Dissertations / Theses on the topic 'Watershed management Hydrology'

Watershed ecosystems consist of numerous resources which have important environmental, social, cultural, and economic values. The mutual existence and interaction among different resources within the watershed ecosystem calls for a multiobjective watershed resources management analysis. These objectives are often uncertain since they are based on estimation and/or measurement data. Probabilistic methods or fuzzification are usually the methods used in modeling these uncertainties. Selection of the best decision alternative is based on using some Multiple Criterion Decision Making (MCDM) technique. Through simulation in this dissertation, we examine the probabilistic model to address the watershed management problem. In particular, the distance-based methods, which are the most frequently used MCDM techniques, are employed in the problem analysis. In most cases, several interest groups with conflicting preferences are willing to influence the final decision. In our study, a new method is suggested to incorporate their preference orders into the DM's final preference. The application of MCDM techniques combined with stochastic simulation and conflicting preference orders is new in the watershed management literature. Detailed analysis and comparison of the numerical results will help to decide on the suitability of the MCDM technique in watershed resources management. In particular, our numerical results indicate that in practical applications the best alternative selection is significantly influenced by the uncertainties in the payoff values. Hence, in situations where suitable data are available, our methodology is highly recommended.

Four artificial tracers were applied to a small headwater catchment in south western British Columbia to study runoff generated from topographically distinct landscape units. The seven hectare catchment is located in the University of British Columbia Malcolm Knapp Research Forest at low elevation (190-280 masl). A weir, multiple tipping bucket rain gauges and several piezometers were used to collect hydrological data. Three separate landscape units were identified based on topography, soil properties and proximity to the stream. The units included an area of shallow slope and deep soil, a riparian area along the intermittent stream channel and an area of very shallow soil with bedrock outcrops on a steep slope. Tracers used included rhodamine-WT, uranine, sodium chloride and potassium bromide. A suite of ion selective and fluorometric probes were used along with automated water sampling to monitor tracer breakthrough. The collected samples were analysed in the lab to validate the field measurements. Tracers were dissolved in solution and applied aerially with a backpack sprayer at the onset of forecasted precipitation events to facilitate rapid infiltration into the soil. The first application took place January 4th, 2006. Measurements were then taken continuously until March 20th, 2006, when a second round of tracers was applied to the landscape units. During the first measurement period, 532 mm of precipitation fell below the forest canopy over 75 days. During the second 78 day measurement period, 290 mm of rain fell. It was found that the overall wetness of the catchment affected travel times significantly. Large storms during the first, significantly wetter, application period exhibited similar lag times from peak event discharge to tracer arrival between the different landscape units. During small precipitation events and under dryer conditions, travel times were greatest in the area of shallow slope and deep soils. These lag times are indicative of longer pathways and perhaps the non-initiation of preferential flow below certain thresholds. In general, it was concluded that delineating catchments into groups of similar landscape units based on physical characteristics may be a promising new approach to explaining catchment runoff response.

The goal of this research was to develop a watershed-scale model for predicting changes in plant species distribution and abundance (phytogeography) that might occur as a result of changes in climatic factors with global warming. The model was designed: 1) to be spatially explicit and applicable across the entire watershed; 2) to apply to a number of particular species rather than general vegetation types; 3) to predict abundance as well as presence/absence; and 4) to work with simple environmental data, but reflect a biological rationale. Correlations were sought between current phytogeography in the watershed and the synoptic climate variables mean annual temperature, total annual precipitation and cool-/warm-season precipitation ratio. The contribution of edaphic and topographic variables to correlative models was examined and found to be negligible. The correlations established for current conditions were extended to hypothetical future conditions of changed climate in which the values of the variables were manipulated and the model run to produce predictions of altered future phytogeographies. Twenty-seven different hypothetical climate scenarios were modeled, incorporating a 1°C or 2°C rise in temperature with as much as a 10% increase or decrease in seasonal precipitation. Spatial articulation of the model was achieved through raster analysis of gridcell based data layers in a geographic information system. Primary input layers were a series of high-resolution (360x360m) interpolated climate-variable surfaces and a geographically referenced database of plant species presence and abundance derived from an aerial videography sample of the watershed. Logistic regression analysis was used to calculate, for a given set of conditions, the most probable state (present/absent) and abundance class for ten plant species at each grid-cell location in the watershed. Fragmentation of species' distributions before and after change was examined. Results for all studied species showed marked changes in distribution and abundance with temperature rise. Desert species will likely increase in abundance and occupiable area as forest and woodland species decrease, but much depends on the interaction of precipitation with temperature. Model predictions are conservative compared with paleoecological evidence of past changes.

Thesis (Ph. D.)--Ohio State University, 2005.
Title from first page of PDF file. Document formatted into pages; contains xvii, 180 p.; also includes graphics (some col.). Includes bibliographical references (p. 156-171). Available online via OhioLINK's ETD Center

The problem of selecting a multicriterion decision making (MCDM) technique for watershed resources management is investigated. Of explicit concern in this research is the matching of a watersned resources management problem with an appropriate MCDM technique. More than seventy techniques are recognized while reviewing the area of MCDM. A new classification scheme is developed to categorize these techniques into four groups on the bases of each algorithm's structural formulation and the possible results obtained by using the algorithm. Other standard classification schemes are also discussed to better understand the differences and similarities among the techniques and thereby demonstrate the importance of matching a particular multicriterion decision problem with an appropriate MCDM technique. The desire for selecting the most appropriate MCDM technique for watershed resources management lead to the development of 49 technique choice criteria and an algorithm for selecting a technique. The algorithm divides the technique choice criteria into four groups: (1) DM/analyst-related criteria, (2) technique-related criteria, (3) problem-related criteria and (4) solution-related criteria. To analyze the applicability of MCDM techniques to a particular problem, the levels of performance of the techniques in solving the problem are, at first, evaluated with respect to the choice criteria in each criterion group resulting in four sets of preference rankings. These four sets are then linearly combined using a set of trade-off parameters to determine the overall preference ranking of the techniques. The MUM technique selection process is itself modeled as a multiobjective problem. In this research, for example, a set of 15 techniques, the author is familiar with, are analyzed for their appropriateness to solve a watershed resources management problem. The performance levels of the 15 MCDM techniques in solving such a problem are evaluated with respect to a selected set of technique choice criteria in each criterion group leading to a set of four evaluation matrices of choice criteria versus alternative techniques. This technique choice problem is then analyzed using a two-stage evaluation procedure known as composite programming. The final product of the process resulted in a preference ranking of the alternative MCDM techniques.

