge data if available. A first SCHADEX simulation is done at the global scale, which allows assigning a probability to each simulated event, mainly based on the global areal rainfall drawn for the event (see Paquet el al., 2013 for details). Then the

Monitoring of initial patterns and structures in an artificial catchment

NASA Astrophysics Data System (ADS)

Schaaf, Wolfgang; Gerwin, Werner; Biemelt, Detlef; Fischer, Anton

2010-05-01

To combine process-oriented research on initial development of ecosystems with interactions and co-development of spatial patterns and structures the Transregional Collaborative Research Centre (SFB/TRR) 38 (www.tu-cottbus.de/sfb_trr) was established as an initiative of three universities (BTU Cottbus, TU Munich and ETH Zurich). The objective of the SFB/TRR 38 is to enhance our understanding of structure genesis in ecosystems and of process dynamics as well as their interactions during the initial development phase. The aim is to integrate these feedback mechanisms in the analysis of water and element budgets at the catchment scale and to implement them into models. To allow the clear definition of starting conditions at ´point zeró and to be able to integrate spatially distributed processes and patterns to larger units, an artificial catchment was constructed in the mining area of Lusatia/Germany as the main research site (Gerwin et al. 2009a). With an area of about 6 ha, this catchment ´Chicken Creeḱ is to our knowledge the largest artificial catchment worldwide. It was constructed as a 2-4 m layer of post-glacial sandy to loamy sediments overlying a 1-2 m layer of Tertiary clay that forms a shallow pan and seals the whole catchment at the base. No further measures of restoration like planting, amelioration or fertilization were carried out to allow natural succession and undisturbed development. Due to the artificial construction, boundary conditions of this site are clearly defined including well documented inner structures as compared to natural catchments. It is assumed that the interaction of patterns and processes during initial development will proceed from simpler to more complex states of the systems and that different stages along this phase can be identified at the catchment level. Changes within the catchment are intensively monitored since 2005, when construction finished (Gerwin et al. 2009b), including intensive on-site measurements and micro

Blending Pan-European and local hydrological models for water resource assessment in Mediterranean areas: lessons learnt from a mountainous catchment

NASA Astrophysics Data System (ADS)

José Polo, María; José Pérez-Palazón, María; Saénz de Rodrigáñez, Marta; Pimentel, Rafael; Arheimer, Berit

2017-04-01

Global hydrological models provide scientists and technicians with distributed data over medium to large areas from which assessment of water resource planning and use can be easily performed. However, scale conflicts between global models' spatial resolution and the local significant spatial scales in heterogeneous areas usually pose a constraint for the direct use and application of these models' results. The SWICCA (Service for Water Indicators in Climate Change Adaptation) Platform developed under the Copernicus Climate Change Service (C3S) offers a wide range of both climate and hydrological indicators obtained on a global scale with different time and spatial resolutions. Among the different study cases supporting the SWICCA demonstration of local impact assessment, the Sierra Nevada study case (South Spain) is a representative example of mountainous coastal catchments in the Mediterranean region. This work shows the lessons learnt during the study case development to derive local impact indicator tailored to suit the local end-users of water resource in this snow-dominated area. Different approaches were followed to select the most accurate method to downscale the global data and variables to the local level in a highly abrupt topography, in a sequential step approach. 1) SWICCA global climate variable downscaling followed by river flow simulation from a local hydrological model in selected control points in the catchment, together with 2) SWICCA global river flow values downscaling to the control points followed by corrections with local transfer functions were both tested against the available local river flow series of observations during the reference period. This test was performed for the different models and the available spatial resolutions included in the SWICCA platform. From the results, the second option, that is, the use of SWICCA river flow variables, performed the best approximations, once the local transfer functions were applied to the

Analysis of potential future droughts limiting maize production, in the Luvuvhu River catchment area, South Africa

NASA Astrophysics Data System (ADS)

Masupha, Teboho Elisa; Moeletsi, Mokhele Edmond

2018-06-01

Recurring droughts associated with global warming have raised major concern for the agricultural sector, particularly vulnerable small-scale farmers who rely on rain-fed farming such as in the Luvuvhu River catchment. The Standardized Precipitation Evapotranspiration Index (SPEI) and Water Requirement Satisfaction Index (WRSI) were calculated to assess drought on a 120-day maturing maize crop based on outputs of the CSIRO-Mk3.6.0 under RCP 4.5 emission scenario, for the period 1980/81-2089/90. Results by SPEI show that 40-54% of the agricultural seasons during the base period experienced mild drought conditions (SPEI 0 to -0.99), equivalent to a recurrence of once in two seasons. However, WRSI results clearly indicated that stations in the drier regions (annual rainfall <600 mm) of the catchment experienced mild drought (WRSI 70 - 79) corresponding to satisfactory crop performance every season. Results further showed overall mild to moderate droughts in the beginning of the near-future climate period (2020/21-2036/37) with SPEI values not decreasing below -1.5. These conditions are then expected to change during the far-future climate period (2055/56-2089/90), whereby results on the expected crop performance predicted significantly drier conditions (p < 0.05). This study provided information on how farmers in the area can prepare for future agricultural seasons, while there is sufficient time to implement strategies to reduce drought risk potential. Thus, integrated interventions could provide best options for improving livelihoods and building the capability of farmers to manage climate change-related stresses.

Modeling Land Use Change Impacts on Water Resources in a Tropical West African Catchment (dano, Burkina Faso)

NASA Astrophysics Data System (ADS)

Yira, Y.; Diekkrüger, B.; Steup, G.; Bossa, A. Y.

2015-12-01

This study investigates the impacts of land use change on water resources in the Dano catchment, Burkina Faso, using a physically based hydrological simulation model and land use scenarios. Land use dynamic in the catchment was assessed through the analysis of four land use maps corresponding to the land use status in 1990, 2000, 2007 and 2013. A reclassification procedure of the maps permitted to assess the major land use changes in the catchment from 1990 to 2013. The land use maps were used to build five land use scenarios corresponding to different levels of land use change in the catchment. Water balance was simulated by applying the Water flow and balance Simulation Model (WaSiM) using observed discharge, soil moisture, and groundwater level for model calibration and validation. Model statistical quality measures (R2, NSE and KGE) achieved during the calibration and the validation ranged between 0.9 and 0.6 for total discharge, soil moisture, and groundwater level, indicating satisfying to good agreements between observed and simulated variables. After a successful multi-criteria validation the model was run with the land use scenarios. The land use assessment exhibited a decrease of savannah at an annual rate of 2% since 1990. Conversely, cropland and urban areas have increased. Since urban areas occupy only 3% of the catchment in 2013 it can be assumed that savannah was mainly converted to cropland. The increase in cropland area results from the population growth and the farming system in the catchment. A clear increase in total discharge (+17%) and decrease in evapotranspiration (-5%) was observed following land use change in the catchment. A strong relationship was established between savannah degradation, cropland expansion, discharge increase and reduction of evapotranspiration. The increase in total discharge is related to high discharge and peak flow, suggesting (i) an increase in water resources that is not available for plant growth and the

Prioritization of catchments based on soil erosion using remote sensing and GIS.

PubMed

Khadse, Gajanan K; Vijay, Ritesh; Labhasetwar, Pawan K

2015-06-01

Water and soil are the most essential natural resources for socioeconomic development and sustenance of life. A study of soil and water dynamics at a watershed level facilitates a scientific approach towards their conservation and management. Remote sensing and Geographic Information System are tools that help to plan and manage natural resources on watershed basis. Studies were conducted for the formulation of catchment area treatment plan based on watershed prioritization with soil erosion studies using remote sensing techniques, corroborated with Geographic Information System (GIS), secondary data and ground truth information. Estimation of runoff and sediment yield is necessary in prioritization of catchment for the design of soil conservation structures and for identifying the critical erosion-prone areas of a catchment for implementation of best management plan with limited resources. The Universal Soil Loss Equation, Sediment Yield Determination and silt yield index methods are used for runoff and soil loss estimation for prioritization of the catchments. On the basis of soil erosion classes, the watersheds were grouped into very high, high, moderate and low priorities. High-priority watersheds need immediate attention for soil and water conservation, whereas low-priority watershed having good vegetative cover and low silt yield index may not need immediate attention for such treatments.

Runoff and solute mobilization processes in a semiarid headwater catchment

NASA Astrophysics Data System (ADS)

Hughes, Justin D.; Khan, Shahbaz; Crosbie, Russell S.; Helliwell, Stuart; Michalk, David L.

2007-09-01

Runoff and solute transport processes contributing to streamflow were determined in a small headwater catchment in the eastern Murray-Darling Basin of Australia using hydrometric and tracer methods. Streamflow and electrical conductivity were monitored from two gauges draining a portion of the upper catchment area (UCA) and a saline scalded area, respectively. Runoff in the UCA was related to the formation of a seasonally perched aquifer in the near-surface zone (0-0.4 m). A similar process was responsible for runoff generation in the saline scalded area. However, saturation in the scald area was related to the proximity of groundwater rather than low subsurface hydraulic conductivity. Because of higher antecedent water content, runoff commenced earlier in winter from the scald than did the UCA. Additionally, areal runoff from the scald was far greater than from the UCA. Total runoff from the UCA was higher than the scald (15.7 versus 3.5 mL), but salt export was far lower (0.6 and 5.4 t for the UCA and scald area, respectively) since salinity of the scald runoff was far higher than that from the UCA, indicating the potential impact of saline scalded areas at the catchment scale. End-member mixing analysis modeling using six solutes indicated that most runoff produced from the scald was "new" (40-71%) despite the proximity of the groundwater surface and the high antecedent moisture levels. This is a reflection of the very low hydraulic conductivity of soils in the study area. Nearly all chloride exported to the stream from the scald emanated from the near-surface zone (77-87%). Runoff and solute mobilization processes depend upon seasonal saturation occurring in the near-surface zone during periods of low evaporative demand and generation of saturated overland flow.

Validation of catchment models for predicting land-use and climate change impacts. 2. Case study for a Mediterranean catchment

NASA Astrophysics Data System (ADS)

Parkin, G.; O'Donnell, G.; Ewen, J.; Bathurst, J. C.; O'Connell, P. E.; Lavabre, J.

1996-02-01

Validation methods commonly used to test catchment models are not capable of demonstrating a model's fitness for making predictions for catchments where the catchment response is not known (including hypothetical catchments, and future conditions of existing catchments which are subject to land-use or climate change). This paper describes the first use of a new method of validation (Ewen and Parkin, 1996. J. Hydrol., 175: 583-594) designed to address these types of application; the method involves making 'blind' predictions of selected hydrological responses which are considered important for a particular application. SHETRAN (a physically based, distributed catchment modelling system) is tested on a small Mediterranean catchment. The test involves quantification of the uncertainty in four predicted features of the catchment response (continuous hydrograph, peak discharge rates, monthly runoff, and total runoff), and comparison of observations with the predicted ranges for these features. The results of this test are considered encouraging.

Runoff Response to Rainfall in Small Catchments Burned by the 2015 Valley Fire

NASA Astrophysics Data System (ADS)

Wagenbrenner, J. W.; Coe, D. B. R.; Lindsay, D.

2016-12-01

Burned areas often produce runoff volumes and peak flows much larger than unburned forests. However, very few studies demonstrate the effect of burn severity on runoff responses, and post-fire data are especially sparse in California. We measured the effects of different degrees of burn severity on rainfall-runoff responses in six small catchments (0.15-0.65 ha) in the Northern Coast Ranges. Weirs and tipping bucket rain gages were installed after the 2015 Valley Fire and prior to any substantial rainfall. In the first wet season (Nov 2015-May 2016), one runoff event was recorded in the catchment with the lowest burn severity (42% bare soil), while 13 runoff events occurred in the catchment with the highest burn severity (68% bare soil). Preliminary results indicate the thirty minute maximum rainfall intensity that generated runoff ranged from 27 mm hr-1 in the lowest severity catchment to only 8.6 mm hr-1 in the highest severity catchment. Peak flow rates for the most intense event (27 mm hr-1), a two-year, 30-min storm, were 1.1 m3 s-1 km-2 in the lowest severity catchment and 17 m3 s-1 km-2 in the highest severity catchment. Longer duration, moderate intensity rain events produced runoff in the highest severity catchments but not the lowest severity catchments. These results are on the high end of the range of post-fire peak flow rates reported in the western US and provide an idea of potential post-fire flood potential to land and emergency management agencies.

Catchment systems science and management: from evidence to resilient landscapes

NASA Astrophysics Data System (ADS)

Quinn, Paul

2014-05-01

There is an urgent need to reassess both the scientific understanding and the policy making approaches taken to manage flooding, water scarcity and pollution in intensively utilised catchments. Many European catchments have been heavily modified and natural systems have largely disappeared. However, working with natural processes must still be at the core of any future management strategy. Many catchments have greatly reduced infiltration rates and buffering capacity and this process needs to be reversed. An interventionist and holistic approach to managing water quantity and quality at the catchment scale is urgently required through the active manipulation of natural flow processes. Both quantitative (field experiments and modelling) and qualitative evidence (local knowledge) is required to demonstrate that catchment have become 'unhealthy'. For example, dense networks of low cost instrumentation could provide this multiscale evidence and, coupled with stakeholder knowledge, build a comprehensive understanding of whole system function. Proactive Catchment System Management is an interventionist approach to altering the catchment scale runoff regime through the manipulation of landscape scale hydrological flow pathways. Many of the changes to hydrological processes cannot be detected at the catchment scale as the primary causes of flooding and pollution. Evidence shows it is the land cover and the soil that are paramount to any change. Local evidence shows us that intense agricultural practices reduce the infiltration capacity through soil degradation. The intrinsic buffering capacity has also been lost across the landscape. The emerging hydrological process is one in which the whole system responds too quickly (driven by near surface and overland flow processes). The bulk of the soil matrix is bypassed during storm events and there is little or no buffering capacity in the riparian areas or in headwater catchments. The prospect of lower intensity farming rates is

Tropical Montane Cloud Forests: Hydrometeorological variability in three neighbouring catchments with different forest cover

NASA Astrophysics Data System (ADS)

Ramírez, Beatriz H.; Teuling, Adriaan J.; Ganzeveld, Laurens; Hegger, Zita; Leemans, Rik

2017-09-01

Mountain areas are characterized by a large heterogeneity in hydrological and meteorological conditions. This heterogeneity is currently poorly represented by gauging networks and by the coarse scale of global and regional climate and hydrological models. Tropical Montane Cloud Forests (TMCFs) are found in a narrow elevation range and are characterized by persistent fog. Their water balance depends on local and upwind temperatures and moisture, therefore, changes in these parameters will alter TMCF hydrology. Until recently the hydrological functioning of TMCFs was mainly studied in coastal regions, while continental TMCFs were largely ignored. This study contributes to fill this gap by focusing on a TMCF which is located on the northern eastern Andes at an elevation of 1550-2300 m asl, in the Orinoco river basin highlands. In this study, we describe the spatial and seasonal meteorological variability, analyse the corresponding catchment hydrological response to different land cover, and perform a sensitivity analysis on uncertainties related to rainfall interpolation, catchment area estimation and streamflow measurements. Hydro-meteorological measurements, including hourly solar radiation, temperature, relative humidity, wind speed, precipitation, soil moisture and streamflow, were collected from June 2013 to May 2014 at three gauged neighbouring catchments with contrasting TMCF/grassland cover and less than 250 m elevation difference. We found wetter and less seasonally contrasting conditions at higher elevations, indicating a positive relation between elevation and fog or rainfall persistence. This pattern is similar to that of other eastern Andean TMCFs, however, the study site had higher wet season rainfall and lower dry season rainfall suggesting that upwind contrasts in land cover and moisture can influence the meteorological conditions at eastern Andean TMCFs. Contrasting streamflow dynamics between the studied catchments reflect the overall system response

An INCA model for pathogens in rivers and catchments: Model structure, sensitivity analysis and application to the River Thames catchment, UK.

PubMed

Whitehead, P G; Leckie, H; Rankinen, K; Butterfield, D; Futter, M N; Bussi, G

2016-12-01

Pathogens are an ongoing issue for catchment water management and quantifying their transport, loss and potential impacts at key locations, such as water abstractions for public supply and bathing sites, is an important aspect of catchment and coastal management. The Integrated Catchment Model (INCA) has been adapted to model the sources and sinks of pathogens and to capture the dominant dynamics and processes controlling pathogens in catchments. The model simulates the stores of pathogens in soils, sediments, rivers and groundwaters and can account for diffuse inputs of pathogens from agriculture, urban areas or atmospheric deposition. The model also allows for point source discharges from intensive livestock units or from sewage treatment works or any industrial input to river systems. Model equations are presented and the new pathogens model has been applied to the River Thames in order to assess total coliform (TC) responses under current and projected future land use. A Monte Carlo sensitivity analysis indicates that the input coliform estimates from agricultural sources and decay rates are the crucial parameters controlling pathogen behaviour. Whilst there are a number of uncertainties associated with the model that should be accounted for, INCA-Pathogens potentially provides a useful tool to inform policy decisions and manage pathogen loading in river systems. Copyright © 2016. Published by Elsevier B.V.

How young water fractions can delineate travel time distributions in contrasting catchments

NASA Astrophysics Data System (ADS)

Lutz, Stefanie; Zink, Matthias; Merz, Ralf

2017-04-01

Travel time distributions (TTDs) are crucial descriptors of flow and transport processes in catchments. Tracking fluxes of environmental tracers such as stable water isotopes offers a practicable method to determine TTDs. The mean transit time (MTT) is the most commonly reported statistic of TTDs; however, MTT assessments are prone to large aggregation biases resulting from spatial heterogeneity and non-stationarity in real-world catchments. Recently, the young water fraction (Fyw) has been introduced as a more robust statistic that can be derived from seasonal tracer cycles. In this study, we aimed at improving the assessment of TTDs by using Fyw as additional information in lumped isotope models. First, we calculated Fyw from monthly δ18O-samples for 24 contrasting sub-catchments in a meso-scale catchment (3300 km2). Fyw ranged from 0.01 to 0.27 (mean= 0.11) and was not significantly correlated with catchment characteristics (e.g., mean slope, catchment area, and baseflow index) apart from the dominant soil type. Second, assuming gamma-shaped TTDs, we determined time-invariant TTDs for each sub-catchment by optimization of lumped isotope models using the convolution integral method. Whereas multiple optimization runs for the same sub-catchment showed a wide range of TTD parameters, the use of Fyw as additional information allowed constraining this range and thus improving the assessment of MTTs. Hence, the best model fit to observed isotope data might not be the desired solution, as the resulting TTD might define a young water fraction non-consistent with the tracer-cycle based Fyw. Given that the latter is a robust descriptor of fast-flow contribution, isotope models should instead aim at accurately describing both Fyw and the isotope time series in order to improve our understanding of flow and transport in catchments.

A bottom up approach for engineering catchments through sustainable runoff management

NASA Astrophysics Data System (ADS)

Wilkinson, M.; Quinn, P. F.; Jonczyk, J.; Burke, S.

2010-12-01

There is no doubt that our catchments are under great stress. There have been many accounts around the world of severe flood events and water quality issues within channels. As a result of these, ecological habitats in rivers are also under pressure. Within the United Kingdom, all these issues have been identified as key target areas for policy. Traditionally this has been managed by a policy driven top down approach which is usually ineffective. A one ‘size fits all’ attitude often does not work. This paper presents a case study in northern England whereby a bottom up approach is applied to multipurpose managing of catchments at the source (in the order of 1-10km2). This includes simultaneous tackling of water quality, flooding and ecological issues by creating sustainable runoff management solutions such as storage ponds, wetlands, beaver dams and willow riparian features. In order to identify the prevailing issues in a specific catchment, full and transparent stakeholder engagement is essential, with everybody who has a vested interest in the catchment being involved from the beginning. These problems can then be dealt with through the use of a novel catchment management toolkit, which is transferable to similar scale catchments. However, evidence collected on the ground also allows for upscaling of the toolkit. The process gathers the scientific evidence about the effectiveness of existing or new measures, which can really change the catchment functions. Still, we need to get better at communicating the science to policy makers and policy therefore must facilitate a bottom up approach to land and water management. We show a test site for this approach in the Belford burn catchment (6km2), northern England. This catchment has problems with flooding and water quality. Increased sediment loads are affecting the nearby estuary which is an important ecological zone and numerous floods have affected the local village. A catchment engineering toolkit has been

Microbial water pollution: a screening tool for initial catchment-scale assessment and source apportionment.

PubMed

Kay, D; Anthony, S; Crowther, J; Chambers, B J; Nicholson, F A; Chadwick, D; Stapleton, C M; Wyer, M D

2010-11-01

The European Union Water Framework Directive requires that Management Plans are developed for individual River Basin Districts. From the point of view of faecal indicator organisms (FIOs), there is a critical need for screening tools that can provide a rapid assessment of the likely FIO concentrations and fluxes within catchments under base- and high-flow conditions, and of the balance ('source apportionment') between agriculture- and sewage-derived sources. Accordingly, the present paper reports on: (1) the development of preliminary generic models, using water quality and land cover data from previous UK catchment studies for assessing FIO concentrations, fluxes and source apportionment within catchments during the summer bathing season; (2) the calibration of national land use data, against data previously used in the models; and (3) provisional FIO concentration and source-apportionment assessments for England and Wales. The models clearly highlighted the crucial importance of high-flow conditions for the flux of FIOs within catchments. At high flow, improved grassland (and associated livestock) was the key FIO source; FIO loadings derived from catchments with high proportions of improved grassland were shown to be as high as from urbanized catchments; and in many rural catchments, especially in NW and SW England and Wales, which are important areas of lowland livestock (especially dairy) farming, ≥ 40% of FIOs was assessed to be derived from agricultural sources. In contrast, under base-flow conditions, when there was little or no runoff from agricultural land, urban (i.e. sewerage-related) sources were assessed to dominate, and even in rural areas the majority of FIOs were attributed to urban sources. The results of the study demonstrate the potential of this type of approach, particularly in light of climate change and the likelihood of more high-flow events, in underpinning informed policy development and prioritization of investment. Copyright © 2009

From Points to Patterns - Functional Relations between Groundwater Connectivity and Catchment-scale Streamflow Response

NASA Astrophysics Data System (ADS)

Rinderer, M.; McGlynn, B. L.; van Meerveld, I. H. J.

2016-12-01

Groundwater measurements can help us to improve our understanding of runoff generation at the catchment-scale but typically only provide point-scale data. These measurements, therefore, need to be interpolated or upscaled in order to obtain information about catchment scale groundwater dynamics. Our approach used data from 51 spatially distributed groundwater monitoring sites in a Swiss pre-alpine catchment and time series clustering to define six groundwater response clusters. Each of the clusters was characterized by distinctly different site characteristics (i.e., Topographic Wetness Index and curvature), which allowed us to assign all unmonitored locations to one of these clusters. Time series modeling and the definition of response thresholds (i.e., the depth of more transmissive soil layers) allowed us to derive maps of the spatial distribution of active (i.e., responding) locations across the catchment at 15 min time intervals. Connectivity between all active locations and the stream network was determined using a graph theory approach. The extent of the active and connected areas differed during events and suggests that not all active locations directly contributed to streamflow. Gate keeper sites prevented connectivity of upslope locations to the channel network. Streamflow dynamics at the catchment outlet were correlated to catchment average connectivity dynamics. In a sensitivity analysis we tested six different groundwater levels for a site to be considered "active", which showed that the definition of the threshold did not significantly influence the conclusions drawn from our analysis. This study is the first one to derive patterns of groundwater dynamics based on empirical data (rather than interpolation) and provides insight into the spatio-temporal evolution of the active and connected runoff source areas at the catchment-scale that is critical to understanding the dynamics of water quantity and quality in streams.

What is the Source? Post-glacial sediment flux from the Waipaoa Catchment, New Zealand

NASA Astrophysics Data System (ADS)

Bilderback, E. L.; Pettinga, J. R.; Litchfield, N. J.; Quigley, M.; Marden, M.

2011-12-01

In the Waipaoa, and for much of the eastern North Island, the shift from the last glacial coldest period to the current interglacial climatic regime resulted in Late Pleistocene-Holocene catchment-wide channel incision (Berryman et al., 2000; Litchfield and Berryman, 2005). Only ~25% of the total post 18 ka sediment yield for the Waipaoa Catchment can be accounted for by channel incision, one of the most widespread and most effective erosive processes in the catchment (Orpin et al., 2006; Marden et al., 2008). We find that deep-seated landslides, which are pervasive, cannot make up this apparent source area sediment deficit. This presents a challenge to our current understanding of the Waipaoa Sedimentary System. New high resolution topographic data sets (lidar and photogrammetry) combined with tephrochronology and field mapping have enabled us to approximate the sediment flux from post 18 ka deep-seated landslides. The sediment delivered to the offshore sink from these upper Waipaoa landslides is likely to be less than 20% of the sediment volume calculated for channel incision. A further GIS analysis of the ~2500 km2 Waipaoa catchment using work from Crosby and Whipple (2006) delineating relict topography and Marden et al. (2008) accounting for river incision and slopes stabilized behind terrace remnants indicates that only about half of the available catchment area could have contributed additional large volumes of sediment to the offshore post 18 ka sink. The presence of tephra cover older than 18 ka on landforms ranging from flat ridgelines to steep (>30 degree) slopes in this remaining terrestrial source area suggests that it has not been eroded en mass. The apparent source deficit remains even though many of the major erosive processes available to fill this deficit have been studied and the potentially contributing catchment area is dramatically reduced by these studies. This analysis raises questions about erosive processes and our ability to balance large

Nitrogen Concentrations and Exports in Baseflow and Stormflow from Three Small Urban Catchments in Central Florida

NASA Astrophysics Data System (ADS)

Luo, J.; Hochmuth, G.; Clark, M. W.

2014-12-01

Export of nitrogen from different watersheds across the United States is receiving increasing attention due to the impairment of water quality in receiving water bodies. Researchers have indicated that different land uses exerted a substantial influence on the water quality. Nitrogen loadings on the watershed scale are being studied in many large ecosystems, such as the Baltimore Ecosystem and Arizona Ecosystem, but only a few focuses in a smaller scale such as catchment scale. Characterization of the land use in catchment scale can better explain the observed environmental phenomena under the watershed scale and enrich the related watershed studies. Nitrogen fluxes have been studied at Lake Alice watershed in Gainesville, Florida with a focus on the rarely studied catchments such as sports fields with intensive fertilization management (SFC), urban area with reclaimed water irrigation (RWC) and urban area without irrigation (CC). The entire study started from May 2013. Discharge was monitored in the three catchments by transducers every 5 minutes. Regular biweekly grab samples in the three catchments were used to estimate the baseflow N loads, composite samples in 13 storms were collected to estimate the stormflow N loads. The results showed that in the baseflow, the average NO3-N concentration in SFC was 12.19 mg/l, which was significantly different from the urban catchments. Also there was a significant difference between the NO3-N concentrations in RWC (1.17 mg/l on average) and CC (0.60 mg/l on average). A separate log-log relationship was developed between discharge and N loads to estimate the baseflow N loads and stormflow N loads. It showed that baseflow contributed more N loads than stormflow in the three catchments in the annual N load. In conclusion, the recreational catchment received the greatest N load compared to the other catchments, so it should be the priority catchment when it comes to adopting nutrient management practices in the Lake Alice

Flow processes on the catchment scale - modeling of initial structural states and hydrological behavior in an artificial exemplary catchment

NASA Astrophysics Data System (ADS)

Maurer, Thomas; Caviedes-Voullième, Daniel; Hinz, Christoph; Gerke, Horst H.

2017-04-01

Landscapes that are heavily disturbed or newly formed by either natural processes or human activity are in a state of disequilibrium. Their initial development is thus characterized by highly dynamic processes under all climatic conditions. The primary distribution and structure of the solid phase (i.e. mineral particles forming the pore space) is one of the decisive factors for the development of hydrological behavior of the eco-hydrological system and therefore (co-) determining for its - more or less - stable final state. The artificially constructed ‚Hühnerwasser' catchment (a 6 ha area located in the open-cast lignite mine Welzow-Süd, southern Brandenburg, Germany) is a landscape laboratory where the initial eco-hydrological development is observed since 2005. The specific formation (or construction) processes generated characteristic sediment structures and distributions, resulting in a spatially heterogeneous initial state of the catchment. We developed a structure generator that simulates the characteristic distribution of the solid phase for such constructed landscapes. The program is able to generate quasi-realistic structures and sediment compositions on multiple spatial levels (1 cm up to 100 m scale). The generated structures can be i) conditioned to actual measurement values (e.g., soil texture and bulk distribution); ii) stochastically generated, and iii) calculated deterministically according to the geology and technical processes at the excavation site. Results are visualized using the GOCAD software package and the free software Paraview. Based on the 3D-spatial sediment distributions, effective hydraulic van-Genuchten parameters are calculated using pedotransfer functions. The hydraulic behavior of different sediment distribution (i.e. versions or variations of the catchment's porous body) is calculated using a numerical model developed by one of us (Caviedes-Voullième). Observation data are available from catchment monitoring are available

Parameter Set Cloning Based on Catchment Similarity for Large-scale Hydrologic Modeling

NASA Astrophysics Data System (ADS)

Liu, Z.; Kaheil, Y.; McCollum, J.

2016-12-01

Parameter calibration is a crucial step to ensure the accuracy of hydrological models. However, streamflow gauges are not available everywhere for calibrating a large-scale hydrologic model globally. Thus, assigning parameters appropriately for regions where the calibration cannot be performed directly has been a challenge for large-scale hydrologic modeling. Here we propose a method to estimate the model parameters in ungauged regions based on the values obtained through calibration in areas where gauge observations are available. This parameter set cloning is performed according to a catchment similarity index, a weighted sum index based on four catchment characteristic attributes. These attributes are IPCC Climate Zone, Soil Texture, Land Cover, and Topographic Index. The catchments with calibrated parameter values are donors, while the uncalibrated catchments are candidates. Catchment characteristic analyses are first conducted for both donors and candidates. For each attribute, we compute a characteristic distance between donors and candidates. Next, for each candidate, weights are assigned to the four attributes such that higher weights are given to properties that are more directly linked to the hydrologic dominant processes. This will ensure that the parameter set cloning emphasizes the dominant hydrologic process in the region where the candidate is located. The catchment similarity index for each donor - candidate couple is then created as the sum of the weighted distance of the four properties. Finally, parameters are assigned to each candidate from the donor that is "most similar" (i.e. with the shortest weighted distance sum). For validation, we applied the proposed method to catchments where gauge observations are available, and compared simulated streamflows using the parameters cloned by other catchments to the results obtained by calibrating the hydrologic model directly using gauge data. The comparison shows good agreement between the two models

Investigating the potential to reduce flood risk through catchment-based land management techniques and interventions in the River Roe catchment, Cumbria,UK

NASA Astrophysics Data System (ADS)

Pearson, Callum; Reaney, Sim; Bracken, Louise; Butler, Lucy

2015-04-01

potential to transfer these benefits to the Roe catchment (~69km2) have been assessed. Furthermore these flood mitigation features have the potential to deliver wider environmental improvements throughout the catchment and hence the potential for multiple benefits such as diffuse pollution reduction and habitat creation are considered. The research explores the impact of NFM techniques, flood storage areas or afforestation for example, with a view to enhancing local scale habitats. The research combines innovative catchment modelling techniques, both risk-based approaches (SCIMAP Flood) and spatially distributed hydrological simulation modelling (CRUM3), with in-field monitoring and observation of flow pathways and tributary response to rainfall using time-lapse cameras. Additional work with the local community and stakeholders will identify the range and location of potential catchment-based land management techniques and interventions being assessed; natural flood management implementation requires the participation and cooperation of landowners and local community to be successful (Howgate and Kenyon, 2009).

Effects of broadleaf woodland cover on streamwater chemistry and risk assessments of streamwater acidification in acid-sensitive catchments in the UK.

PubMed

Gagkas, Z; Heal, K V; Stuart, N; Nisbet, T R

2008-07-01

Streamwater was sampled at high flows from 14 catchments with different (0-78%) percentages of broadleaf woodland cover in acid-sensitive areas in the UK to investigate whether woodland cover affects streamwater acidification. Significant positive correlations were found between broadleaf woodland cover and streamwater NO3 and Al concentrations. Streamwater NO3 concentrations exceeded non-marine SO4 in three catchments with broadleaf woodland cover>or=50% indicating that NO3 was the principal excess acidifying ion in the catchments dominated by woodland. Comparison of calculated streamwater critical loads with acid deposition totals showed that 11 of the study catchments were not subject to acidification by acidic deposition. Critical loads were exceeded in three catchments, two of which were due to high NO3 concentrations in drainage from areas with large proportions of broadleaved woodland. The results suggest that the current risk assessment methodology should protect acid-sensitive catchments from potential acidification associated with broadleaf woodland expansion.

Spatio-temporal variability of streamwater chemistry within a Peri-urban Mediterranean catchment

NASA Astrophysics Data System (ADS)

Ferreira, Carla S. S.; Walsh, Rory P. D.; Ferreira, António J. D.; Coelho, Celeste O. A.

2015-04-01

The complex landscape of peri-urban areas, characterized by a mosaic of land-uses and urban fabric, provides different sources of runoff and pollutants which affect stream ecosystems. This study investigates the impact of land-uses and their location within catchments on streamwater quality in a peri-urban Mediterranean catchment, including temporal variations driven by antecedent weather and rainstorm characteristics. The study is based in Ribeira dos Covões, a small (6 km2) catchment in the city of Coimbra, central Portugal. Land-use is dominated by woodland (56%) and urban cover (40%), with a small agriculture area (4%). Streamwater was monitored at the catchment outlet (ESAC) and three upstream locations: Espírito Santo and Porto Bordalo, with similar urban cover (42% and 49%) but different imperviousness (27% and 15%) and lithologies (sandstone versus limestone), and Quinta with lower urban extent (25%) but including a construction site covering 10% of the area. Samples collected throughout ten rainfall events between October 2011 and March 2013 were analysed for natural water chemistry and major pollutants (notably ammonium, nitrates, total phosphorus, COD and metals). In the paper, temporal variations in water quality are explored via hysteresis loop and correlation analysis. Hydrological regime exerted a major influence on water quality. Major nutrients declined within and after the dry summer than in winter events, because of limited dilution by the low stream baseflow. Through the wet season, increasing baseflow led to increased concentrations of major cations (Na, Mg and Ca) because of reduced dilution by solute-poor stormflow. Espírito Santo, the most urbanized sub-catchment, displayed higher concentrations of COD and NO3 (tended to peak with stormflow), but the latter was thought to result from agricultural fields located adjacent the tributary. At the catchment outlet (ESAC), the high Nk and NH4 concentrations exceeded water quality standards (2 mg

East African wetland-catchment data base for sustainable wetland management

NASA Astrophysics Data System (ADS)

Leemhuis, Constanze; Amler, Esther; Diekkrüger, Bernd; Gabiri, Geofrey; Näschen, Kristian

2016-10-01

Wetlands cover an area of approx. 18 Mio ha in the East African countries of Kenya, Rwanda, Uganda and Tanzania, with still a relative small share being used for food production. Current upland agricultural use intensification in these countries due to demographic growth, climate change and globalization effects are leading to an over-exploitation of the resource base, followed by an intensification of agricultural wetland use. We aim on translating, transferring and upscaling knowledge on experimental test-site wetland properties, small-scale hydrological processes, and water related ecosystem services under different types of management from local to national scale. This information gained at the experimental wetland/catchment scale will be embedded as reference data within an East African wetland-catchment data base including catchment physical properties and a regional wetland inventory serving as a base for policy advice and the development of sustainable wetland management strategies.

Predicting nutrient responses to mitigation at catchment to national scale: the UK research platform (Invited)

NASA Astrophysics Data System (ADS)

Johnes, P.

2013-12-01

Nutrient enrichment of waters from land-based and atmospheric sources presents a significant management challenge, requiring effective stakeholder engagement and policy development, properly underpinned by robust scientific evidence. The challenge is complex, raising significant questions about the specific sources, apportionment and pathways that determine nutrient enrichment and the key priorities for effective management and policy intervention. This paper presents outputs from 4 major UK research programmes: the Defra Demonstration Test Catchments programme (DTC), the Environment Agency's Catchment Sensitive Farming monitoring and evaluation programme (CSF), Natural Resources Wales Welsh Catchment Initiative (WCI) and the NERC Environmental Virtual Observatory programme (EVOp). Funded to meet this challenge, they are delivering new understanding of the rates and sources of pollutant fluxes from land to water, their impacts on ecosystem goods and services, and likely trends under future climate and land use change from field to national scale. DTC, a 12m investment by the UK Government, has set up long-term, high resolution research platforms equipped with novel telemetered sensor networks to monitor stream ecosystem responses to on-farm mitigation measures at a representative scale for catchment management. Ecosystem structural and functional responses and bulk hydrochemistry are also being monitored using standard protocols. CSF has set up long-term, enhanced monitoring in 8 priority catchments, with monthly monitoring in a further 72 English catchments and 6 Welsh priority catchments, to identify shifts in pollutant flux to waters resulting from mitigation measures in priority areas and farming sectors. CSF and WCI have contributed to >50 million of targeted farm improvements to date, representing a significant shift in farming practice. Each programme has generated detailed evidence on stream ecosystem responses to targeted mitigation. However, to provide

Transport of cyazofamid and kresoxim methyl in runoff at the plot and catchment scales

NASA Astrophysics Data System (ADS)

Lefrancq, Marie; Joaquín García Verdú, Antonio; Maillard, Elodie; Imfeld, Gwenaël; Payraudeau, Sylvain

2013-04-01

Surface runoff and erosion during the course of rainfall events represent major processes of pesticides transport from agricultural land to aquatic ecosystem. In general, field and catchment studies on pesticide transfer are carried out separately. A study at both scales may enable to improve the understanding of scale effects on processes involved in pesticides transport and to give clues on the source areas within an agricultural catchment. In this study, the transport in runoff of two widely used fungicides, i.e. kresoxim methyl (KM) and cyazofamid (CY) was assessed in a 43 ha vineyard catchment and the relative contribution of the total fungicides export from one representative plot was evaluated. During an entire period of fungicide application, from May to August 2011, the discharge and loads of dissolved and particle-laden KM and CY were monitored at the plot and catchment scales. The results showed larger export coefficient of KM and CY from catchment (0.064 and 0.041‰ for KM and CY respectively) than from the studied plot (0.009 and 0.023 ‰ for KM and CY respectively). It suggests that the plot margins especially the road network contributed as well to the fungicide loads. This result underlines the impact of fungicide drift on non-target areas. Furthermore, a larger rainfall threshold is necessary at the plot scale to trigger runoff and mobilise pesticides than on the road network. At the plot scale, a rapid dissipation of the both fungicides in the top soil was observed. It highlights that the risky period encompasses the first rainfall events triggering runoff after the applications. At both scales, KM and CY were not detected in suspended solids (i.e. > 0.7 µm). However their partitioning in runoff water differed. 64.1 and 91.8% of the KM load was detected in the dissolved phase (i.e. < 0.22 µm) at the plot and catchment scales respectively, whereas 98.7 and 100% of the CY load was detected in the particulate phase (i.e. between 0.22 and 0.7 µm

Elevated Annual Runoff Ratios in Pacific Northwest Catchments Impacted by Epidemic Foliage Disease of Douglas-fir

NASA Astrophysics Data System (ADS)

Bladon, K. D.; Bywater-Reyes, S.; LeBoldus, J. M.; Segura, C.; Ritokova, G.; Shaw, D. C.

2017-12-01

Catchments in the Western United States are undergoing unprecedented levels of tree die-off and/or reduced vigor due to increased severity of wildfire, drought, insect outbreaks, and disease. In the U.S. Pacific Northwest, Swiss needle cast (SNC) is the most damaging foliar disease of Douglas-fir (Pseudotsuga menziesii), physically obstructing stomata and preventing CO2 uptake and transpiration. A recent analysis in coastal Oregon indicated a substantial increase in area affected by the disease, from 530.5 km2 in 1996 to 2,387.1 km2 in 2015. Deforestation or reduced tree vigor can have profound impacts on catchment hydrology, in theory, producing increased streamflow due to reduced interception and transpiration. However, these increases have not always been detectable as impacts also depend on factors such as climate and vegetation composition. Moreover, press disturbances, such as insect outbreaks or disease, often do not result in complete removal of understorey or canopy vegetation. We analyzed trends in annual runoff ratios (quotient of discharge divided by precipitation) from 1990-2015 in 12 catchments (183-1,744 km2) in western Oregon. In general, runoff ratios increased by 10-27% in catchments with a total area of SNC >10%, with the most substantial runoff increases in catchments with SNC impacting >25% of the area. Interestingly, the most severely impacted catchment ( 90.5% SNC) showed a decrease in runoff. This is consistent with a potential compensatory response from understory western hemlock (Tsuga heterophylla) trees, a phenomenon observed in the most severely impacted sites. Findings from this study are important for assessing the impacts of biotic forest disturbances on water supply and aquatic ecosystem health.

Catchment Power and the Joint Distribution of Elevation and Travel Distance to the Outlet

NASA Astrophysics Data System (ADS)

Sklar, L. S.; Riebe, C. S.; Bellugi, D. G.; Lukens, C. E.; Noll, C.

2014-12-01

The delivery of water, sediment and solutes by catchments is influenced by the distribution of source elevations and their travel distances to the outlet. For example, elevation affects the magnitude and phase of precipitation, as well as the climatic factors that govern rock weathering, which influences the particle size and production rate of sediment from slopes. Travel distance, in turn, affects the timing of flood peaks at the outlet and the degree of sediment size reduction by wear, which affect particle size distributions at the outlet. The distributions of elevation and travel distance have been studied extensively but separately, as the hypsometric curve and width function. Yet a catchment can be considered as a collection of points, each with paired values of elevation and travel distance. We refer to the joint distribution of these two fundamental catchment attributes as "catchment power," recognizing that the ratio of elevation to travel distance is proportional to the average rate of loss of the potential energy provided by source elevation, as water or sediment travel to the outlet. We explore patterns in catchment power across a suite of catchments spanning a range of relief, drainage area and channel network geometry. We also develop an empirical algorithm for generating synthetic catchment power distributions, which can be parameterized with data from natural catchments, and used to explore the effects of varying the shape of the distribution on fluxes of water, sediment, isotopes and other landscape products passing through catchment outlets. Ultimately, our goal is to understand how catchment power distributions arise from the branching properties of networks and the relief structure of landscapes. This new way of quantifying catchment geometry may provide a fresh perspective on problems of both practical and theoretical interest.

A MULTIDISCIPLINARY APPROACH TO STORMWATER MANAGEMENT AT THE catchment SCALE

EPA Science Inventory

Stormwater runoff from extensive impervious surfaces in urban and suburban areas has led to human safety risks and stream ecosystem impairment, triggering an interest in catchment-scale retrofit stormwater management. Such stormwater management is of multidisciplinary relevance, ...

Occurrence of multi-antibiotic resistant Pseudomonas spp. in drinking water produced from karstic hydrosystems.

PubMed

Flores Ribeiro, Angela; Bodilis, Josselin; Alonso, Lise; Buquet, Sylvaine; Feuilloley, Marc; Dupont, Jean-Paul; Pawlak, Barbara

2014-08-15

Aquatic environments could play a role in the spread of antibiotic resistance genes by enabling antibiotic-resistant bacteria transferred through wastewater inputs to connect with autochthonous bacteria. Consequently, drinking water could be a potential pathway to humans and animals for antibiotic resistance genes. The aim of this study was to investigate occurrences of Escherichia coli and Pseudomonas spp. in drinking water produced from a karst, a vulnerable aquifer with frequent increases in water turbidity after rainfall events and run-offs. Water samples were collected throughout the system from the karstic springs to the drinking water tap during three non-turbid periods and two turbid events. E. coli densities in the springs were 10- to 1000-fold higher during the turbid events than during the non-turbid periods, indicating that, with increased turbidity, surface water had entered the karstic system and contaminated the spring water. However, no E. coli were isolated in the drinking water. In contrast, Pseudomonas spp. were isolated from the drinking water only during turbid events, while the densities in the springs were from 10- to 100-fold higher than in the non-turbid periods. All the 580 Pseudomonas spp. isolates obtained from the sampling periods were resistant (to between 1 and 10 antibiotics), with similar resistance patterns. Among all the Pseudomonas isolated throughout the drinking water production system, between 32% and 86% carried the major resistance pattern: ticarcillin, ticarcillin-clavulanic acid, cefsulodin, and/or aztreonam, and/or sulfamethoxazol-trimethoprim, and/or fosfomycin. Finally, 8 Pseudomonas spp. isolates, related to the Pseudomonas putida and Pseudomonas fluorescens species, were isolated from the drinking water. Thus, Pseudomonas could be involved in the dissemination of antibiotic resistance via drinking water during critical periods. Copyright © 2014 Elsevier B.V. All rights reserved.

Groundwater vulnerability assessment for the Banyas Catchment of the Syrian coastal area using GIS and the RISKE method.

PubMed

Kattaa, Bassam; Al-Fares, Walid; Al Charideh, Abdul Rahman

2010-05-01

Vulnerability assessment to delineate areas that are more susceptible to contamination from anthropogenic sources has become an important element for sensible resource management and landuse planning. This contribution aims at estimating aquifer vulnerability by applying the RISKE model in Banyas Catchment Area (BCA), Tartous Prefecture, west Syria. An additional objective is to demonstrate the combined use of the RISKE model and a geographical information system (GIS) as an effective method for groundwater pollution risk assessment. The RISKE model uses five environmental parameters (Rock of aquifer media, Infiltration, Soil media, Karst, and Epikarst) to characterize the hydro-geological setting and evaluate aquifer vulnerability. The elevated eastern and low western part of the study area was dominated by high vulnerability classes, while the middle part was characterized by moderate vulnerability classes. Based on the vulnerability analysis, it was found that 2% and 39% of BCA is under low and high vulnerability to groundwater contamination, respectively, while more than 52% and 5% of the area of BCA can be designated as an area of moderate and very high vulnerability to groundwater contamination, respectively. The GIS technique has provided an efficient environment for analyses and high capabilities of handling a large amount of spatial data. Copyright 2009 Elsevier Ltd. All rights reserved.

Modeling micropollutant fate at the catchment scale: from science to practice

NASA Astrophysics Data System (ADS)

Seuntjens, P.; Desmet, N.; Holvoet, K.; van Griensven, A.; van Hoey, S.; Tang, X. Y.; Nopens, I.

2009-04-01

Micropollutants, such as pesticides, personal care products, veterinary and human pharmaceuticals, pose a possible threat to human and ecological health. Humans and ecosystems may be exposed to these chemicals via the water system. Catchment models can be used to optimise management in view of risk reduction of the chemicals. Along the trajectory of science to practice a number of catchment models are available that simulate the fate and transport of micropollutants. They range from physically-based fully-coupled soil, groundwater, and surface water models, over empirical management models, to purely statistical database-driven models. For assessing effects on ecosystems, models need to be able to predict the observed highly dynamic behaviour of pesticide concentrations in the surface water, since adverse effects will be determined by the number, intensity and frequency of ecological threshold exceedances. For assessing effects on humans, models need to predict the dilution between areas where the pesticide is released and the location of the drinking water intake, sometimes tens or hundreds of kilometres further downstream. We adapted management models to simulate dynamic pesticide behaviour and fate at the catchment scale. The models were also used to illustrate the effects of specific management options on risk reduction and to derive the dominant sources of pollutants in a catchment area. The results show that the concentrations of pesticides in river systems are attributed to (1) fast flow over and in soils or pavements, and to (2) point sources. Therefore, future models for improved estimation of chemical fate at the catchment scale need a combination of stochastic source characterisation, higher spatial resolution and reduced complexity of the mathematical description of fast flow processes. This will be illustrated by recent developments in model simplification coupled to increased spatial detail.

Climatic and Catchment-Scale Predictors of Chinese Stream Insect Richness Differ between Taxonomic Groups

PubMed Central

Tonkin, Jonathan D.; Shah, Deep Narayan; Kuemmerlen, Mathias; Li, Fengqing; Cai, Qinghua; Haase, Peter; Jähnig, Sonja C.

2015-01-01

Little work has been done on large-scale patterns of stream insect richness in China. We explored the influence of climatic and catchment-scale factors on stream insect (Ephemeroptera, Plecoptera, Trichoptera; EPT) richness across mid-latitude China. We assessed the predictive ability of climatic, catchment land cover and physical structure variables on genus richness of EPT, both individually and combined, in 80 mid-latitude Chinese streams, spanning a 3899-m altitudinal gradient. We performed analyses using boosted regression trees and explored the nature of their influence on richness patterns. The relative importance of climate, land cover, and physical factors on stream insect richness varied considerably between the three orders, and while important for Ephemeroptera and Plecoptera, latitude did not improve model fit for any of the groups. EPT richness was linked with areas comprising high forest cover, elevation and slope, large catchments and low temperatures. Ephemeroptera favoured areas with high forest cover, medium-to-large catchment sizes, high temperature seasonality, and low potential evapotranspiration. Plecoptera richness was linked with low temperature seasonality and annual mean, and high slope, elevation and warm-season rainfall. Finally, Trichoptera favoured high elevation areas, with high forest cover, and low mean annual temperature, seasonality and aridity. Our findings highlight the variable role that catchment land cover, physical properties and climatic influences have on stream insect richness. This is one of the first studies of its kind in Chinese streams, thus we set the scene for more in-depth assessments of stream insect richness across broader spatial scales in China, but stress the importance of improving data availability and consistency through time. PMID:25909190

Storage as a Metric of Catchment Comparison

USGS Publications Warehouse

McNamara, J.P.; Tetzlaff, D.; Bishop, K.; Soulsby, C.; Seyfried, M.; Peters, N.E.; Aulenbach, Brent T.; Hooper, R.

2011-01-01

The volume of water stored within a catchment, and its partitioning among groundwater, soil moisture, snowpack, vegetation, and surface water are the variables that ultimately characterize the state of the hydrologic system. Accordingly, storage may provide useful metrics for catchment comparison. Unfortunately, measuring and predicting the amount of water present in a catchment is seldom done; tracking the dynamics of these stores is even rarer. Storage moderates fluxes and exerts critical controls on a wide range of hydrologic and biologic functions of a catchment. While understanding runoff generation and other processes by which catchments release water will always be central to hydrologic science, it is equally essential to understand how catchments retain water. We have initiated a catchment comparison exercise to begin assessing the value of viewing catchments from the storage perspective. The exercise is based on existing data from five watersheds, no common experimental design, and no integrated modelling efforts. Rather, storage was estimated independently for each site. This briefing presents some initial results of the exercise, poses questions about the definitions and importance of storage and the storage perspective, and suggests future directions for ongoing activities. ?? 2011 John Wiley & Sons, Ltd.

Are catchment-wide erosion rates really "Catchment-Wide"? Effects of grain size on erosion rates determined from 10Be

NASA Astrophysics Data System (ADS)

Reitz, M. A.; Seeber, L.; Schaefer, J. M.; Ferguson, E. K.

2012-12-01

Early studies pioneering the method for catchment wide erosion rates by measuring 10Be in alluvial sediment were taken at river mouths and used the sand size grain fraction from the riverbeds in order to average upstream erosion rates and measure erosion patterns. Finer particles (<0.0625 mm) were excluded to reduce the possibility of a wind-blown component of sediment and coarser particles (>2 mm) were excluded to better approximate erosion from the entire upstream catchment area (coarse grains are generally found near the source). Now that the sensitivity of 10Be measurements is rapidly increasing, we can precisely measure erosion rates from rivers eroding active tectonic regions. These active regions create higher energy drainage systems that erode faster and carry coarser sediment. In these settings, does the sand-sized fraction fully capture the average erosion of the upstream drainage area? Or does a different grain size fraction provide a more accurate measure of upstream erosion? During a study of the Neto River in Calabria, southern Italy, we took 8 samples along the length of the river, focusing on collecting samples just below confluences with major tributaries, in order to use the high-resolution erosion rate data to constrain tectonic motion. The samples we measured were sieved to either a 0.125 mm - 0.710 mm fraction or the 0.125 mm - 4 mm fraction (depending on how much of the former was available). After measuring these 8 samples for 10Be and determining erosion rates, we used the approach by Granger et al. [1996] to calculate the subcatchment erosion rates between each sample point. In the subcatchments of the river where we used grain sizes up to 4 mm, we measured very low 10Be concentrations (corresponding to high erosion rates) and calculated nonsensical subcatchment erosion rates (i.e. negative rates). We, therefore, hypothesize that the coarser grain sizes we included are preferentially sampling a smaller upstream area, and not the entire

Phosphorus and dissolved organic carbon export during peak flow periods in three small homogenous catchments in eastern Germany

NASA Astrophysics Data System (ADS)

Benning, R.; Schwärzel, K.; Feger, K. H.

2012-04-01

Regional climate change scenarios for Central Europe predict both an overall increase in temperature and alterations in annual precipitation regimes. For large parts of Central Europe, climate change is expected to result in an increase in winter precipitation and a decrease in summer precipitation. In addition, an increase in extreme conditions, such as heat waves, prolonged drought periods, and heavy rainfall events are predicted. This research examines the potential impacts of increased heavy rainfall events on matter export from small catchment areas, and how different vegetation cover and land management options effects these exports. In order to evaluate the export of matter from different land-use types in the Eastern Ore Mountains (Saxony, NE Germany, 50° 48'18.06" North, 13° 36'24.54" East), study sites were established in three small catchments with homogeneous land-use. These study areas are each sub-catchments of the Ammelsdorf catchment, which provides inflow to the Lehnmühle reservoir (a major water supply for the city of Dresden). Each sub catchment represents one of the three main land-use types in the catchment area of the reservoir: crops (winter oilseed rape, winter wheat), grasslands, and forests (primarily spruce). Since November 2009 the discharge from these sub catchments has been continuously measured and water quality was analyzed on a weekly basis. During peak flow events, discharge was collected using automatic water samplers, which allowed for high temporal resolution analysis of matter export during these periods to be made. During the 2010 and 2011 hydrological years, several heavy rainfall events occurred which have been evaluated. During a 110-hour long precipitation event (P = 170 mm) between 37 and 81 water samples per sub catchment were collected and analyzed. The resulting export of dissolved phosphorus (ortho-PO4-) and dissolved organic carbon (DOC) from the sub catchments during this event is provided in the results. In

Hydrologic data for urban storm runoff from three localities in the Denver metropolitan area, Colorado

USGS Publications Warehouse

Ellis, Sherman R.

1978-01-01

Urban storm-runoff data, collected from 1975 to 1977, on three catchment areas in the Denver, Colo., metropolitan area are presented. The catchment are predominantly a single-family residential catchment area in Littleton, a multifamily residential and commercial catchment area in Lakewood, and a high-density residential and commercial catchment area in Denver. Precipitation, rainfall-runoff, snowmelt-runoff, water-quality (common constituents, nutrients, biochemical oxygen demand, coliform bacteria, and solids, trace elements, and pesticides), and catchment-area data are necessary to use the U.S. Environmental Protection Agency 's Storm Water Management Model II. The urban storm-runoff data may be used by planning, water-management, and environmental-protection agencies to assess the impact of urban storm runoff on the hydrologic system. (Woodard-USGS)

Development of a hydrological model for simulation of runoff from catchments unbounded by ridge lines

NASA Astrophysics Data System (ADS)

Vema, Vamsikrishna; Sudheer, K. P.; Chaubey, I.

2017-08-01

Watershed hydrological models are effective tools for simulating the hydrological processes in the watershed. Although there are a plethora of hydrological models, none of them can be directly applied to make water conservation decisions in irregularly bounded areas that do not confirm to topographically defined ridge lines. This study proposes a novel hydrological model that can be directly applied to any catchment, with or without ridge line boundaries. The model is based on the water balance concept, and a linear function concept to approximate the cross-boundary flow from upstream areas to the administrative catchment under consideration. The developed model is tested in 2 watersheds - Riesel Experimental Watershed and a sub-basin of Cedar Creek Watershed in Texas, USA. Hypothetical administrative catchments that did not confirm to the location of ridge lines were considered for verifying the efficacy of the model for hydrologic simulations. The linear function concept used to account the cross boundary flow was based on the hypothesis that the flow coming from outside the boundary to administrative area was proportional to the flow generated in the boundary grid cell. The model performance was satisfactory with an NSE and r2 of ≥0.80 and a PBIAS of <25 in all the cases. The simulated hydrographs for the administrative catchments of the watersheds were in good agreement with the observed hydrographs, indicating a satisfactory performance of the model in the administratively bounded areas.

Geodesic and hydrogeophysic long term observations in the Durzon karstic aquifer (Larzac, France)

NASA Astrophysics Data System (ADS)

Le Moigne, Nicolas; Bayer, Roger; Boudin, Frederick; Champollion, Cedric; Chery, Jean; Collard, Philippe; Daignières, Marc; Deville, Sabrina; Doerflinger, Erik; Vernant, Philippe

2010-05-01

Karsts are generally characterized by high heterogeneity at all scales for both the water storage properties and the mode of water transport. The Durzon karst system is located in south of France and is characterized by a unsaturated zone of 100-150 m width. The water input is exclusively rainfall and draining occurs at the Durzon perennial spring in a karstic valley. The Durzon aquifer has been monitored by our group by different geophysical methods (gravimetry, tiltmetry, more details below) for several years. The present-day stage of the project is to setup long term observations to assess hydrological properties of the karst in a small area of 500m*500m with numerous caves (up to 100 m deep and more than 2 km of development). The observations are of four major types: - Continuous high frequency and high accuracy gravimetry: Gravimetric observations can be directly linked to the variations of water masses in the unsaturated zone. The iGrav™ Superconducting Gravity Meter from GWR (San Diego, USA) will be used to record continuous gravity variations and track water mass variations at a few millimeters level. The iGrav™ is a new SG model from GWR that has been simplified for portable and field operation, but retains the stability and precision of previous SGs. With a drift rate of less than 0.5 microGal/month and a virtually constant scale factory, the iGrav™ will provide a much higher stability and precision than can be achieved with mechanical spring-type gravity meters. - Water flux measurements (atmospheric and in-situ): A flux tower provides evapo-transpiration measurements (output) allowing complete budget calculation with the help of gravity (storage variations) and rainfall (input). An original measurement corresponds to the measure of the in-situ flow inside karstic caves (stalactites and underground river). - Tiltmetry: In situ (in caves) measurements are completed by long base silica tiltmeters. Tiltmeters are sensible to water storage in fractures

The role of event water, a rapid shallow flow component, and catchment size in summer stormflow

USGS Publications Warehouse

Brown, V.A.; McDonnell, Jeffery J.; Burns, Douglas A.; Kendall, C.

1999-01-01

Seven nested headwater catchments (8 to 161 ha) were monitored during five summer rain events to evaluate storm runoff components and the effect of catchment size on water sources. Two-component isotopic hydrograph separation showed that event-water contributions near the time of peakflow ranged from 49% to 62% in the 7 catchments during the highest intensity event. The proportion of event water in stormflow was greater than could be accounted for by direct precipitation onto saturated areas. DOC concentrations in stormflow were strongly correlated with stream 18O composition. Bivariate mixing diagrams indicated that the large event water contributions were likely derived from flow through the soil O-horizon. Results from two-tracer, three-component hydrograph separations showed that the throughfall and O-horizon soil-water components together could account for the estimated contributions of event water to stormflow. End-member mixing analysis confirmed these results. Estimated event-water contributions were inversely related to catchment size, but the relation was significant for only the event with greatest rainfall intensity. Our results suggest that perched, shallow subsurface flow provides a substantial contribution to summer stormflow in these small catchments, but the relative contribution of this component decreases with catchment size.Seven nested headwater catchments (8 to 161 ha) were monitored during five summer rain events to evaluate storm runoff components and the effect of catchment size on water sources. Two-component isotopic hydrograph separation showed that event-water contributions near the time of peakflow ranged from 49% to 62% in the 7 catchments during the highest intensity event. The proportion of event water in stormflow was greater than could be accounted for by direct precipitation onto saturated areas. DOC concentrations in stormflow were strongly correlated with stream 18O composition. Bivariate mixing diagrams indicated that the

Sulphur cycling in the drinking water catchment area of Torgau-Mockritz (Germany): insights from hydrochemical and stable isotope investigations

NASA Astrophysics Data System (ADS)

Knöller, K.; Trettin, R.; Strauch, G.

2005-11-01

The hydrochemical composition of groundwater and the isotopic composition of sulphur compounds in sediments (34S of sulphide, inorganic sulphate) and groundwater (34S, 18O of dissolved sulphate) have been investigated to reveal the reasons for elevated concentrations of dissolved groundwater sulphate in the drinking water catchment area of Torgau-Mockritz (Germany).The three most important anthropogenic sources of sulphate identified in this study are historic atmospheric sulphate deposition, predominantly of anthropogenic origin, inorganic fertilization, and dissolution of gypsum from waste dumps. Owing to their overlapping isotopic range, no clear differentiation between the individual anthropogenic sources is possible. Sulphate from the oxidation of sedimentary sulphides, however, was recognized by its negative sulphur isotope signature (34S < - 5).The mobilization of sulphate from different soil sulphur species is closely connected with variable isotopic fractionations, resulting in a wide isotopic variation range for the sulphate entering the saturated zone. Generally, sulphur and oxygen isotope ratios of the dissolved groundwater sulphate range from -19 to +37 (Vienna Cañon Diablo troilite) and from -2 to +19 (Vienna standard mean ocean water), respectively. Sulphate from the majority of groundwater samples can be assigned to anthropogenic sources. Sulphate from sulphide oxidation is especially present in samples from the upper sampling level and the groundwater surface. Sulphate concentrations above 700 mg l-1 are mostly caused by the oxidation of sulphide. Sulphate that occurs in low and moderate concentrations dominantly originates from anthropogenic sources.34S distribution patterns were used to locate the sources for the elevated sulphate concentrations in the raw water. It was shown that the sulphate is not mobilized in the immediate vicinity of the production wells. Rather, it originates in an area 1.5 km west of the intake. The main mobilization

Water Catchment and Storage Monitoring

NASA Astrophysics Data System (ADS)

Bruenig, Michael; Dunbabin, Matt; Moore, Darren

2010-05-01

Sensors and Sensor Networks technologies provide the means for comprehensive understanding of natural processes in the environment by radically increasing the availability of empirical data about the natural world. This step change is achieved through a dramatic reduction in the cost of data acquisition and many orders of magnitude increase in the spatial and temporal granularity of measurements. Australia's Commonwealth Scientific and Industrial Research Organisation (CSIRO) is undertaking a strategic research program developing wireless sensor network technology for environmental monitoring. As part of this research initiative, we are engaging with government agencies to densely monitor water catchments and storages, thereby enhancing understanding of the environmental processes that affect water quality. In the Gold Coast hinterland in Queensland, Australia, we are building sensor networks to monitor restoration of rainforest within the catchment, and to monitor methane flux release and water quality in the water storages. This poster will present our ongoing work in this region of eastern Australia. The Springbrook plateau in the Gold Coast hinterland lies within a World Heritage listed area, has uniquely high rainfall, hosts a wide range of environmental gradients, and forms part of the catchment for Gold Coast's water storages. Parts of the plateau are being restored from agricultural grassland to native rainforest vegetation. Since April 2008, we have had a 10-node, multi-hop sensor network deployed there to monitor microclimate variables. This network will be expanded to 50-nodes in February 2010, and to around 200-nodes and 1000 sensors by mid-2011, spread over an area of approximately 0.8 square kilometers. The extremely dense microclimate sensing will enhance knowledge of the environmental factors that enhance or inhibit the regeneration of native rainforest. The final network will also include nodes with acoustic and image sensing capability for

Assessing metaldehyde concentrations in surface water catchments and implications for drinking water abstraction

NASA Astrophysics Data System (ADS)

Asfaw, Alemayehu; Shucksmith, James; Smith, Andrea; Cherry, Katherine

2015-04-01

Metaldehyde is an active ingredient in agricultural pesticides such as slug pellets, which are heavily applied to UK farmland during the autumn application season. There is current concern that existing drinking water treatment processes may be inadequate in reducing potentially high levels of metaldehyde in surface waters to below the UK drinking water quality regulation limit of 0.1 µg/l. In addition, current water quality monitoring methods can miss short term fluctuations in metaldehyde concentration caused by rainfall driven runoff, hampering prediction of the potential risk of exposure. Datasets describing levels, fate and transport of metaldehyde in river catchments are currently very scarce. This work presents results from an ongoing study to quantify the presence of metaldehyde in surface waters within a UK catchment used for drinking water abstraction. High resolution water quality data from auto-samplers installed in rivers are coupled with radar rainfall, catchment characteristics and land use data to i) understand which hydro-meteorological characteristics of the catchment trigger the peak migration of metaldehyde to surface waters; ii) assess the relationship between measured metaldehyde levels and catchment characteristics such as land use, topographic index, proximity to water bodies and runoff generation area; iii) describe the current risks to drinking water supply and discuss mitigation options based on modelling and real-time control of water abstraction. Identifying the correlation between catchment attributes and metaldehyde generation will help in the development of effective catchment management strategies, which can help to significantly reduce the amount of metaldehyde finding its way into river water. Furthermore, the effectiveness of current water quality monitoring strategy in accurately quantifying the generation of metaldehyde from the catchment and its ability to benefit the development of effective catchment management practices

Effect of bedrock permeability on stream base flow mean transit time scaling relations: 1. A multiscale catchment intercomparison

NASA Astrophysics Data System (ADS)

Hale, V. Cody; McDonnell, Jeffrey J.

2016-02-01

The effect of bedrock permeability and underlying catchment boundaries on stream base flow mean transit time (MTT) and MTT scaling relationships in headwater catchments is poorly understood. Here we examine the effect of bedrock permeability on MTT and MTT scaling relations by comparing 15 nested research catchments in western Oregon; half within the HJ Andrews Experimental Forest and half at the site of the Alsea Watershed Study. The two sites share remarkably similar vegetation, topography, and climate and differ only in bedrock permeability (one poorly permeable volcanic rock and the other more permeable sandstone). We found longer MTTs in the catchments with more permeable fractured and weathered sandstone bedrock than in the catchments with tight, volcanic bedrock (on average, 6.2 versus 1.8 years, respectively). At the permeable bedrock site, 67% of the variance in MTT across catchments scales was explained by drainage area, with no significant correlation to topographic characteristics. The poorly permeable site had opposite scaling relations, where MTT showed no correlation to drainage area but the ratio of median flow path length to median flow path gradient explained 91% of the variance in MTT across seven catchment scales. Despite these differences, hydrometric analyses, including flow duration and recession analysis, and storm response analysis, show that the two sites share relatively indistinguishable hydrodynamic behavior. These results show that similar catchment forms and hydrologic regimes hide different subsurface routing, storage, and scaling behavior—a major issue if only hydrometric data are used to define hydrological similarity for assessing land use or climate change response.

Catchment Engineering: A New Paradigm in Water Management

NASA Astrophysics Data System (ADS)

Quinn, P. F.; Burke, S.; O'Donnell, G. M.; Wilkinson, M.; Jonczyk, J.; Barber, N.; Nicholson, A.; Proactive Team

2011-12-01

Recent catchment initiatives have highlighted the need for new holistic approaches to sustainable water management. Here, a catchment engineering approach seeks to describe catchment 'function' (or role) as the principal driver for evaluating how it should be managed in the future. Catchment engineering does not seek to re-establish a natural system but seeks to work with natural processes in order to engineer landscapes so that multiple benefits accrue. This approach involves quantifying and assessing catchment change and impacts but most importantly suggests an urgent and proactive agenda for future planning. In particular, an interventionist approach to managing hydrological flow pathways across scale is proposed. It is already accepted that future management will require a range of scientific expertise and full engagement with stakeholders, namely the general public and policy makers. This inclusive concept under a catchment engineering agenda forces any consortia to commit to actively changing and perturbing the catchment system and thus learn, in situ, how to manage the environment for collective benefits. The shared cost, the design, the implementation, the evaluation and any subsequent modifications should involve all relevant parties in the consortia. This joint ownership of a 'hands on' interventionist agenda to catchment change is at the core of catchment engineering. In this paper we show a range of catchment engineering projects from the UK that have addressed multi-disciplinary approaches to flooding, pollution and ecosystem management whilst maintaining economic food production. Local scale demonstration activities, led by local champions, have proven to be an effective means of encouraging wider uptake. Catchment engineering is a concept that relies on all relevant parties within a catchment to take responsibility for the water quantity and quality that arises from the catchment. Further, any holistic solution requires a bottom up, problem solving

Hydrological response of the Mediterranean catchments- A review

NASA Astrophysics Data System (ADS)

Merheb, Mohammad; Moussa, Roger; Abdallah, Chadi; Colin, François; Perrin, Charles; Baghdadi, Nicolas

2015-04-01

-stressed region that witnesses long low-flows periods. Predictions of runoff hydrograph give poor results. For flow duration curves and low flows regionalization, statistical and geo-statistical methods appear to outperform parametric approaches and regression respectively. Mixed results were found for regional flood analysis which appears to be the most common regionalization practice in the area. Finally, given the great heterogeneity in the hydrological responses of Mediterranean catchments and the increasing anthropogenic and climatic pressures, the region appears to be in need for more detailed observations and new modeling techniques adapted to its specificities. Keywords: hydrology, catchment, Mediterranean, modeling, regionalization, anthropogenic impact, climate change.