For this dissertation I studied groundwater and surface water interactions in the Kenai Lowlands, Alaska. In particular, I examine two important aspects of groundwater and surface water interactions: 1) Groundwater's influence on surface-water temperature; and 2) Groundwater's role in forming hydrologic flow paths that can connect uplands to streamside wetlands and streams. Chapter 2 investigates the controls on stream temperature in salmon-bearing headwater streams in two common hydrogeologic settings: 1) drainage-ways, which are low-gradient streams that flow through broad valleys; and 2) discharge-slopes, which are high gradient streams that flow through narrow valleys. The results from chapter 2 showed significant differences in stream temperatures between the two hydrogeologic settings. Observed stream temperatures were higher in drainage-way sites than in discharge-slope sites, and showed strong correlations as a continuous function with the calculated topographic metric flow-weighted slope. Additionally, modeling results indicated that the potential for groundwater discharge to moderate stream temperature is not equal between the two hydrogeologic settings, with groundwater having a greater moderating effect on stream temperature at the low gradient drainage-way sites. Chapter 3 examines the influence of groundwater on juvenile coho salmon winter habitat along the Anchor River. Two backwater habitats were selected from the larger set of 25 coho overwintering sites from a previous study for an in-depth hydrologic analysis. The results from chapter 3 showed that the type of groundwater discharge (i.e., focused versus diffuse groundwater discharge) can play an important role in determining habitat suitability in these backwater sites. During winter, focused discharge from a local groundwater seep maintained higher surface-water temperatures and higher concentrations of dissolved oxygen compared to the site with more diffuse groundwater discharge. Chapter 4 investigates the linkages along hydrologic flow paths among alder (Alnus spp.) stands, streamside wetlands, and headwater streams. Chapter 4 tested four related hypotheses: 1) groundwater nitrate concentrations are greater along flow paths with alder compared to flow paths without alder; 2) on hillslopes with alder, groundwater nitrate concentrations are highest when alder stands are located near the streamside wetlands at the base of the hillslope; 3) primary production of streamside wetland vegetation is N limited and wetlands are less N limited when alder stands are located nearby along flow paths; and 4) stream reaches at the base of flow paths with alder have higher nitrate concentrations than reaches at the base of flow paths without alder. The results from chapter 4 showed that groundwater nitrate concentrations were highest along flow paths with alder, however no difference was observed between flow paths with alder located near versus alder located further from streamside wetlands. Vegetation had a greater response to N fertilization in streamside wetlands that were connected to flow paths without alder and less when alder stands were near. Finally, higher nitrate concentrations were measured in streams at the base of flow paths with alder. The combined results of this dissertation showed that, in the Kenai Lowlands, groundwater and surface water interactions have a direct influence on the local ecology and that a fundamental understanding of the hydrology can aid in the successful management and protection of this unique and important ecosystem.

From the Proceedings of the 1995 Meetings of the Arizona Section - American Water Resources Association and the Hydrology Section - Arizona-Nevada Academy of Science - April 22, 1995, Northern Arizona University, Flagstaff, Arizona

A prototype spatial decision support system for rangeland watershed management was developed to simplify the process of incorporating advances in technology into the decision process. The application utilizes an open framework by using Web services that are components that communicate using text-based messages, thus eliminating proprietary protocols. This new framework provides an extensible, accessible, and interoperable approach for spatial decision support systems. An important input into the SDSS is digital elevation data where data are produced using different methods, and with different accuracies and resolutions. Six digital elevation models were compared with survey data to evaluate accuracies at different locations in the Walnut Gulch Experimental Watershed. The sensitivity of the SDSS was evaluated using six management systems that were ranked based on minimizing sediment yield. The sensitivity of the DEM, contributing source area value, and precipitation event size on management system rankings was evaluated. Results provide assistance for users in selecting these data and modeling values. This research illustrated that recent advances in information technology can be effectively utilized in watershed decision support technology. The Internet-based SDSS provides core functionality required for rangeland watershed management education and decision-making. In comparing digital elevation data of different sources and resolutions with survey data, the DEM data approximated surfaces well, with the higher resolution data producing lower root mean square error values. And finally, different digital elevation models, contributing source area values, and precipitation event sizes produced different management system rankings. (Abstract shortened by UMI.)

Water managers for the City of Phoenix face the need to make informed policy decisions regarding long-term impacts of climate change on the Salt-Verde River basin. To provide a scientifically informed basis for this, we estimate the evolution of important components of the basin-scale water balance through the end of the 21st century. Bias-corrected and spatially downscaled climate projections from the Phase-3 Coupled Model Intercomparison Project of the World Climate Research Programme were used to drive a spatially distributed variable infiltration capacity model of the hydrologic processes in the Salt-Verde basin. From the many Global Climate Model's participating in the IPCC fourth assessment, we selected a five-model ensemble, including three that best reproduce the historical climatology for our study region, plus two others to represent wetter and drier than model average conditions; the latter two were requested by City of Phoenix water managers to more fully represent the full range of GCM prediction uncertainty. For each GCM, data for three emission scenarios (A1B, A2, B1) was used to drive the hydrologic model into the future. The model projections indicate a statistically significant 25% decrease in streamflow by the end of the 21st century. Contrary to previous assessments, this is not caused primarily by changes in the P/E ratio, but is found to result mainly from decreased winter precipitation accompanied by significant (temperature driven) reductions in storage of snow. The results show clearly the manner in which water management in central Arizona is likely to be impacted by changes in regional climate.

Green Stormwater Infrastructure (GSI) has become a popular method for flood mitigation as it can prevent runoff from entering streams during heavy precipitation. In this study, a recently developed neighborhood in Gresham, Oregon hosts a comparison of various GSI projects on runoff dynamics. The study site includes dispersed GSI (rain gardens, retention chambers, green streets) and centralized GSI (bioswales, detention ponds, detention pipes). For the 2017-2018 water year, hourly rainfall and observed discharge data is used to calibrate the EPA's Stormwater Management Model to simulate rainfall-runoff dynamics, achieving a Nash-Sutcliffe efficiency of 0.75 and Probability Bias statistic of 3.3%. A synthetic scenario analysis quantifies the impact of the study site GSI and compares dispersed and centralized arrangements. Each test was performed under four precipitation scenarios (of differing intensity and duration) for four metrics: runoff ratio, peak discharge, lag time, and flashiness. Design structure has significant impacts, reducing runoff ratio 10 to 20%, reducing peak discharge 26 to 68%, and reducing flashiness index 56 to 70%. There was a reverse impact on lag time, increasing it to 50 to 80%. Distributed GSI outperform centralized structures for all metrics, reducing runoff ratio 22 to 32%, reducing peak discharge 67 to 69%, increasing lag time 133 to 500%, and reducing flashiness index between 32 and 62%. This research serves as a basis for researchers and stormwater managers to understand potential impact of GSI on reducing runoff and downstream flooding in small urban watersheds with frequent rain.

Three hydrologic simulation models of different resolutions were evaluated to determine model response to predicting runoff under changing vegetation cover. Two empirically-based regression models (Baker-Kovner Streamflow Regression Model and ECOSIM) and one multiple component water balance model (Yield) were modified, using FORTRAN 77 and calibrated on a southwestern ponderosa pine ecosystem. Statistical analysis indicate no significant difference between the Baker-Kovner and Yield models, while ECOSIM consistently under predicts by as much as 50 percent from the observed runoff. This is mainly attributed to a sensitivity to the insolation factor. Yield is the best predictor for moderate and high flows, to within 10 and 20 percent respectively. Of the four watershed treatments, the light overstory thinning on Watershed 8 yielded the best response for all three models. This is in contrast to the strip-cut treatment on Watershed 14 which consistently over-predicted, in large part due an inaccurate estimation of snowpack evaporation on the exposed, south-facing strip-cuts. Runoff responses are highly influenced by the precipitation regime, soil and topographic characteristics of a watershed as well as by a reduction in evapotranspiration losses from changes in vegetation cover.

In situ radiometric field data and data simulated with a radiative transfer model were used to evaluate the performance and biophysical interpretation of spectral indices Concurrently with remotely sensed measurements, temporal biophysical measurements for different vegetation types for two semi-arid regions in Niger were made, including leaf area index (LAI), fraction of absorbed photosynthetically active radiation (fAPAR), percent vegetation cover, and biomass. The spectral dynamics of vegetation and soil were characterized at the leaf and canopy scale by optical measurements under many adverse conditions, including variability in vegetation optical and structural properties, soil reflectance properties, sun and view geometry and atmospheric perturbations. The spectral indices evaluated in this research comprised spectral vegetation indices and spectral mixture model indices, computed from spectral reflectances. The performance of different vegetation indices and their sensitivity to green and non-green vegetation and soils were compared and quantified by utilizing estimates of percent relative error in spectral vegetation indices, and estimates of vegetation equivalent noise expressed in terms of biophysical parameters (LAI, fAPAR). The soil adjusted vegetation index (SAVI) and modified normalized vegetation index (MIND VI) were improvements over the normalized difference vegetation index (NDVI), but were still sensitive to many perturbing variables such as soil and vegetation distribution, soil optical properties, litter and green vegetation optical properties and leaf angle distribution. The spectral mixture model indices were designed to be sensitive to vegetation, soil and non-green vegetation components and were shown to provide useful surface information that can aid in minimizing the noise in spectral vegetation indices, and also in improving their biophysical interpretation. Vegetation and soil brightness imagery were created from remotely sensed reflectance data, by calibrating the spectral mixture model with the data generated with a radiative transfer model. The effect of standing litter on spectral indices was shown to possibly cause both an increase and a decrease in the vegetation index, depending on the coupled spectral and structural properties of litter, green vegetation and soil. In situ measurements confirmed the results obtained from the analysis of data sets generated with a radiative transfer model. The implications of the effect of perturbing variables on spectral indices were also discussed.

This study investigated two important aspects of hydrologic effects of low impact development (LID) practices at the watershed scale by (1) examining the potential benefits of scaling up of LID design, and (2) evaluating downstream effects of LID design and its spatial translation within a watershed. The Personal Computer Storm Water Management Model (PCSWMM) was used to model runoff reduction with the implementation of LID practices in Deer Creek watershed (DCW), Missouri. The model was calibrated from 2003 to 2007 (R² = 0.58 and NSE = 0.57), and validated from 2008 to 2012 (R² = 0.64 and NSE = 0.65) for daily direct runoff. Runoff simulated for the study period, 2003 to 2012 (NSE = 0.61; R² = 0.63), was used as the baseline for comparison to LID scenarios. Using 1958 areal imagery to assign land cover, a predevelopment scenario was constructed and simulated to assess LID scenarios' ability to restore predevelopment hydrologic conditions. The baseline and all LID scenarios were simulated using 2006 National Land Cover Dataset.

The watershed was divided in 117 subcatchments, which were clustered in six groups of approximately equal areas and two scaling concepts consisting of incremental scaling and spatial scaling were modelled. Incremental scaling was investigated using three LID practices (rain barrel, porous pavement, and rain garden). Each LID practice was simulated at four implementation levels (25%, 50%, 75%, and 100%) in all subcatchments for the study period (2003 to 2012). Results showed an increased runoff reduction, ranging from 3% to 31%, with increased implementation level. Spatial scaling was investigated by increasing the spatial extent of LID practices using the subcatchment groups and all three LID practices (combined) implemented at 50% level. Results indicated that as the spatial extent of LID practices increased the runoff reduction at the outlet also increased, ranging from 3% to 19%. Spatial variability of LID implementation was examined by normalizing LID treated area to impervious area for each subcatchment group. The normalized LID implementation levels for each group revealed a reduction in runoff at the outlet of the watershed, ranging from 0.6% to 3.7%. This study showed that over a long-term period LID practices could restore pre-development hydrologic conditions. The optimal location for LID practice implementation within the study area was found to be near the outlet; however, these results cannot be generalized for all watersheds.

Concerns have been raised on the deterioration of heather moorland due to management in the UK. A study was therefore conducted on the impacts of moorland management on the soils and hydrology of a catchment on Dartmoor. Soil moisture was measured gridwise using TDR on 19 occasions. At 23 sites within this grid, physical properties of the topsoil were obtained. At three locations, tensiometer nests were installed, recording soil suction at 10 cm depth intervals. At the catchment scale, stream discharge and rainfall were recorded. Grazing densities within the watershed were estimated and the observed patterns were related to vegetation types. Results from the TDR grid showed that in dry conditions, soil moisture patterns are heterogeneous in contrast to a more uniform pattern in wet periods. A threshold soil moisture content of about 0.60 cm3 cm-3 divides the two conditions. The exponential relationship between average hillslope soil moisture content and stream discharge also revealed the division between wet and dry states. A regression analysis showed that during dry conditions, the vegetation plays a significant role in determining the soil water status. During wet conditions, topography becomes more important. In these conditions, the soil water movement is mainly lateral, whereas in the dry state, this is vertical in the soil profile. Tensiometer data showed that most soil water movement is in the topsoil. Analyses suggested that soil moisture under vegetation classes associated with higher grazing pressures is higher in similar topographic conditions. Soil bulk density is higher and the total porosity is lower near the soil surface. This suggests that less rainfall is required to reach the soil moisture threshold and water will be transported laterally down the slope. A heather burning experiment revealed that the direct effect of temperature is shallow. Soil moisture levels do not change over the course of the burn. However, in dry situations during summer, soil moisture contents under burned plots are higher than under unburned vegetation probably due to reduced transpiration. If this effect is similar at the hillslope scale, when the soil is wetting up, the soil moisture threshold value could be reached at an earlier stage and accelerated lateral water movement could be the result. It can be concluded therefore, that moorland management could accelerate water movement on the hillslopes causing higher discharge peaks in wet periods and consequently low flows in summer. However, the effects are subtle and encouraging vegetation heterogeneity could play a role in buffering water to prevent loss to the stream.