Sediment budget for Rediu reservoir catchment, North-Eastern Romania

NASA Astrophysics Data System (ADS)

Todosi, Cristian; Niculita, Mihai

2016-04-01

Sediment budgets are a useful tool for geomorphologic analysis, catchment management and environmental assessment, despite the uncertainties related to their assessment. We present the sediment budget construction and validation for a small catchment of 9.5319 kmp (953.19 ha) situated in the North-Eastern part of Romania. The Rediu reservoir was built between 1986 and 1988, on Rediu valley, a left tributary of Bahlui river, north-west from Iasi city. The catchment of the reservoir has 6.5 km in length and 2.5 km in maximum width, the altitudes decreasing from 170 m in the northern part, to 52 m in the southern part. The valley is symmetric, the altitude of the hillslopes going between 200 m to 75 m in one km length, in the transversal section with the maximum width. The floodplain is narrow having between 20 m to 210 m (in the area of confluence with Breazu tributary). The mean slope of the catchment is 6.4 degree, the maximum slope being 24.6 degrees. The length of channels which show banks of up to 2 m is 19.98 km. The land is used predominantly as crops (58.1 %), 16.7 % being covered by pastures (from which over half are eroded), 11.5 % percent of the catchment being covered by planted forests, 9.2 % by rural constructions and roads, 2.9 % by hayfields, 1.5 % by lakes and 0.1 % by orchards. Beside the Rediu reservoir, there are three ponds (15 771, 1761 and 751 sqm) in the catchment. We considered the trap efficiency for the reservoir and the ponds to be 95%. Aerial images from 1963, 1978 , 1984, 2005, 2008, 2010, 2012 and 2014 were used to assess the state of geomorphological processes before and after the reservoir construction. After 1970 a gully system situated in Breazu tributary sub-catchment and several active landslides along the main valley left side were forested. Beside these processes, soil erosion and human impact by constructions are the main processes generating sediment in the study area. The sediment yields were quantified by estimating the

Impact of climate change on low flow characteristics in a small catchment of central Poland

NASA Astrophysics Data System (ADS)

Banasik, K.; Kaznowska, E.

2016-12-01

The Zagozdzonka catchment (left tributary of Vistula River) is a small lowland agricultural catchment, located in central Poland, about 100 km south of Warsaw. Hydrological investigations of the Zagozdzonka River at Plachty (N51°26'43.8''; E21°27'35.6''), have been carried out by the Department of River Engineering of Warsaw University of Life Science (WULS) since 1962. The catchment area is 82.4 km2 at the Plachty river gauging station. Annual data of temperature, annual and seasonal rainfall and runoff characteristics, as well as annual N-day (1-, 2-, 3-, 7-, 14- and 30-day) low flow from the catchment of the period of 53-year (1963-2015) were analysed. Mann-Kendall test was used for trend analysis. Analysis has revealed a long term decrease in annual discharge and in all of the analysed N-day low flows from the catchment, as well as a corresponding increase in annul temperature (1.61ºC/50 years) for this area of Poland. No trend was detected for annual precipitation nor summer/winter half year precipitation. There was little land use change in the catchment but remarkable increase of crop yields from the arable land in this region of Poland in the last 50 years, due to fertilisation. So the long term decrease of annual discharge and N-day low flows is assumed to be effect of higher evapotranspiration. The decrease of water resources in summer periods may cause problems when more intensive agriculture practice is planned (and water for irrigation is needed).

Recent advances in catchment hydrology

NASA Astrophysics Data System (ADS)

van Meerveld, I. H. J.

2017-12-01

Despite the consensus that field observations and catchment studies are imperative to understand hydrological processes, to determine the impacts of global change, to quantify the spatial and temporal variability in hydrological fluxes, and to refine and test hydrological models, there is a decline in the number of field studies. This decline and the importance of fieldwork for catchment hydrology have been described in several recent opinion papers. This presentation will summarize these commentaries, describe how catchment studies have evolved over time, and highlight the findings from selected recent studies published in Water Resources Research.

Winter streamflow analysis in frozen, alpine catchments to quantify groundwater contribution and properties

NASA Astrophysics Data System (ADS)

Stoelzle, Michael; Weiler, Markus

2016-04-01

Alpine catchments are often considered as quickly responding systems where streamflow contributions from subsurface storages (groundwater) are mostly negligible due to the steep topography, low permeable bedrock and the absence of well-developed soils. Many studies in high altitude catchments have hence focused on water stored in snowpack and glaciers or on rainfall-runoff processes as the dominant streamflow contributions. Interestingly less effort has been devoted to winter streamflow analysis when melt- or rainfall-driven contributions are switched off due to the frozen state of the catchment. Considering projected changes in the alpine cryosphere (e.g. snow, glacier, permafrost) quantification of groundwater storage and contribution to streamflow is crucial to assess the social and ecological implications for downstream areas (e.g. water temperature, drought propagation). In this study we hypothesize that groundwater is the main streamflow contribution during winter and thus being responsible for the perennial regime of many alpine catchments. The hypothesis is investigated with well-known methods based on recession and breakpoint analysis of the streamflow regimes and temperature data to determine frozen periods. Analyzing nine catchments in Switzerland with mean elevation between 1000 and 2400 m asl, we found that above a mean elevation of 1800 m asl winter recessions are sufficient long and persistent enough to quantify groundwater contribution to streamflow and to characterize the properties of subsurface storage. The results show that groundwater in alpine catchment is the dominant streamflow contribution for nearly half a year and accountable for several hundred millimeter of annual streamflow. In sub-alpine catchments, driven by a mix of snowmelt and rainfall, a clear quantification of groundwater contributions is rather challenging due to discontinuous frozen periods in winter. We found that the inter-annual variability of different streamflow

USLE-Based Assessment of Soil Erosion by Water in the Nyabarongo River Catchment, Rwanda

PubMed Central

Karamage, Fidele; Zhang, Chi; Kayiranga, Alphonse; Shao, Hua; Fang, Xia; Ndayisaba, Felix; Nahayo, Lamek; Mupenzi, Christophe; Tian, Guangjin

2016-01-01

Soil erosion has become a serious problem in recent decades due to unhalted trends of unsustainable land use practices. Assessment of soil erosion is a prominent tool in planning and conservation of soil and water resource ecosystems. The Universal Soil Loss Equation (USLE) was applied to Nyabarongo River Catchment that drains about 8413.75 km2 (33%) of the total Rwanda coverage and a small part of the Southern Uganda (about 64.50 km2) using Geographic Information Systems (GIS) and Remote Sensing technologies. The estimated total annual actual soil loss was approximately estimated at 409 million tons with a mean erosion rate of 490 t·ha−1·y−1 (i.e., 32.67 mm·y−1). The cropland that occupied 74.85% of the total catchment presented a mean erosion rate of 618 t·ha−1·y−1 (i.e., 41.20 mm·y−1) and was responsible for 95.8% of total annual soil loss. Emergency soil erosion control is required with a priority accorded to cropland area of 173,244 ha, which is extremely exposed to actual soil erosion rate of 2222 t·ha−1·y−1 (i.e., 148.13 mm·y−1) and contributed to 96.2% of the total extreme soil loss in the catchment. According to this study, terracing cultivation method could reduce the current erosion rate in cropland areas by about 78%. Therefore, the present study suggests the catchment management by constructing check dams, terracing, agroforestry and reforestation of highly exposed areas as suitable measures for erosion and water pollution control within the Nyabarongo River Catchment and in other regions facing the same problems. PMID:27556474

USLE-Based Assessment of Soil Erosion by Water in the Nyabarongo River Catchment, Rwanda.

PubMed

Karamage, Fidele; Zhang, Chi; Kayiranga, Alphonse; Shao, Hua; Fang, Xia; Ndayisaba, Felix; Nahayo, Lamek; Mupenzi, Christophe; Tian, Guangjin

2016-08-20

Soil erosion has become a serious problem in recent decades due to unhalted trends of unsustainable land use practices. Assessment of soil erosion is a prominent tool in planning and conservation of soil and water resource ecosystems. The Universal Soil Loss Equation (USLE) was applied to Nyabarongo River Catchment that drains about 8413.75 km² (33%) of the total Rwanda coverage and a small part of the Southern Uganda (about 64.50 km²) using Geographic Information Systems (GIS) and Remote Sensing technologies. The estimated total annual actual soil loss was approximately estimated at 409 million tons with a mean erosion rate of 490 t·ha(-1)·y(-1) (i.e., 32.67 mm·y(-1)). The cropland that occupied 74.85% of the total catchment presented a mean erosion rate of 618 t·ha(-1)·y(-1) (i.e., 41.20 mm·y(-1)) and was responsible for 95.8% of total annual soil loss. Emergency soil erosion control is required with a priority accorded to cropland area of 173,244 ha, which is extremely exposed to actual soil erosion rate of 2222 t·ha(-1)·y(-1) (i.e., 148.13 mm·y(-1)) and contributed to 96.2% of the total extreme soil loss in the catchment. According to this study, terracing cultivation method could reduce the current erosion rate in cropland areas by about 78%. Therefore, the present study suggests the catchment management by constructing check dams, terracing, agroforestry and reforestation of highly exposed areas as suitable measures for erosion and water pollution control within the Nyabarongo River Catchment and in other regions facing the same problems.

Hydrogeologic controls on nitrate transport in a small agricultural catchment, Iowa

USGS Publications Warehouse

Schilling, K.E.; Tomer, M.D.; Zhang, Y.-K.; Weisbrod, T.; Jacobson, P.; Cambardella, C.A.

2007-01-01

Effects of subsurface deposits on nitrate loss in stream riparian zones are recognized, but little attention has been focused on similar processes occurring in upland agricultural settings. In this paper, we evaluated hydrogeologic controls on nitrate transport processes occurring in a small 7.6 ha Iowa catchment. Subsurface deposits in the catchment consisted of upland areas of loess overlying weathered pre-Illinoian till, drained by two ephemeral drainageways that consisted of Holocene-age silty and organic rich alluvium. Water tables in upland areas fluctuated more than 4 m per year compared to less than 0.3 m in the drainageway. Water quality patterns showed a distinct spatial pattern, with groundwater in the drainageways having lower nitrate concentrations (10 mg L-1) as wells as lower pH, dissolved oxygen and redox, and higher ammonium and dissolved organic carbon levels. Several lines of evidence suggested that conditions are conducive for denitrification of groundwater flowing from uplands through the drainageways. Field-measured nitrate decay rates in the drainageways (???0.02 day-1) were consistent with other laboratory studies and regional patterns. Results from MODFLOW and MT3DMS simulations indicated that soils in the ephemeral drainageways could process all upland groundwater nitrate flowing through them. However, model-simulated tile drainage increased both water flux and nitrate loss from the upland catchment. Study results suggest that ephemeral drainageways can provide a natural nitrate treatment system in our upland glaciated catchments, offering management opportunities to reduce nitrate delivery to streams. Copyright 2007 by the American Geophysical Union.

How does landscape structure influence catchment transit time across different geomorphic provinces?

USGS Publications Warehouse

Tetzlaff, D.; Seibert, J.; McGuire, K.J.; Laudon, H.; Burns, Douglas A.; Dunn, S.M.; Soulsby, C.

2009-01-01

Despite an increasing number of empirical investigations of catchment transit times (TTs), virtually all are based on individual catchments and there are few attempts to synthesize understanding across different geographical regions. Uniquely, this paper examines data from 55 catchments in five geomorphic provinces in northern temperate regions (Scotland, United States of America and Sweden). The objective is to understand how the role of catchment topography as a control on the TTs differs in contrasting geographical settings. Catchment inverse transit time proxies (ITTPs) were inferred by a simple metric of isotopic tracer damping, using the ratio of standard deviation of ??18O in streamwater to the standard deviation of ??18O in precipitation. Quantitative landscape analysis was undertaken to characterize the catchments according to hydrologically relevant topographic indices that could be readily determined from a digital terrain model (DTM). The nature of topographic controls on transit times varied markedly in different geomorphic regions. In steeper montane regions, there are stronger gravitational influences on hydraulic gradients and TTs tend to be lower in the steepest catchments. In provinces where terrain is more subdued, direct topographic control weakened; in particular, where flatter areas with less permeable soils give rise to overland flow and lower TTs. The steeper slopes within this flatter terrain appear to have a greater coverage of freely draining soils, which increase sub-surface flow, therefore increasing TTs. Quantitative landscape analysis proved a useful tool for intercatchment comparison. However, the critical influence of sub-surface permeability and connectivity may limit the transferability of predictive tools of hydrological function based on topographic parameters alone. Copyright ?? 2009 John Wiley & Sons, Ltd.

Community Perception of Water Quality in a Mining-Affected Area: A Case Study for the Certej Catchment in the Apuseni Mountains in Romania

NASA Astrophysics Data System (ADS)

Dogaru, Diana; Zobrist, Jürg; Balteanu, Dan; Popescu, Claudia; Sima, Mihaela; Amini, Manouchehr; Yang, Hong

2009-06-01

Mining-contaminated sites and the affected communities at risk are important issues on the agenda of both researchers and policy makers, particularly in the former communist block countries in Eastern Europe. Integrated analyses and expert based assessments concerning mining affected areas are important in providing solid policy guidelines for environmental and social risk management and mitigation. Based on a survey for 103 households conducted in a former mining site in the Certej Catchment of the Apuseni Mountains, western Romania, this study assesses local communities’ perceptions on the quality of water in their living area. Logistic regression was used to examine peoples’ perception on the quality of the main river water and of the drinking water based on several predictors relating to social and economic conditions. The results from the perception analysis were then compared with the measurements of heavy metal contamination of the main river and drinking water undertaken in the same study area. The findings indicate that perception and measurement results for the water quality in the Certej Catchment are convergent, suggesting an obvious risk that mining activities pose on the surface water. However, the perception on drinking water quality was little predicted by the regression model and does not seem to be so much related to mining as to other explanatory factors, such as special mineralogy of rock and soils or improper water treatment infrastructure, facts suggested by the measurements of the contaminants. Discussion about the implications of these joint findings for risk mitigation policies completes this article.

Community perception of water quality in a mining-affected area: a case study for the Certej catchment in the Apuseni Mountains in Romania.

PubMed

Dogaru, Diana; Zobrist, Jürg; Balteanu, Dan; Popescu, Claudia; Sima, Mihaela; Amini, Manouchehr; Yang, Hong

2009-06-01

Mining-contaminated sites and the affected communities at risk are important issues on the agenda of both researchers and policy makers, particularly in the former communist block countries in Eastern Europe. Integrated analyses and expert based assessments concerning mining affected areas are important in providing solid policy guidelines for environmental and social risk management and mitigation. Based on a survey for 103 households conducted in a former mining site in the Certej Catchment of the Apuseni Mountains, western Romania, this study assesses local communities' perceptions on the quality of water in their living area. Logistic regression was used to examine peoples' perception on the quality of the main river water and of the drinking water based on several predictors relating to social and economic conditions. The results from the perception analysis were then compared with the measurements of heavy metal contamination of the main river and drinking water undertaken in the same study area. The findings indicate that perception and measurement results for the water quality in the Certej Catchment are convergent, suggesting an obvious risk that mining activities pose on the surface water. However, the perception on drinking water quality was little predicted by the regression model and does not seem to be so much related to mining as to other explanatory factors, such as special mineralogy of rock and soils or improper water treatment infrastructure, facts suggested by the measurements of the contaminants. Discussion about the implications of these joint findings for risk mitigation policies completes this article.

Residence times and age distributions of spring waters at the Semmering catchment area, Eastern Austria, as inferred from tritium, CFCs and stable isotopes.

PubMed

Han, Liangfeng; Hacker, Peter; Gröning, Manfred

2007-03-01

The groundwater system in the mountainous area of Semmering, Austria, was studied by environmental tracers in several karst springs. The tracers used included stable isotopes ((18)O, (2)H), tritium ((3)H) and chlorofluorocarbons (CFCs). The tracers provided valuable information in regard to (1) the mean altitude of the spring catchment areas; (2) the residence time and age distribution of the spring waters; and (3) the interconnection of the springs to a sinkhole. The combination of the stable isotopic data and the topography/geology provided the estimates of the mean altitudes of the catchment areas. Based on the stable isotopic data the recharge temperature of the spring waters was estimated. The smoothing of precipitation's isotopic signal in spring discharge provided information on the minimum transit time of the spring waters. Due to short observation time, (3)H data alone cannot be used for describing the mean residence time of the karst waters. CFCs, though useful in recognizing the co-existence of young (post-1993) water with old (CFC-free) water, could not be used to resolve age distribution models. It is shown in this article, however, that the combined use of tritium and CFCs can provide a better assessment of models to account for different groundwater age distributions. In Appendix A, a simplified method for collecting groundwater samples for the analysis of CFCs is described. The method provides a real facilitation for fieldwork. Test data are given for this sampling method in regard to potential contamination by atmospheric CFCs.

Simulation of quantity and quality of storm runoff for urban catchments in Fresno, California

USGS Publications Warehouse

Guay, J.R.; Smith, P.E.

1988-01-01

Rainfall-runoff models were developed for a multiple-dwelling residential catchment (2 applications), a single-dwelling residential catchment, and a commercial catchment in Fresno, California, using the U.S. Geological Survey Distributed Routing Rainfall-Runoff Model (DR3M-II). A runoff-quality model also was developed at the commercial catchment using the Survey 's Multiple-Event Urban Runoff Quality model (DR3M-qual). The purpose of this study was: (1) to demonstrate the capabilites of the two models for use in designing storm drains, estimating the frequency of storm runoff loads, and evaluating the effectiveness of street sweeping on an urban drainage catchment; and (2) to determine the simulation accuracies of these models. Simulation errors of the two models were summarized as the median absolute deviation in percent (mad) between measured and simulated values. Calibration and verification mad errors for runoff volumes and peak discharges ranged from 14 to 20%. The estimated annual storm-runoff loads, in pounds/acre of effective impervious area, that could occur once every hundred years at the commercial catchment was 95 for dissolved solids, 1.6 for the dissolved nitrite plus nitrate, 0.31 for total recoverable lead, and 120 for suspended sediment. Calibration and verification mad errors for the above constituents ranged from 11 to 54%. (USGS)

Spatial and temporal resolution effects on urban catchments with different imperviousness degrees

NASA Astrophysics Data System (ADS)

Cristiano, Elena; ten Veldhuis, Marie-Claire; van de Giesen, Nick C.

2015-04-01

One of the main problems in urban hydrological analysis is to measure the rainfall at urban scale with high resolution and use these measurements to model urban runoff processes to predict flows and reduce flood risk. With the aim of building a semi-distribute hydrological sewer model for an urban catchment, high resolution rainfall data are required as input. In this study, the sensitivity of hydrological response to high resolution precipitation data for hydrodynamic models at urban scale is evaluated with different combinations of spatial and temporal resolutions. The aim is to study sensitivity in relation to catchment characteristics, especially drainage area size, imperviousness degree and hydraulic properties such as special structures (weirs, pumping stations). Rainfall data of nine storms are considered with 4 different spatial resolutions (3000m, 1000m, 500m and 100m) combined with 4 different temporal resolutions (10min, 5min, 3min and 1min). The dual polarimetric X-band weather radar, located in the Cabauw Experimental Site for Atmospheric Research (CESAR) provided the high resolution rainfall data of these rainfall events, used to improve the sewer model. The effects of spatial-temporal rainfall input resolution on response is studied in three Districts of Rotterdam (NL): Kralingen, Spaanse Polder and Centrum district. These catchments have different average drainage area size (from 2km2 to 7km2), and different general characteristics. Centrum district and Kralingen are, indeed, more various and include residential and commercial areas, big green areas and a small industrial area, while Spaanse Polder is a industrial area, densely urbanized, and presents a high percentage of imperviousness.

Groundwater impacts on surface water quality and nutrient loads in lowland polder catchments: monitoring the greater Amsterdam area

NASA Astrophysics Data System (ADS)

Yu, Liang; Rozemeijer, Joachim; van Breukelen, Boris M.; Ouboter, Maarten; van der Vlugt, Corné; Broers, Hans Peter

2018-01-01

The Amsterdam area, a highly manipulated delta area formed by polders and reclaimed lakes, struggles with high nutrient levels in its surface water system. The polders receive spatially and temporally variable amounts of water and nutrients via surface runoff, groundwater seepage, sewer leakage, and via water inlets from upstream polders. Diffuse anthropogenic sources, such as manure and fertiliser use and atmospheric deposition, add to the water quality problems in the polders. The major nutrient sources and pathways have not yet been clarified due to the complex hydrological system in lowland catchments with both urban and agricultural areas. In this study, the spatial variability of the groundwater seepage impact was identified by exploiting the dense groundwater and surface water monitoring networks in Amsterdam and its surrounding polders. A total of 25 variables (concentrations of total nitrogen (TN), total phosphorus (TP), NH4, NO3, HCO3, SO4, Ca, and Cl in surface water and groundwater, N and P agricultural inputs, seepage rate, elevation, land-use, and soil type) for 144 polders were analysed statistically and interpreted in relation to sources, transport mechanisms, and pathways. The results imply that groundwater is a large source of nutrients in the greater Amsterdam mixed urban-agricultural catchments. The groundwater nutrient concentrations exceeded the surface water environmental quality standards (EQSs) in 93 % of the polders for TP and in 91 % for TN. Groundwater outflow into the polders thus adds to nutrient levels in the surface water. High correlations (R2 up to 0.88) between solutes in groundwater and surface water, together with the close similarities in their spatial patterns, confirmed the large impact of groundwater on surface water chemistry, especially in the polders that have high seepage rates. Our analysis indicates that the elevated nutrient and bicarbonate concentrations in the groundwater seepage originate from the decomposition of

Hydrogeochemical signatures of catchment evolution - the role of calcium and sulphate release in the constructed Hühnerwasser ("Chicken Creek") catchment

NASA Astrophysics Data System (ADS)

Pohle, Ina; Hu, Yuzhu; Schaaf, Wolfgang; Gerwin, Werner; Hinz, Christoph

2016-04-01

The constructed Hühnerwasser ("Chicken Creek") catchment is an ecohydrological system in an initial state of development. The catchment with an area of 6 ha was built up from quaternary sediments in the post-mining landscape of Lusatia in Eastern Germany and serves as a critical zone observatory for detecting ecosystem transition. The soil substrate is characterized as sands to loamy sands with low carbonate contents but significant amounts of gypsum in the sediments of the catchment. The catchment undergoes a strong transition from an abiotic system in the initial years to a system with growing influence of biota. Concerning the hydrology, a regime shift from surface runoff to groundwater flow dominated processes is significant. It is of interest, whether the catchment transition is also reflected by hydrogeochemical indicators. We assume gypsum dissolution as dominant process at the catchment scale. In order to investigate the hydrogeochemical evolution of the catchment we analysed electric conductivity, calcium and sulphate concentrations and pH-values of biweekly composite samples from 2007-2013 of the atmospheric deposition, of runoff and soil water. The two observation points in the flowing water represent surface runoff and groundwater discharge respectively. Soil water has been analysed at four soil pits in three depths. The monitoring data were provided by the Research Platform Chicken Creek (https://www.tu-cottbus.de/projekte/en/oekosysteme/startseite.html). From the macroscopic data analysis we found an exponential decay of the electric conductivity, calcium and sulphate concentrations in the flowing waters and some of the soil pits. In the flowing water, the decrease slope of the electric conductivity and the calcium and sulphate concentrations is almost identical. The calcium / sulphate molar ratio as an indicator of gypsum dissolution is almost equal to one up to 2010, afterwards more calcium than sulphate is released. The pH-values in the flowing

The influence of synthetic hyetograph parameters on simulation results of runoff from urban catchment

NASA Astrophysics Data System (ADS)

Mazurkiewicz, Karolina; Skotnicki, Marcin

2018-02-01

The paper presents the results of analysis of the influence of the maximum intensity (peak) location in the synthetic hyetograph and rainfall duration on the maximum outflow from urban catchment. For the calculation Chicago hyetographs with a duration from 15 minutes to 180 minutes and peak location between 20% and 50% of the total rainfall duration were design. Runoff simulation was performed using the SWMM5 program for three models of urban catchment with area from 0.9 km2 to 6.7 km2. It was found that the increase in the rainfall peak location causes the increase in the maximum outflow up to 17%. For a given catchment the greatest maximum outflow is generated by the rainfall, which time to peak corresponds to the flow time through the catchment. Presented results may be useful for choosing the rainfall parameters for storm sewer systems modeling.

Catchment classification by runoff behaviour with self-organizing maps (SOM)

NASA Astrophysics Data System (ADS)

Ley, R.; Casper, M. C.; Hellebrand, H.; Merz, R.

2011-09-01

Catchments show a wide range of response behaviour, even if they are adjacent. For many purposes it is necessary to characterise and classify them, e.g. for regionalisation, prediction in ungauged catchments, model parameterisation. In this study, we investigate hydrological similarity of catchments with respect to their response behaviour. We analyse more than 8200 event runoff coefficients (ERCs) and flow duration curves of 53 gauged catchments in Rhineland-Palatinate, Germany, for the period from 1993 to 2008, covering a huge variability of weather and runoff conditions. The spatio-temporal variability of event-runoff coefficients and flow duration curves are assumed to represent how different catchments "transform" rainfall into runoff. From the runoff coefficients and flow duration curves we derive 12 signature indices describing various aspects of catchment response behaviour to characterise each catchment. Hydrological similarity of catchments is defined by high similarities of their indices. We identify, analyse and describe hydrologically similar catchments by cluster analysis using Self-Organizing Maps (SOM). As a result of the cluster analysis we get five clusters of similarly behaving catchments where each cluster represents one differentiated class of catchments. As catchment response behaviour is supposed to be dependent on its physiographic and climatic characteristics, we compare groups of catchments clustered by response behaviour with clusters of catchments based on catchment properties. Results show an overlap of 67% between these two pools of clustered catchments which can be improved using the topologic correctness of SOMs.

Catchment classification by runoff behaviour with self-organizing maps (SOM)

NASA Astrophysics Data System (ADS)

Ley, R.; Casper, M. C.; Hellebrand, H.; Merz, R.

2011-03-01

Catchments show a wide range of response behaviour, even if they are adjacent. For many purposes it is necessary to characterise and classify them, e.g. for regionalisation, prediction in ungauged catchments, model parameterisation. In this study, we investigate hydrological similarity of catchments with respect to their response behaviour. We analyse more than 8200 event runoff coefficients (ERCs) and flow duration curves of 53 gauged catchments in Rhineland-Palatinate, Germany, for the period from 1993 to 2008, covering a huge variability of weather and runoff conditions. The spatio-temporal variability of event-runoff coefficients and flow duration curves are assumed to represent how different catchments "transform" rainfall into runoff. From the runoff coefficients and flow duration curves we derive 12 signature indices describing various aspects of catchment response behaviour to characterise each catchment. Hydrological similarity of catchments is defined by high similarities of their indices. We identify, analyse and describe hydrologically similar catchments by cluster analysis using Self-Organizing Maps (SOM). As a result of the cluster analysis we get five clusters of similarly behaving catchments where each cluster represents one differentiated class of catchments. As catchment response behaviour is supposed to be dependent on its physiographic and climatic characteristics, we compare groups of catchments clustered by response behaviour with clusters of catchments based on catchment properties. Results show an overlap of 67% between these two pools of clustered catchments which can be improved using the topologic correctness of SOMs.

Influence of rainfall and catchment characteristics on urban stormwater quality.

PubMed

Liu, An; Egodawatta, Prasanna; Guan, Yuntao; Goonetilleke, Ashantha

2013-02-01

The accuracy and reliability of urban stormwater quality modelling outcomes are important for stormwater management decision making. The commonly adopted approach where only a limited number of factors are used to predict urban stormwater quality may not adequately represent the complexity of the quality response to a rainfall event or site-to-site differences to support efficient treatment design. This paper discusses an investigation into the influence of rainfall and catchment characteristics on urban stormwater quality in order to investigate the potential areas for errors in current stormwater quality modelling practices. It was found that the influence of rainfall characteristics on pollutant wash-off is step-wise based on specific thresholds. This means that a modelling approach where the wash-off process is predicted as a continuous function of rainfall intensity and duration is not appropriate. Additionally, other than conventional catchment characteristics, namely, land use and impervious surface fraction, other catchment characteristics such as impervious area layout, urban form and site specific characteristics have an important influence on both, pollutant build-up and wash-off processes. Finally, the use of solids as a surrogate to estimate other pollutant species was found to be inappropriate. Individually considering build-up and wash-off processes for each pollutant species should be the preferred option. Copyright © 2012 Elsevier B.V. All rights reserved.

Interest of A Morphological Explanation of The Unit Hydrograph Concept: Case of Urban Catchments

NASA Astrophysics Data System (ADS)

Rodriguez, F.; Cudennec, C.; Cellier, G.; Andrieu, H.

Expansion of urbanised areas has put emphasis on related water management prob- lems, such as flooding and pollution control, which requires a good knowledge of the hydrological response of urban catchments. Unfortunately, most of urban catchments are ungauged and their hydrological features must be deduced from existent data. A good description of the urban characteristics can give some advances in the field of urban hydrology : the geographical and physical knowledge of the city is made eas- ier by the emergence of urban data banks, introducing a meter-scale morphological description of the city. Linking the hydrological response of a catchment to its geo- morphology has been successfully implemented in natural settings within the concept of GIUH (Geomorphologic Instantaneous Unit Hydrograph). In the same manner, the available description of urban catchments makes it possible to deduce their hydrolog- ical behaviour throughout the Unit Hydrograph concept. We suggest to compare three complementary methods of determination of Unit Hydrographs, with increasing de- grees of description of the catchment morphology. The first method, presenting a high degree of accounting for the catchment morphology, is called MIUH (Morphologi- cal Instantaneous Unit Hydrograph; Rodriguez et al., 2000), and is derived from the analysis of urban databanks allowing an explicit description of the runoff production areas and their downstream flow channels. The second one, called H2U (Duchesne et al., 1997) and corresponding to a moderate degree, is a gamma law whose 2 pa- rameters are based on the Strahler order of the catchment and the mean hydraulic length of water paths through the drainage system. The third method, called FDTF (First Derivative Transfert Function; Duband et al., 1993) and corresponding to a low degree, is a validation method deriving Unit Hydrograph by a deconvolution itera- tive identification technique, from a sample of observed rainfall and flow data. The three

Response of current phosphorus mitigation measures across the nutrient transfer continuum in two hydrological contrasting agricultural catchments

NASA Astrophysics Data System (ADS)

McDonald, Noeleen; Shore, Mairead; Mellander, Per-Erik; Shortle, Ger; Jordan, Phil

2015-04-01

Effective assessment of National Action Programme (NAP) measures introduced under the EU Nitrates Directive (ND), to manage nutrient use and risk of loss to waters from agriculture, is best achieved when examined across the nutrient transfer continuum at catchment scale. The Irish NAP measures are implemented on a whole-territory basis for both nitrogen (N) and phosphorus (P), with P being the key trophic pressure. The aim of this research was to observe the efficacy of P regulation measures and P source management across the transfer continuum and resultant water quality status (i.e. source to impact), in two contrasting agricultural catchments over a four year period. The catchments are ca. 11 km2 and are located in the south-east of Ireland. One is well-drained and arable dominated, while the other is mostly poorly-drained and grassland dominated. In 2009 and 2013 soil surveys for plant-available P were carried out (<2 ha sample areas) in both catchments. Concurrently, high temporal resolution monitoring of water discharge and P concentration was conducted at each catchment outlet across four hydrological years (April to March). Ecological impact surveys were carried out at four sites within each catchment in May and September across the observed four year period (2009-2013). Importantly, the proportion of farmland with excessive soil P concentrations decreased in both the arable (20% to 11.8%) and grassland catchments (5.9 to 3.6%). However, soil P concentrations also declined critically in both catchments, as proportional areas below the national crop agronomic optimum thresholds (grassland; <5 mg P l-1, arable; <6 mg P l-1) increased from 57% to 68% in the arable catchment and 75% to 87% in the grassland catchment. This decline in plant available P strongly indicates a reduced or sustained level of P inputs in both catchments. Indications of responses to soil P change in the surface waters of these catchments appeared to be highly influenced by their

Mean transit times in headwater catchments: insights from the Otway Ranges, Australia

NASA Astrophysics Data System (ADS)

Howcroft, William; Cartwright, Ian; Morgenstern, Uwe

2018-01-01

to be vulnerable to decadal changes in land use or climate. Additionally, there may be considerable delay in contaminants reaching the stream. An increase in nitrate and sulfate concentrations in several catchments at high streamflows may represent the input of contaminants through the shallow groundwater that contributes to streamflow during the wetter months. Poor correlations between 3H activities and catchment area, drainage density, land use, and average slope imply that the MTTs are not controlled by a single parameter but a variety of factors, including catchment geomorphology and the hydraulic properties of the soils and aquifers.

Flushing of distal hillslopes as an alternative source of stream dissolved organic carbon in a headwater catchment

USGS Publications Warehouse

Gannon, John P; Bailey, Scott W.; McGuire, Kevin J.; Shanley, James B.

2015-01-01

We investigated potential source areas of dissolved organic carbon (DOC) in headwater streams by examining DOC concentrations in lysimeter, shallow well, and stream water samples from a reference catchment at the Hubbard Brook Experimental Forest. These observations were then compared to high-frequency temporal variations in fluorescent dissolved organic matter (FDOM) at the catchment outlet and the predicted spatial extent of shallow groundwater in soils throughout the catchment. While near-stream soils are generally considered a DOC source in forested catchments, DOC concentrations in near-stream groundwater were low (mean = 2.4 mg/L, standard error = 0.6 mg/L), less than hillslope groundwater farther from the channel (mean = 5.7 mg/L, standard error = 0.4 mg/L). Furthermore, water tables in near-stream soils did not rise into the carbon-rich upper B or O horizons even during events. In contrast, soils below bedrock outcrops near channel heads where lateral soil formation processes dominate had much higher DOC concentrations. Soils immediately downslope of bedrock areas had thick eluvial horizons indicative of leaching of organic materials, Fe, and Al and had similarly high DOC concentrations in groundwater (mean = 14.5 mg/L, standard error = 0.8 mg/L). Flow from bedrock outcrops partially covered by organic soil horizons produced the highest groundwater DOC concentrations (mean = 20.0 mg/L, standard error = 4.6 mg/L) measured in the catchment. Correspondingly, stream water in channel heads sourced in part by shallow soils and bedrock outcrops had the highest stream DOC concentrations measured in the catchment. Variation in FDOM concentrations at the catchment outlet followed water table fluctuations in shallow to bedrock soils near channel heads. We show that shallow hillslope soils receiving runoff from organic matter-covered bedrock outcrops may be a major source of DOC in headwater catchments in forested mountainous regions

Keeping the secret: Insights from repeated catchment-scale tracer experiments under transient conditions

NASA Astrophysics Data System (ADS)

Bogner, Christina; Hauhs, Michael; Lange, Holger

2016-04-01

Catchment-level tracer experiments are generally performed to identify site-specific hydrological response functions of the catchment. The existence and uniqueness of these response functions are hardly ever questioned. Here, we report on a series of replicated tracer experiments in two small first-order catchments, G1 (0.6 ha, roofed) and F4 (2.3 ha, without roof) at Gårdsjön in SW Sweden. The soils in both catchments are shallow (< 50 cm) with the bedrock partly visible at the surface. In G1 (irrigated area approximately 1000 m2), tracer experiments were conducted under a roof between 1993 and 2003 during steady state flow conditions. In contrast, in F4 (irrigated area approximately 500 m2) the experiments were done without a roof mostly at transient conditions. The catchment F4 was equipped with a sprinkler system with a watering capacity of around 38-45 m3 day-1. Natural rainfall comes in addition. A bromide tracer solution was injected to groundwater at a single location about 40 m upstream the weir over a period of less than an hour, and was monitored using a set of groundwater tubes and the weir at the outlet over the following 4 days. In addition, discharge was measured. The experiments were repeated each summer from 2007 to 2015. While steady state conditions were guaranteed in G1, steady runoff has been achieved only four times in F4. We investigated tracer recovery rates against cumulated runoff since tracer application. Substantially different transit times and qualitatively different behaviour of the breakthrough curves were observed, even under steady state conditions. In G1, no single system response function could be identified in 5 replicates. Similarly, the catchment response functions in F4 under steady state differed between experiments. However, they remained in a similar range as in G1. Based on these results, we question the identifiability of flow paths and system properties, such as saturated water content or hydrologic transmissivity, at

Application of Temperature Index Model to Assess the Future Hydrological Regime of the Glacierized Catchments in Nepal.