Spatial variability is all that stands between hydrology and science, forcing us to deal in probabilities and averages. Because of scale, we can not consider forces on individual soil particles, water molecules and solute ions when addressing human size problems. We must therefore look at aggregate properties and mean values for parameters and inputs in computer modeling of hydrologic phenomena. This research explores the impact of spatially variable inputs on the Water Erosion Prediction Project soil erosion computer program. Distributions of input variables are generated and assigned randomly to a grid of homogeneous rangeland hillslope elements. Values for runoff volume and sediment loss from each flow path are recorded and averaged to provide a distribution of outputs in the form of a sensitivity analysis. Variabilities of slope, slope length, soil textures, soil characteristics, terrain, convex and concave slopes, soil saturation, rainfall amount and vegetation were examined. Results show that use of mean inputs values in the WEPP representative hillslope model yields very similar outputs to the spatially variable research model using a distribution of inputs in all simulations in the case of totally random bare rangeland soils. When a decreasing trend in soil clay content is introduced in the variable model, the hillslope model using average values as inputs no longer provides a good estimate of the sediment loss. When random vegetation is generated and added to the simulation, runoff volume continues to be similar between the two models, but the sediment loss is much higher in the spatially variable model. In addition, the results of the standard hillslope model are much less responsive to changes in slope than those of the spatially variable model. It is concluded that spatial variability of soils must be considered when there is a linear change in input values with slope position. Likewise spatial variability of vegetation needs to be addressed in order to accurately estimate erosion on the rangeland watersheds considered in this dissertation. It is also found that this type of simulation provides a model for sensitivity analysis of a complex computer programs. Physically related inputs can be generated in such a way as to preserve the desired interrationships and distributions of inputs can be directly compared to generated distributions of outputs.

In 1985 the USDA - Agricultural Research Service initiated a national project called Water Erosion Prediction Project (WEPP) to develop a new generation water erosion prediction technology which will replace the USLE by 1992, the most widely used technology for estimating soil erosion by water. For simplicity, the WEPP model was developed assuming quasi-steady state conditions. An evaluation of the effects of formulating the unsteady state sediment continuity equation by assuming quasi-steady state conditions is presented. A methodology was developed to study soil erosion process in rainfall simulator plots treated as a microwatersheds. This was achieved by explicitly separating interrill and rill areas in the rainfall simulator plots using areal photographs and microtopographic data. A detailed analysis was conducted using response surface plots on the model structure of both formulations of the sediment continuity equation. The shape of the response surface plots indicated for each formulation whether the soil erosion parameter estimates were successfully identified. As an additional information, the sediment concentration graphs and the total sediment yield were used to determine major differences between the two formulations of the sediment continuity equation. Rainfall simulator plot data collected in five locations of the US were used for the calibration and validation of the model WESP. The unsteady state approach yielded lower values of the objective function than the quasi-steady state formulation. Using the unsteady state approach, physical interpretation may be associated with the soil erosion parameter values Kᵣ, T(cr), and Vₑ. The quasi-steady state soil erosion estimates showed a weak and unclear physical association. The shape of the sediment concentration graphs were similar for both formulations of the sediment continuity equation. The benefit obtained by using the more complicated unsteady state approach was a more accurate estimation of the peak, or maximum, sediment concentration. Total sediment yield estimates from both formulations were similar. Thus, insignificant benefit was obtained from using the unsteady state approach. In this study hydrographs reached equilibrium due to the long duration of simulated rainfall. The two model formulations might perform far differently under experimental conditions where steady state runoff is not reached.

Changes in redox potential (Eh), major sulfur species and the solubility of selenium and boron in reduced flue gas desulfurization (FGD) sludge, when exposed to atmosphere were studied in laboratory experiments. Also the effect of organic carbon and temperature on reduction of FGD sludge and changes in concentration of major S species was studied. Stable isotopic ratios of sulfur and carbon compounds were used to investigate the possible pathways of S transformation in FGD sludge disposal site. Oxidation of reduced sludge appears to be a two step process, a fast step of chemical oxidation followed by a slow step of biological oxidation and is significantly affected by moisture content and mixing of the sludge. With the addition of organic carbon Eh of the FGD sludge dropped exponentially and reduction of sulfate initiated at Eh of about -75 mV and was maximum in the range of -265 to -320 mV. Temperatur8e of the profile and organic carbon appear to be the key factors affecting the rate and extent of reduction in flooded FGD sludge. Selenium solubility decreased four times as Eh dropped from 215 mV to -350 mV while boron solubility was unchanged in this range of Eh. Stable isotopic ratio of sulfate and sulfide are typical of bacterial reduction and suggest that only aqueous sulfate was being reduced. The low δ³⁴S values of CaSO₄ from the upper layers of profile indicate the production and upward movement of hydrogen sulfide gas in the FGD sludge.

Thesis (M.ScEng.)--Stellenbosch University, 2001.
ENGLISH ABSTRACT: Historically, urban waterresources have too often been managed without recognition that the flow in a river integrates many landscape and biological features. This has often resulted in the elimination of natural processes and their replacement by man-made streamlined structures with the effects of increased urbanisation being primarily addressed from an engineering and economics point of view to the detriment of environmental and social issues. Catchment Management, as legislated in the Water Act, No. 36 of 1998, is a management approach to address the negative consequences of an urban stormwater design philosophy restricted to flood restriction. It is a systems approach that integrates engineering and scientific skills, socio-economic concerns, and environmental constraints within a new multidisciplinary decision-making process that recognises the different components of the hydrological and aquatic cycles are linked, and each component is affected by changes in every other component. In order to make effective management decisions, catchment managers require tools to provide reliable information about the performance of alternative arrangements of stormwater management facilities and to quantify the effects of possible management decisions on the water environment. A deterministic hydrological model is such a tool, which provides the link between the conceptual understanding of the physical catchment characteristics and the empirical quantification of the hydrological, water quality and ecological response. In order to provide effective computer based decision support, the hydrological model must be part of an integrated software application in which a collection of data manipulation, analysis, modelling and interpretation tools, including GIS, can be efficiently used together to manage a large potion of the overall decision process. This decision support system must have a simple and intuitive user interface able to produce easily interpreted output. It must have powerful graphical presentation capabilities promoting effective communication and be designed to solve ill-structured problems by flexibly combining statistical analysis, models and data. The Great Lotus River canal, situated on the Cape Flats, Cape Town, has been designed and controlled through extensive canalisation and the construction of detention pond facilities to avoid the flooding of urban areas of the catchment. This approach has resulted in these channels becoming stormwater drains, transporting waste and nutrients in dissolved and particulate forms, and reducing their assimilatory capacity for water quality improvement. In order to investigate the use of hydrological modelling in decision support for Catchment Management, the semi-distributed, physically based model, SWMM, was applied to the Great Lotus River canal. SWMM consists of a number of independent modules allowing the hydrological and hydraulic simulations of urban catchments and their conveyance networks on an event or continuous basis. In order to ease the application of the Fortran based SWMM model, the GUl, PCSWMM98, was developed by Computational Hydraulics Inc (CH!). This provides decision support for SWMM through large array of tools for file management, data file creation, output visualisation and interpretation, model calibration and error analysis and storm dynamic analysis thus easing any simulations with SWMM. In addition, PCSWMM was developed with a GIS functionality for graphically creating, editing and/or querying SWMM model entities and attributes, displaying these SWMM layers with background layers and dynamic model results, and exporting data to SWMM input files thus providing an interface between a GIS and SWMM. In terms of Catchment Management, the above DSS can be used effectively to assist decisionmaking. This is to address tensions between the fundamental catchment management considerations of physical development, social considerations and maintaining ecological sustainability. It is at the stages of Assessment and Planning that the model can play the most significant role in providing decision support to the Catchment Management process. Assessment in the Catchment Management process refers to the collection, storage, modelling and interpretation of catchment information. It is in this quantification, interpretation and assessment of catchment information that a hydrological model contributes to an increase in knowledge in the Catchment Management process. In identifying and quantifying, at a sufficient temporal and spatial scale, the dominant cause and effect relationships in the urban physical environment, a hydrological model is able to highlight the main contributing factors to an issue. This is used in the Planning stage of the Catchment Management process and when combining these contributing factors with assessments of the socio-economic and administrative environments, enables the prioritisation of the principal issues requiring attention in a Catchment Management Strategy. It is possible to link the multiple decision-making requirements of Catchment Management with the abilities of a hydrological model to provide information on these requirements in a conceptual framework. This framework consists of the fundamental catchment considerations of Physical Development, Environmental Management and Social Development and resolves these considerations into the various management issues associated with each consideration ~s well as its management solution. The management solutions are linked to the model through formulating the solution in terms of the model parameters and perturbing the affected parameters in ways to simulate the management solution. This results in model output and graphical interpretation of the effects of the suggested management solution. A comparison between the simulated effects of each management solution allows the Catchment Management body to identify optimal management solutions for the various management Issues. The present model of the Great Lotus River catchment is sufficient to simulate the overland and subsurface flows from individual parts of the catchment and to route these flows and associated pollutant loadings to the catchment outlet. At its present level of complexity, the finely discretised model subcatchment and conveyance network provides decision support for Catchment Management through the simulation, at a pre-feasibility stage, of various Catchment Management issues and their proposed solutions. Given more detailed canal and drainage network dimensions and water quality data, it is possible for the model to incorporate hydraulic calculation routines to assess the implications of alternative river rehabilitation techniques and waste management strategies. This would allow greater capability in assessing the role of the various BMPs in ameliorating stormwater impacts and pollutant loading. In addition, a detailed level survey of the stormwater pipe and canal network could result in hydrological modelling being utilised to identify critical areas where stormwater upgrading would be necessary. In order to facilitate future complex, finely discretised catchment hydrological models, it is imperative that complete and detailed drainage patterns and stormwater network characteristics are available. In addition, to minimise model generation costs and time of model setup, this spatially representative data must be captured in a GIS for rapid inclusion into the model. Furthermore, complete spatially representative precipitation datasets are necessary to ensure that model error is reduced. These two issues of available spatial data and comprehensive precipitation records are crucial for the generated models to function as effective decision support systems for Catchment Management.
AFRIKAANSE OPSOMMING: Histories is stedelike waterbronne te dikwels bestuur sonder inagneming dat die vloei van die rivier baie landskap- en biologiese kenmerke insluit. Dit het dikwels daartoe gelei dat natuurlike prosesse uitgeskakel is en vervang is deur mensgemaakte, stroombelynde strukture waarvan die effek van toenemende verstedeliking hoofsaaklik aangespreek word vanuit 'n ingenieurs- en ekonomiese oogpunt tot nadeel van omgewings- en sosiale kwessies. Opvangsgebiedsbestuur, soos bepaal deur die Waterwet, Wet 36 van 1998, is 'n bestuursbenadering om die negatiewe gevolge van 'n stedelike stormwaterontwerpfilosofie wat beperk is tot vloedbeperking aan te spreek. Dit is 'n stelselbenadering wat ingenieurs- en wetenskaplike vaardighede, sosio-ekonomiese probleme en omgewingsbeperkings integreer in 'n nuwe multidissiplinêre besluitnemingsproses wat erkenning daaraan gee dat die verskillende komponente van die hidrologiese en watersiklusse verbind is, en elke komponent beïnvloed word deur veranderings in elke ander komponent. Om doeltreffende bestuursbesluite te neem, benodig opvangsgebiedsbestuur die hulpmiddels om betroubare inligting oor die prestasie van alternatiewe moontlikhede VIr stormwaterbestuurfasiliteite en om die effek van moontlike bestuursbesluite op die wateromgewing te kwantifiseer. 'n Deterministiese hidrologiese model is so 'n hulpmiddel wat die skakel daarstel tussen die konseptueie begrip van die fisiese opvangsgebiedskenmerke en die empiriese kwantifisering van die water-, waterkwaliteit- en ekologiese reaksie. Om doeltreffende rekenaarbesluitnemingsteun te verskaf, moet die hidrologiese model deel wees van 'n geïntegreerde sagteware-aanwending waarin 'n versameling datamanipulasie-, analise-, modellerings- en interpreteringshulpmiddels, insluitend GIS, doeltreffend saam gebruik kan word om 'n groot deel van die algehele besluitnemingsproses te bestuur. Hierdie besluitnemingsteunstelsel moet 'n eenvoudige en intuïtiewe gebruikersvlak hê wat in staat is om maklik interpreteerbare uitsette te lewer. Dit moet goeie grafiese voorleggingsvermoëns hê wat doeltreffende kommunikasie vergemaklik en ontwerp wees om swak gestruktureerde probleme deur die buigsame samevoeging van statistiese analise, modelle en data op te los. Die Groot Lotusrivierkanaal op die Kaapse Vlakte, Kaapstad is ontwerp en word beheer deur uitgebreide kanalisasie en die konstruksie van detensiedamfasiliteite om die oorstroming van stedelike opvangsgebiede te vermy. Hierdie benadering het daartoe gelei dat hierdie kanale stormwaterafvoerpype geword het wat afval en nutriënte in opgelosde en partikelvorm vervoer en hulle assimilasievermoë vir die verbetering van waterkwaliteit verminder. Om die gebruik van hidrologiese modelle in besluitnemingsteun vir Opvangsgebiedsbestuur te ondersoek, is die semi-verspreide, fisiesgebaseerde model, SWMM, op die Groot Lotusrivierkanaal toegepas. SWMM bestaan uit 'n aantalonafhanklike modules wat die hidrologiese en hidroulika simulasies van stedelike opvangsgebiede en hulle vervoemetwerke per geleentheid of deurlopend monitor. Om die aanwending van die Fortran gebaseerde SWMM model te vergemaklik is die GUl, PCSWMM98 deur Computational Hydraulics Inc (CHD ontwikkel. Dit verskaf besluitnemingsteun vir SWMM deur 'n groot aantal hulpmiddels vir lêerbestuur, die skep van datalêers, uitsetvisualisering en interpretasie, modelkalibrasie, foutanalise en stormdinamikaanalise om enige simulasies met SWMM te vergemaklik. Daarby is PCSWMM ontwikkel met 'n GIS funksionaliteit vir die grafiese daarstelling, redigering en/of navraagfunksie van SWMM model entiteite en kenmerke, wat hierdie SWMM vlakke met agtergrondvlakke en dinamiese modelresultate vertoon en data in SWMM inset1êers plaas en op daardie manier 'n koppelvlak tussen 'n GIS en SWMM verskaf. Volgens Opvangsgebiedsbestuur kan bogenoemde DSS doeltreffend gebruik word in besluitneming. Dit IS om die spanning tussen fundamentele opvangsgebiedsbestuursoorwegings van fisiese ontwikkeling, sosiale oorwegings en ekologiese volhoubaarheid aan te spreek. Dis in die stadiums van Waardebepaling en Beplanning wat die model die belangrikste rol kan vervul in die verskaffing van besluitnemingsteun vir die Opvangsgebiedsbestuursproses. Waardebepaling in die Opvangsgebiedbestuursproses verwys na die versameling, berging, modellering en interpretasie van opvangsgebiedsinligting. Deur hierdie kwantifisering, interpretasie en waardebepaling van opvangsgebiedsinligting dra 'n hidrologiese model by tot 'n verhoging in kennis in die Opvangsgebiedsbestuur. Deur die identifisering en kwantifisering, op 'n ruim genoeg tydelike en ruimtelike skaal, van die dominante oorsaak en gevolg verhoudings in die stedelike fisiese omgewing, kan die hidrologiese model die hoof bydraende faktore uitlig. Dit word gebruik in die Beplanningsfase van die Opvangsgebiedproses en wanneer hierdie bydraende faktore by die waardebepaling van die sosio-ekonomiese en administratiewe omgewings saamgevoeg word, maak dit moontlik om die belangrike kwessies wat aandag behoort te kry in 'n Opvangsgebiedsbestuurstrategie in volgorde van voorrang te plaas. Dit is moontlik om die verskeidenheid besluitnemingsvereistes van Opvangsgebiedsbestuur met die vermoëns van 'n hidrologiese model te koppel om inligting oor hierdie vereistes in 'n konseptuele raamwerk te verskaf. Die raamwerk bestaan uit die fundamentele opvangsgebiedsoorwegings van Fisiese Ontwikkeling, Omgewingsbestuur en Sosiale Ontwikkeling en los hierdie oorwegings op in die verskillende bestuursaangeleenthede wat met elke oorweging en die bestuuroplossing geassosieer word. Die bestuursoplossings word aan die model gekoppel deur die formulering van die oplossing volgens die modelparameters en versteuring van die relevante parameters op sekere manier om die bestuursoplossing te simuleer. Dit lei tot modeluitset en grafiese interpretasie van die effek van die voorgestelde bestuursoplossing. 'n Vergelyking tussen die gesimuleerde effek van elke bestuursoplossing laat die Opvangsgebiedsbestuursliggaam toe om die optimale bestuursoplossings vir die verskeie bestuursaangeleenthede te identifiseer. Die huidige model van die Groot Lotusrivieropvang is genoegsaam om die bo- en ondergrondse vloei vanaf individuele dele van die opvangsgebied te simuleer en om die watervloei en geassosieerde besoedelstofladings na die opvangsgebiedsuitlaatplek te lei. Op sy huidige vlak van kompleksiteit verskaf die fyn gediskretiseerde model subopvangsgebied en vervoernetwerk besluitnemingsteun aan Opvangsgebiedsbestuur deur die simulasie, teen 'n voor-lewensvatbaarheidstudie, van verskeie opvangsgebiedsbestuurkwessies en die voorgestelde oplossings. Indien meer gedetailleerde kanaal- en dreineringsnetwerkdimensies- en waterkwaliteitdata ingevoer word, is dit moontlik vir die model om hidroulikaberekeningsroetines te inkorporeer om die implikasies van alternatiewe rivierrehabilitasietegnieke en afvalbestuurstrategieë te beoordeel. Dit sou die vermoë verbeter om die waarde van die verskeie BMPs te bepaal om die impak van stormwater en besoedelstoflading te versag. Daarby kan 'n gedetailleerde vlakopname van die stormwaterpyp en -kanaalnetwerk daartoe lei dat hidrologiese modelle gebruik kan word om kritieke areas te identifiseer waar stormwateropgradering nodig is. Om toekomstige komplekse, gediskretiseerde opvangsgebiedshidrologiese modelle te verbeter, is dit noodsaaklik dat volledige en gedetailleerde dreineringspatrone en stormwaternetwerkkenmerke beskikbaar is. Om die model-ontwikkelingskoste en tyd bestee aan die opstel van 'n model te minimiseer, moet hierdie ruimtelik verteenwoordigende data ingelees word in 'n GIS vir vinnige insluiting in die model. Daarbenewens is volledige, ruimtelik verteenwoordigende presipitasie datastelle nodig om te verseker dat modelfoute verminder word. Hierdie twee kwessies van beskikbare ruimtelike data en omvattende presipitasierekords is van die uiterste belang sodat die gegenereerde modelle as doeltreffende besluitnemingsteun vir Opvangsgebiedsbestuur kan funksioneer.