NASA Astrophysics Data System (ADS)

Kayastha, R.; Kayastha, R. B.

2017-12-01

Unavailability of hydro meteorological data in the Himalayan regions is challenging on understanding the flow regimes. Temperature index model is simple yet the powerful glacio-hydrological model to simulate the discharge in the glacierized basin. Modified Positive Degree Day (MPDD) Model Version 2.0 is a grid-ded based semi distributed model with baseflow module is a robust melt modelling tools to estimate the discharge. MPDD model uses temperature and precipitation as a forcing datasets to simulate the discharge and also to obtain the snowmelt, icemelt, rain and baseflow contribution on total discharge. In this study two glacierized, Marsyangdi and Langtang catchment were investigated for the future hydrological regimes. Marsyangdi encompasses an area of 4026.19 sq. km with 20% glaciated area, whereas Langtang catchment with area of 354.64 sq. km with 36% glaciated area is studied to examine for the future climatic scenarios. The model simulates discharge well for the observed period; (1992-1998) in Marsyangdi and from (2007-2013) in Langtang catchment. The Nash-Sutcliffe Efficiency (NSE) for the both catchment were above 0.75 with the volume difference less than - 8 %. The snow and ice melts contribution in Marsyangdi were 4.7% and 10.2% whereas in Langtang the contribution is 15.3% and 23.4%, respectively. Rain contribution ( 40%) is higher than the baseflow contribution in total discharge in both basins. The future river discharge is also predicted using the future climate data from the regional climate models (RCMs) of CORDEX South Asia experiments for the medium stabilization scenario RCP4.5 and very high radiative forcing scenario RCP8.5 after bias correction. The projected future discharge of both catchment shows slightly increase in both scenarios with increase of snow and ice melt contribution on discharge. The result generated from the model can be utilized to understand the future hydrological regimes of the glacierized catchment also the impact of

Catchment chemostasis revisited: water quality responds differently to variations in weather and climate

NASA Astrophysics Data System (ADS)

Godsey, Sarah; Kirchner, James

2017-04-01

Solute concentrations in streamflow typically vary systematically with stream discharge, and the resulting concentration-discharge relationships are important signatures of catchment (bio)geochemical processes. Solutes derived from mineral weathering often exhibit decreasing concentrations with increasing flows, suggesting dilution of a kinetically limited weathering flux by a variable flux of water. However, Godsey et al. (2009) showed that concentration-discharge relationships of weathering-derived solutes in 59 headwater catchments were much flatter than this simple dilution model would predict. Instead, their analysis showed that these catchments behaved almost like chemostats, with rates of solute production and/or mobilization that were nearly proportional to water fluxes, on both event and inter-annual time scales. Here we re-examine these findings using data from roughly 1000 catchments, ranging from ˜10 to >1,000,000 km2 in drainage area, and spanning a wide range of lithologic and climatic settings. Concentration-discharge relationships among this much larger set of much larger catchments are broadly consistent with the chemostatic behavior described by Godsey et al. (2009). Among these same catchments, however, site-to-site variations in mean concentrations are strongly (negatively) correlated with long-term average precipitation and discharge, suggesting strong dilution of stream concentrations under long-term leaching of the critical zone. The picture that emerges is one in which, on event and inter-annual time scales, stream solute concentrations are chemostatically buffered by groundwater storage and fast chemical reactions (such as ion exchange), but on much longer time scales, the catchment's chemostatic "set point" is determined by climatically driven critical zone evolution. Examples illustrating the different influences of (short-term) weather and (long-term) climate on water quality will be presented, and their implications will be discussed

Sediment dynamics in an overland flow-prone forest catchment

NASA Astrophysics Data System (ADS)

Zimmermann, Alexander; Elsenbeer, Helmut

2010-05-01

Vegetation controls erosion in many respects, and it is assumed that forest cover is an effective control. Currently, most literature on erosion processes in forest ecosystems support this impression and estimates of sediment export from forested catchments serve as benchmarks to evaluate erosion processes under different land uses. Where soil properties favor near-surface flow paths, however, vegetation may not mitigate surface erosion. In the forested portion of the Panama Canal watershed overland flow is widespread and occurs frequently, and indications of active sediment transport are hard to overlook. In this area we selected a 9.7 ha catchment for a high-resolution study of suspended sediment dynamics. We equipped five nested catchments to elucidate sources, drivers, magnitude and timing of suspended sediment export by continuous monitoring of overland flow and stream flow and by simultaneous, event-based sediment sampling. The support program included monitoring throughfall, splash erosion, overland-flow connectivity and a survey of infiltrability, permeability, and aggregate stability. This dataset allowed a comprehensive view on erosion processes. We found that overland flow controls the suspended-sediment dynamics in channels. Particularly, rainfalls of high intensity at the end of the rainy season have a superior impact on the overall sediment export. During these events, overland flow occurs catchment-wide up to the divide and so does erosion. With our contribution we seek to provide evidence that forest cover and large sediment yields are no contradiction in terms even in the absence of mass movements.

Integrated hydro-environmental impact assessment and alternative selection of low impact development practices in small urban catchments.

PubMed

Yang, Yang; Chui, Ting Fong May

2018-06-20

Attention is increasingly being paid to low impact development (LID) practices in urban stormwater management. Because LID practices offer a wide variety of hydro-environmental benefits, it is often necessary to account for these benefits collectively in cost-benefit analysis and LID alternative selection. The conventional methods of quantifying these benefits, however, can hardly incorporate the preferences of decision makers, and commonly involve tedious parameter estimations. To address these shortcomings, this study adopts a relative performance evaluation method to assess the various hydro-environmental impacts of LID alternatives in small urban catchments. This study considers several categories of hydro-environmental impacts, including water balance impact, surface pollutant load abatement, and combined sewer overflow and flood risk mitigation. Several performance indicators are used for each impact category. The system-wide effectiveness of an LID alternative is then derived by the weighted aggregation of its indicator scores, which are obtained by comparing its performance with that of all of the other alternatives. The hydro-environmental impact of green roofs and bioretention cells of varying areas in New York City, U.S. are investigated in detail. The results suggest that a green roof that covers the whole catchment is as effective as a bioretention cell that covers 3%-5% of the catchment in terms of stormwater management, and that the effectiveness of a bioretention cell doubles when its surface area increases from 2% to 10% of the catchment area. These assessment results are influenced by catchment-specific assessment criteria (e.g., the high flow threshold) and management interests, which suggests that design guidelines for different catchments should be tailored to their natural and drainage characteristics. The framework used in this study allows stakeholders' interests to be reflected in LID alternative selections and the implications of different

Land degradation trends in upper catchments and morphological developments of braided rivers in drylands: the case of a marginal graben of the Ethiopian Rift Valley

NASA Astrophysics Data System (ADS)

Demissie, Biadgilgn; Frankl, Amaury; Haile, Mitiku; Nyssen, Jan

2014-05-01

Braided rivers have received relatively little attention in research and development activities in drylands. However, they strongly impact agroecology and agricultural activities and thereby local livelihoods. The Raya Graben (3750 km² including the escarpment) is a marginal graben of the Ethiopian Rift Valley located in North Ethiopia. In order to study the dynamics of braided rivers and the relationship with biophysical controls, 20 representative catchments were selected, ranging between 15 and 311 km². First, the 2005 morphology (length, area) of the braided rivers was related to biophysical controls (vegetation cover, catchment area and slope gradient in the steep upper catchments and gradient in the graben bottom). Second, the changes in length of the braided rivers were related to vegetation cover changes in the upper catchments since 1972. Landsat imagery was used to calculate the Normalized Difference Vegetation Index (NDVI), and to map vegetation cover and the total length of the braided rivers. Spot CNES imagery available from Google Earth was used to identify the total area of the braided rivers in 2005. A linear regression analysis revealed that the length of braided rivers was positively related to the catchment area (R²=0.32, p<0.01), but insignificantly related to vegetation cover in the upper catchments. However, there is an indication that it is an important factor in the relationship calculated for 2005 (R²=0.2, p=0.064). Similarly, the area occupied by the braided rivers was related to NDVI (R²=0.24, p<0.05) and upper catchment area (R²=0.447, p<0.01). Slope gradient is not an important explanatory factor. This is related to the fact that slope gradients are steep (average of 38.1%) in all upper and gentle (average of 3.4%) in graben bottom catchments. The vegetation cover in the upper catchments shows a statistically insignificant increasing trend (R²=0.73, p=0.067) over the last 40 years, whereas length of rivers in the graben bottom

Spatial and temporal patterns of pesticide losses in a small Swedish agricultural catchment

NASA Astrophysics Data System (ADS)

Sandin, Maria; Piikki, Kristin; Jarvis, Nicholas; Larsbo, Mats; Bishop, Kevin; Kreuger, Jenny

2017-04-01

Research at catchment and regional scales shows that losses of pesticides to surface water often originate from a relatively small fraction of the agricultural landscape. These 'hydrologic source areas' represent areas of land that are highly susceptible to fast transport processes, primarily surface runoff or rapid subsurface flows through soil macropores, either to subsurface field drainage systems or as shallow interflow on more strongly sloping land. A good understanding of the nature of transport pathways for pesticides to surface water in agricultural landscapes is essential for cost-effective identification and implementation of mitigation measures. However, the relative importance of surface and subsurface flows for transport of pesticides to surface waters in Sweden remains largely unknown, since very few studies have been performed under Swedish agro-environmental conditions. We conducted a monitoring study in a small sub-surface drained agricultural catchment in one of the main crop production regions in Sweden. Three small sub-catchments were selected for water sampling based on a high-resolution soil map developed from proximal sensing data; one sub-catchment was dominated by clay soils, another by coarse sandy soils while the third comprised a mix of soil types. Samples were collected from the stream, from field drains discharging into the stream and from within-field surface runoff during spring and early summer in three consecutive years. LC-MS/MS analyses of more than 100 compounds, covering the majority of the polar and semi-polar pesticides most frequently used in Swedish agriculture, were performed on all samples using accredited methods. Information on pesticide applications (products, doses and timing) was obtained from annual interviews with the farmers. There were clear and consistent differences in pesticide losses between the three sub-catchments, with the largest losses occurring in the area with clay soils, and negligible losses from the

Catchment controls and human disturbances on the geomorphology of small Mediterranean estuarine systems

NASA Astrophysics Data System (ADS)

Estrany, Joan; Grimalt, Miquel

2014-10-01

Geographic signatures are physical and human-induced characteristics or processes that identify comparable or unique features of estuaries along latitudinal gradients. In Mediterranean areas, the microtidal regime and the strong seasonal and inter-annual contrasts cause an alternation between relatively high runoff and arid conditions. Furthermore, the long history of human settlement also increases the complexity in the study of these estuarine systems. This study investigates these signatures of the estuaries located within the Mallorcan eastern coast, which are geomorphologically homogeneous because of a similar bedrock geology and Holocene history. A multi-method approach focused on the integration of geomorphometry, hydraulics, historical sources and statistics was used. We explore the role played by catchment morphometric parameters, severe flash flood events and human disturbances in controlling the geomorphology of 10 beach-barrier enclosed, fluvial incised lagoons. Most of the lagoons discharge into 'calas', ranging in size from 1345 to 17,537 m2 and their related catchments are representative of the Mediterranean hydrological systems. Multiple regression models illustrate that the size, slope and drainage network development of the catchments explain the variance in length (r2 = 0.67), volume (r2 = 0.49), area (r2 = 0.64), circularity (r2 = 0.72) and average width (r2 = 0.81) of the lagoons. Depending on these catchment morphometric variables, the shape of the lagoons is also determined by the occurrence of catastrophic flash floods, which cause scouring and dredging, whereas the ordinary flood events and sea storms promote refilling and sedimentation. A historical analysis since 1850 documented 18 flood events, 5 of which were catastrophic with destructive effects along the catchments and large morphological changes in coastal lagoons. High intensity rainfall (up to 200 mm in 2 h), the geomorphometry of the catchments and the massive construction of

High resolution modeling of a small urban catchment

NASA Astrophysics Data System (ADS)

Skouri-Plakali, Ilektra; Ichiba, Abdellah; Gires, Auguste; Tchiguirinskaia, Ioulia; Schertzer, Daniel

2016-04-01

Flooding is one of the most complex issues that urban environments have to deal with. In France, flooding remains the first natural risk with 72% of decrees state of natural disaster issued between October 1982 and mid-November 2014. Flooding is a result of meteorological extremes that are usually aggravated by the hydrological behavior of urban catchments and human factors. The continuing urbanization process is indeed changing the whole urban water cycle by limiting the infiltration and promoting runoff. Urban environments are very complex systems due to their extreme variability, the interference between human activities and natural processes but also the effect of the ongoing urbanization process that changes the landscape and hardly influences their hydrologic behavior. Moreover, many recent works highlight the need to simulate all urban water processes at their specific temporal and spatial scales. However, considering urban catchments heterogeneity still challenging for urban hydrology, even after advances noticed in term of high-resolution data collection and computational resources. This issue is more to be related to the architecture of urban models being used and how far these models are ready to take into account the extreme variability of urban catchments. In this work, high spatio-temporal resolution modeling is performed for a small and well-equipped urban catchment. The aim of this work is to identify urban modeling needs in terms of spatial and temporal resolution especially for a very small urban area (3.7 ha urban catchment located in the Perreux-sur-Marne city at the southeast of Paris) MultiHydro model was selected to carry out this work, it is a physical based and fully distributed model that interacts four existing modules each of them representing a portion of the water cycle in urban environments. MultiHydro was implemented at 10m, 5m and 2m resolution. Simulations were performed at different spatio-temporal resolutions and analyzed with

Catchment-scale environmental controls of sediment-associated contaminant dispersal

NASA Astrophysics Data System (ADS)

Macklin, Mark

2010-05-01

Globally river sediment associated contaminants, most notably heavy metals, radionuclides, Polychlorinated Biphenyls (PCBs), Organochlorine pesticides (OCs) and phosphorous, constitute one the most significant long-term risks to ecosystems and human health. These can impact both urban and rural areas and, because of their prolonged environmental residence times, are major sources of secondary pollution if contaminated soil and sediment are disturbed by human activity or by natural processes such as water or wind erosion. River catchments are also the primary source of sediment-associated contaminants to the coastal zone, and to the ocean, and an understanding of the factors that control contaminated sediment fluxes and delivery in river systems is essential for effective environmental management and protection. In this paper the catchment-scale controls of sediment-associated contaminant dispersal are reviewed, including climate-related variations in flooding regime, land-use change, channel engineering, restoration and flood defence. Drawing on case studies from metal mining impacted catchments in Bolivia (Río Pilcomayo), Spain (Río Guadiamar), Romania (River Tisa) and the UK (River Swale) some improved methodologies for identifying, tracing, modelling and managing contaminated river sediments are proposed that could have more general application in similarly affected river systems worldwide.

Spatial and Temporal Variation of Water Quality in the Bertam Catchment, Cameron Highlands, Malaysia.

PubMed

Rasul, M G; Islam, Mir Sujaul; Yunus, Rosli Bin Mohd; Mokhtar, Mazlin Bin; Alam, Lubna; Yahaya, F M

2017-12-01

  The spatio-temporal variability of water quality associated with anthropogenic activities was studied for the Bertam River and its main tributaries within the Bertam Catchment, Cameron Highlands, Malaysia. A number of physico-chemical parameters of collected samples were analyzed to evaluate their spatio-temporal variability. Nonparametric statistical analysis showed significant temporal and spatial differences (p < 0.05) in most of the parameters across the catchment. Parameters except dissolved oxygen and chemical oxygen demand displayed higher values in rainy season. The higher concentration of total suspended solids was caused by massive soil erosion and sedimentation. Seasonal variations in contaminant concentrations are largely affected by precipitation and anthropogenic influences. Untreated domestic wastewater discharge as well as agricultural runoff significantly influenced the water quality. Poor agricultural practices and development activities at slope areas also affected the water quality within the catchment. The analytical results provided a basis for protection of river environments and ecological restoration in mountainous Bertam Catchment.

Map Showing Geology and Hydrostratigraphy of the Edwards Aquifer Catchment Area, Northern Bexar County, South-Central Texas

USGS Publications Warehouse

Clark, Amy R.; Blome, Charles D.; Faith, Jason R.

2009-01-01

Rock units forming the Edwards and Trinity aquifers in northern Bexar County, Texas, are exposed within all or parts of seven 7.5-minute quadrangles: Bulverde, Camp Bullis, Castle Hills, Helotes, Jack Mountain, San Geronimo, and Van Raub. The Edwards aquifer is the most prolific ground-water source in Bexar County, whereas the Trinity aquifer supplies water for residential, commercial, and industrial uses for areas north of the San Antonio. The geologic map of northern Bexar County shows the distribution of informal hydrostratigraphic members of the Edwards Group and the underlying upper member of the Glen Rose Limestone. Exposures of the Glen Rose Limestone, which forms the Trinity aquifer alone, cover approximately 467 km2 in the county. This study also describes and names five informal hydrostratigraphic members that constitute the upper member of the Glen Rose Limestone; these include, in descending order, the Caverness, Camp Bullis, Upper evaporite, Fossiliferous, and Lower evaporite members. This study improves our understanding of the hydrogeologic connection between the two aquifers as it describes the geology that controls the infiltration of surface water and subsurface flow of ground water from the catchment area (outcropping Trinity aquifer rocks) to the Edwards water-bearing exposures.

Human Impact on Biogeochemical Cycles and Deposition Dynamics in Karstic Lakes: El Tobar Lake Record (Central Iberian Range, Spain)

NASA Astrophysics Data System (ADS)

Barreiro-Lostres, F.; Moreno-Caballud, A.; Giralt, S.; Hillman, A. L.; Brown, E. T.; Abbott, M. B.; Valero-Garces, B. L.

2014-12-01

Karstic lakes in the Iberian Range (Central Spain) provide a unique opportunity to test the human impact in the watersheds and the aquatic environments during historical times. We reconstruct the depositional evolution and the changes in biogeochemical cycles of El Tobar karstic lake, evaluating the response and the resilience of this Mediterranean ecosystem to both anthropogenic impacts and climate forcing during the last 1000 years. Lake El Tobar (40°32'N, 3°56'W; 1200 m a.s.l.; see Figure), 16 ha surface area, 20 m max. depth and permanent meromictic conditions, has a relatively large watershed (1080 ha). Five 8 m long sediment cores and short gravity cores where recovered, imaged, logged with a Geotek, described and sampled for geochemical analyses (elemental TOC, TIC, TN, TS), XRF scanner and ICP-MS, and dated (137Cs and 10 14C assays). The record is a combination of: i) laminated dark silts with terrestrial remains and diatoms and ii) massive to banded light silts (mm to cm -thick layers) interpreted as flood deposits. Sediments, TOC, and Br/Ti and Sr/Ca ratios identify four periods of increased sediment delivery occurred about 1500, 1800, 1850 and 1900 AD, coinciding with large land uses changes of regional relevance such as land clearing and increased population. Two main hydrological changes are clearly recorded in El Tobar sequence. The first one, marked by a sharp decrease in Mg, Ca and Si concentrations, took place about 1200 AD, and during a period of increasing lake level, which shifted from shallower to deeper facies and from carbonatic to clastic and organic-rich deposition. This change was likely related to increased water availability synchronous to the transition from the Medieval Climate Anomaly to the Little Ice Age. The second one was a canal construction in 1967 AD when a nearby reservoir provided fresh water influx to the lake, and resulted in stronger meromictic conditions in the system after canal construction, which is marked by lower

Sediment budgets of unglaciated alpine catchments - the example of the Johnsbach and Schöttlbach valleys in Styria

NASA Astrophysics Data System (ADS)

Sass, Oliver; Rascher, Eric; Stangl, Johannes; Lutzmann, Silke

2017-04-01

Extensive research has been performed in glacier forefields and in glaciated catchments in order to predict their future behaviour in a warming climate. However, the majority of medium-scale torrential catchments in the European Alps are non-glaciated and their response to disturbance events (e.g. changing climate) is more subtle and hard to predict. We report from two torrential catchments in the Eastern Alps, the Johnsbach and the Schöttlbach valleys, that have been monitored for several years. The catchments are located in Styria (Austria) and are remarkably similar in terms of size (60-70 km3) and elevation (600/800 - 2400 m). The main difference is the geological setting of the sediment delivering areas which is limestone and brittle dolomite at Johnsbach, and a prominent late-pleistocene valley fill at Schöttlbach, respectively. Slope processes in both areas were monitored by means of repeated TLS surveys of active slope and channel areas and by ALS and/or UAV surveys. Fluvial transport in the main channels was measured using Helly-Smith samplers and recorded continuously by means of new developed, low-budget sediment impact sensors (SIS). In both areas, the catchment output was quantified: by regular surveys of a retention basin at Schöttlbach and by a bedload measurement station (geophone sill) at Johnsbach. The results show that at Johnsbach, the sediment source areas are active tributary trenches in the lower third of the catchment. The sediments derive from brittle dolomite rockwalls and are transported to the main river episodically during rainstorm events. In a 2-yr period, 7400 m3 yr-1 were eroded in the surveyed areas and 9900 m3 yr-1 m3 yr-1 were deposited; of this amount, only a minor portion of 650 m3 yr-1 reached the Johnsbach River. The degree of coupling between tributaries and creek is strongly influenced by anthropogenic measures, e.g. former disturbance by gravel mining and undersized bridge openings. Besides limited bank erosion

Contribution of rainfall, snow and ice melt to the hydrological regime of the Arve upper catchment and to severe flood events

NASA Astrophysics Data System (ADS)

Lecourt, Grégoire; Revuelto, Jesús; Morin, Samuel; Zin, Isabella; Lafaysse, Matthieu; Condom, Thomas; Six, Delphine; Vionnet, Vincent; Charrois, Luc; Dumont, Marie; Gottardi, Frédéric; Laarman, Olivier; Coulaud, Catherine; Esteves, Michel; Lebel, Thierry; Vincent, Christian

2016-04-01

In Alpine catchments, the hydrological response to meteorological events is highly influenced by the precipitation phase (liquid or solid) and by snow and ice melt. It is thus necessary to simulate accurately the snowpack evolution and its spatial distribution to perform relevant hydrological simulations. This work is focused on the upper Arve Valley (Western Alps). This 205 km2 catchment has large glaciated areas (roughly 32% of the study area) and covers a large range of elevations (1000-4500 m a.s.l.). Snow presence is significant year-round. The area is also characterized by steep terrain and strong vegetation heterogeneity. Modelling hydrological processes in such a complex catchment is therefore challenging. The detailed ISBA land surface model (including the Crocus snowpack scheme) has been applied to the study area using a topography based discretization (classifying terrain by aspect, elevation, slope and presence of glacier). The meteorological forcing used to run the simulations is the reanalysis issued from the SAFRAN model which assimilates meteorological observations from the Meteo-France networks. Conceptual reservoirs with calibrated values of emptying parameters are used to represent the underground water storage. This approach has been tested to simulate the discharge on the Arve catchment and three sub-catchments over 1990-2015. The simulations were evaluated with respect to observed water discharges for several headwaters with varying glaciated areas. They allow to quantify the relative contribution of rainfall, snow and ice melt to the hydrological regime of the basin. Additionally, we present a detailed analysis of several particular flood events. For these events, the ability of the model to correctly represent the catchment behaviour is investigated, looking particularly to the relevance of the simulated snowpack. Particularly, its spatial distribution is evaluated using MODIS snow cover maps, punctual snowpack observations and summer

In-patient costs of agitation and containment in a mental health catchment area.

PubMed

Serrano-Blanco, Antoni; Rubio-Valera, Maria; Aznar-Lou, Ignacio; Baladón Higuera, Luisa; Gibert, Karina; Gracia Canales, Alfredo; Kaskens, Lisette; Ortiz, José Miguel; Salvador-Carulla, Luis

2017-06-06

There is a scarce number of studies on the cost of agitation and containment interventions and their results are still inconclusive. We aimed to calculate the economic consequences of agitation events in an in-patient psychiatric facility providing care for an urban catchment area. A mixed approach combining secondary analysis of clinical databases, surveys and expert knowledge was used to model the 2013 direct costs of agitation and containment events for adult inpatients with mental disorders in an area of 640,572 adult inhabitants in South Barcelona (Spain). To calculate costs, a seven-step methodology with novel definition of agitation was used along with a staff survey, a database of containment events, and data on aggressive incidents. A micro-costing analysis of specific containment interventions was used to estimate both prevalence and direct costs from the healthcare provider perspective, by means of a mixed approach with a probabilistic model evaluated on real data. Due to the complex interaction of the multivariate covariances, a sensitivity analysis was conducted to have empirical bounds of variability. During 2013, 918 patients were admitted to the Acute Inpatient Unit. Of these, 52.8% were men, with a mean age of 44.6 years (SD = 15.5), 74.4% were compulsory admissions, 40.1% were diagnosed with schizophrenia or non-affective psychosis, with a mean length of stay of 24.6 days (SD = 16.9). The annual estimate of total agitation events was 508. The cost of containment interventions ranges from 282€ at the lowest level of agitation to 822€ when verbal containment plus seclusion and restraint have to be used. The annual total cost of agitation was 280,535€, representing 6.87% of the total costs of acute hospitalisation in the local area. Agitation events are frequent and costly. Strategies to reduce their number and severity should be implemented to reduce costs to the Health System and alleviate patient suffering.

Seasonal exports of phosphorus from intensively fertilised nested grassland catchments.

PubMed

Lewis, Ciaran; Rafique, Rashad; Foley, Nelius; Leahy, Paul; Morgan, Gerard; Albertson, John; Kumar, Sandeep; Kiely, Gerard

2013-09-01

We carried out a one year (2002) study of phosphorus (P) loss from soil to water in three nested grassland catchments with known P input in chemical fertilizer and animal liquid slurry applications. Chemical fertilizer was applied to the grasslands between March and September and animal slurry was applied over the twelve months. The annual chemical P fertilizer applications for the 17 and 211 ha catchments were 16.4 and 23.7 kg P/ha respectively and the annual slurry applications were 10.7 and 14.0 kg P/ha, respectively. The annual total phosphorus (TP) export in stream-flow was 2.61, 2.48 and 1.61 kg P/ha for the 17, 211 and 1524 ha catchments, respectively, compared with a maximum permissible (by regulation) annual export of ca. 0.35 kg P/ha. The export rate (ratio of P export to P in land applications) was 9.6% and 6.6% from the 17 and 211 ha catchments, respectively. On average, 70% of stream flow and 85% of the P export occurred during the five wet months (October to February) indicating that when precipitation is much greater than evaporation, the hydrological conditions are most favourable for P export. However the soil quality and land use history may vary the results. Particulate P made up 22%, 43% and 37% of the TP export at the 17, 211 and 1524 ha catchment areas, respectively. As the chemical fertilizer was spread during the grass growth months (March to September), it has less immediate impact on stream water quality than the slurry applications. We also show that as the catchment scale increases, the P concentrations and P export decrease, confirming dilution due to increasing rural catchment size. In the longer term, the excess P from fertilizer maintains high soil P levels, an antecedent condition favourable to P loss from soil to water. This study confirms the significant negative water quality impact of excess P applications, particularly liquid animal slurry applications in wet winter months. The findings suggest that restricted P application in

Framework for measuring sustainable development in catchment systems.

PubMed

Walmsley, Jay J

2002-02-01

Integrated catchment management represents an approach to managing the resources of a catchment by integrating environmental, economic, and social issues. It is aimed at deriving sustainable benefits for future generations, while protecting natural resources, particularly water, and minimizing possible adverse social, economic, and environmental consequences. Indicators of sustainable development, which summarize information for use in decision-making, are invaluable when trying to assess the diverse, interacting components of catchment processes and resource management actions. The Driving-Forces--Pressure--State--Impact--Response (DPSIR) indicator framework is useful for identifying and developing indicators of sustainable development for catchment management. Driving forces have been identified as the natural conditions occurring in a catchment and the level of development and economic activity. Pressures include the natural and anthropogenic supply of water, water demand, and water pollution. State indicators can be split into those of quantity and those of quality. Impacts include those that affect the ecosystems directly and those that impact the use value of the resource. It core indicators are identified within each of the categories given in the framework, most major catchment-based management issues can be evaluated. This framework is applied to identify key issues in catchment management in South Africa, and develop a set of indicators for evaluating catchments throughout the country.

Typecasting catchments: Classification, directionality, and the pursuit of universality

NASA Astrophysics Data System (ADS)

Smith, Tyler; Marshall, Lucy; McGlynn, Brian

2018-02-01

Catchment classification poses a significant challenge to hydrology and hydrologic modeling, restricting widespread transfer of knowledge from well-studied sites. The identification of important physical, climatological, or hydrologic attributes (to varying degrees depending on application/data availability) has traditionally been the focus for catchment classification. Classification approaches are regularly assessed with regard to their ability to provide suitable hydrologic predictions - commonly by transferring fitted hydrologic parameters at a data-rich catchment to a data-poor catchment deemed similar by the classification. While such approaches to hydrology's grand challenges are intuitive, they often ignore the most uncertain aspect of the process - the model itself. We explore catchment classification and parameter transferability and the concept of universal donor/acceptor catchments. We identify the implications of the assumption that the transfer of parameters between "similar" catchments is reciprocal (i.e., non-directional). These concepts are considered through three case studies situated across multiple gradients that include model complexity, process description, and site characteristics. Case study results highlight that some catchments are more successfully used as donor catchments and others are better suited as acceptor catchments. These results were observed for both black-box and process consistent hydrologic models, as well as for differing levels of catchment similarity. Therefore, we suggest that similarity does not adequately satisfy the underlying assumptions being made in parameter regionalization approaches regardless of model appropriateness. Furthermore, we suggest that the directionality of parameter transfer is an important factor in determining the success of parameter regionalization approaches.

Catchment Systems Engineering: A New Paradigm in Water Management

NASA Astrophysics Data System (ADS)

Quinn, P. F.; Wilkinson, M. E.; Burke, S.; O'Donnell, G. M.; Jonczyk, J.; Barber, N.; Nicholson, A.

2012-04-01

Recent catchment initiatives have highlighted the need for new holistic approaches to sustainable water management. Catchment Systems Engineering seeks to describe catchment the function (or role) as the principal driver for evaluating how it should be managed in the future. Catchment Systems Engineering does not seek to re-establish a natural system but rather works with natural processes in order to engineer landscapes to accrue multiple benefits. The approach involves quantifying and assessing catchment change, impacts and most importantly, suggests an urgent and proactive agenda for future planning. In particular, an interventionist approach to managing hydrological flow pathways across scale is proposed. It is already accepted that future management will require a range of scientific expertise and full engagement with stakeholders. This inclusive concept under a Catchment Systems Engineering agenda forces any consortia to commit to actively changing and perturbing the catchment system and thus learn, in situ, how to manage the environment for collective benefits. The shared cost, the design, the implementation, the evaluation and any subsequent modifications should involve all relevant parties in the consortia. This joint ownership of a 'hands on' interventionist agenda to catchment change is at the core of Catchment Systems Engineering. In this paper we show a range of catchment engineering projects from the UK that have addressed multi-disciplinary approaches to flooding, pollution and ecosystem management, whilst maintaining economic food production. Examples using soft engineered features such as wetlands, ponds, woody debris dams and infiltration zones will be shown. Local scale demonstration activities, led by local champions, have proven to be an effective means of encouraging wider uptake. Evidence that impacts can be achieved at local catchment scale will be introduced. Catchment Systems Engineering is a concept that relies on all relevant parties

Historic change in catchment land use and metal loading to Sydney estuary, Australia (1788-2010).

PubMed

Birch, G F; Lean, J; Gunns, T

2015-09-01

Sydney estuary has a long history of environmental degradation and is one of the most modified water ways in Australia due to a highly urbanised catchment (~77 %) and a high population (4.6 million). The objectives of the present study were to map historical land use change from European settlement (1788) to 2010 to determine catchment evolutionary pathways and to estimate catchment loading (total suspended solids, Cu, Pb and Zn) to the estuary over this period. Land use distribution in Sydney catchment, determined for seven time horizons over this period, indicated that a substantial increase in residential land use through subdivision of large estates and an increase in road area resulted in a marked increase in metal loading to Sydney estuary between 1892 and 1936. The decline in industrial activity from a maximum in 1978 (3.9 %) to 1.8 % in 2010 and the introduction of unleaded fuel during this time was accompanied by reduction in metal loading to the estuary. Land use time horizon maps enabled the creation of novel, ternary diagrams to represent temporal evolution in catchment land use. The 15 sub-catchments of Sydney estuary were combined into three major catchment categories, i.e., urban, dense urban and commercial. Present-day annual discharge of stormwater from the Sydney catchment was calculated to be 466,000 ML and annual loadings of total suspended sediment (TSS), Cu, Pb and Zn in tonnes were 49,239, 27, 37 and 57, respectively. Stormwater has superseded industry as the main source of anthropogenic metals to this estuary in recent times.

Hillslope hydrologic connectivity controls riparian groundwater turnover: Implications of catchment structure for riparian buffering and stream water sources

Treesearch

Kelsey G. Jencso; Brian L. McGlynn; Michael N. Gooseff; Kenneth E. Bencala; Steven M. Wondzell

2010-01-01

Hydrologic connectivity between catchment upland and near stream areas is essential for the transmission of water, solutes, and nutrients to streams. However, our current understanding of the role of riparian zones in mediating landscape hydrologic connectivity and the catchment scale export of water and solutes is limited. We tested the relationship between the...

GIS-based modeling of debris flow processes in an Alpine catchment, Antholz valley, Italy

NASA Astrophysics Data System (ADS)

Sandmeier, Christine; Damm, Bodo; Terhorst, Birgit

2010-05-01

Debris flows are frequent natural hazards in mountain regions, which seriously can threat human lives and economic values. In the European Alps the occurrence of debris flows might even increase with respect to climate change, including permafrost degradation, glacier retreat and variable precipitation patterns. Thus, detailed understanding of process parameters and spatial distribution of debris flows is necessary to take appropriate protection measures for risk assessment. In this context, numerical models have been developed and applied successfully for simulation and prediction of debris-flow hazards and related process areas. In our study a GIS-based model is applied in an alpine catchment to address the following questions: Where are potential initiating areas of debris flows? How much material can be mobilized? What is the influence of topography and precipitation? The study area is located in the Antholz valley in the eastern Alps of Northern Italy. The investigated catchment of the Klammbach creek comprises 6.5 km² and is divided into two sub-catchments. Geologically it is dominated by metamorphic rock and altitudes range between 1310 and 3270 m. In summer 2005 a debris flow of more than 100000 m³ took place, originating from a steep, sparsely vegetated debris cone in the western part of the catchment. According to a regional study, the lower permafrost boundary in this area has risen by 250 m. In a first step, during a field survey, geomorphological mapping was performed, several channel cross-sections were measured and sediment samples were taken. Using mapping results and aerial images, a geomorphological map was created. In further steps, results from the field work, the geomorphological map and existing digital data sets, including a digital elevation model with 2.5 m resolution, are used to derive input data for the modeling of debris flow processes. The model framework ‘r.debrisflow' based on GRASS GIS is applied (Mergili, 2008*), as it is

Hysteresis and parent-metabolite analyses unravel characteristic pesticide transport mechanisms in a mixed land use catchment.