Sub-Saharan Africa is today facing a big challenge regarding food deficiency and water scarcity due to climate change. One of these countries is Rwanda, a small landlocked country in the middle of Africa. Rwanda strongly depend on agriculture, both in the aspect of reducing poverty and hunger but also because their economy security depend on it. Because of increasingly fluctuating rainfalls their agriculture becomes more dependent on irrigation and the availability to water resources. To investigate how the climate change will affect the amount of water resources in the coming decades, this study is focusing on the watershed and marshland of Muvumba P8 in Nyagatare, Rwanda. A hydrological model was created, in a software called Soil and Water Assessment Tool (SWAT), with soil, land use and slope maps for the watershed. Calibrating the model was done with help of Climate Forecast System Reanalysis (CFSR) data and run for nine different climate model datasets. An uncertainty had to be taken into account regarding both the measured local data and the downloaded data. To be able to compare the amount of water resources and the irrigation requirements for the rice crop the farmers were growing on the marshland, the crop water requirements for rice was estimated with FAO’s program called CROPWAT. The irrigation system on the marshland allows a double cropping of rice every year and consist of a system depending on elevation differences to create natural fall. There was three reservoirs along the marshland but to limit the project, only the first reservoir was taken into account. This was complemented with existing data and field survey. Six out of nine climate models showed a decrease in median discharge over the coming 30 years compared to the CFSR historical median discharge. This means that less water in general will reach the outlet of the watershed in the years to come. At the same time all climate models indicate an increase in irrigation requirements for the rice crops. The seasons are probably going to change, a longer and drier season between June and August and a rainier season between September and November are projected.

It is difficult to assess rangeland management practices at a hillslope scale because of the spatial and temporal variability of ecohydrological processes across a landscape. The Conservation Effects Assessment Project (CEAP) aims to provide a cost-effective method for quantifying benefits of conservation practices on rangelands. This study uses the Rangeland Hydrology and Erosion Model (RHEM) to develop a framework to assess rangeland management practices by quantifying sediment yield and runoff. Kaler Ranch, located in Eastern Arizona, was used as a study site because of their recently implemented rangeland conservation practices. Vegetation parameters were developed based on field data collected across the ranch and used to represent various rangeland management scenarios in RHEM. Peak flow and sediment yield rates were determined for each scenario using RHEM and were used as metrics to evaluate rangeland condition. RHEM provided an adequate method to evaluate the relative differences between upland rangeland management scenarios; however, it was less effective at evaluating changes in management practices within a riparian area.