PubMed

Tang, Ting; Stamm, Christian; van Griensven, Ann; Seuntjens, Piet; Bronders, Jan

2017-11-01

To properly estimate and manage pesticide occurrence in urban rivers, it is essential, but often highly challenging, to identify the key pesticide transport pathways in association to the main sources. This study examined the concentration-discharge hysteresis behaviour (hysteresis analysis) for three pesticides and the parent-metabolite concentration dynamics for two metabolites at sites with different levels of urban influence in a mixed land use catchment (25 km 2 ) within the Swiss Greifensee area, aiming to identify the dominant pesticide transport pathways. Combining an adapted hysteresis classification framework with prior knowledge of the field conditions and pesticide usage, we demonstrated the possibility of using hysteresis analysis to qualitatively infer the dominant pesticide transport pathway in mixed land-use catchments. The analysis showed that hysteresis types, and therefore the dominant transport pathway, vary among pesticides, sites and rainfall events. Hysteresis loops mostly correspond to dominant transport by flow components with intermediate response time, although pesticide sources indicate that fast transport pathways are responsible in most cases (e.g. urban runoff and combined sewer overflows). The discrepancy suggests the fast transport pathways can be slowed down due to catchment storages, such as topographic depressions in agricultural areas, a wastewater treatment plant (WWTP) and other artificial storage units (e.g. retention basins) in urban areas. Moreover, the WWTP was identified as an important factor modifying the parent-metabolite concentration dynamics during rainfall events. To properly predict and manage pesticide occurrence in catchments of mixed land uses, the hydrological delaying effect and chemical processes within the artificial structures need to be accounted for, in addition to the catchment hydrology and the diversity of pesticide sources. This study demonstrates that in catchments with diverse pesticide sources

Vulnerability of a public supply well in a karstic aquifer to contamination

USGS Publications Warehouse

Katz, B.G.; McBride, W.S.; Hunt, A.G.; Crandall, C.A.; Metz, P.A.; Eberts, S.M.; Berndt, M.P.

2009-01-01

To assess the vulnerability of ground water to contamination in the karstic Upper Floridan aquifer (UFA), age-dating tracers and selected anthropogenic and naturally occurring compounds were analyzed in multiple water samples from a public supply well (PSW) near Tampa, Florida. Samples also were collected from 28 monitoring wells in the UFA and the overlying surficial aquifer system (SAS) and intermediate confining unit located within the contributing recharge area to the PSW. Age tracer and geochemical data from the earlier stage of the study (2003 through 2005) were combined with new data (2006) on concentrations of sulfur hexafluoride (SF6), tritium (3H), and helium-3, which were consistent with binary mixtures of water for the PSW dominated by young water (less than 7 years). Water samples from the SAS also indicated mostly young water (less than 7 years); however, most water samples from monitoring wells in the UFA had lower SF6 and 3H concentrations than the PSW and SAS, indicating mixtures containing high proportions of older water (more than 60 years). Vulnerability of the PSW to contamination was indicated by predominantly young water and elevated nitrate-N and volatile organic compound concentrations that were similar to those in the SAS. Elevated arsenic (As) concentrations (3 to 19 ??g/L) and higher As(V)/As(III) ratios in the PSW than in water from UFA monitoring wells indicate that oxic water from the SAS likely mobilizes As from pyrite in the UFA matrix. Young water found in the PSW also was present in UFA monitoring wells that tap a highly transmissive zone (43- to 53-m depth) in the UFA. ?? 2008 National Ground Water Association.

Vulnerability of a public supply well in a karstic aquifer to contamination.

PubMed

Katz, B G; McBride, W S; Hunt, A G; Crandall, C A; Metz, P A; Eberts, S M; Berndt, M P

2009-01-01

To assess the vulnerability of ground water to contamination in the karstic Upper Floridan aquifer (UFA), age-dating tracers and selected anthropogenic and naturally occurring compounds were analyzed in multiple water samples from a public supply well (PSW) near Tampa, Florida. Samples also were collected from 28 monitoring wells in the UFA and the overlying surficial aquifer system (SAS) and intermediate confining unit located within the contributing recharge area to the PSW. Age tracer and geochemical data from the earlier stage of the study (2003 through 2005) were combined with new data (2006) on concentrations of sulfur hexafluoride (SF(6)), tritium ((3)H), and helium-3, which were consistent with binary mixtures of water for the PSW dominated by young water (less than 7 years). Water samples from the SAS also indicated mostly young water (less than 7 years); however, most water samples from monitoring wells in the UFA had lower SF(6) and (3)H concentrations than the PSW and SAS, indicating mixtures containing high proportions of older water (more than 60 years). Vulnerability of the PSW to contamination was indicated by predominantly young water and elevated nitrate-N and volatile organic compound concentrations that were similar to those in the SAS. Elevated arsenic (As) concentrations (3 to 19 microg/L) and higher As(V)/As(III) ratios in the PSW than in water from UFA monitoring wells indicate that oxic water from the SAS likely mobilizes As from pyrite in the UFA matrix. Young water found in the PSW also was present in UFA monitoring wells that tap a highly transmissive zone (43- to 53-m depth) in the UFA.

The impact of hydrologic segmentation on the Critical Zone water fluxes of headwater catchments

NASA Astrophysics Data System (ADS)

Gutierrez-Jurado, H. A.; Dominguez, M.; Guan, H.

2017-12-01

Headwater catchments are usually located on areas with complex terrain, where variability in aspect and microclimate give rise to contrasting vegetation cover and soil properties. This fine-scale variability in land surface conditions within a catchment is usually overlooked in hydrologic models, and the resulting differences in hydrologic dynamics across the slopes neglected. In this work we evaluate the impact of the differential hydrologic response, or as we define it here, "hydrologic segmentation" on the partition of water fluxes of contrasting slopes within a series of headwater catchments across a latitudinal gradient. Our aim is to investigate the effect of hydrologically segmenting the slopes of headwater catchments as a function of their unique aspect-vegetation-soils associations, on the water fluxes of the catchments and their potential consequences on the water balance at a regional scale. Using a distributed hydrologic model and data from a series of catchments with varying land cover and climatic conditions, we run a set of simulations with and without hydrologic segmentation to assess the effect of changing the architecture of the top part of the critical zone on the evaporation, transpiration, infiltration and runoff fluxes of each catchment slope. We calibrate and compare the simulation results with observations from a network of hydrologic sensors and independent field estimates of the various water fluxes. Our results suggest that hydrologic segmentation will significantly affect both the timing and partition of evapotranspiration fluxes with direct impacts on soil moisture residence times and the potential for deep infiltration and aquifer recharge.

Controls on old and new water contributions to stream flow at some nested catchments in Vermont, USA

USGS Publications Warehouse

Shanley, J.B.; Kendall, C.; Smith, T.E.; Wolock, D.M.; McDonnell, Jeffery J.

2002-01-01

Factors controlling the partitioning of old and new water contributions to stream flow were investigated for three events in four catchments (three of which were nested) at Sleepers River Research Watershed in Danville, Vermont. In the 1993 snowmelt period, two-component isotopic hydrograph separations showed that new water (meltwater) inputs to the stream ranged widely from 41 to 74%, and increased with catchment size (41 to 11 125 ha) (with one exception) and with open land cover (0-73%). Peak dissolved organic carbon concentrations and relative alkalinity dilution in stream water ranked in the same order among catchments as the new water fractions, suggesting that new water followed shallow flow paths. During the 1994 snowmelt, despite similar timing and magnitude of melt inputs, the new-water contribution to stream flow ranged only from 30 to 36% in the four catchments. We conclude that the uncommonly high and variable new water fractions in streamwater during the 1993 melt were caused by direct runoff of meltwater over frozen ground, which was prevalent in open land areas during the 1993 winter. In a high-intensity summer rainstorm in 1993, new water fractions were smaller relative to the 1993 snowmelt, ranging from 28 to 46%, but they ranked in the identical catchment order. Reconciliation of the contrasting patterns of new-old water partitioning in the three events appears to require an explanation that invokes multiple processes and effects, including: 1 topographically controlled increase in surface-saturated area with increasing catchment size; 2 direct runoff over frozen ground; 3 low infiltration in agriculturally compacted soils; 4 differences in soil transmissivity, which may be more relevant under dry antecedent conditions. These data highlight some of the difficulties faced by catchment hydrologists in formulating a theory of runoff generation at varying basin scales. Copyright ?? 2002 John Wiley and Sons, Ltd.

Controls on old and new water contributions to stream flow at some nested catchments in Vermont, USA

NASA Astrophysics Data System (ADS)

Shanley, James B.; Kendall, Carol; Smith, Thor E.; Wolock, David M.; McDonnell, Jeffrey J.

2002-02-01

Factors controlling the partitioning of old and new water contributions to stream flow were investigated for three events in four catchments (three of which were nested) at Sleepers River Research Watershed in Danville, Vermont. In the 1993 snowmelt period, two-component isotopic hydrograph separations showed that new water (meltwater) inputs to the stream ranged widely from 41 to 74%, and increased with catchment size (41 to 11 125 ha) (with one exception) and with open land cover (0-73%). Peak dissolved organic carbon concentrations and relative alkalinity dilution in stream water ranked in the same order among catchments as the new water fractions, suggesting that new water followed shallow flow paths. During the 1994 snowmelt, despite similar timing and magnitude of melt inputs, the new-water contribution to stream flow ranged only from 30 to 36% in the four catchments. We conclude that the uncommonly high and variable new water fractions in streamwater during the 1993 melt were caused by direct runoff of meltwater over frozen ground, which was prevalent in open land areas during the 1993 winter. In a high-intensity summer rainstorm in 1993, new water fractions were smaller relative to the 1993 snowmelt, ranging from 28 to 46%, but they ranked in the identical catchment order. Reconciliation of the contrasting patterns of new-old water partitioning in the three events appears to require an explanation that invokes multiple processes and effects, including: 1.topographically controlled increase in surface-saturated area with increasing catchment size;2.direct runoff over frozen ground;3.low infiltration in agriculturally compacted soils;4.differences in soil transmissivity, which may be more relevant under dry antecedent conditions. These data highlight some of the difficulties faced by catchment hydrologists in formulating a theory of runoff generation at varying basin scales.

Temperature signal in suspended sediment export from an Alpine catchment

NASA Astrophysics Data System (ADS)

Costa, Anna; Molnar, Peter; Stutenbecker, Laura; Bakker, Maarten; Silva, Tiago A.; Schlunegger, Fritz; Lane, Stuart N.; Loizeau, Jean-Luc; Girardclos, Stéphanie

2018-01-01

Suspended sediment export from large Alpine catchments ( > 1000 km2) over decadal timescales is sensitive to a number of factors, including long-term variations in climate, the activation-deactivation of different sediment sources (proglacial areas, hillslopes, etc.), transport through the fluvial system, and potential anthropogenic impacts on the sediment flux (e.g. through impoundments and flow regulation). Here, we report on a marked increase in suspended sediment concentrations observed near the outlet of the upper Rhône River Basin in the mid-1980s. This increase coincides with a statistically significant step-like increase in basin-wide mean air temperature. We explore the possible explanations of the suspended sediment rise in terms of changes in water discharge (transport capacity), and the activation of different potential sources of fine sediment (sediment supply) in the catchment by hydroclimatic forcing. Time series of precipitation and temperature-driven snowmelt, snow cover, and ice melt simulated with a spatially distributed degree-day model, together with erosive rainfall on snow-free surfaces, are tested to explore possible reasons for the rise in suspended sediment concentration. We show that the abrupt change in air temperature reduced snow cover and the contribution of snowmelt, and enhanced ice melt. The results of statistical tests show that the onset of increased ice melt was likely to play a dominant role in the suspended sediment concentration rise in the mid-1980s. Temperature-driven enhanced melting of glaciers, which cover about 10 % of the catchment surface, can increase suspended sediment yields through an increased contribution of sediment-rich glacial meltwater, increased sediment availability due to glacier recession, and increased runoff from sediment-rich proglacial areas. The reduced extent and duration of snow cover in the catchment are also potential contributors to the rise in suspended sediment concentration through

Hydrologic response to modeled snowmelt input in alpine catchments in the Southwestern United States

NASA Astrophysics Data System (ADS)

Driscoll, J. M.; Molotch, N. P.; Jepsen, S. M.; Meixner, T.; Williams, M. W.; Sickman, J. O.

2012-12-01

Snowmelt from high elevation catchments is the primary source of water resources in the Southwestern United States. Timing and duration of snowmelt and resulting catchment response can show the physical and chemical importance of storage at the catchment scale. Storage of waters in subsurface materials provides a physical and chemical buffer to hydrologic input variability. We expect the hydrochemistry of catchments with less storage capacity will more closely reflect input waters than a catchment with more storage and therefore more geochemical evolution of waters. Two headwater catchments were compared for this study; Emerald Lake Watershed (ELW) in the southern Sierra Nevada and Green Lake 4 (GL4) in the Colorado Front Range. These sites have geochemically similar granitic terrane, and negligible evaporation and transpiration due to their high-elevation setting. Eleven years of data (1996-2006) from spatially-distributed snowmelt models were spatially and temporally aggregated to generate daily values of snowmelt volume for each catchment area. Daily storage flux was calculated as the difference between snowmelt input and catchment outflow at a daily timestep, normalized to the catchment area. Daily snowmelt values in GL4 are more consistent (the annual standard deviation ranged from 0.19 to 0.76 cm) than the daily snowmelt in ELW (0.60 to 1.04 cm). Outflow follows the same trend, with an even narrower range of standard deviations from GL4 (0.27 to 0.54 cm) compared to the standard deviation of outflow in ELW (0.38 to 0.98 cm). The dampening of the input variability could be due to storage in the catchment; the larger effect would mean a larger storage capacity in the catchment. Calculations of storage flux (the input snowmelt minus the output catchment discharge) show the annual sum of water into storage in ELW ranges from -0.9200 to 1.1124 meters, in GL4 the ranger is narrower, from -0.655 to 0.0992 meters. Cumulative storage for each year can be negative

Safeguarding the provision of ecosystem services in catchment systems.

PubMed

Everard, Mark

2013-04-01

A narrow technocentric focus on a few favored ecosystem services (generally provisioning services) has led to ecosystem degradation globally, including catchment systems and their capacities to support human well-being. Increasing recognition of the multiple benefits provided by ecosystems is slowly being translated into policy and some areas of practice, although there remains a significant shortfall in the incorporation of a systemic perspective into operation management and decision-making tools. Nevertheless, a range of ecosystem-based solutions to issues as diverse as flooding and green space provision in the urban environment offers hope for improving habitat and optimization of beneficial services. The value of catchment ecosystem processes and their associated services is also being increasingly recognized and internalized by the water industry, improving water quality and quantity through catchment land management rather than at greater expense in the treatment costs of contaminated water abstracted lower in catchments. Parallel recognition of the value of working with natural processes, rather than "defending" built assets when catchment hydrology is adversely affected by unsympathetic upstream development, is being progressively incorporated into flood risk management policy. This focus on wider catchment processes also yields a range of cobenefits for fishery, wildlife, amenity, flood risk, and other interests, which may be optimized if multiple stakeholders and their diverse value systems are included in decision-making processes. Ecosystem services, particularly implemented as a central element of the ecosystem approach, provide an integrated framework for building in these different perspectives and values, many of them formerly excluded, into commercial and resource management decision-making processes, thereby making tractable the integrative aspirations of sustainable development. This can help redress deeply entrenched inherited assumptions

Developing a multi-pollutant conceptual framework for the selection and targeting of interventions in water industry catchment management schemes.

PubMed

Bloodworth, J W; Holman, I P; Burgess, P J; Gillman, S; Frogbrook, Z; Brown, P

2015-09-15

In recent years water companies have started to adopt catchment management to reduce diffuse pollution in drinking water supply areas. The heterogeneity of catchments and the range of pollutants that must be removed to meet the EU Drinking Water Directive (98/83/EC) limits make it difficult to prioritise areas of a catchment for intervention. Thus conceptual frameworks are required that can disaggregate the components of pollutant risk and help water companies make decisions about where to target interventions in their catchments to maximum effect. This paper demonstrates the concept of generalising pollutants in the same framework by reviewing key pollutant processes within a source-mobilisation-delivery context. From this, criteria are developed (with input from water industry professionals involved in catchment management) which highlights the need for a new water industry specific conceptual framework. The new CaRPoW (Catchment Risk to Potable Water) framework uses the Source-Mobilisation-Delivery concept as modular components of risk that work at two scales, source and mobilisation at the field scale and delivery at the catchment scale. Disaggregating pollutant processes permits the main components of risk to be ascertained so that appropriate interventions can be selected. The generic structure also allows for the outputs from different pollutants to be compared so that potential multiple benefits can be identified. CaRPow provides a transferable framework that can be used by water companies to cost-effectively target interventions under current conditions or under scenarios of land use or climate change. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Quantifying navigational information: The catchment volumes of panoramic snapshots in outdoor scenes.

PubMed

Murray, Trevor; Zeil, Jochen

2017-01-01

Panoramic views of natural environments provide visually navigating animals with two kinds of information: they define locations because image differences increase smoothly with distance from a reference location and they provide compass information, because image differences increase smoothly with rotation away from a reference orientation. The range over which a given reference image can provide navigational guidance (its 'catchment area') has to date been quantified from the perspective of walking animals by determining how image differences develop across the ground plane of natural habitats. However, to understand the information available to flying animals there is a need to characterize the 'catchment volumes' within which panoramic snapshots can provide navigational guidance. We used recently developed camera-based methods for constructing 3D models of natural environments and rendered panoramic views at defined locations within these models with the aim of mapping navigational information in three dimensions. We find that in relatively open woodland habitats, catchment volumes are surprisingly large extending for metres depending on the sensitivity of the viewer to image differences. The size and the shape of catchment volumes depend on the distance of visual features in the environment. Catchment volumes are smaller for reference images close to the ground and become larger for reference images at some distance from the ground and in more open environments. Interestingly, catchment volumes become smaller when only above horizon views are used and also when views include a 1 km distant panorama. We discuss the current limitations of mapping navigational information in natural environments and the relevance of our findings for our understanding of visual navigation in animals and autonomous robots.

Quantitative Generalizations for Catchment Sediment Yield Following Plantation Logging

NASA Astrophysics Data System (ADS)

Bathurst, James; Iroume, Andres

2014-05-01

While there is a reasonably clear qualitative understanding of the impact of forest plantations on sediment yield, there is a lack of quantitative generalizations. Such generalizations would be helpful for estimating the impacts of proposed forestry operations and would aid the spread of knowledge amongst both relevant professionals and new students. This study therefore analyzed data from the literature to determine the extent to which quantitative statements can be established. The research was restricted to the impact of plantation logging on catchment sediment yield as a function of ground disturbance in the years immediately following logging, in temperate countries, and does not consider landslides consequent upon tree root decay. Twelve paired catchment studies incorporating pre- and post-logging measurements of sediment yield were identified, resulting in forty-three test catchments (including 14 control catchments). Analysis yielded the following principal conclusions: 1) Logging generally provokes maximum annual sediment yields of less than a few hundred t km-2 yr-1; best management practice can reduce this below 100 t km-2 yr-1. 2) At both the annual and event scales, the sediment yield excess of a logged catchment over a control catchment is within one order of magnitude, except with severe ground disturbance. 3) There is no apparent relationship between sediment yield impact and the proportion of catchment logged. The effect depends on which part of the catchment is altered and on its connectivity to the stream network. 4) The majority of catchments delivered their maximum sediment yield in the first two years after logging. The logging impacts were classified in terms of the absolute values of specific sediment yield, the values relative to those in the control catchments for the same period and the values relative both to the control catchment and the pre-logging period. Most studies have been for small catchments (< 10 km2) and temperate regions

Water and salt balance modelling to predict the effects of land-use changes in forested catchments. 1. Small catchment water balance model

NASA Astrophysics Data System (ADS)

Sivapalan, Murugesu; Ruprecht, John K.; Viney, Neil R.

1996-03-01

A long-term water balance model has been developed to predict the hydrological effects of land-use change (especially forest clearing) in small experimental catchments in the south-west of Western Australia. This small catchment model has been used as the building block for the development of a large catchment-scale model, and has also formed the basis for a coupled water and salt balance model, developed to predict the changes in stream salinity resulting from land-use and climate change. The application of the coupled salt and water balance model to predict stream salinities in two small experimental catchments, and the application of the large catchment-scale model to predict changes in water yield in a medium-sized catchment that is being mined for bauxite, are presented in Parts 2 and 3, respectively, of this series of papers.The small catchment model has been designed as a simple, robust, conceptually based model of the basic daily water balance fluxes in forested catchments. The responses of the catchment to rainfall and pan evaporation are conceptualized in terms of three interdependent subsurface stores A, B and F. Store A depicts a near-stream perched aquifer system; B represents a deeper, permanent groundwater system; and F is an intermediate, unsaturated infiltration store. The responses of these stores are characterized by a set of constitutive relations which involves a number of conceptual parameters. These parameters are estimated by calibration by comparing observed and predicted runoff. The model has performed very well in simulations carried out on Salmon and Wights, two small experimental catchments in the Collie River basin in south-west Western Australia. The results from the application of the model to these small catchments are presented in this paper.

Assessment of surface water resources availability using catchment modelling and the results of tracer studies in the mesoscale Migina Catchment, Rwanda

NASA Astrophysics Data System (ADS)

Munyaneza, O.; Mukubwa, A.; Maskey, S.; Uhlenbrook, S.; Wenninger, J.

2014-12-01

In the present study, we developed a catchment hydrological model which can be used to inform water resources planning and decision making for better management of the Migina Catchment (257.4 km2). The semi-distributed hydrological model HEC-HMS (Hydrologic Engineering Center - the Hydrologic Modelling System) (version 3.5) was used with its soil moisture accounting, unit hydrograph, liner reservoir (for baseflow) and Muskingum-Cunge (river routing) methods. We used rainfall data from 12 stations and streamflow data from 5 stations, which were collected as part of this study over a period of 2 years (May 2009 and June 2011). The catchment was divided into five sub-catchments. The model parameters were calibrated separately for each sub-catchment using the observed streamflow data. Calibration results obtained were found acceptable at four stations with a Nash-Sutcliffe model efficiency index (NS) of 0.65 on daily runoff at the catchment outlet. Due to the lack of sufficient and reliable data for longer periods, a model validation was not undertaken. However, we used results from tracer-based hydrograph separation from a previous study to compare our model results in terms of the runoff components. The model performed reasonably well in simulating the total flow volume, peak flow and timing as well as the portion of direct runoff and baseflow. We observed considerable disparities in the parameters (e.g. groundwater storage) and runoff components across the five sub-catchments, which provided insights into the different hydrological processes on a sub-catchment scale. We conclude that such disparities justify the need to consider catchment subdivisions if such parameters and components of the water cycle are to form the base for decision making in water resources planning in the catchment.

Assessing calves as carriers of Cryptosporidium and Giardia with zoonotic potential on dairy and beef farms within a water catchment area by mutation scanning.

PubMed

Abeywardena, Harshanie; Jex, Aaron R; Firestone, Simon M; McPhee, Sandra; Driessen, Nicole; Koehler, Anson V; Haydon, Shane R; von Samson-Himmelstjerna, Georg; Stevens, Melita A; Gasser, Robin B

2013-08-01

In the present study, we undertook a molecular epidemiological survey of Cryptosporidium and Giardia in calves on three dairy and two beef farms within an open drinking water catchment area (Melbourne, Australia). Faecal samples (n = 474) were collected from calves at two time points (5 months apart) and tested using a PCR-based mutation scanning-targeted sequencing phylogenetic approach, employing regions within the genes of small subunit (SSU) of ribosomal RNA (designated partial SSU), 60 kDa glycoprotein (pgp60) and triose phosphate isomerase (ptpi) as genetic markers. Using partial SSU, the C. bovis, C. parvum, C. ryanae and a new genotype of Cryptosporidium were characterised from totals of 74 (15.6%), 35 (7.3%), 37 (7.8%) and 9 (1.9%) samples, respectively. Using pgp60, C. parvum genotype IIa subgenotype A18G3R1 was detected in 29 samples. Using ptpi, G. duodenalis assemblages A and E were detected in totals of 10 (2.1%) and 130 (27.4%) samples, respectively. The present study showed that a considerable proportion of dairy and beef calves in this open water catchment region excreted Cryptosporidium (i.e. subgenotype IIaA18G3R1) and Giardia (e.g. assemblage A) that are consistent with those infecting humans, inferring that they are of zoonotic importance. Future work should focus on exploring, in a temporal and spatial way, whether these parasites occur in the environment and water of the catchment reservoir. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Future streamflow droughts in glacierized catchments: the impact of dynamic glacier modelling and changing thresholds

NASA Astrophysics Data System (ADS)

Van Tiel, Marit; Van Loon, Anne; Wanders, Niko; Vis, Marc; Teuling, Ryan; Stahl, Kerstin

2017-04-01

In glacierized catchments, snowpack and glaciers function as an important storage of water and hydrographs of highly glacierized catchments in mid- and high latitudes thus show a clear seasonality with low flows in winter and high flows in summer. Due to the ongoing climate change we expect this type of storage capacity to decrease with resultant consequences for the discharge regime. In this study we focus on streamflow droughts, here defined as below average water availability specifically in the high flow season, and which methods are most suitable to characterize future streamflow droughts as regimes change. Two glacierized catchments, Nigardsbreen (Norway) and Wolverine (Alaska), are used as case study and streamflow droughts are compared between two periods, 1975-2004 and 2071-2100. Streamflow is simulated with the HBV light model, calibrated on observed discharge and seasonal glacier mass balances, for two climate change scenarios (RCP 4.5 & RCP 8.5). In studies on future streamflow drought often the same variable threshold of the past has been applied to the future, but in regions where a regime shift is expected this method gives severe "droughts" in the historic high-flow period. We applied the new alternative transient variable threshold, a threshold that adapts to the changing hydrological regime and is thus better able to cope with this issue, but has never been thoroughly tested in glacierized catchments. As the glacier area representation in the hydrological modelling can also influence the modelled discharge and the derived streamflow droughts, we evaluated in this study both the difference between the historical variable threshold (HVT) and transient variable threshold (TVT) and two different glacier area conceptualisations (constant area (C) and dynamical area (D)), resulting in four scenarios: HVT-C, HVT-D, TVT-C and TVT-D. Results show a drastic decrease in the number of droughts in the HVT-C scenario due to increased glacier melt. The deficit

The role of groundwater in streamflow in a headwater catchment with sub-humid climate

NASA Astrophysics Data System (ADS)

Liu, Yaping; Tian, Fuqiang; Hu, Hongchang; Tie, Qiang

2015-04-01

Recent studies have suggested that bedrock groundwater can exert considerable influence on streamflow in headwater catchments under humid climate. However, study of the role of bedrock groundwater is still challenged due to limited direct observation data. In this study, by utilizing observed hydrometric and hydrochemical data, we aimed at characterize the bedrock groundwater's response to rainfall at hillslope and catchment scales in a small headwater catchment with sub-humid climate. We selected Xitaizi catchment with area of 6.7 km in the earth-rock mountain region, which located in the north of Beijing, China, as study area. The catchment bedrock is mainly consist of fractured granite. Four weather stations were installed to observe the weather condition and soil volumetric water content (VWC) at depth of 10-60 cm with 10-minute interval. Five wells with depth of 10 m were drilled in two slopes to monitor the bedrock water table by pneumatic water gauge. At slope 1, the soil VWC at depth of 10-80 cm were also observed by soil moisture sensors, and surface/subsurface hillslope runoff at three different layers (0-20cm, 20-80cm, 80-300cm) was observed by three recording buckets. Field works were conducted from July 2013 to November 2014. During the period, precipitation, river, spring and groundwater were sampled nearly monthly. Water temperature, electrical conductivity (EC) and pH were measured in site with portable instruments. In addition, the precipitation, river and groundwater were also sampled intensively during two storm events. All the samples were subjected to stable isotope analysis, the samples taken monthly during the period from July 2013 to July 2014 were subjected to hydrochemistry analysis. Our results show that: (1) the bedrock groundwater is the dominant component of streamflow in the headwater catchment with sub-humid climate; (2) stream is recharged by groundwater sourcing from different mountains with different hydrochemistry characteristics

Integrative investigations on sediments in the Belauer See catchment (northern Germany)

NASA Astrophysics Data System (ADS)

Dreibrodt, Stefan

2015-04-01

The Holocene history of lake development, catchment vegetation, soil formation and human impact since the onset of the Neolithic period was reconstructed via the analysis of sediment sequences at Lake Belau (northern Germany). The chronology of the annually laminated lake sediment sequence was established via varve counts, radiocarbon dating and tephra analysis. Sequences of colluvial sediments and buried soils studied in 19 large exposures and supplementing auger cores within the lake catchment area were dated via radiocarbon dating and archaeological dating of embedded artifacts. The long term development of the lake status was found to be strongly influenced by local human activity. This is indicated by coincidence of phases of landscape openness deduced from pollen data with input of detritus and solutes into the lake. A comparison with palaeo-climate reconstructions reveals that calcite precipitation in the lake reflects climate variability at least to a certain degree. Calibrating the sediment record of the sub-recent lake sediments (micro-facies) on limnological and meteorological records discovered the influence of the NAO as well as solar activity on the limnological processes during the last century reflected by distinguished sedimentation patterns. A comparative study of additional laminated surface sediment sequences from northern Germany corroborates the results. A high resolution reconstruction of Neolithic weather conditions in northern Germany based on the varves of Lake Belau and Lake Poggensee was facilitated by the calibration. The quantitative records of sediments originating from soil erosion (colluvial sediments, allochthonous input into the lake) illustrate the dominance of short distance surface processes (slopes) acting in Holocene mid-latitude landscapes. Coincidence of gully incision in the lake catchment area and increased allochthonous input into the lake indicates the former occurrence of hydrological high energy runoff events (e. g

Developing a vulnerability index for assessing riverbank erosion in large catchments

NASA Astrophysics Data System (ADS)

Regan, Siôn; Smith, Hugh

2017-04-01

Riverbank erosion is a natural process involved in floodplain development, but can have negative impacts such as excessive sediment supply to the river channel, undermining infrastructure and eroding valuable agricultural land. Catchment managers often work with limited budgets and for remediation efforts to be the most effective they should be targeted in areas that are at the highest risk of suffering excessive riverbank erosion. Recent developments in high resolution spatial data capture, such as aerial LiDAR have allowed for much more detailed representation of the riparian area, including the channel location and riparian vegetation. This presentation will propose a new dimensionless index that has been developed to identify and rank sections of river channel according to erosion vulnerability. The index combines information on channel position, slope and curvature extracted from LiDAR-derived DEMs with riparian vegetation cover. It also accounts for the extent of lateral confinement limiting erosion and bank silt-clay composition influencing erodibility. The index is designed to be applied to alluvial channels across large catchments (>500 km2) to support the identification riverbank erosion 'hotspots' at the reach scale (approximating 50-200 m intervals). The performance of the vulnerability index in discriminating actively eroding and non-eroding channel reaches was assessed in the River Lugg catchment, UK. Historic mapping and aerial photographs were used to determine the channel position, slope and riparian vegetation coverage in the 1960s. The index was then calculated for the historic river channel position and compared with ranked metrics of lateral channel change that occurred between the 1960s and present. This approach provides a basis for evaluating the utility of a simple vulnerability index that could be used for prioritising the location of future investments to reduce excessive riverbank erosion in large catchments.

Spatial patterns of stream temperatures and electric conductivity in a mesoscale catchment

NASA Astrophysics Data System (ADS)

Lieder, Ernestine; Weiler, Markus; Blume, Theresa

2017-04-01

Stream temperature and electric conductivity (EC) are both relatively easily measured and can provide valuable information on runoff generation processes and catchment storage.This study investigates the spatial variability of stream temperature and EC in a mesoscale basin. We focus on the mesoscale (sub-catchments and reach scale), and long term (seasonal / annual) stream temperature and EC patterns. Our study basin is the Attert catchment in Luxembourg (288km2), which contains multiple sub-catchments of different geology, topography and land use patterns. We installed 90 stream temperature and EC sensors at sites across the basin in summer 2015. The collected data is complemented by land use and discharge data and an extensive climate data set. Thermal sensitivity was calculated as the slope of daily air temperature-water-temperature regression line and describes the sensitivity of stream temperature to long term environmental change. Amplitude sensitivity was calculated as slope of the daily air and water temperature amplitude regression and describes the short term warming capacity of the stream. We found that groups with similar long term thermal and EC patterns are strongly related to different geological units. The sandstone reaches show the coldest temperatures and lowest annual thermal sensitivity to air temperature. The slate reaches are characterized by comparably low EC and high daily temperature amplitudes and amplitude sensitivity. Furthermore, mean annual temperatures and thermal sensitivities increase exponentially with drainage area, which can be attributed to the accumulation of heat throughout the system. On the reach scale, daily stream temperature fluctuations or sensitivities were strongly influenced by land cover distribution, stream shading and runoff volume. Daily thermal sensitivities were low for headwater streams; peaked for intermediate reaches in the middle of the catchment and then decreased again further downstream with increasing

Using hydrochemical tracers to conceptualise hydrological function in a larger scale catchment draining contrasting geologic provinces

NASA Astrophysics Data System (ADS)

Capell, R.; Tetzlaff, D.; Malcolm, I. A.; Hartley, A. J.; Soulsby, C.

2011-09-01

SummaryA year-long multivariate tracer study in the 749 km 2 catchment of the North-Esk in north east Scotland was carried out to infer the dominant runoff generation processes in two markedly different geologic provinces. The upper 60% of the catchment has montane headwaters dominated by impermeable metamorphic rocks, steep topography, peaty soils and a sub-arctic climate with over 1400 mm of precipitation. The lowlands of the catchment are underlain by a major sandstone aquifer, and mainly have freely draining, fertile soils that support intensive arable farming under a drier climate with around 800 mm of precipitation. Storm runoff in the uplands is dominated by near-surface processes in soils and sedimentary layers which generate around 60% of annual stream flows with water of low alkalinity and ionic strength. In contrast, tributaries in the lower parts of the catchment are dominated by groundwater-fed base flows which account for 75% of annual runoff and are characterised by alkaline waters with high concentrations of base cations and high levels of nitrate. Multivariate statistical methods were used to derive a generic typology of catchment source waters, their spatial and temporal dynamics and particularly, how they integrate together at the larger catchment scale. The uplands dominate the winter high flow response of the whole catchment. The influence of lowland groundwater from major aquifers becomes more apparent under low flows. However, groundwater from small upland aquifers plays a critical role for ecosystem service in dry periods providing baseflows which dilute pollutant inputs from lowland areas at the large catchment scale.

REXPO: A catchment model designed to understand and simulate the loss dynamics of plant protection products and biocides from agricultural and urban areas

NASA Astrophysics Data System (ADS)

Wittmer, I. K.; Bader, H.-P.; Scheidegger, R.; Stamm, C.

2016-02-01

During rain events, biocides and plant protection products are transported from agricultural fields but also from urban sources to surface waters. Originally designed to be biologically active, these compounds may harm organisms in aquatic ecosystems. Although several models allow either urban or agricultural storm events to be predicted, only few combine these two sources, and none of them include biocide losses from building envelopes. This study therefore aims to develop a model designed to predict water and substance flows from urban and agricultural sources to surface waters. We developed a model based on physical principles for water percolation and substance flow including micro- (also called matrix-) and macropore-flows for the agricultural areas together with a model representing sources, sewer systems and a wastewater treatment plant for urban areas. In a second step, the combined model was applied to a catchment where an extensive field study had been conducted. The modelled and measured discharge and compound results corresponded reasonably well in terms of quantity and dynamics. The total cumulative discharge was only slightly lower than the total measured discharge (factor 0.94). The total modelled losses of the agriculturally used herbicide atrazine were slightly lower (∼25%) than the measured losses when the soil pore water distribution coefficient (describing the partition between soil particles and pore water) (Kd) was kept constant and slightly higher if it was increased with time. The modelled urban losses of diuron from facades were within a factor of three with respect to the measured values. The results highlighted the change in importance of the flow components during a rain event from urban sources during the most intensive rain period towards agricultural ones over a prolonged time period. Applications to two other catchments, one neighbouring and one on another continent showed that the model can be applied using site specific data for

Identifying fine sediment sources to alleviate flood risk caused by fine sediments through catchment connectivity analysis

NASA Astrophysics Data System (ADS)

Twohig, Sarah; Pattison, Ian; Sander, Graham

2017-04-01

Fine sediment poses a significant threat to UK river systems in terms of vegetation, aquatic habitats and morphology. Deposition of fine sediment onto the river bed reduces channel capacity resulting in decreased volume to contain high flow events. Once the in channel problem has been identified managers are under pressure to sustainably mitigate flood risk. With climate change and land use adaptations increasing future pressures on river catchments it is important to consider the connectivity of fine sediment throughout the river catchment and its influence on channel capacity, particularly in systems experiencing long term aggradation. Fine sediment erosion is a continuing concern in the River Eye, Leicestershire. The predominately rural catchment has a history of flooding within the town of Melton Mowbray. Fine sediment from agricultural fields has been identified as a major contributor of sediment delivery into the channel. Current mitigation measures are not sustainable or successful in preventing the continuum of sediment throughout the catchment. Identifying the potential sources and connections of fine sediment would provide insight into targeted catchment management. 'Sensitive Catchment Integrated Modelling Analysis Platforms' (SCIMAP) is a tool often used by UK catchment managers to identify potential sources and routes of sediment within a catchment. SCIMAP is a risk based model that combines hydrological (rainfall) and geomorphic controls (slope, land cover) to identify the risk of fine sediment being transported from source into the channel. A desktop version of SCIMAP was run for the River Eye at a catchment scale using 5m terrain, rainfall and land cover data. A series of SCIMAP model runs were conducted changing individual parameters to determine the sensitivity of the model. Climate Change prediction data for the catchment was used to identify potential areas of future connectivity and erosion risk for catchment managers. The results have been

Development of a large-sample catchment-scale hydro-meteorological, land cover and physical dataset for Chile

NASA Astrophysics Data System (ADS)

Alvarez-Garreton, C. D.; Mendoza, P. A.; Zambrano-Bigiarini, M.; Galleguillos, M. H.; Boisier, J. P.; Lara, A.; Cortés, G.; Garreaud, R.; McPhee, J. P.; Addor, N.; Puelma, C.

2017-12-01

We provide the first catchment-based hydrometeorological, vegetation and physical data set over 531 catchments in Chile (17.8 S - 55.0 S). We compiled publicly available streamflow records at daily time steps for the period 1980-2015, and generated basin-averaged time series of the following hydrometeorological variables: 1) daily precipitation coming from three different gridded sources (re-analysis and satellite-based); 2) daily maximum and minimum temperature; 3) 8-days potential evapotranspiration (PET) based on MODIS imagery and daily PET based on Hargreaves formula; and 4) daily snow water equivalent. Additionally, catchments are characterized by their main physical (area, mean elevation, mean slope) and land cover characteristics. We synthetized these datasets with several indices characterizing the spatial distribution of climatic, hydrological, topographic and vegetation attributes. The new catchment-based dataset is unprecedented in the region and provides information that can be used in a myriad of applications, including catchment classification and regionalization studies, impacts of different land cover types on catchment response, characterization of drought history and projections, climate change impacts on hydrological processes, etc. Derived practical applications include water management and allocation strategies, decision making and adaptation planning to climate change. This data set will be publicly available and we encourage the community to use it.

Climate, runoff and landuse trends in the Owo River Catchment in Nigeria

NASA Astrophysics Data System (ADS)

Adegun, O.; Odunuga, S.; Ajayi, O. S.

2015-06-01

The Owo River is an important surface water source in Lagos particularly to the western section. It is the source of direct water intake for water supply by Lagos State Water Corporation to Amuwo-Odofin, Ojo and parts of Badagry Local Government Areas. This paper examines the complex interactions and feedbacks between many variables and processes within that catchment and analyses the future ability of this semi-urban watershed in sustaining water supply in the face of cumulative environmental change. Stationarity analysis on rainfall, change detection analysis and morphometry analysis were combined to analyse the non-stationarity of Owo River catchment. On rainfall trend analysis, since the correlation coefficient (0.38) with test statistic of 2.17 did not satisfy the test condition we concluded that there is trend and that rainfall in the watershed is not stationary. The dominant land use impacting on the bio-geochemical fluxes is built up area (including structures and paved surfaces) which grew from about 142.92 km2 (12.20%) in 1984 to 367.22 km2 (31.36%) in 2013 recording gain of 224.3 km2 at average growth rate of 7.73 km2 per annum. Total length of streams within the catchment reduced from 622.24 km in 1964 to 556 km in 2010, while stream density reduced from 0.53 in 1964 to 0.47 in 2010 an indication of shrinking hydrological network. The observed trends in both natural and anthropogenic processes indicated non-stationarity of the hydrological fluxes within the Catchment and if this continues, the urban ecosystem services of water supply will be compromised.

The spatial relationships between geodiversity and biodiversity; the Dębnica catchment, Poland

NASA Astrophysics Data System (ADS)

Najwer, Alicja; Borysiak, Janina; Gudowicz, Joanna; Mazurek, Małgorzata; Zwoliński, Zbigniew

2016-04-01

Natural environment consists of a variety of correlated abiotic and biotic systems, which are responsible for diversity in nature. Geodiversity determines biodiversity but occasionally an inverse relationship may occur, e.g. the impact of diversity and multiplicity of species on the character of biogenic sediments. Recognizing parts of the territory that are the most diversified turns out to be a very crucial for management and planning of natural protected areas. The main aim of the presentation is to determine spatial relationships between geodiversity and biodiversity using a unique combination of maps for the Dębnica catchment (West Pomerania, Poland) as well as an attempt to integrate geodiversity and biodiversity assessments of the lowland areas of the postglacial origin. The collected field and literature data, both analogue and digital, allowed for assessing geodiversity and biodiversity. Seven factor maps were obtained, i.e. five maps for the diversity of abiotic elements (lithology, relative heights, landform fragmentation, hydrological elements and mesoclimate) and two for the diversity of biotic elements (potential natural vegetation and real vegetation based on hemeroby and vegetation origin), which became the basis for the creation of the final geodiversity and biodiversity maps. A unique combination of geodiversity and biodiversity maps in the catchment of Dębnica was created. These combinations reflect the coexistence of five distinguished classes of geodiversity and biodiversity assessment and their spatial relationships occurring between individual units. In Dębnica catchment there are all possible cases of 25 unique categories. The largest areas are units of low geodiversity with medium and high biodiversity (47.05%), high geodiversity with medium and high biodiversity (22.89%) and medium geodiversity with medium biodiversity (14.37%). Units of low biodiversity in combination with geodiversity occupy only 7% of the whole catchment area of D�

Glacial landform assemblages in the catchment area of the upper Quitarasca valley (Cordillera Blanca, Perú)

NASA Astrophysics Data System (ADS)

Iturrizaga, L.

2012-04-01

The research project focuses on the glacial landform sequences in the upper Quitarasca valley (8°51´S/77°36´W) with particular consideration of the Pucahirca glacier. The study area is located at the eastern side of the Cordillera Blanca, about almost 40 km valley upstream of the confluence with the Rio Santa valley. The highest catchment area is the Pucahirca Massif (6020 m a.s.l.). The present glacier tongue terminates at an elevation of 4500 m a.s.l.. The investigations analyzed the extent of the glaciations from the Last Glacial Maximum to modern times in regard to the transition of the moraine types during the course of deglaciation. The distinct moraine stages were correlated with existent glacial chronologies of adjacent valleys. Due to the hazard potential of the Laguna Safuna Alta, which developed in the late 1940s at the terminus of the Pucahirca glacier, detailed studies have been carried out by various research groups in regard to the composition of the historical / Neoglacial moraine composition providing at the same time valuable material for multi-temporal comparison of the recent development of the glacier tongue. The investigations presented here are part of a project on the glacial geomorphology in the Tropical Andes, financed by the Alexander von Humboldt Foundation.

Understanding sediment sources in a peri-urban Mediterranean catchment using geochemical tracers

NASA Astrophysics Data System (ADS)

Ferreira, Carla; Walsh, Rory; Kikuchi, Ryunosuke; Blake, Will

2016-04-01

One of the main physical environmental impacts of urbanization is an increase in suspended sediment concentrations and loads, particularly in the constructional phase. Impacts in peri-urban catchments characterized by a mosaic of urban and non-urban landscape elements with varying roles in acting as sources and sinks of overland flow and slope wash have received little attention, particularly in Mediterranean environments. The present study uses a sediment 'fingerprinting' approach to determine the main sediment sources in the peri-urban Ribeira dos Covões catchment (6.2km2) in Portugal and how they change during storm events following contrasting antecedent weather. The catchment, rural until 1972, underwent discontinuous urbanization in 1973-1993, followed by an urban consolidation phase. Currently, its land-use is a complex mosaic of woodland (56%), urban (40%) and agricultural (4%) land parcels. Distinct urban patterns include some well-defined urban residential centres, but also areas of discontinuous urban sprawl. Since 2010, a major road was built and an enterprise park has been under construction, covering 1% and 5% of the catchment, respectively. The catchment has a Mediterranean climate. The geology comprises sandstone (56%), limestone (41%) and alluvial deposits (3%). Soils are generally deep (>3.0m), but shallow (<0.4m) on steeper limestone terrain. The catchment has an average slope of 9° , but includes steep slopes of up to 46° . The sediment fingerprinting methodology involved characterizing the chemical properties of sediments from individual upstream sub-catchments and comparing these to the properties of downstream transported fluvial material. Three fine bed-sediment sampling surveys were carried out after (i) a long dry period (21/09/2012), (ii) a winter storm of relatively high rainfall intensity (23.2mm day-1) (19/02/2015), and (iii) after several storms in Spring (22/04/2015). All samples were oven-dried (at 38° C) and sieved to obtain

What causes similarity in catchments?

NASA Astrophysics Data System (ADS)

Savenije, Hubert

2014-05-01

One of the biggest issues in hydrology is how to handle the heterogeneity of catchment properties at different scales. But is this really such a big issue? Is this problem not merely the consequence of how we conceptualise and how we model catchments? Is there not far more similarity than we observe. Maybe we are not looking at the right things or at the right scale to see the similarity. The identity of catchments is largely determined by: the landscape, the ecosystem living on the landscape, and the geology, in that order. Soils, which are often seen as a crucial aspect of hydrological behaviour, are far less important, as will be demonstrated. The main determinants of hydrological behaviour are: the landscape composition, the rooting depth and the phenology. These determinants are a consequence of landscape and ecosystem evolution, which, in turn, are the manifestations of entropy production. There are striking similarities between catchments. The different runoff processes from hillslopes are linked and similar in different environments (McDonnell, 2013). Wetlands behave similarly all over the world. The key is to classify landscapes and to link the ecosystems living on them to climate. The ecosystem then is the main controller of hydrological behaviour. Besides phenology, the rooting depth is key in determining runoff behaviour. Both are strongly linked to climate and much less to soil properties. An example is given of how rooting depth is determined by climate, and how rooting depth can be predicted without calibration, providing a strong constraints on the prediction of rainfall partitioning and catchment runoff.

Projected impacts of urbanisation on hydrological resource flows: A case study within the uMngeni Catchment, South Africa.

PubMed

Schütte, S; Schulze, R E

2017-07-01

Significant land use changes from natural/agricultural to urban land uses have been proposed within the Mpushini/Mkhondeni sub-catchments of the uMngeni Catchment in South Africa. A better understanding of the influences which such land use changes are likely to have on hydrological flows, is required, in order to make informed land use decisions for a sustainable future. As a point of departure, an overview of linkages between urbanisation and hydrological flow responses within this sub-humid study area is given. The urban characteristics of increased impervious areas and the potential return flows from transfers of potable water from outside the catchment were identified as being important in regard to hydrological flow responses. A methodology was developed to model urban response scenarios with urban characteristics as variables, using the daily time-step process based ACRU model. This is a hydrological multi-process model and not an urban hydraulic model and it addresses the landscape as well as the channel components of a catchment, and in addition to runoff components includes evaporation and transpiration losses as outputs. For the study area strong links between proposed urbanisation and hydrological resource flow responses were found, with increases in stormflows, together with increased and more regulated baseflows, and with impacts varying markedly between dry or wet years and by season. The impacts will depend on the fractions of impervious areas, whether or not these are connected to permeable areas, the amount of imported water and water system leaks. Furthermore, the urban hydrological impacts were found to be relatively greater in more arid than humid areas because of changes in the rainfall to runoff conversion. Flow changes due to urbanisation are considered to have important environmental impacts, requiring mitigation. The methodology used in this paper could be used for other urbanising areas. Copyright © 2017 Elsevier Ltd. All rights reserved.

Estimating sedimentation rates and sources in a partially urbanized catchment using caesium-137

NASA Astrophysics Data System (ADS)

Ormerod, L. M.

1998-06-01

While there has been increased interest in determining sedimentation rates and sources in agricultural and forested catchments in recent years, there have been few studies dealing with urbanized catchments. A study of sedimentation rates and sources within channel and floodplain deposits of a partially urbanized catchment has been undertaken using the 137Cs technique. Results for sedimentation rates showed no particular downstream pattern. This may be partially explained by underestimation of sedimentation rates at some sites by failure to sample the full 137Cs profile, floodplain erosion and deliberate removal of sediment. Evidence of lateral increases in net sedimentation rates with distance from the channel may be explained by increased floodplain erosion at sites closer to the channel and floodplain formation by lateral deposition. Potential sediment sources for the catchment were considered to be forest topsoil, subsurface material and sediments derived from urban areas, which were found to be predominantly subsurface material. Tracing techniques showed an increase in subsurface material for downstream sites, confirming expectations that subsurface material would increase in the downstream direction in response to the direct and indirect effects of urbanization.

Assessing the controls and uncertainties on mean transit times in contrasting headwater catchments

NASA Astrophysics Data System (ADS)

Cartwright, Ian; Irvine, Dylan; Burton, Chad; Morgenstern, Uwe

2018-02-01

Estimating the time required for water to travel through headwater catchments from where it recharges to where it discharges into streams (the transit time) is important for understanding catchment behaviour. This study uses tritium (3H) activities of stream water to estimate the mean transit times of water in the upper Latrobe and Yarra catchments, southeast Australia, at different flow conditions. The 3H activities of the stream water were between 1.26 and 1.99 TU, which are lower than those of local rainfall (2.6 to 3.0 TU). 3H activities in individual subcatchments are almost invariably lowest at low streamflows. Mean transit times calculated from the 3H activities using a range of lumped parameter models are between 7 and 62 years and are longest during low streamflows. Uncertainties in the estimated mean transit times result from uncertainties in the geometry of the flow systems, uncertainties in the 3H input, and macroscopic mixing. In addition, simulation of 3H activities in FEFLOW indicates that heterogeneous hydraulic conductivities increase the range of mean transit times corresponding to a specific 3H activity. The absolute uncertainties in the mean transit times may be up to ±30 years. However, differences between mean transit times at different streamflows in the same catchment or between different subcatchments in the same area are more reliably estimated. Despite the uncertainties, the conclusions that the mean transit times are years to decades and decrease with increasing streamflow are robust. The seasonal variation in major ion geochemistry and 3H activities indicate that the higher general streamflows in winter are sustained by water displaced from shallower younger stores (e.g., soils or regolith). Poor correlations between 3H activities and catchment area, drainage density, mean slope, distance to stream, and landuse, imply that mean transit times are controlled by a variety of factors including the hydraulic properties of the soils and

Monitoring of fluvial transport in small upland catchments - methods and preliminary results

NASA Astrophysics Data System (ADS)

Janicki, Grzegorz; Rodzik, Jan; Chabudziński, Łukasz; Franczak, Łukasz; Siłuch, Marcin; Stępniewski, Krzysztof; Dyer, Jamie L.; Kołodziej, Grzegorz; Maciejewska, Ewa

2014-06-01

In April 2011 a study was initiated, financed from resources of the Polish National Science Centre, entitled: ‘Rainstorm prediction and mathematic modelling of their environmental and social-economical effects’ (No. NN/306571640). The study, implemented by a Polish-American team, covers meteorological research, including: (1) monitoring of single cell storms developing in various synoptic situations, (2) detection of their movement courses, and (3) estimation of parameters of their rain field. Empirical studies, including hydrological and geomorphological measurements, are conducted in objects researched thoroughly in physiographic terms (experimental catchments) in the Lublin region (SE Poland), distinguished by high frequency of occurrence of the events described. For comparative purposes, studies are also carried out on selected model areas in the lower course of the Mississippi River valley (USA), in a region with high frequency of summer rainstorms. For detailed studies on sediment transport processes during rainstorm events, catchments of low hydrological rank and their sub-catchments in a cascade system were selected. For the basic, relatively uniform geomorpho logical units distinguished this way, erosion and deposition balance of material transported was determined. The aim of work was to determine influence of weather condition on fluvial transport rate in small catchment with low hydrological order

Assessment of surface water resources availability using catchment modeling and the results of tracer studies in the meso-scale Migina Catchment, Rwanda

NASA Astrophysics Data System (ADS)

Munyaneza, O.; Mukubwa, A.; Maskey, S.; Wenninger, J.; Uhlenbrook, S.

2013-12-01

In the last couple of years, different hydrological research projects were undertaken in the Migina catchment (243.2 km2), a tributary of the Kagera river in Southern Rwanda. These projects were aimed to understand hydrological processes of the catchment using analytical and experimental approaches and to build a pilot case whose experience can be extended to other catchments in Rwanda. In the present study, we developed a hydrological model of the catchment, which can be used to inform water resources planning and decision making. The semi-distributed hydrological model HEC-HMS (version 3.5) was used with its soil moisture accounting, unit hydrograph, liner reservoir (for base flow) and Muskingum-Cunge (river routing) methods. We used rainfall data from 12 stations and streamflow data from 5 stations, which were collected as part of this study over a period of two years (May 2009 and June 2011). The catchment was divided into five sub-catchments each represented by one of the five observed streamflow gauges. The model parameters were calibrated separately for each sub-catchment using the observed streamflow data. Calibration results obtained were found acceptable at four stations with a Nash-Sutcliffe Model Efficiency of 0.65 on daily runoff at the catchment outlet. Due to the lack of sufficient and reliable data for longer periods, a model validation (split sample test) was not undertaken. However, we used results from tracer based hydrograph separation from a previous study to compare our model results in terms of the runoff components. It was shown that the model performed well in simulating the total flow volume, peak flow and timing as well as the portion of direct runoff and base flow. We observed considerable disparities in the parameters (e.g. groundwater storage) and runoff components across the five sub-catchments, that provided insights into the different hydrological processes at sub-catchment scale. We conclude that such disparities justify the need

The soil water regime of stony soils in a mountain catchment

NASA Astrophysics Data System (ADS)

Hlaváčiková, Hana; Danko, Michal; Holko, Ladislav; Hlavčo, Jozef; Novák, Viliam

2016-04-01

Investigation of processes related to runoff generation is an important topic in catchment hydrology. Observations are usually carried out in small catchments or on hillslopes. Many of such catchments are located in mountain or forested areas. From many studies it is evident that soil conditions and soil characteristics are one of the crucial factors in runoff generation. Mountainous or forest soils have usually high rock fragments content. Nevertheless, the influence of soil stoniness on water flow was not sufficiently studied up to now at catchment and hillslope scales due to flow formation complexity or problems with stony soil properties measurement (installing measuring devices, interpretation of measured data). Results of this work can be divided in two groups: (1) hydrophysical properties of stony soils measurements, and (2) water flow dynamic modelling in stony soils. Properties of stony soils were measured in the Jalovecky creek catchment, the Western Tatra Mts., Slovakia. Altitude of particular study sites varies from 780 to1500 m a.s.l. We measured and analyzed the stoniness of reference soil profiles, as well as retention properties of stony soils (fine soil fraction and rock fragments separately) and hydraulic conductivities of surface and subsurface soil layers. The methodology for determination of the effective hydrophysical properties of a stony soil (later used in modelling) was proposed using results from measurements, calculation, and numerical Darcy experiments. Modelling results show that the presence of rock fragments with low water retention in a stony soil with moderate or high stoniness can cause the soil water storage decrease by 16-31% in compared to the soil without rock fragments. In addition, decreased stony soil retention capacity resulted in faster outflow increase at the bottom of the soil profile during non-ponding infiltration. Furthermore, the presence of rock fragments can increase maximum outflow value. It is not possible to

Hydrological Controls on Nutrient Concentrations and Fluxes in Agricultural Catchments

NASA Astrophysics Data System (ADS)

Petry, J.; Soulsby, C.

2002-12-01

This investigation into diffuse agricultural pollution and the hydrological controls that exert a strong influence on both nutrient concentrations and fluxes, was conducted in an intensively farmed lowland catchment in north-east Scotland. The study focuses on spatial and seasonal variations in nutrient concentrations and fluxes at the catchment scale, over a 15-month period. The water quality of the 14.5 km2 Newmills Burn catchment has relatively high nutrient levels with mean concentrations of NO3-N and NH3-N at 6.09 mg/l and 0.28 mg/l respectively. Average PO4-P concentrations are 0.06 mg/l. Over short timescales nutrient concentrations and fluxes are greatest during storm events when PO4-P and NH3-N are mobilised by overland flow in riparian areas, where soils have been compacted by livestock or machinery. Delivery of deeper soil water in subsurface storm flow, facilitated by agricultural under-drainage, produces a marked increase in NO3-N (6.9 mg/l) concentrations on the hydrograph recession limb. A more detailed insight into the catchment response to storm events, and in particular the response of the hydrological pathways which provide the main sources of runoff during storm events, was gained by sampling stream water at 2-hourly intervals during 5 events. End Member Mixing Analysis (EMMA) was carried out using event specific end-member chemistries to differentiate three catchment-scale hydrological pathways (overland flow, subsurface storm flow, groundwater flow) on the basis of observed Si and NO3-N concentrations in sampled source waters. Results show that overland flow generally dominates the storm peak and provides the main flow path by which P is transferred to stream channels during storm events, whilst subsurface storm flows usually dominate the storm hydrograph volumetrically and route NO3-rich soil water to the stream. The study shows that altering hydrological pathways in a catchment can have implications for nutrient management. Whilst buffer

Catchment scale afforestation for mitigating flooding

NASA Astrophysics Data System (ADS)

Barnes, Mhari; Quinn, Paul; Bathurst, James; Birkinshaw, Stephen

2016-04-01

After the 2013-14 floods in the UK there were calls to 'forest the uplands' as a solution to reducing flood risk across the nation. At present, 1 in 6 homes in Britain are at risk of flooding and current EU legislation demands a sustainable, 'nature-based solution'. However, the role of forests as a natural flood management technique remains highly controversial, due to a distinct lack of robust evidence into its effectiveness in reducing flood risk during extreme events. SHETRAN, physically-based spatially-distributed hydrological models of the Irthing catchment and Wark forest sub-catchments (northern England) have been developed in order to test the hypothesis of the effect trees have on flood magnitude. The advanced physically-based models have been designed to model scale-related responses from 1, through 10, to 100km2, a first study of the extent to which afforestation and woody debris runoff attenuation features (RAFs) may help to mitigate floods at the full catchment scale (100-1000 km2) and on a national basis. Furthermore, there is a need to analyse the extent to which land management practices, and the installation of nature-based RAFs, such as woody debris dams, in headwater catchments can attenuate flood-wave movement, and potentially reduce downstream flood risk. The impacts of riparian planting and the benefits of adding large woody debris of several designs and on differing sizes of channels has also been simulated using advanced hydrodynamic (HiPIMS) and hydrological modelling (SHETRAN). With the aim of determining the effect forestry may have on flood frequency, 1000 years of generated rainfall data representative of current conditions has been used to determine the difference between current land-cover, different distributions of forest cover and the defining scenarios - complete forest removal and complete afforestation of the catchment. The simulations show the percentage of forestry required to have a significant impact on mitigating

To what extent can green infrastructure mitigate downstream flooding in a peri-urban catchment?

NASA Astrophysics Data System (ADS)

Schubert, J. E.; Burns, M.; Sanders, B. F.; Flethcher, T.

2016-12-01

In this research, we couple an urban hydrologic model (MUSIC, eWater, AUS) with a fine resolution 2D hydrodynamic model (BreZo, UC Irvine, USA) to test to what extent retrofitting an urban watershed with stormwater control measures (SCMs) can propagate flood management benefits downstream. Our study site is the peri-urban Little Stringybark Creek (LSC) catchment in eastern Melbourne, AUS, with an area of 4.5 km2 and connected impervious area of 9%. Urban development is mainly limited to the upper 2 km2of the catchment. Since 2009 the LSC catchment has been the subject of a large-scale experiment aiming to restore morenatural flow by implementing over 300 SCMs, such as rain tanks and infiltration trenches, resulting in runoff from 50% of connected impervious areas now being intercepted by some form of SCM. For our study we calibrated the hydrologic and hydraulic models based on current catchment conditions, then we developed models representing alternative SCM scenarios including a complete lack of SCMs versus a full implementation of SCMs. Flow in the hydrologic/hydraulic models is forced using a range of synthetic rainfall events with annual exceedance probabilities (AEPs) between 63-1% and durations between 10 min to 24 hr. Metrics of SCM efficacy in changing flood regime include flood depths and extents, flow intensity (m2/s), flood duration, and critical storm duration leading to maximum flood conditions. Results indicate that across the range of AEPs tested and for storm durations equal or less than 3 hours, current SCM conditions reduce downstream flooded area on average by 29%, while a full implementation of SCMs would reduce downstream flooded area on average by 91%. A full implementation of SCMs could also lower maximum flow intensities by 83% on average, reducing damage potential to structures in the flow path and increasing the ability for vehicles to evacuate flooded streets. We also found that for storm durations longer than 3 hours, the SCMs capacity

Spatial Distribution of Acid Neutralizing Processes in Steep Headwater Catchments in Tanakami Mountains, Central Japan

NASA Astrophysics Data System (ADS)

Asano, Y.; Uchida, T.; Ohte, N.; Tani, M.

2001-05-01

The areas characterized by steep slope, thin soils, and unreactive bedrock types are often considered as acid-sensitive. The purpose of this study is to investigate the spatial distribution of acid neutralizing processes in steep headwater catchment in the humid temperate region, and to discuss the long-term change in acid neutralizing processes associated with the forest growth and soil development. The observations were conducted at two adjacent unchannelled steep catchment, Fudoji (0.10ha) and Rachidani (0.18ha). Two catchments share similar climatic condition and the same bedrock geology (granite). The mean hollow gradient is 37degrees in Fudoji and 34degrees in Rachidani. Fudoji is forested with mean soil depth of 77cm, while Rachidani is non-vegetated with mean soil depth of about 10cm. In both catchments, hydrometric and isotopic measurements illustrated the substantial downward water flux into the bedrock in upslope area and emerging of this water from bedrock to soil layer within 2m from the perennial spring points. The mean pH of soil water and groundwater were dispersed over a wide range of 4.00 to 5.84 in Fudoji and 5.29 to 6.28 in Rachidani, while stream pHs converged very closely to neutral value in two catchments. In both catchments, major H+ sources distributed at the near-surface soil layer and the intensity of internal H+ production was greater in forested Fudoji than non-vegetated Rachidani, attributed to the biological cycles in forest ecosystems. Calculation of budget for base cations (Na+, K+, Ca2+ and Mg2+) presented that 72 to 84 percent (Fudoji) and 34percent (Rachidani) of the net base cation production in each catchment was derived from the bedrock, indicating that a considerable amount of the H+ was consumed within the bedrock. Moreover, the H+ consumption rate per unit volume of soil in Fudoji was almost one order of magnitude smaller than that of Rachidani. These results suggested that the dominant H+ sink in catchments shifted from

SIMULATED IMPACTS OF SMALL-SCALE SPATIAL DISTRIBUTION OF IMPERVIOUS AREA ON RUNOFF RESPONSE OF FIELD-SCALE CATCHMENTS

EPA Science Inventory

Impervious surface is known to negatively affect catchment hydrology through both its extent and spatial distribution. In this study, we empirically quantify via model simulations the impacts of different configurations of impervious surface on watershed response to rainfall. An ...

Modeller's attitude in catchment modelling: a comparative study

NASA Astrophysics Data System (ADS)

Battista Chirico, Giovanni

2010-05-01

Ten modellers have been invited to predict, independently from each other, the discharge of the artificial Chicken Creek catchment in North-East Germany for simulation period of three years, providing them only soil texture, terrain and meteorological data. No data concerning the discharge or other sources of state variables and fluxes within the catchment have been provided. Modellers had however the opportunity to visit the experimental catchment and inspect areal photos of the catchments since its initial development stage. This study has been a unique comparative study focussing on how different modellers deal with the key issues in predicting the discharge in ungauged catchments: 1) choice of the model structure; 2) identification of model parameters; 3) identification of model initial and boundary conditions. The first general lesson learned during this study was that the modeller is just part of the entire modelling process and has a major bearing on the model results, particularly in ungauged catchments where there are more degrees of freedom in making modelling decisions. Modellers' attitudes during the stages of the model implementation and parameterisation have been deeply influenced by their own experience from previous modelling studies. A common outcome was that modellers have been mainly oriented to apply process-based models able to exploit the available data concerning the physical properties of the catchment and therefore could be more suitable to cope with the lack of data concerning state variables or fluxes. The second general lesson learned during this study was the role of dominant processes. We believed that the modelling task would have been much easier in an artificial catchment, where heterogeneity were expected to be negligible and processes simpler, than in catchments that have evolved over a longer time period. The results of the models were expected to converge, and this would have been a good starting point to proceed for a model

Catchment Classification: Connecting Climate, Structure and Function

NASA Astrophysics Data System (ADS)

Sawicz, K. A.; Wagener, T.; Sivapalan, M.; Troch, P. A.; Carrillo, G. A.

2010-12-01

Hydrology does not yet possess a generally accepted catchment classification framework. Such a classification framework needs to: [1] give names to things, i.e. the main classification step, [2] permit transfer of information, i.e. regionalization of information, [3] permit development of generalizations, i.e. to develop new theory, and [4] provide a first order environmental change impact assessment, i.e., the hydrologic implications of climate, land use and land cover change. One strategy is to create a catchment classification framework based on the notion of catchment functions (partitioning, storage, and release). Results of an empirical study presented here connects climate and structure to catchment function (in the form of select hydrologic signatures), based on analyzing over 300 US catchments. Initial results indicate a wide assortment of signature relationships with properties of climate, geology, and vegetation. The uncertainty in the different regionalized signatures varies widely, and therefore there is variability in the robustness of classifying ungauged basins. This research provides insight into the controls of hydrologic behavior of a catchment, and enables a classification framework applicable to gauged and ungauged across the study domain. This study sheds light on what we can expect to achieve in mapping climate, structure and function in a top-down manner. Results of this study complement work done using a bottom-up physically-based modeling framework to generalize this approach (Carrillo et al., this session).

Applications of high resolution rainfall radar data to quantify water temperature dynamics in urban catchments

NASA Astrophysics Data System (ADS)

Croghan, Danny; Van Loon, Anne; Bradley, Chris; Sadler, Jon; Hannnah, David

2017-04-01

�C) over short durations (<30 minutes) during storm events in urbanised sub-catchments, however WTemp recovery times were more prolonged. Use of the rainfall radar data allowed increased accuracy in estimates of storm flow timings and rainfall quantities at each sub-catchment, from which the impact of storm flow on WTemp could be quantified. We are currently using the radar data to derive thresholds for rainfall amount and intensity at which these storm deviations occur for each logger, from which the relative effects of land use and other catchment characteristics in each sub-catchment can be assessed. Our use of the rainfall radar data calls into question the validity of using station based data for small scale studies, particularly in urban areas, with high variation apparent in rainfall intensity both spatially and temporally. Variation was particularly high within the heavily urbanised catchment. For water quality studies, high resolution rainfall radar can be implemented to increase the reliability of interpretations of the response of water quality variables to storm water inputs in urban catchments.

Merging perspectives in the catchment sciences: the US-Japan Joint Seminar on catchment hydrology and forest biogeochemistry

Treesearch

Kevin J. McGuire; Stephen D. Sebestyen; Nobuhito Ohte; Emily M. Elliott; Takashi Gomi; Mark B. Green; Brian L. McGlynn; Naoko Tokuchi

2014-01-01

Japan has strong research programmes in the catchment sciences that overlap with interests in the US catchment science community, particularly in experimental and field-based research. Historically, however, there has been limited interaction between these two hydrologic science communities because of differences in language, culture, and research approaches. These...

Geological controls on isotopic signatures of streamflow: results from a nested catchment experiment in Luxembourg (Europe)

NASA Astrophysics Data System (ADS)

Pfister, Laurent; McDonnell, Jeffrey J.; Hissler, Christophe; Martinez-Carreras, Nuria; Gourdol, Laurent; Klaus, Julian; François Iffly, Jean; Barnich, François; Stewart, Mike K.