India is a country with progressing technical and economical development, but the development is not evenly distributed. Farmers in the Indian rural areas are struggling. There are worries that climate changes could have a negative impact on agriculture. This study was performed in Kancheepuram with support from the non-governmental organization Hand in Hand. The aims of this study were to analyze effects on agriculture due to watershed management in a village and to describe the crop patterns in a village and compare the yield with a village without watershed management. Data was collected by interviewing farmers in the villages Arapedu and Tenpakkam. In Arapedu watershed management was applied and in Tenpakkam it was not. Data collected by Hand in Hand on precipitation, village records, well inventory and maps were analyzed. The water level in the wells increased in most wells between 2007 and 2008, but due to short data series it was not possible to affirm if this was due to the watershed management or increased rainfall in the early months of 2008 compared to 2007. No evidence of change in precipitation in the area was observed. Only precipitation data was analyzed since other climate data was absent. Hand in Hand was working within a broad spectrum in the village. Apart from the watershed project they are working with empowerment of women´s situation, self-help groups, microfinance and against child labor. This study period was too short to confirm effects of watershed management. However this study can be used as a baseline study for future evaluations. Key words: Rainwater harvesting, watershed management, Tamil Nadu

This study conducts a dam-scale cost versus benefit analysis in order to explore the feasibility of each the 13 U.S. Army Corps of Engineers (USACE) commissioned dams in Oregon’s Willamette River network. Constructed between 1941 and 1969, these structures function in collaboration to comprise the Willamette River Basin Reservoir System (WRBRS). The motivation for this project derives from a growing awareness of the biophysical impacts that dam structures can have on riparian habitats. This project compares each of the 13 dams being assessed, to prioritize their level of utility within the system. The study takes the metrics from the top three services (flood regulation, hydropower generation and recreation) and disservices (fish mortality, structural risk and water temperature hazards) and creates a rubric that scores the feasibility of each dam within the system. Within a range between 0 to 3 for three dam services and 0 to -4.5 for two disservices, the overall calculated score elucidates for each structure whether its contribution to the WRBRS is positive or negative. Further analysis searches for spatiotemporal trends such as anomalous tributaries or magnified structural risk for structures exceeding a certain age. GIS data from the National Inventory of Dams (NID), U.S. Geologic Survey (USGS) water measurements, raw data from USACE, and peer-reviewed studies comprise the statistics that generate results for this analysis. The computed scores for each dam yield an average overall score of -1.31, and nine of the 13 structures have negative results, indicating that the WRBRS faces challenges going forward. The study seeks to contribute to the increasingly relevant examination of dam networks at the watershed scale.

The goal of this study is to develop a model using GIS to estimate the source and quantity of accumulated sediment in the Emory & Henry College (EHC) duck pond.  Located in the Highlands of Southwest Virginia, the 1,194 acre duck pond watershed consists primarily of agricultural, forested, and low density urban land uses.

The Revised Universal Soil Loss Equation (RUSLE) and the Sediment Distributed Delivery (SEDD) prediction models were used to determine the quantity of eroded sediment and the sediment yield at the duck pond, respectively.  These models require numerous computations, which were performed at the watershed scale with the aid of ArcGIS software.  In ArcGIS the watershed was broken into a raster grid of approximately 5,200 discrete 100 foot by 100 foot grid cells.

The resulting watershed erosion model identified two main sources of sediment: a cluster of farms relatively close to and east of the duck pond, and a harvested timber site north of the duck pond.  The model predicted that 1,076 tons of sediment are delivered into the duck pond annually.

The estimated sediment yield was then compared to the estimated amount deposited between October 2011 and September 2012, as measured by a topographic survey.  The model prediction was found to be within a factor of 6.3x of the measured value.  The predicted and measured sediment yields as well as identified erosion sources can be used to develop a water quality improvement plan and to help alleviate the need for periodic dredging.

Master of Science

One of the most important purposes of surface water resource management is to develop predictive models to assist in identifying and evaluating operational and structural measures for improving water quality. To better understand the effects of external and internal nutrient and organic loading and the effects of reservoir operation, a model is often developed, calibrated, and used for sensitivity and management simulations. The importance of modeling and simulation in the scientific community has drawn interest towards methods for automated calibration. This study addresses using an automatic technique to calibrate the water quality model CE-QUAL-W2 (Cole and Wells, 2013). CE-QUAL-W2 is a two-dimensional (2D) longitudinal/vertical hydrodynamic and water quality model for surface water bodies, modeling eutrophication processes such as temperature-nutrient-algae-dissolved oxygen-organic matter and sediment relationships. The numerical method used for calibration in this study is the particle swarm optimization method developed by Kennedy and Eberhart (1995) and inspired by the paradigm of birds flocking. The objective of this calibration procedure is to choose model parameters and coefficients affecting temperature, chlorophyll a, dissolved oxygen, and nutrients (such as NH4, NO3, and PO4). A case study is presented for the Karkheh Reservoir in Iran with a capacity of more than 5 billion cubic meters that is the largest dam in Iran with both agricultural and drinking water usages. This algorithm is shown to perform very well for determining model parameters for the reservoir water quality and hydrodynamic model. Implications of the use of this procedure for other water quality models are also shown.

The vast majority of large river systems in the United States cross (or comprise) one or more state lines, creating numerous administrative challenges. Addressing these multijurisdictional challenges in an efficient and equitable manner often requires the development of sophisticated institutional arrangements. Several types of "regional organizations" have been created for this purpose, including compact commissions, interstate councils, basin interagency committees, interagency-interstate commissions, federal-interstate compact commissions, federal regional agencies, and the single federal administrator format. These organizations feature a wide variety of authorities and responsibilities; what they inevitably share in common is a hostile political environment, a consequence of political geography and bureaucratic entrenchment. In this study, the challenges associated with the governance, administration, and management of interstate water resources are examined, using the Colorado River Basin as a case study. The Colorado is the only major river in the United States utilizing the "single federal administrator" format, an institutional arrangement that is often criticized for its subordination of the states and its concentration of policy-making authorities in the hands of administrators. When evaluated against carefully defined normative criteria, the Colorado is shown to feature many institutional deficiencies that are, in part, derivative of the Colorado's unique institutional arrangements. The primary objective of this study is to determine if the governance and management of the Colorado could be improved by the establishment of an alternative form of regional water organization. It is concluded that a type of federal-interstate compact commission, if carefully tailored to the political realities of the region, could improve many of the observed institutional deficiencies. This study also presents a widely-applicable methodology for the description and evaluation of institutional arrangements.

In developing natural resources, decision makers are seeking to achieve different objectives, which cannot be reduced to a single objective such as economic efficiency, this covers only part of the problem. Tradeoffs between multiple objective of unequal importance is unavoidable in the process of selection or ranking of alternative developmental projects or plans. Multiobjective technique has the ability to deal with qualitative and quantitative objectives, also it enhances the planning process by involving broader segments of the society in the process of decision making. Compromise programming (CP) and utility worth analysis (UWA), two multiobjective methods were applied on Zarqa River Basin Project (ZRBP) in Jordan. Their appropriateness and suitability as decision aiding tools was examined in this study. For the purpose of the study, five criteria were developed to serve as a basis for the evaluation and 61 farmers and 15 technicians, planners and decision makers were interviewed. High consistency was observed among the results of ranking the six alternatives when both methods were applied, at the same time the ranking of the alternatives according to benefit/cost ratio and the internal rates of return as economic efficiency measures showed no agreement with the multiobjective ranking.