2014-05-01

Controls of geology and topography on hydrological metrics, like summer low flow (Grant and Tague, 2004) or dynamic storage (Sayama et al., 2011), have been identified in nested catchment experiments. However, most tracer-based studies on streamflow generation have been carried out in small (10 km2) homogenous catchments (Klaus and McDonnell, 2013). The controlling effects of catchment physiography on how catchments store and release water, and how this eventually controls stream isotope behaviour over a large range of scale are poorly understood. Here, we present results from a nested catchment analysis in the Alzette River basin (Luxembourg, Europe). Our hydro-climatological network consists of 16 recording streamgauges and 21 pluviographs. Catchment areas range from 0.47 to 285 km2, with clean and mixed combinations of distinct geologies ranging from schists to marls, sandstone, dolomite and limestone. Our objective was to identify geological controls on (i) winter runoff ratios, (ii) maximum storage and (iii) isotopic signatures in streamflow. For each catchment we determined average runoff ratios from winter season precipitation-discharge double-mass curves. Maximum catchment storage was based on the dynamic storage change approach of Sayama et al. (2011). Changes in isotopic signatures of streamflow were documented along individual catchment flow duration curves. We found strong correlations between average winter runoff ratios, maximum storage and the prevailing geological settings. Catchments with impermeable bedrock (e.g. marls or schists) were characterised by small storage potential and high average filling ratios. As a consequence, these catchments also exhibited the highest average runoff ratios. In catchments underlain by permeable bedrock (e.g. sandstone), storage potential was significantly higher and runoff ratios were considerably smaller. The isotopic signatures of streamflow showed large differences between catchments. In catchments dominated by

Effects of gully erosion on sediment connectivity in a small agrarian catchment: basis of an experimental proposal

NASA Astrophysics Data System (ADS)

Zubieta, Elena; Casalí, Javier; Masselink, Rens J. H.; Giménez, Rafael; Keesstra, Saskia D.

2017-04-01

Connectivity aims to explain the transit of substances in a certain (natural) area. Thereby, the connectivity of sediments from soil erosion involves complex factors determining the subsequent movement of detached matter across the land (for instance, a hydrographic catchment). Agricultural soil erosion in Navarre has been studied mainly by recording sediments at the outlets of experimental catchments. These studies have revealed a complex dynamics in the sediments. For example, a clear seasonality was noticed, with the highest records in winter and the beginning of spring, coinciding, however, with rainfall events of a relatively low erosion capacity. In fact, this dynamics was not only conditioned by the intensity and duration of precipitations, but also, for instance, by the soil's previous humidity, use and management, and by plant cover. Further, it was suspected that a key factor in sediment connectivity would be erosion due to concentrated flows (i.e. ephemeral gullies), which would act as a source and transport of sediments. The aim of this research is to monitor, long-term, the movement of sediments generated by erosion from ephemeral gullies within a typical agrarian catchment in Navarra, in order to clarify the role played by those gullies in sediment connectivity. The experiments will be performed in the experimental catchment of "La Tejería" (169 ha) located in the Central Area of Navarre, and which is frequently affected by concentrated flow erosion and with long-term records of sediments at its outlet. The climate is humid submediterranean, with an average annual precipitation of approximately 725 mm. The prevailing soil class is Vertic Haploxerept and cereal crops usually cover over 90% of the total area. Our previous experience in the study area would permit the prediction, with a high degree of certainty, of the appearance of ephemeral gullies at least in 4-5 watercourses selected. A specific tracer (a rare-earth oxide) will be sprinkled over

Crop structure in a gully catchment and the development of a loess gully (Lublin Upland, E Poland)

NASA Astrophysics Data System (ADS)

Mędrek, Karolina; Rodzik, Jan

2015-04-01

The study was conducted in a loess gully catchment with an area of 1.23 km2 and height differences of less than 50 m (213-165 m above sea level), located in Kolonia Celejów in the Nałęczów Plateau. This is one of mesoregions of Lublin Upland. In the investigated catchment, loess cover with a thickness of 10-20 m, accumulated during the Vistulian Glaciation, is dissected by a gully system with a depth of 5-15 m and total length of 7.5 km. The gully system is forested in 30% of its area. Until recently, the remaining part of the catchment under agricultural use has been dominated by conventional farming of cereals, potatoes, and sugar beets. Today, 15% of the non-forested area of the catchment is occupied by housing premises, dirt roads, and fallow land, and 45% by orchards with maintained turf, including berry plantations. This type of land management contributes to the retention of precipitation, and protects the soil from flushing. Approximately 20% of the agricultural land is occupied by conventional crops (cereals and root crops), protecting the soil to a moderate degree. Water runoff in the area does not occur every year. Approximately 20% of the agricultural land is currently occupied by cruciferous vegetables (broccoli and cauliflower), decorative shrubs, and orchards without turf in the first 2 years of use. Water and soil runoff from these crops occurs even several times per year. The majority of the material is retained in the lower part of the field, and the water flows into the gully. The crops in the fields adjacent to the ravine have a direct impact on the development of the gully. If the field is located on a raised headland, the flowing water dissects the edge of the gully, and the eroded material is accumulated on the gully bottom. If the field is located in a valley above the gullyhead, the flowing water dissects the bottom of the gully, and the eroded material is discharged outside the catchment.

Spatial variations of storm runoff pollution and their correlation with land-use in a rapidly urbanizing catchment in China.

PubMed

Qin, Hua-Peng; Khu, Soon-Thiam; Yu, Xiang-Ying

2010-09-15

The composition of land use for a rapidly urbanizing catchment is usually heterogeneous, and this may result in significant spatial variations of storm runoff pollution and increase the difficulties of water quality management. The Shiyan Reservoir catchment, a typical rapidly urbanizing area in China, is chosen as a study area, and temporary monitoring sites were set at the downstream of its 6 sub-catchments to synchronously measure rainfall, runoff and water quality during 4 storm events in 2007 and 2009. Due to relatively low frequency monitoring, the IHACRES and exponential pollutant wash-off simulation models are used to interpolate the measured data to compensate for data insufficiency. Three indicators, event pollutant loads per unit area (EPL), event mean concentration (EMC) and pollutant loads transported by the first 50% of runoff volume (FF50), were used to describe the runoff pollution for different pollutants in each sub-catchment during the storm events, and the correlations between runoff pollution spatial variations and land-use patterns were tested by Spearman's rank correlation analysis. The results indicated that similar spatial variation trends were found for different pollutants (EPL or EMC) in light storm events, which strongly correlate with the proportion of residential land use; however, they have different trends in heavy storm events, which correlate with not only the residential land use, but also agricultural and bare land use. And some pairs of pollutants (such as COD/BOD, NH(3)-N/TN) might have the similar source because they have strong or moderate positive spatial correlation. Moreover, the first flush intensity (FF50) varies with impervious land areas and different interception ratio of initial storm runoff volume should be adopted in different sub-catchments. Copyright 2010 Elsevier B.V. All rights reserved.

[Ichthyofauna of karstic wetlands under anthropic impact: the "petenes" of Campeche, Mexico].

PubMed

Torres-Castro, Ivette Liliana; Vega-Cendejas, María Eugenia; Schmitter-Soto, Juan Jacobo; Palacio-Aponte, Gerardo; Rodiles-Hernández, Rocío

2009-01-01

"Petenes" are small springs and associated streams that drain into wetlands near the coast in karstic areas. We studied composition, distribution, and abundance of the ichthyofauna in Los Petenes region (northwest Campeche). Two petenes displaying different degrees and types of anthropic impact were selected, Hampolol and El Remate. Hampolol has a smaller area but a longer derived stream; it is located within a protected area, but has been invaded by tilapia. El Remate is a popular spa, with no tilapia; it has a larger area but a shorter derived stream. At each "petén", several sites in the main spring, the associated stream, and secondary (temporary) springs were sampled in the rainy and dry seasons. Fishing gear was variable (throw net, gill net, small and large seine nets), but effort was uniform. We recorded temperature, dissolved oxygen, salinity, and depth at each site and season; also, we noted the different types and intensities of anthropic impact (channelization, presence of exotic species, recreational use, etc.) at each petén. We compared the petenes in terms of their environmental quality and fish fauna (composition, distribution, abundance, biomass); we also tested for effects of season and site within each petén. The study found 27 species of fishes, included in 18 genera and eight families, 24 species in Hampolol and 20 in El Remate. The geographical range of 'Cichlasoma' salvini, Rivulus tenuis, Phallichthys fairweatheri, Xiphophorus hellerii, and X maculatus is extended. The dominant species in both seasons was Astyanax (probable hybrids A. aeneus x altior at Hampolol, pure A. altior at El Remate), which contributed most of the abundance and biomass, together with Vieja synspila and Poecilia velifera. A significantly greater overall diversity (H'n=3.31) was recorded in Hampolol compared to El Remate (H'n=2.10). Cluster analysis of sites by species presence allowed distinction of two groupings within each petén: permanent waters (i.e., main

Modeling long-term suspended-sediment export from an undisturbed forest catchment

NASA Astrophysics Data System (ADS)

Zimmermann, Alexander; Francke, Till; Elsenbeer, Helmut

2013-04-01

Most estimates of suspended sediment yields from humid, undisturbed, and geologically stable forest environments fall within a range of 5 - 30 t km-2 a-1. These low natural erosion rates in small headwater catchments (≤ 1 km2) support the common impression that a well-developed forest cover prevents surface erosion. Interestingly, those estimates originate exclusively from areas with prevailing vertical hydrological flow paths. Forest environments dominated by (near-) surface flow paths (overland flow, pipe flow, and return flow) and a fast response to rainfall, however, are not an exceptional phenomenon, yet only very few sediment yields have been estimated for these areas. Not surprisingly, even fewer long-term (≥ 10 years) records exist. In this contribution we present our latest research which aims at quantifying long-term suspended-sediment export from an undisturbed rainforest catchment prone to frequent overland flow. A key aspect of our approach is the application of machine-learning techniques (Random Forest, Quantile Regression Forest) which allows not only the handling of non-Gaussian data, non-linear relations between predictors and response, and correlations between predictors, but also the assessment of prediction uncertainty. For the current study we provided the machine-learning algorithms exclusively with information from a high-resolution rainfall time series to reconstruct discharge and suspended sediment dynamics for a 21-year period. The significance of our results is threefold. First, our estimates clearly show that forest cover does not necessarily prevent erosion if wet antecedent conditions and large rainfalls coincide. During these situations, overland flow is widespread and sediment fluxes increase in a non-linear fashion due to the mobilization of new sediment sources. Second, our estimates indicate that annual suspended sediment yields of the undisturbed forest catchment show large fluctuations. Depending on the frequency of large

Identification of dominant interactions between climatic seasonality, catchment characteristics and agricultural activities on Budyko-type equation parameter estimation

NASA Astrophysics Data System (ADS)

Xing, Wanqiu; Wang, Weiguang; Shao, Quanxi; Yong, Bin

2018-01-01

Quantifying precipitation (P) partition into evapotranspiration (E) and runoff (Q) is of great importance for global and regional water availability assessment. Budyko framework serves as a powerful tool to make simple and transparent estimation for the partition, using a single parameter, to characterize the shape of the Budyko curve for a "specific basin", where the single parameter reflects the overall effect by not only climatic seasonality, catchment characteristics (e.g., soil, topography and vegetation) but also agricultural activities (e.g., cultivation and irrigation). At the regional scale, these influencing factors are interconnected, and the interactions between them can also affect the single parameter of Budyko-type equations' estimating. Here we employ the multivariate adaptive regression splines (MARS) model to estimate the Budyko curve shape parameter (n in the Choudhury's equation, one form of the Budyko framework) of the selected 96 catchments across China using a data set of long-term averages for climatic seasonality, catchment characteristics and agricultural activities. Results show average storm depth (ASD), vegetation coverage (M), and seasonality index of precipitation (SI) are three statistically significant factors affecting the Budyko parameter. More importantly, four pairs of interactions are recognized by the MARS model as: The interaction between CA (percentage of cultivated land area to total catchment area) and ASD shows that the cultivation can weaken the reducing effect of high ASD (>46.78 mm) on the Budyko parameter estimating. Drought (represented by the value of Palmer drought severity index < -0.74) and uneven distribution of annual rainfall (represented by the value of coefficient of variation of precipitation > 0.23) tend to enhance the Budyko parameter reduction by large SI (>0.797). Low vegetation coverage (34.56%) is likely to intensify the rising effect on evapotranspiration ratio by IA (percentage of irrigation area to

Temporal and Spatial Patterns of Preferential Flow Occurrence in the Shale Hills Catchment: From the Hillslope to the Catchment Scales

NASA Astrophysics Data System (ADS)

Liu, H.; Lin, H.

2013-12-01

Understanding temporal and spatial patterns of preferential flow (PF) occurrence is important in revealing hillslope and catchment hydrologic and biogeochemical processes. Quantitative assessment of the frequency and control of PF occurrence in the field, however, has been limited, especially at the landscape scale of hillslope and catchment. By using 5.5-years' (2007-2012) real-time soil moisture at 10 sites response to 323 precipitation events, we tested the temporal consistency of PF occurrence at the hillslope scale in the forested Shale Hills Catchment; and by using 25 additional sites with at least 1-year data (2011-2012), we evaluated the spatial patterns of PF occurrence across the catchment. To explore the potential effects of PF occurrence on catchment hydrology, wavelet analysis was performed on the recorded time series of hydrological signals (i.e., precipitation, soil moisture, catchment discharge). Considerable temporal consistence was observed in both the frequency and the main controls of PF occurrence at the hillslope scale, which was attributed largely to the statistical stability of precipitation pattern over the monitoring period and the relatively stable subsurface preferential pathways. Preferential flow tended to occur more often in response to intense rainfall events, and favored the conditions at dry hilltop or wet valley floor sites. When upscaling to the entire catchment, topographic control on the PF occurrence was amplified remarkably, leading to the identification of a subsurface PF network in the catchment. Higher frequency of PF occurrence was observed at the valley floor (average 48%), hilltop (average 46%), and swales/hillslopes near the stream (average 40%), while the hillslopes in the eastern part of the catchment were least likely to experience PF (0-20%). No clear relationship, however, was observed between terrain attributes and PF occurrence, because the initiation and persistency of PF in this catchment was controlled

The Influence of temporal sampling regime on the WFD classification of catchments within the Eden Demonstration Test Catchment Project

NASA Astrophysics Data System (ADS)

Jonczyk, Jennine; Haygarth, Phil; Quinn, Paul; Reaney, Sim

2014-05-01

A high temporal resolution data set from the Eden Demonstration Test Catchment (DTC) project is used to investigate the processes causing pollution and the influence of temporal sampling regime on the WFD classification of three catchments. This data highlights WFD standards may not be fit for purpose. The Eden DTC project is part of a UK government-funded project designed to provide robust evidence regarding how diffuse pollution can be cost-effectively controlled to improve and maintain water quality in rural river catchments. The impact of multiple water quality parameters on ecosystems and sustainable food production are being studied at the catchment scale. Three focus catchments approximately 10 km2 each, have been selected to represent the different farming practices and geophysical characteristics across the Eden catchment, Northern England. A field experimental programme has been designed to monitor the dynamics of agricultural diffuse pollution at multiple scales using state of the art sensors providing continuous real time data. The data set, which includes Total Phosphorus and Total Reactive Phosphorus, Nitrate, Ammonium, pH, Conductivity, Turbidity and Chlorophyll a reveals the frequency and duration of nutrient concentration target exceedance which arises from the prevalence of storm events of increasing magnitude. This data set is sub-sampled at different time intervals to explore how different sampling regimes affects our understanding of nutrient dynamics and the ramification of the different regimes to WFD chemical status. This presentation seeks to identify an optimum temporal resolution of data for effective catchment management and to question the usefulness of the WFD status metric for determining health of a system. Criteria based on high frequency short duration events needs to be accounted for.

A Catchment-Based Approach to Modeling Land Surface Processes in a GCM. Part 1; Model Structure

NASA Technical Reports Server (NTRS)

Koster, Randal D.; Suarez, Max J.; Ducharne, Agnes; Stieglitz, Marc; Kumar, Praveen

2000-01-01

A new strategy for modeling the land surface component of the climate system is described. The strategy is motivated by an arguable deficiency in most state-of-the-art land surface models (LSMs), namely the disproportionately higher emphasis given to the formulation of one-dimensional, vertical physics relative to the treatment of horizontal heterogeneity in surface properties -- particularly subgrid soil moisture variability and its effects on runoff generation. The new strategy calls for the partitioning of the continental surface into a mosaic of hydrologic catchments, delineated through analysis of high-resolution surface elevation data. The effective "grid" used for the land surface is therefore not specified by the overlying atmospheric grid. Within each catchment, the variability of soil moisture is related to characteristics of the topography and to three bulk soil moisture variables through a well-established model of catchment processes. This modeled variability allows the partitioning of the catchment into several areas representing distinct hydrological regimes, wherein distinct (regime-specific) evaporation and runoff parameterizations are applied. Care is taken to ensure that the deficiencies of the catchment model in regions of little to moderate topography are minimized.

Evaluating Monitoring Strategies to Detect Precipitation-Induced Microbial Contamination Events in Karstic Springs Used for Drinking Water

PubMed Central

Besmer, Michael D.; Hammes, Frederik; Sigrist, Jürg A.; Ort, Christoph

2017-01-01

Monitoring of microbial drinking water quality is a key component for ensuring safety and understanding risk, but conventional monitoring strategies are typically based on low sampling frequencies (e.g., quarterly or monthly). This is of concern because many drinking water sources, such as karstic springs are often subject to changes in bacterial concentrations on much shorter time scales (e.g., hours to days), for example after precipitation events. Microbial contamination events are crucial from a risk assessment perspective and should therefore be targeted by monitoring strategies to establish both the frequency of their occurrence and the magnitude of bacterial peak concentrations. In this study we used monitoring data from two specific karstic springs. We assessed the performance of conventional monitoring based on historical records and tested a number of alternative strategies based on a high-resolution data set of bacterial concentrations in spring water collected with online flow cytometry (FCM). We quantified the effect of increasing sampling frequency and found that for the specific case studied, at least bi-weekly sampling would be needed to detect precipitation events with a probability of >90%. We then proposed an optimized monitoring strategy with three targeted samples per event, triggered by precipitation measurements. This approach is more effective and efficient than simply increasing overall sampling frequency. It would enable the water utility to (1) analyze any relevant event and (2) limit median underestimation of peak concentrations to approximately 10%. We conclude with a generalized perspective on sampling optimization and argue that the assessment of short-term dynamics causing microbial peak loads initially requires increased sampling/analysis efforts, but can be optimized subsequently to account for limited resources. This offers water utilities and public health authorities systematic ways to evaluate and optimize their current

Evaluating Monitoring Strategies to Detect Precipitation-Induced Microbial Contamination Events in Karstic Springs Used for Drinking Water.

PubMed

Besmer, Michael D; Hammes, Frederik; Sigrist, Jürg A; Ort, Christoph

2017-01-01

Monitoring of microbial drinking water quality is a key component for ensuring safety and understanding risk, but conventional monitoring strategies are typically based on low sampling frequencies (e.g., quarterly or monthly). This is of concern because many drinking water sources, such as karstic springs are often subject to changes in bacterial concentrations on much shorter time scales (e.g., hours to days), for example after precipitation events. Microbial contamination events are crucial from a risk assessment perspective and should therefore be targeted by monitoring strategies to establish both the frequency of their occurrence and the magnitude of bacterial peak concentrations. In this study we used monitoring data from two specific karstic springs. We assessed the performance of conventional monitoring based on historical records and tested a number of alternative strategies based on a high-resolution data set of bacterial concentrations in spring water collected with online flow cytometry (FCM). We quantified the effect of increasing sampling frequency and found that for the specific case studied, at least bi-weekly sampling would be needed to detect precipitation events with a probability of >90%. We then proposed an optimized monitoring strategy with three targeted samples per event, triggered by precipitation measurements. This approach is more effective and efficient than simply increasing overall sampling frequency. It would enable the water utility to (1) analyze any relevant event and (2) limit median underestimation of peak concentrations to approximately 10%. We conclude with a generalized perspective on sampling optimization and argue that the assessment of short-term dynamics causing microbial peak loads initially requires increased sampling/analysis efforts, but can be optimized subsequently to account for limited resources. This offers water utilities and public health authorities systematic ways to evaluate and optimize their current

Fluvial dissolved organic carbon composition varies spatially and seasonally in a small catchment draining a wind farm and felled forestry.

PubMed

Zheng, Ying; Waldron, Susan; Flowers, Hugh

2018-06-01

Assessing whether land use, from activities such as wind farm construction and tree-felling, impacts on terrestrial C delivery to rivers has focused on quantifying the loss of dissolved organic carbon (DOC), and not the composition changes. Here we explore how land use influences DOC composition by considering fluvial DOC concentration, [DOC], and spectrophotometric composition of a river draining a peat-rich catchment. We find that in this 5.7km 2 catchment differences occur in both the concentration and composition of the DOC in its sub-catchments. This is attributed to differences in how land was used: one tributary (D-WF) drains an area with wind farm construction and forestry in the headwaters, and one tributary (D-FF) drains an area with felled plantation trees. Generally, [DOC] in both streams showed similar seasonal variation, and autumn maxima. However, the felled catchment had greater mean [DOC] than the wind farm catchment. The SUVA 254 and E 4 /E 6 indicated DOC in both streams had similar aromaticity and fulvic:humic acid for most of the time, but SUVA 410 and E 2 /E 4 indicated less DOC humification in the felled catchment. This may be due to young DOC from the breakdown of residual branches and roots, or more humification in soils in the wind farm area. During the dry months, DOC composition showed more spatial variation: the D-WF DOC had smaller SUVA 254 (less total aromatic material) and SUVA 410 (fewer humic substances). The decreased E 2 /E 4 in both streams indicated the total aromatic carbon decreased more than humic substances content. Moreover, the larger E 4 /E 6 for D-WF in summer indicated that the humic substances were richer in fulvic acids than humic acids. Soil disturbance associated with forestry-felling likely contributed to the higher [DOC] and release of less-humified material in D-FF. This research indicates drivers of different DOC concentration and composition can exist even in small catchments. Copyright © 2018 Elsevier B

Hydrological regime shift in a constructed catchment: Effect of vegetation encroachment on surface runoff

NASA Astrophysics Data System (ADS)

Hinz, C.; Caviedes-Voullieme, D.; Andezhath Mohanan, A.; Brueck, Y.; Zaplata, M.

2017-12-01

The Hühnerwasser catchment (Chicken Creek) was constructed to provide discharge for a small stream in the post-mining landscape of Lusatia, Germany. It has an area of 6 ha and quaternary sands with a thickness of 2-4 m were dumped on to a clay liner to prevent deep drainage. After completion of the construction the catchment was left to develop on its own without intervention and has been monitored since 2005. The upper part of the catchment discharges water and sediment into the lower part forming an alluvial fan. Below the alluvial fan is a pond receiving all surface and subsurface water from the upper catchment. After the formation of the drainage network vegetation started growing and surface runoff decreased until the water balance was dominated by evapotranspiration. This regime shift and the rate at which it happened depends on the vegetation encroachment into the rills and the interrill areas. Based on the hypothesis that vegetation will increase surface roughness and infiltration behavior, aerial photos were used to map rills and vegetation within and outside the rills for the last 10 years to obtain a time series of change. Observational evidence clearly shows that vegetation encroaches from the bottom, from the interrill areas as well as from the top. The rills themselves did not change their topology, however, the width of the erosion rills and gully increased at the bottom. For a subcatchment area a high resolution a physical based numerical model of overland flow was developed to explicitly assess the importance of increasing roughness and infiltration capacity for surface runoff. For the purpose of analyzing the effect of rainfall variability a rainfall generator was developed to carry out large sets of simulations. The simulations provide a means to assess how the roughness/infiltration feedback affects the rate of regime shift for a set of parameters that are consistent with the observed hydrological behavior of the drainage network.

Carbon stocks of tropical coastal wetlands within the karstic landscape of the Mexican Caribbean.

PubMed

Adame, Maria Fernanda; Kauffman, J Boone; Medina, Israel; Gamboa, Julieta N; Torres, Olmo; Caamal, Juan P; Reza, Miriam; Herrera-Silveira, Jorge A

2013-01-01

Coastal wetlands can have exceptionally large carbon (C) stocks and their protection and restoration would constitute an effective mitigation strategy to climate change. Inclusion of coastal ecosystems in mitigation strategies requires quantification of carbon stocks in order to calculate emissions or sequestration through time. In this study, we quantified the ecosystem C stocks of coastal wetlands of the Sian Ka'an Biosphere Reserve (SKBR) in the Yucatan Peninsula, Mexico. We stratified the SKBR into different vegetation types (tall, medium and dwarf mangroves, and marshes), and examined relationships of environmental variables with C stocks. At nine sites within SKBR, we quantified ecosystem C stocks through measurement of above and belowground biomass, downed wood, and soil C. Additionally, we measured nitrogen (N) and phosphorus (P) from the soil and interstitial salinity. Tall mangroves had the highest C stocks (987±338 Mg ha(-1)) followed by medium mangroves (623±41 Mg ha(-1)), dwarf mangroves (381±52 Mg ha(-1)) and marshes (177±73 Mg ha(-1)). At all sites, soil C comprised the majority of the ecosystem C stocks (78-99%). Highest C stocks were measured in soils that were relatively low in salinity, high in P and low in N∶P, suggesting that P limits C sequestration and accumulation potential. In this karstic area, coastal wetlands, especially mangroves, are important C stocks. At the landscape scale, the coastal wetlands of Sian Ka'an covering ≈172,176 ha may store 43.2 to 58.0 million Mg of C.

The use of GIS and multi-criteria evaluation (MCE) to identify agricultural land management practices which cause surface water pollution in drinking water supply catchments.

PubMed

Grayson, Richard; Kay, Paul; Foulger, Miles

2008-01-01

Diffuse pollution poses a threat to water quality and results in the need for treatment for potable water supplies which can prove costly. Within the Yorkshire region, UK, nitrates, pesticides and water colour present particular treatment problems. Catchment management techniques offer an alternative to 'end of pipe' solutions and allow resources to be targeted to the most polluting areas. This project has attempted to identify such areas using GIS based modelling approaches in catchments where water quality data were available. As no model exists to predict water colour a model was created using an MCE method which is capable of predicting colour concentrations at the catchment scale. CatchIS was used to predict pesticide and nitrate N concentrations and was found to be generally capable of reliably predicting nitrate N loads at the catchment scale. The pesticides results did not match the historic data possibly due to problems with the historic pesticide data and temporal and spatially variability in pesticide usage. The use of these models can be extended to predict water quality problems in catchments where water quality data are unavailable and highlight areas of concern. IWA Publishing 2008.

Conditional flood frequency and catchment state: a simulation approach

NASA Astrophysics Data System (ADS)

Brettschneider, Marco; Bourgin, François; Merz, Bruno; Andreassian, Vazken; Blaquiere, Simon

2017-04-01

Catchments have memory and the conditional flood frequency distribution for a time period ahead can be seen as non-stationary: it varies with the catchment state and climatic factors. From a risk management perspective, understanding the link of conditional flood frequency to catchment state is a key to anticipate potential periods of higher flood risk. Here, we adopt a simulation approach to explore the link between flood frequency obtained by continuous rainfall-runoff simulation and the initial state of the catchment. The simulation chain is based on i) a three state rainfall generator applied at the catchment scale, whose parameters are estimated for each month, and ii) the GR4J lumped rainfall-runoff model, whose parameters are calibrated with all available data. For each month, a large number of stochastic realizations of the continuous rainfall generator for the next 12 months are used as inputs for the GR4J model in order to obtain a large number of stochastic realizations for the next 12 months. This process is then repeated for 50 different initial states of the soil moisture reservoir of the GR4J model and for all the catchments. Thus, 50 different conditional flood frequency curves are obtained for the 50 different initial catchment states. We will present an analysis of the link between the catchment states, the period of the year and the strength of the conditioning of the flood frequency compared to the unconditional flood frequency. A large sample of diverse catchments in France will be used.

Uncertainty in hydrological signatures for gauged and ungauged catchments

NASA Astrophysics Data System (ADS)

Westerberg, Ida K.; Wagener, Thorsten; Coxon, Gemma; McMillan, Hilary K.; Castellarin, Attilio; Montanari, Alberto; Freer, Jim

2016-03-01

Reliable information about hydrological behavior is needed for water-resource management and scientific investigations. Hydrological signatures quantify catchment behavior as index values, and can be predicted for ungauged catchments using a regionalization procedure. The prediction reliability is affected by data uncertainties for the gauged catchments used in prediction and by uncertainties in the regionalization procedure. We quantified signature uncertainty stemming from discharge data uncertainty for 43 UK catchments and propagated these uncertainties in signature regionalization, while accounting for regionalization uncertainty with a weighted-pooling-group approach. Discharge uncertainty was estimated using Monte Carlo sampling of multiple feasible rating curves. For each sampled rating curve, a discharge time series was calculated and used in deriving the gauged signature uncertainty distribution. We found that the gauged uncertainty varied with signature type, local measurement conditions and catchment behavior, with the highest uncertainties (median relative uncertainty ±30-40% across all catchments) for signatures measuring high- and low-flow magnitude and dynamics. Our regionalization method allowed assessing the role and relative magnitudes of the gauged and regionalized uncertainty sources in shaping the signature uncertainty distributions predicted for catchments treated as ungauged. We found that (1) if the gauged uncertainties were neglected there was a clear risk of overconditioning the regionalization inference, e.g., by attributing catchment differences resulting from gauged uncertainty to differences in catchment behavior, and (2) uncertainty in the regionalization results was lower for signatures measuring flow distribution (e.g., mean flow) than flow dynamics (e.g., autocorrelation), and for average flows (and then high flows) compared to low flows.

Catchments' hedging strategy on evapotranspiration for climatic variability

NASA Astrophysics Data System (ADS)

Ding, W.; Zhang, C.; Li, Y.; Tang, Y.; Wang, D.; Xu, B.

2017-12-01

Hydrologic responses to climate variability and change are important for human society. Here we test the hypothesis that natural catchments utilize hedging strategies for evapotranspiration and water storage carryover with uncertain future precipitation. The hedging strategy for evapotranspiration in catchments under different levels of water availability is analytically derived from the economic perspective. It is found that there exists hedging between evapotranspiration for current and future only with a portion of water availability. Observation data sets of 160 catchments in the United States covering the period from 1983 to 2003 demonstrate the existence of hedging in catchment hydrology and validate the proposed hedging strategies. We also find that more water is allocated to carryover storage for hedging against the future evapotranspiration risk in the catchments with larger aridity indexes or with larger uncertainty in future precipitation, i.e., long-term climate and precipitation variability control the degree of hedging.

Operational validation of a multi-period and multi-criteria model conditioning approach for the prediction of rainfall-runoff processes in small forest catchments

NASA Astrophysics Data System (ADS)

Choi, H.; Kim, S.

2012-12-01

Most of hydrologic models have generally been used to describe and represent the spatio-temporal variability of hydrological processes in the watershed scale. Though it is an obvious fact that hydrological responses have the time varying nature, optimal values of model parameters were normally considered as time invariants or constants in most cases. The recent paper of Choi and Beven (2007) presents a multi-period and multi-criteria model conditioning approach. The approach is based on the equifinality thesis within the Generalised Likelihood Uncertainty Estimation (GLUE) framework. In their application, the behavioural TOPMODEL parameter sets are determined by several performance measures for global (annual) and short (30-days) periods, clustered using a Fuzzy C-means algorithm, into 15 types representing different hydrological conditions. Their study shows a good performance on the calibration of a rainfall-runoff model in a forest catchment, and also gives strong indications that it is uncommon to find model realizations that were behavioural over all multi-periods and all performance measures, and multi-period model conditioning approach may become new effective tool for predictions of hydrological processes in ungauged catchments. This study is a follow-up study on the Choi and Beven's (2007) model conditioning approach to test how the approach is effective for the prediction of rainfall-runoff responses in ungauged catchments. To achieve this purpose, 6 small forest catchments are selected among the several hydrological experimental catchments operated by Korea Forest Research Institute. In each catchment, long-term hydrological time series data varying from 10 to 30 years were available. The areas of the selected catchments range from 13.6 to 37.8 ha, and all areas are covered by coniferous or broad-leaves forests. The selected catchments locate in the southern coastal area to the northern part of South Korea. The bed rocks are Granite gneiss, Granite or

Intra-basin variability of snowmelt water balance calculations in a subarctic catchment

NASA Astrophysics Data System (ADS)

McCartney, Stephen E.; Carey, Sean K.; Pomeroy, John W.

2006-03-01

The intra-basin variability of snowmelt and melt-water runoff hydrology in an 8 km2 subarctic alpine tundra catchment was examined for the 2003 melt period. The catchment, Granger Creek, is within the Wolf Creek Research Basin, Yukon, which is typical of mountain subarctic landscapes in northwestern Canada. The study catchment was segmented into nine internally uniform zones termed hydrological response units (HRUs) based on their similar hydrological, physiographic, vegetation and soil properties. Snow accumulation exhibited significant variability among the HRUs, with greatest snow water equivalent in areas of tall shrub vegetation. Melt began first on southerly exposures and at lower elevations, yet average melt rates for the study period varied little among HRUs with the exception of those with steep aspects. In HRUs with capping organic soils, melt water first infiltrated this surface horizon, satisfying its storage capacity, and then percolated into the frozen mineral substrate. Infiltration and percolation into frozen mineral soils was restricted where melt occurred rapidly and organic soils were thin; in this case, melt-water delivery rates exceeded the frozen mineral soil infiltration rate, resulting in high runoff rates. In contrast, where there were slower melt rates and thick organic soils, infiltration was unlimited and runoff was suppressed. The snow water equivalent had a large impact on runoff volume, as soil storage capacity was quickly surpassed in areas of deep snow, diverting the bulk of melt water laterally to the drainage network. A spatially distributed water balance indicated that the snowmelt freshet was primarily controlled by areas with tall shrub vegetation that accumulate large quantities of snow and by alpine areas with no capping organic soils. The intra-basin water balance variability has important implications for modelling freshet in hydrological models.

The role of glacier changes and threshold definition in the characterisation of future streamflow droughts in glacierised catchments

NASA Astrophysics Data System (ADS)

Van Tiel, Marit; Teuling, Adriaan J.; Wanders, Niko; Vis, Marc J. P.; Stahl, Kerstin; Van Loon, Anne F.

2018-01-01

Glaciers are essential hydrological reservoirs, storing and releasing water at various timescales. Short-term variability in glacier melt is one of the causes of streamflow droughts, here defined as deficiencies from the flow regime. Streamflow droughts in glacierised catchments have a wide range of interlinked causing factors related to precipitation and temperature on short and long timescales. Climate change affects glacier storage capacity, with resulting consequences for discharge regimes and streamflow drought. Future projections of streamflow drought in glacierised basins can, however, strongly depend on the modelling strategies and analysis approaches applied. Here, we examine the effect of different approaches, concerning the glacier modelling and the drought threshold, on the characterisation of streamflow droughts in glacierised catchments. Streamflow is simulated with the Hydrologiska Byråns Vattenbalansavdelning (HBV-light) model for two case study catchments, the Nigardsbreen catchment in Norway and the Wolverine catchment in Alaska, and two future climate change scenarios (RCP4.5 and RCP8.5). Two types of glacier modelling are applied, a constant and dynamic glacier area conceptualisation. Streamflow droughts are identified with the variable threshold level method and their characteristics are compared between two periods, a historical (1975-2004) and future (2071-2100) period. Two existing threshold approaches to define future droughts are employed: (1) the threshold from the historical period; (2) a transient threshold approach, whereby the threshold adapts every year in the future to the changing regimes. Results show that drought characteristics differ among the combinations of glacier area modelling and thresholds. The historical threshold combined with a dynamic glacier area projects extreme increases in drought severity in the future, caused by the regime shift due to a reduction in glacier area. The historical threshold combined with a

Tropical montane forest conversion affects spatial and temporal nitrogen dynamics in Kenyan headwater catchment

NASA Astrophysics Data System (ADS)

Jacobs, Suzanne; Weeser, Björn; Breuer, Lutz; Butterbach-Bahl, Klaus; Guzha, Alphonce; Rufino, Mariana

2017-04-01

export in catchments under managed land use. Furthermore, the changes in diurnal patterns in the forest catchment and absence of similar patterns in the other catchments are an indication that biogeochemical processes such as nitrification and denitrification in areas under different land use are affected as well. This could have implications for regional N-cycling.

Identification of internal flow dynamics in two experimental catchments

USGS Publications Warehouse

Hansen, D.P.; Jakeman, A.J.; Kendall, C.; Weizu, G.

1997-01-01

Identification of the internal flow dynamics in catchments is difficult because of the lack of information in precipitation -stream discharge time series alone. Two experimental catchments, Hydrohill and Nandadish, near Nanjing in China, have been set up to monitor internal flows reaching the catchment stream at various depths, from the surface runoff to the bedrock. With analysis of the precipitation against these internal discharges, it is possible to quantify the time constants and volumes associated with various flowpaths in both catchments.

Groundwater as an emergency source for drought mitigation in the Crocodile River catchment, South Africa

NASA Astrophysics Data System (ADS)

Mussá, F. E. F.; Zhou, Y.; Maskey, S.; Masih, I.; Uhlenbrook, S.

2015-02-01

Global climate change has received much attention worldwide in the scientific as well as in the political community, indicating that changes in precipitation, extreme droughts and floods may increasingly threaten many regions. Drought is a natural phenomenon that causes social, economical and environmental damage to society. In this study, we assess the drought intensity and severity and the groundwater potential to be used as a supplementary source of water to mitigate drought impacts in the Crocodile River catchment, a water-stressed sub-catchment of the Incomati River catchment in South Africa. The research methodology consists of three parts. First, the spatial and temporal variation of the meteorological and hydrological drought severity and intensity over the catchment were evaluated. The Standardized Precipitation Index (SPI) was used to analyse the meteorological drought and the Standardized Runoff Index (SRI) was used for the hydrological drought. Second, the water deficit in the catchment during the drought period was computed using a simple water balance method. Finally, a groundwater model was constructed in order to assess the feasibility of using groundwater as an emergency source for drought impact mitigation. Results show that the low-rainfall areas are more vulnerable to severe meteorological droughts (lower and upper crocodile). Moreover, the most water stressed sub-catchments with high level of water uses but limited storage, such as the Kaap located in the middle catchment and the Lower Crocodile sub-catchments, are more vulnerable to severe hydrological droughts. The analysis of the potential groundwater use during droughts showed that a deficit of 97 Mm3 yr-1 could be supplied from groundwater without considerable adverse impacts on the river base flow and groundwater storage. Abstraction simulations for different scenarios of extremely severe droughts reveal that it is possible to use groundwater to cope with the droughts in the catchment

Groundwater as an emergency source for drought mitigation in the Crocodile River catchment, South Africa

NASA Astrophysics Data System (ADS)

Mussá, F. E. F.; Zhou, Y.; Maskey, S.; Masih, I.; Uhlenbrook, S.

2014-03-01

Global climate change has received much attention worldwide in the scientific as well as in the political community, indicating that changes in precipitation, extreme droughts and floods may threaten increasingly many regions. Drought is a natural phenomenon that may cause social, economical and environmental damages to the society. In this study, we assess the drought intensity and severity and the groundwater potential to be used as a supplement source of water to mitigate drought impacts in the Crocodile River catchment, a water-stressed sub-catchment of the Incomati River catchment in South Africa. The research methodology consists mainly of three parts. First, the spatial and temporal variation of the meteorological and hydrological drought severity and intensity over the catchment were evaluated. The Standardized Precipitation Index (SPI) was used to analyse the meteorological drought and the Standardized Runoff Index (SRI) was used for the hydrological drought. Second, the water deficit in the catchment during the drought period was computed using a simple water balance method. Finally, a groundwater model was constructed in order to assess the feasibility of using groundwater as an emergency source for drought impact mitigation. Results show that the meteorological drought severity varies accordingly with the precipitation; the low rainfall areas are more vulnerable to severe meteorological droughts (lower and upper crocodile). Moreover, the most water stressed sub-catchments with high level of water uses but limited storage, such as the Kaap located in the middle catchment and the Lower Crocodile sub-catchments are those which are more vulnerable to severe hydrological droughts. The analysis of the potential groundwater use during droughts showed that a deficit of 97 Mm3 yr-1 could be supplied from groundwater without considerable adverse impacts on the river base flow and groundwater storage. Abstraction simulations for different scenarios of extremely

Catchment Water-Energy Balance Model: Development and Applications

NASA Astrophysics Data System (ADS)

Yang, D.; Yang, H.

2017-12-01

International Hydrological community has widely recognized that the catchment water-energy balance exists, which can be expressed as a general form of E/P = f(E0/P, c), where P is precipitation, E0 is potential evaporation, and c is a parameter. Many empirical/rational formulations of the catchment water-energy balance have been proposed. Several analytical solutions of the water-energy balance equation E/P = f(E0/P, c) have been derived by using dimensional analysis and mathematic reasoning and introducing additional boundary conditions. This paper will summarize the catchment water-energy balance equations and discuss their advantages and limitations. Catchment hydrology has been greatly influenced by the intensive variability in land use/cover, precipitation and air temperature due to climate change and local human activities. The water-energy balance equation, which are usually called the Budyko framework is widely used to analyze the impacts of climate and landscape changes on regional hydrology especially the annual runoff change. In order to quantify impacts of climate change and landscape change on the catchment runoff, the climate elasticity and landscape elasticity are estimated theoretically from the catchment water-energy balance equation. The elasticity of runoff has less of a dependency on the aridity index when the climate is drier (larger aridity index). The precipitation elasticity of runoff was close to 1.0 and that of potential evaporation close to 0.0 in the extreme humid climate with no relation to the landscape conditions, which implies that catchment water balance under extremely wet condition is controlled mainly by the climate condition. We establishes a relationship between the change in the landscape parameter in the catchment water-energy balance equation and vegetation change represented by fPAR, the fraction of Photosynthetically Active Radiation absorbed by vegetation. The fPAR elasticity of runoff is introduced and estimated over

Using Emergent and Internal Catchment Data to Elucidate the Influence of Landscape Structure and Storage State on Hydrologic Response in a Piedmont Watershed

NASA Astrophysics Data System (ADS)

Putnam, S. M.; Harman, C. J.

2017-12-01

chemograph is explored. The results suggest that the quantity of quickflow can be accounted for by direct precipitation onto < 5.2% of the catchment area, representing a zero-order swale plus the riparian area. rSAS modeling suggests that quickflow is largely composed of pre-event, stored water, generated through a process such as groundwater ridging.

Exploration of a Dynamic Merging Scheme for Precipitation Estimation over a Small Urban Catchment

NASA Astrophysics Data System (ADS)

Al-Azerji, Sherien; Rico-Ramirez, Miguel, ,, Dr.; Han, Dawei, ,, Prof.

2016-04-01

The accuracy of quantitative precipitation estimation is of significant importance for urban areas due to the potentially damaging consequences that can result from pluvial flooding. Improved accuracy could be accomplished by merging rain gauge measurements with weather radar data through different merging methods. Several factors may affect the accuracy of the merged data, and the gauge density used for merging is one of the most important. However, if there are no gauges inside the research area, then a gauge network outside the research area can be used for the merging. Generally speaking, the denser the rain gauge network is, the better the merging results that can be achieved. However, in practice, the rain gauge network around the research area is fixed, and the research question is about the optimal merging area. The hypothesis is that if the merging area is too small, there are fewer gauges for merging and thus the result would be poor. If the merging area is too large, gauges far away from the research area can be included in merging. However, due to their large distances, those gauges far away from the research area provide little relevant information to the study and may even introduce noise in merging. Therefore, an optimal merging area that produces the best merged rainfall estimation in the research area could exist. To test this hypothesis, the distance from the centre of the research area and the number of merging gauges around the research area were gradually increased and merging with a new domain of radar data was then performed. The performance of the new merging scheme was compared with a gridded interpolated rainfall from four experimental rain gauges installed inside the research area for validation. The result of this analysis shows that there is indeed an optimum distance from the centre of research area and consequently an optimum number of rain gauges that produce the best merged rainfall data inside the research area. This study is of

Which catchment characteristics control the temporal dependence structure of daily river flows?

NASA Astrophysics Data System (ADS)

Chiverton, Andrew; Hannaford, Jamie; Holman, Ian; Corstanje, Ron; Prudhomme, Christel; Bloomfield, John; Hess, Tim

2014-05-01

A hydrological classification system would provide information about the dominant processes in the catchment enabling information to be transferred between catchments. Currently there is no widely-agreed upon system for classifying river catchments. This paper developed a novel approach to assess the influence that catchment characteristics have on the precipitation-to-flow relationship, using a catchment classification based on the average temporal dependence structure in daily river flow data over the period 1980 to 2010. Temporal dependence in river flow data is driven by the flow pathways, connectivity and storage within the catchment. Temporal dependence was analysed by creating temporally averaged semi-variograms for a set of 116 near-natural catchments (in order to prevent direct anthropogenic disturbances influencing the results) distributed throughout the UK. Cluster analysis, using the variogram, classified the catchments into four well defined clusters driven by the interaction of catchment characteristics, predominantly characteristics which influence the precipitation-to-flow relationship. Geology, depth to gleyed layer in soils, slope of the catchment and the percentage of arable land were significantly different between the clusters. These characteristics drive the temporal dependence structure by influencing the rate at which water moves through the catchment and / or the storage in the catchment. Arable land is correlated with several other variables, hence is a proxy indicating the residence time of the water in the catchment. Finally, quadratic discriminant analysis was used to show that a model with five catchment characteristics is able to predict the temporal dependence structure for un-gauged catchments. This work demonstrates that a variogram-based approach is a powerful and flexible methodology for grouping catchments based on the precipitation-to-flow relationship which could be applied to any set of catchments with a relatively complete

Effects of land use and land cover changes on water quality in the uMngeni river catchment, South Africa

NASA Astrophysics Data System (ADS)

Namugize, Jean Nepomuscene; Jewitt, Graham; Graham, Mark

2018-06-01

Land use and land cover change are major drivers of water quality deterioration in watercourses and impoundments. However, understanding of the spatial and temporal variability of land use change characteristics and their link to water quality parameters in catchments is limited. As a contribution to address this limitation, the objective of this study is to assess the linkages between biophysico-chemical water quality parameters and land use and land cover (LULC) classes in the upper reaches of the uMngeni Catchment, a rapidly developing catchment in South Africa. These were assessed using Geographic Information Systems tools and statistical analyses for the years 1994, 2000, 2008 and 2011 based on changes over time of eight LULC classes and available water quality information. Natural vegetation, forest plantations and cultivated areas occupy 85% of the catchment. Cultivated, urban/built-up and degraded areas increased by 6%, 4.5% and 3%, respectively coinciding with a decrease in natural vegetation by 17%. Variability in the concentration of water quality parameters from 1994 to 2011 and an overall decline in water quality were observed. Escherichia coli (E. coli) levels exceeding the recommended guidelines for recreation and public health protection was noted as a major issue at seven of the nine sampling points. Overall, water supply reservoirs in the catchment retained over 20% of nutrients and over 85% of E. coli entering them. A relationship between land use types and water quality variables was found. However, the degree and magnitude of the associations varies between sub-catchments and is difficult to quantify. This highlights the complexity and the site-specific nature of relationships between land use types and water quality parameters in the catchment. Thus, this study provides useful findings on the general relationship between land use and land cover and water quality degradation, but highlights the risks of applying simple relationships or adding

Describing the environmental fate of diuron in a tropical river catchment.

PubMed

Camenzuli, Louise; Scheringer, Martin; Gaus, Caroline; Ng, Carla A; Hungerbühler, Konrad

2012-12-01

The use of the herbicide diuron on sugarcane fields along the river catchments of the Great Barrier Reef (GBR) in Australia is an issue of concern due to high levels of diuron reported in the GBR lagoon, and has recently led to a restriction on the use of diuron during the 2011/12 wet season. An important question in this context is how much diuron is mobilised from the agricultural area by strong rainfall and floods in the wet season and transferred to the GBR lagoon. We have set up a multimedia chemical fate model for a tropical catchment to describe the fate of diuron within the Tully River catchment, Queensland, Australia. The model includes highly variable rainfall based on meteorological data from the Tully River catchment and a flood water compartment on top of the agricultural soil that is present during times for which floods were reported. The model is driven by diuron application data estimated for the Tully River catchment and is solved for time-dependent diuron concentrations in agricultural soil and seawater. Model results show that on average 25% of the diuron applied every year is transferred to the GBR lagoon with rainwater and flood water runoff. Diuron concentrations estimated for the seawater range from 0.1 ng/L to 12 ng/L and are in good agreement with concentrations measured in the GBR lagoon. The uncertainty of the diuron concentrations estimated for seawater is approximately a factor of two and mainly derives from uncertainty in the diuron degradation half-life in soil, properties of the soil compartment such as organic matter content, and the speed of the seawater current removing diuron dissolved in seawater from the seawater compartment of the model. Copyright © 2012 Elsevier B.V. All rights reserved.

Identifying hydrologically sensitive areas using LiDAR DEMs to mitigate critical source areas of diffuse pollution: development and application

NASA Astrophysics Data System (ADS)

Thomas, Ian; Jordan, Phil; Mellander, Per-Erik; Fenton, Owen; Shine, Oliver; hUallacháin, Daire Ó.; Creamer, Rachel; McDonald, Noeleen; Dunlop, Paul; Murphy, Paul

2016-04-01

Identifying critical source areas (CSAs) of diffuse pollution in agricultural catchments requires the accurate identification of hydrologically sensitive areas (HSAs) at highest propensity for generating surface runoff and transporting pollutants such as phosphorus (P). A new GIS-based HSA Index is presented that identifies HSAs at the sub-field scale. It uses a soil topographic index (STI) and accounts for the hydrological disconnection of overland flow via topographic impediment from flow sinks such as hedgerows and depressions. High resolution (0.25-2 m) LiDAR Digital Elevation Models (DEMs) are utilised to capture these microtopographic controls on flow pathways and hydrological connectivity. The HSA Index was applied to four agricultural catchments (~7.5-12 km2) with contrasting topography and soil types. Catchment HSA sizes were estimated using high resolution rainfall-quickflow measurements during saturated winter storm events in 2009-2014, and mapped using the HSA Index. HSA sizes ranged from 1.6-3.4% of the catchment area during median storm events and 2.9-8.5% during upper quartile events depending on whether well or poorly drained soils dominated, which validated HSA Index value distributions. Total flow sink volume capacities ranged from 8,298-59,584 m3 and caused 8.5-24.2% of overland-flow-generating-areas and 16.8-33.4% of catchment areas to become hydrologically disconnected from the open drainage channel network. HSA maps identified 'delivery points' along surface runoff pathways where transported pollutants such as P are delivered to the open drainage network. Using these as proposed locations for targeting mitigation measures such as riparian buffer strips (RBS) reduced costs compared to blanket implementation within an example agri-environment scheme by 66% and 91% over 1 and 5 years respectively, which included LiDAR DEM acquisition costs. Considering that HSAs are often the dominant P CSA factor in agricultural catchments and can override

Variables Associated With Perceived Unmet Need for Mental Health Care in a Canadian Epidemiologic Catchment Area.

PubMed

Fleury, Marie-Josée; Grenier, Guy; Bamvita, Jean-Marie; Perreault, Michel; Caron, Jean

2016-01-01

This study identified variables associated with perceived partially met and unmet needs for information, medication, and counseling, as well as overall perceived unmet needs, related to mental health among 571 people in a Canadian epidemiologic catchment area. Needs were measured with the Perceived Need for Care Questionnaire and a comprehensive set of independent variables based on Andersen's behavioral model. Four models were constructed for the following dependent variables: perceived unmet needs for information, medication, and counseling (multinomial logistic regression) and overall perceived unmet needs (multiple logistic regression). The proportions reporting fully unmet need were as follows: counseling, 30%; information, 18%; and medication, 4%. Variables associated with unmet needs for information, medication, and counseling were quite distinct. Enabling factors (for example, neighborhood perception variables) were strongly associated with perceived unmet need for information. Need factors were more strongly associated with unmet need for medication, predisposing factors with unmet needs for information and medication, and health service use with unmet information and counseling needs. People whose overall needs went unmet tended to be younger, to have an addiction, and to have consulted fewer professionals. Mental health services should facilitate access to psychologists or other clinicians to better meet counseling and information needs. They should also take neighborhoods into account when assessing needs and provide more information about mental disorders and the treatments and services offered in disadvantaged areas. Finally, services should be further developed for younger people with addiction, who tend to be stigmatized and avoid using health services.

Picturing and modelling catchments by representative hillslopes

NASA Astrophysics Data System (ADS)

Loritz, Ralf; Hassler, Sibylle; Jackisch, Conrad; Zehe, Erwin

2016-04-01

Hydrological modelling studies often start with a qualitative sketch of the hydrological processes of a catchment. These so-called perceptual models are often pictured as hillslopes and are generalizations displaying only the dominant and relevant processes of a catchment or hillslope. The problem with these models is that they are prone to become too much predetermined by the designer's background and experience. Moreover it is difficult to know if that picture is correct and contains enough complexity to represent the system under study. Nevertheless, because of their qualitative form, perceptual models are easy to understand and can be an excellent tool for multidisciplinary exchange between researchers with different backgrounds, helping to identify the dominant structures and processes in a catchment. In our study we explore whether a perceptual model built upon an intensive field campaign may serve as a blueprint for setting up representative hillslopes in a hydrological model to reproduce the functioning of two distinctly different catchments. We use a physically-based 2D hillslope model which has proven capable to be driven by measured soil-hydrological parameters. A key asset of our approach is that the model structure itself remains a picture of the perceptual model, which is benchmarked against a) geo-physical images of the subsurface and b) observed dynamics of discharge, distributed state variables and fluxes (soil moisture, matric potential and sap flow). Within this approach we are able to set up two behavioral model structures which allow the simulation of the most important hydrological fluxes and state variables in good accordance with available observations within the 19.4 km2 large Colpach catchment and the 4.5 km2 large Wollefsbach catchment in Luxembourg without the necessity of calibration. This corroborates, contrary to the widespread opinion, that a) lower mesoscale catchments may be modelled by representative hillslopes and b) physically

Catchments as non-linear filters: evaluating data-driven approaches for spatio-temporal predictions in ungauged basins

NASA Astrophysics Data System (ADS)

Bellugi, D. G.; Tennant, C.; Larsen, L.

2016-12-01

Catchment and climate heterogeneity complicate prediction of runoff across time and space, and resulting parameter uncertainty can lead to large accumulated errors in hydrologic models, particularly in ungauged basins. Recently, data-driven modeling approaches have been shown to avoid the accumulated uncertainty associated with many physically-based models, providing an appealing alternative for hydrologic prediction. However, the effectiveness of different methods in hydrologically and geomorphically distinct catchments, and the robustness of these methods to changing climate and changing hydrologic processes remain to be tested. Here, we evaluate the use of machine learning techniques to predict daily runoff across time and space using only essential climatic forcing (e.g. precipitation, temperature, and potential evapotranspiration) time series as model input. Model training and testing was done using a high quality dataset of daily runoff and climate forcing data for 25+ years for 600+ minimally-disturbed catchments (drainage area range 5-25,000 km2, median size 336 km2) that cover a wide range of climatic and physical characteristics. Preliminary results using Support Vector Regression (SVR) suggest that in some catchments this nonlinear-based regression technique can accurately predict daily runoff, while the same approach fails in other catchments, indicating that the representation of climate inputs and/or catchment filter characteristics in the model structure need further refinement to increase performance. We bolster this analysis by using Sparse Identification of Nonlinear Dynamics (a sparse symbolic regression technique) to uncover the governing equations that describe runoff processes in catchments where SVR performed well and for ones where it performed poorly, thereby enabling inference about governing processes. This provides a robust means of examining how catchment complexity influences runoff prediction skill, and represents a contribution

Evaluation and assessment of water quality in Likangala River and its catchment area

NASA Astrophysics Data System (ADS)

Chidya, R. C. G.; Sajidu, S. M. I.; Mwatseteza, J. F.; Masamba, W. R. L.

Likangala is one of the perennial rivers in Malawi that flow into a closed Lake Chilwa, a designated wetland ratified by Ramsar Convention in 1997. Earlier work conducted on this river revealed considerable social-economic activities at riverbanks resulting in indiscriminate disposal of wastes. This study intended to evaluate water quality in Likangala River and its catchment area. Water samples were collected thrice (dry, early rainy and mid rainy seasons) and tested for major physico-chemical and microbiological parameters. The EC, pH, and selected ions ( NO3-, PO43-, Na +, K +, Mg 2+, and Ca 2+) were analysed in soil samples obtained in crop fields along the river banks. Elevated EC levels (>1035.00 μS/cm) were measured during mid rainy season at site S15 (Zomba Sewage Works), near and in the lake. Most of the water samples (86%, n = 28) registered phosphate levels above 1.50 mg/L during mid rainy season with a maximum value (10.70 ± 0.01 mg/L) at site S15. Lower amounts (<0.05 mg/L) of Pb 2+, Cd 2+, Cr 3+, Zn 2+ and Mn 2+ were measured at few sites, while Cu 2+ and Ni 2+ were all below detection limits. The water was classified as soft (0-75 mg/L CaCO 3) to moderately hard (75-150 mg/L CaCO 3). The total and fecal coliform counts above the World Health Organisation (2008) and Malawi Bureau of Standards (2005) limits (0 cfu/100 ml) at some sites signified that the water is unsuitable for human consumption without treatment. The study showed that the river is fairly polluted, the effects being significant in the urban area, near and in the lake. This calls for awareness campaigns aiming at behavioural change and integrated control of water, land use and waste management in order to prevent escalation of the effects.

Spatial and temporal patterns of pesticide concentrations in streamflow, drainage and runoff in a small Swedish agricultural catchment.

PubMed

Sandin, Maria; Piikki, Kristin; Jarvis, Nicholas; Larsbo, Mats; Bishop, Kevin; Kreuger, Jenny

2018-01-01

A better understanding of the dominant source areas and transport pathways of pesticide losses to surface water is needed for targeting mitigation efforts in a more cost-effective way. To this end, we monitored pesticides in surface water in an agricultural catchment typical of one of the main crop production regions in Sweden. Three small sub-catchments (88-242ha) were selected for water sampling based on a high-resolution digital soil map developed from proximal sensing methods and soil sampling; one sub-catchment had a high proportion of clay soils, another was dominated by coarse sandy soils while the third comprised a mix of soil types. Samples were collected from the stream, from field drains discharging into the stream and from within-field surface runoff during spring and early summer in three consecutive years. These samples were analyzed by LC-MS/MS for 99 compounds, including most of the polar and semi-polar pesticides frequently used in Swedish agriculture. Information on pesticide applications (products, doses and timing) was obtained from annual interviews with the farmers. There were clear and consistent differences in pesticide occurrence in the stream between the three sub-catchments, with both the numbers of detected compounds and concentrations being the largest in the area with a high proportion of clay soils and with very few detections in the sandy sub-catchment. Macropore flow to drains was most likely the dominant loss pathway in the studied area. Many of the compounds that were detected in drainage and stream water samples had not been applied for several years. This suggests that despite the predominant role of fast flow pathways in determining losses to the stream, long-term storage along the transport pathways also occurs, presumably in subsoil horizons where degradation is slow. Copyright © 2017 Elsevier B.V. All rights reserved.

A numerical solution to define channel heads and hillslope parameters from digital topography of glacially conditioned catchments

NASA Astrophysics Data System (ADS)

Salcher, Bernhard; Baumann, Sebastian; Kober, Florian; Robl, Jörg; Heiniger, Lukas

2016-04-01

The analysis of the slope-area relationship in bedrock streams is a common way for discriminating the channel from the hillslope domain and associated landscape processes. Spatial variations of these domains are important indicators of landscape change. In fluvial catchments, this relationship is a function of contributing drainage area, channel slope and the threshold drainage area for fluvial erosion. The resulting pattern is related to climate, tectonic and underlying bedrock. These factors may become secondary in catchments affected by glacial erosion, as it is the case in many mid- to high-latitude mountain belts. The perturbation (i.e. the destruction) of an initial steady state fluvial bedrock morphology (where uplift is balanced by surface lowering rates) will tend to become successively larger if the repeated action of glacial processes exceeds the potential of fluvial readjustment during deglaciated periods. Topographic change is associated with a decrease and fragmentation of the channel network and an extension of the hillslope domain. In case of glacially conditioned catchments discrimination of the two domains remains problematic and a discrimination inconsistent. A definition is therefore highly needed considering that (i) a spatial shift in the domains affect the process and rate of erosion and (ii) topographic classifications of alpine catchments often base on channel and hillslope parameters (i.e.channel or hillslope relief). Here we propose a novel numerical approach to topographically define channel heads from digital topography in glacially conditioned mountain range catchments in order to discriminate the channel from the hillslope domain. We analyzed the topography of the southern European Central Alps, a region which (i) has been glaciated multiple times during the Quaternary, shows (ii) little lithological variations, is (iii) home of very low erodible rocks and is (iv) known as a region were tectonic processes have largely ceased. The

Physical-chemical modeling of elements' behavior in mixing sea and fresh waters of minor rivers in the White Sea catchment area.

PubMed

Maksimova, Victoria V; Mazukhina, Svetlana I; Cherepanova, Tatiana A; Gorbacheva, Tamara T

2017-07-29

The physical-chemical stage of marginal filters in minor rivers of the White Sea catchment area by the example of the Umba River, flowing to Kandalaksha Gulf, has been explored. Application of the method of physical-chemical modeling on the basis of field data allowed establishing migration forms of a number of elements in the "river-sea" system and deposition of solid phases when mixing waters. The mixing of river and sea water is accompanied by the sedimentation of predominantly goethite, hydromuscovite, and hydroxylapatite. Sediments in mixing river and sea waters were found to be mainly composed by goethite, hydromuscovite, and hydroxylapatite. The research has added to the knowledge of the role of the abiotic part in the marginal filters of small rivers in the Arctic.

Landscape dynamics in the Otterbach catchment (Bavarian Forest, Southern Germany)

NASA Astrophysics Data System (ADS)

Schwindt, Daniel; Scheck, Sebastian; Scholz, Emanuel; Waltl, Peter; Völkel, Jörg

2017-04-01

As part of the TUM-CZO (TU-Munich Critical Zone Observatory), the Otterbach Valley has been focus of numerous research approaches, focusing on soil carbon dynamics, hydrological processes as well as landscape dynamics. Aim of this contribution is the reconstruction of the landscape evolution of the Otterbach catchment in context with anthropogenic land use and natural process dynamics. Therefore, studies focus on alluvial and colluvial sediments which are usually regarded as correlated with anthropogenically induced erosion. Located in the western Bavarian Forest the Otterbach is a creek of 2nd stream order and runs directly into the Danube River. Geologically, most parts of the catchment are composed of granitic rocks, mylonites and saprolites. While agricultural land use is dominant in the upper and lower reaches of the Otterbach, the steep middle reaches are forested, floodplains are used as grasslands. Settlement history points out that the forest of the so-called "Thiergarten", covering large parts of the catchment, has been used invariably for forestry, makes this study site valuable for the reconstruction of anthropogenic impact on landscape evolution. Characterization of the shallow subsurface is based on the analysis of soil pits (up to 2 m depth), core samples (up to 18 m depth) and geophysical measurements (electrical resistivity tomography, seismic refraction tomography). Temporal contextualization of sediments is achieved using radiocarbon dating. As a result of illuvial processes, clay curtains are observed almost continuously up to 18 m depth within the slope sediments, suggesting a genesis during Pleistocene warm stages. Radiocarbon dating in the alluvial floodplain point to pronounced sedimentary relocation processes between around 2.400 and 1.000 BP. This emphasizes the importance of naturally caused process dynamics as population density in the surroundings of the Otterbach catchment was low during this period and the area was mostly forested

Catchment-scale groundwater recharge and vegetation water use efficiency

NASA Astrophysics Data System (ADS)

Troch, P. A. A.; Dwivedi, R.; Liu, T.; Meira, A.; Roy, T.; Valdés-Pineda, R.; Durcik, M.; Arciniega, S.; Brena-Naranjo, J. A.

2017-12-01

Precipitation undergoes a two-step partitioning when it falls on the land surface. At the land surface and in the shallow subsurface, rainfall or snowmelt can either runoff as infiltration/saturation excess or quick subsurface flow. The rest will be stored temporarily in the root zone. From the root zone, water can leave the catchment as evapotranspiration or percolate further and recharge deep storage (e.g. fractured bedrock aquifer). Quantifying the average amount of water that recharges deep storage and sustains low flows is extremely challenging, as we lack reliable methods to quantify this flux at the catchment scale. It was recently shown, however, that for semi-arid catchments in Mexico, an index of vegetation water use efficiency, i.e. the Horton index (HI), could predict deep storage dynamics. Here we test this finding using 247 MOPEX catchments across the conterminous US, including energy-limited catchments. Our results show that the observed HI is indeed a reliable predictor of deep storage dynamics in space and time. We further investigate whether the HI can also predict average recharge rates across the conterminous US. We find that the HI can reliably predict the average recharge rate, estimated from the 50th percentile flow of the flow duration curve. Our results compare favorably with estimates of average recharge rates from the US Geological Survey. Previous research has shown that HI can be reliably estimated based on aridity index, mean slope and mean elevation of a catchment (Voepel et al., 2011). We recalibrated Voepel's model and used it to predict the HI for our 247 catchments. We then used these predicted values of the HI to estimate average recharge rates for our catchments, and compared them with those estimated from observed HI. We find that the accuracies of our predictions based on observed and predicted HI are similar. This provides an estimation method of catchment-scale average recharge rates based on easily derived catchment

Density and population estimate of gibbons (Hylobates albibarbis) in the Sabangau catchment, Central Kalimantan, Indonesia.

PubMed

Cheyne, Susan M; Thompson, Claire J H; Phillips, Abigail C; Hill, Robyn M C; Limin, Suwido H

2008-01-01

We demonstrate that although auditory sampling is a useful tool, this method alone will not provide a truly accurate indication of population size, density and distribution of gibbons in an area. If auditory sampling alone is employed, we show that data collection must take place over a sufficient period to account for variation in calling patterns across seasons. The population of Hylobates albibarbis in the Sabangau catchment, Central Kalimantan, Indonesia, was surveyed from July to December 2005 using methods established previously. In addition, auditory sampling was complemented by detailed behavioural data on six habituated groups within the study area. Here we compare results from this study to those of a 1-month study conducted in 2004. The total population of the Sabangau catchment is estimated to be about in the tens of thousands, though numbers, distribution and density for the different forest subtypes vary considerably. We propose that future density surveys of gibbons must include data from all forest subtypes where gibbons are found and that extrapolating from one forest subtype is likely to yield inaccurate density and population estimates. We also propose that auditory census be carried out by using at least three listening posts (LP) in order to increase the area sampled and the chances of hearing groups. Our results suggest that the Sabangau catchment contains one of the largest remaining contiguous populations of Bornean agile gibbon.

Recession-based hydrological models for estimating low flows in ungauged catchments in the Himalayas

NASA Astrophysics Data System (ADS)

Rees, H. G.; Holmes, M. G. R.; Young, A. R.; Kansakar, S. R.

The Himalayan region of Nepal and northern India experiences hydrological extremes from monsoonal floods during July to September, when most of the annual precipitation falls, to periods of very low flows during the dry season (December to February). While the monsoon floods cause acute disasters such as loss of human life and property, mudslides and infrastructure damage, the lack of water during the dry season has a chronic impact on the lives of local people. The management of water resources in the region is hampered by relatively sparse hydrometerological networks and consequently, many resource assessments are required in catchments where no measurements exist. A hydrological model for estimating dry season flows in ungauged catchments, based on recession curve behaviour, has been developed to address this problem. Observed flows were fitted to a second order storage model to enable average annual recession behaviour to be examined. Regionalised models were developed, using a calibration set of 26 catchments, to predict three recession curve parameters: the storage constant; the initial recession flow and the start date of the recession. Relationships were identified between: the storage constant and catchment area; the initial recession flow and elevation (acting as a surrogate for rainfall); and the start date of the recession and geographic location. An independent set of 13 catchments was used to evaluate the robustness of the models. The regional models predicted the average volume of water in an annual recession period (1st of October to the 1st of February) with an average error of 8%, while mid-January flows were predicted to within ±50% for 79% of the catchments in the data set.

The situation of sanitary systems in rural areas in the Miyun catchment, China.

PubMed

Kröger, C; Xu, A; Duan, S; Zhang, B; Eckstädt, H; Meissner, R

2012-01-01

The Miyun Reservoir provides most of Beijing's drinking water. Despite its importance, the Miyun reservoir suffers from decreasing water quality caused by uncontrolled wastewater discharges, inadequate land use and over fertilization, which increase the pressure on soil and water resources. The major pollutants are nitrogen and phosphorus which emanate to some extent from untreated sewage. So far there is little data about the existing wastewater quantity and quality in rural settlements in northern China. This study was conducted in typical villages situated along upstream rivers in the catchment of the Miyun Reservoir. The main objective was to determine the current situation and efficiency of the wastewater treatment system in rural settlements.

Contrasting climate change impact on river flows from high-altitude catchments in the Himalayan and Andes Mountains.

PubMed

Ragettli, Silvan; Immerzeel, Walter W; Pellicciotti, Francesca

2016-08-16

Mountain ranges are the world's natural water towers and provide water resources for millions of people. However, their hydrological balance and possible future changes in river flow remain poorly understood because of high meteorological variability, physical inaccessibility, and the complex interplay between climate, cryosphere, and hydrological processes. Here, we use a state-of-the art glacio-hydrological model informed by data from high-altitude observations and the latest climate change scenarios to quantify the climate change impact on water resources of two contrasting catchments vulnerable to changes in the cryosphere. The two study catchments are located in the Central Andes of Chile and in the Nepalese Himalaya in close vicinity of densely populated areas. Although both sites reveal a strong decrease in glacier area, they show a remarkably different hydrological response to projected climate change. In the Juncal catchment in Chile, runoff is likely to sharply decrease in the future and the runoff seasonality is sensitive to projected climatic changes. In the Langtang catchment in Nepal, future water availability is on the rise for decades to come with limited shifts between seasons. Owing to the high spatiotemporal resolution of the simulations and process complexity included in the modeling, the response times and the mechanisms underlying the variations in glacier area and river flow can be well constrained. The projections indicate that climate change adaptation in Central Chile should focus on dealing with a reduction in water availability, whereas in Nepal preparedness for flood extremes should be the policy priority.

Contrasting climate change impact on river flows from high-altitude catchments in the Himalayan and Andes Mountains

PubMed Central

Pellicciotti, Francesca