Infiltration, the process of water movement through the soil surface is one of most important hydrological processes to be considered in watershed management. The process depends on rainfall, soil, vegetation and topographic conditions. The last three variables can be influenced by human land-uses. This study is concerned with the influence of landuse types (categories) on infiltration at the upper Ciliwung watershed of West-Java, Indonesia. Sixty six infiltration measurements were carried out in 5 types of land-uses i.e. natural forest, agriculture, settlement, productive (old) tea and new tea plantation areas. The measurements were done using ring infiltrometers. The data obtained were expressed in the form of Philip's equation I = st1I2 + At, where I is cumulative infiltration; S is sorptivity; t is time; A is a parameter which was calculated from saturated hydraulic conductivity (K). Crown cover, slope gradient and soil variables such as soil moisture, organic carbon content, total porosity, bulk density were also analysed from each of the 66 sites. The results of the study shows that land-use types have significant influence on these soil variables and on infiltration. Crown cover and human activities in term of land management are among the most important factors which affect soil condition. These variables mostly influence total porosity of soil which is the most important variable to determine sorptivity and hydraulic conductivity. High percentage of crown cover and less human activity in forest area result in high accumulation of litter and humus and high total porosity of soil. On the other hand, settlement and new tea plantation areas have comparatively low crown cover and more frequent human activity which result in soil compaction. Discriminant function analysis of land-use categories shows that the soil under forest is very distinct from the soils under other land-use types. However, the soils under the remaining land-use types are more similar to each other, especially between the soil of settlement and tea plantations. The rank of infiltration rate from the highest to the lowest magnitude is as follows; natural forest, agriculture, productive tea plantation, new tea plantation and settlement areas. Infiltration rates under natural forest and agriculture are significantly different from each other as well as from those in the last three land- use types. However, there are no significant differences in infiltration rates among the last three land-use types. The result of this study also provides basic information for landuse management and further research in order to solve soil and water conservation and management problems in the watershed.

The fresh water resources of the world are stressed due to the increasing population. Theclimate change has also affected the water resource availability due to the occurrence offrequent and uneven extreme events such as drought and flash floods. In the context ofPeloponnese, Greece water resource management is an important issue for tourism developmentas well as the water supply for the people in the peninsula. To assess the potential climatechange and to quantify the water resource availability linear regression trend analysis andhydrological modeling has been done in this study. The hydro-climatic data (Temperature,precipitation, evapotranspiration and precipitation surplus) show a decreasing trend when a longstudy period (1951-2008) is considered; however, all the trends are not statistically significantexcept precipitation, actual evapotranspiration and precipitation surplus. Similarly, the case isquite opposite when IPCC standard period (1961-1990) is considered. In this period,precipitation and precipitation surplus is increasing but not statistically significant, whereastemperature and potential evapotranspiration has decreasing and statistically significant trendand actual evapotranspiration is decreasing but not statistically significant. Hence, it cannot beconcluded that the climate has changed in the peninsula with reference to linear regressionanalysis. On the other hand, it should be noted that the water resource availability will decreasein the peninsula if the current trend in the hydro-climatic data continues. Furthermore, a spatialanalysis shows that water availability is less in the eastern part and the coastal area of thepeninsula due to low precipitation and high evapotranspiration. Hence, these areas need to befocused on for the better water resource management and planning. However, the uncertaintiesrelated to data and model should be accounted for in the water resource management andplanning.

Lake Okeechobee is the largest lake in the southeastern United States and is a central component of the hydrology and environment of the Everglades ecosystem in South Florida. The natural state of the lake has been degraded as wetlands and natural habitats in the Lake Okeechobee watershed have been replaced with farms, urban areas, and dairy operations. Excessive phosphorus loadings from these diverse sources have been identified as the leading causes of the lake’s impairment. For more than four decades, many resources have been allocated to regional and local restoration efforts to reduce phosphorus loadings into the lake. However, phosphorus loadings have not decreased and the recovery of the lake could take more time, particularly with today’s limited local budgets. Market-based instruments, such as water quality trading programs, have emerged over the past decades to cost-effectively achieve water quality objectives in impaired watersheds. The main objective of this dissertation was to assess the environmental and economic benefits of implementing a phosphorus trading program in Lake Okeechobee watershed, compared to a conventional command-and-control approach. A comprehensive literature overview of nationally and internationally implemented trading programs was conducted to highlight advantages and challenges of these programs towards achieving water quality goals, and to outline the essential elements of a successful program. Furthermore, a modeling framework, integrating a hydrologic-water quality model with an economic model, was developed to assess the potential cost savings that trading might offer over a command-and-control approach. The modeling framework was applied in three priority basins of the Lake Okeechobee watershed. In each case, while developing trading scenarios to achieve phosphorus load reduction targets, the trading program was less expensive than the conventional command-and-control approach. This research provided the foundation for stakeholders to better understand whether water quality trading has the potential to work in the Lake Okeechobee watershed and to facilitate the development of a pilot program. In addition, it offered some insights on the potential economic opportunities that pollution sources would have by participating in the trading program. The modeling framework developed in this dissertation could facilitate the assessment of future water quality trading programs in other watersheds.

Few elements in surface waters are monitored as closely as phosphorus (P) due to its role in the eutrophication and degradation of surface waters. Limiting P mobilization from source areas is, therefore, a central goal of water quality protection plans. But the work of locating sources in mixed-use watersheds is challenged by the spatial and temporal variability of critical source areas (CSAs) of P. Synoptic sampling is a proven method for capturing the spatial variation of water quality parameters in surface waters, though it's not often used to track temporal dynamics across the same study area. Phosphorus fractionation is an analytical method that divides the total P (TP) in water into fractions, which for this study included total dissolved P (TDP), particulate P (PP), dissolved reactive P (DRP), and dissolved organic P (DOP). The objective of this study was to demonstrate the utility of combining temporally repeated synoptic sampling with simple P fractionation as a unique strategy for locating and characterizing CSAs of P. Seven synoptic sampling campaigns were conducted over a two-year period (March 2015 – July 2016) in a rural, montane watershed in north central Utah, USA. In each campaign, we sampled 18 sites across three tributaries (Main Creek, Spring Creek, and Little Hobble Creek) during three distinct, annual hydrologic periods (rising flow, peak flow, and baseflow). Temporal repetition clearly identified the rising flow period as the period with greatest P loading in the watershed. Combining repeated synoptic sampling and P fractionation successfully identified CSAs of P and most probable transfer pathways. Specifically, stream segments along lower Spring Creek and Main Creek were associated with the greatest increases of PP loads during periods of rising flow and peak flow. In the same time periods, the greatest DOP loads stemmed from forested areas as well as areas in the lower watershed associated with winter grazing of cattle. The watershed exhibited a significant background concentration of DRP from groundwater-driven subsurface sources in the lower half of the watershed that persisted year-round. These assessments can be used to develop management practices that limit various P loads from these respective critical source areas. The characterization of CSAs could not have been made using only a traditional synoptic sampling approach. This study demonstrated that the combination of repeated synoptic sampling and P fractionation can be an effective technique for locating and characterizing critical P source areas in order to guide best management practices that improve surface water quality.