On-site sewage systems, such as septic tank-absorption trenches, are used by approximately 20 000 people who live within the catchments that supply Sydney??s drinking water. These systems discharge sewage, treated to varying degrees depending on the system type and level of maintenance, to the environment. This can result in contamination of drinking water supplies if systems are not designed or managed appropriately. The aim of the project was to develop a methodology to define appropriate buffer distances between on-site sewage systems and waterways in Sydney??s drinking water catchments, to ensure the protection of drinking water quality. Specific objectives included: identifying the current status of on-site sewage management; assessing the effluent quality and treatment performance of septic tanks, aerated wastewater treatment systems (AWTS) with disinfection and an amended material sand mound; and development of an appropriate methodology for delineating buffer distances and assessing development applications. Viruses were used as a focus for delineating the buffer distances due to their mobility and robustness in the environment, and the potential health consequences of their presence in drinking water. A Quantitative Microbial Risk Assessment (QMRA) model was developed to calculate the cumulative impact of the on-site sewage systems in the Warragamba catchment based on data from literature and experiments, with consideration of virus loads from sewage treatment plants within the catchments. The model enabled consideration of what was a tolerable impact in terms of the resulting infections within the community. The QMRA the tolerable loads of viruses from the Warragamba catchment were 108 viruses per year in raw water and 104 viruses per year in treated water. A log reduction method was developed to facilitate individual site development assessments. This method was compared to other management approaches to development assessment: fixed minimum buffer distances of 100m, reducing failure rates to zero, and the use of a preferred system. Each of these methods had a limit for how much they could reduce virus loads to the catchment due to either failure or short buffer distances at some sites. While the log reduction method is limited by the failure rates, the method provides a quantitative measure of risk by which maintenance inspections can be prioritised.

<p> </p><p>High pressure on water from competing users has changed the past perception of water as gift to water as a resource that requires sustainable management. Management of water resource needs active stakeholders’ involvement for its sustainability. Many organizations along with the national water policy have been calling for active stakeholders’ involvement for management of the resource.  In Usangu catchment conflicts over accessing water between farmers and pastoralists and between upstream and downstream have been common. Water allocation in the catchment has been done without involving stakeholders and adequate consideration of the rivers’ carrying capacity. This study focuses on stakeholders’ involvement in Usangu catchment. Six villages in three sub-catchments were studied and data were collected using questionnaire through face to face interview and focus group discussion. The study found that there is limited stakeholders’ involvement in Usangu catchment. In some places involvement is at basic stage, in other places there is no involvement. Interaction within stakeholders’ category was documented, while no stakeholders’ interaction between sub-catchments was discovered. Moreover, some challenges for active involvement were noted, such as lack of coordination between institutions operating in the catchment, high illiteracy rate and lack of awareness, and with lack of legislation support. The issue of limited stakeholders’ involvement in Usangu catchment is complicated, there is no single and comprehensive solution; integration of different approaches which are cross-sectoral in nature is needed for sustainable water management.</p><p> </p>

<p><font face="Times New Roman"> <p align="left">The objective of this study was to determine the hydrosalinity fluxes associated with overland and subsurface (vadose zone) flow for different soils and land uses. For this purpose, the following data were collected during 2005 and 2006 in a typical small scale catchment located near the town of Riebeeck-Wes: weather data, hydrological and water quality measurements, soil water contents and chemistry, and vegetation growth. The area is characterized by a Mediterranean climate receiving winter rainfall of approximately 300 mm a <font face="Times New Roman">catchment is conservative, with Na</font> <font face="Times New Roman" size="1"><font face="Times New Roman" size="1">+ </font></font><font face="Times New Roman">and Cl</font><font face="Times New Roman" size="1"><font face="Times New Roman" size="1">- </font></font><font face="Times New Roman">being the dominant ions.</font></p> </font></p>

Eight agricultural catchments in south Sweden were investigated for factors that may affect phosphorus (P) load and retention in the downstream situated wetlands (WL). P load is known to affect retention, and is determined by hydrological and geographical catchment characteristics. The wetlands were small (0.02-0.88%) in relation to their catchments (CA) and varied in design. Net sedimentation and P retention was determined with sedimentation plates during one year. The variables that best explained differences in particles and TP retention were the hydraulic load (q), TP load and the wetland length to width ratio. Contrary to expectations there was no correlation between factors that could be associated with erosion (i.e. slope and soil clay content) and retention of neither particles nor TP. Generally, the highest amounts of settled particles and P were found close to the wetland inlets, but soil disturbance (i.e. tillage) and high q increased the settling distance. It was likely that the smallest clay particles were too unaggregated to settle within these wetlands. Factors not included, such as wetland vegetation and bioturbation may have a large impact on P retention and this should be further investigated. The study also points to the difficulties in scaling down geological and P loss data from a regional to a local scale, as there can be large local deviations from the regional standard values. An easy method for identification of local “hotspots” for P losses should be of value for planning the location of future wetlands.

In many parts of the world, developed as well as developing, rivers are not gauged for continuous monitoring. Streamflow prediction at such "ungauged" river catchments requires information transfer from gauged catchments that are perceived to be hydrologically similar to them. Achieving good predictability at ungauged catchments requires an in-depth understanding of the physical and climatic controls on hydrologic similarity among catchments. This dissertation attempts to gain a better understanding of these controls through three independent research studies that use data from catchments across the continental United States. In the first study, I explore whether streamflow similarity among nearby catchments is preserved across flow conditions. Catchments located across four river basins in the northeast United States are analyzed to quantify the spatio-temporal variability in streamflows across flow percentiles. Results show that similarity in catchment stream response is dynamic and highly dependent on flow conditions. Specifically, the coefficient of variation is high at low flow percentiles and gradually reduces for higher flow percentiles. This study concludes that high variability at low flows is controlled by the dominance of high evaporative demand, whereas low variability at high flows is controlled by the dominance of precipitation input relative to evapotranspiration. In the second study, I examine whether streamflow similarity among catchments exists across a wide range of climatic and geographic regions. Data from 756 catchments across the United States is used and daily streamflow at each catchment is simulated using distance-based streamflow interpolation from neighboring catchments. With this approach, high predictability at a catchment indicates that catchments in its vicinity have similar streamflows. Results show that high predictability catchments are mainly confined to the Appalachian Mountains, the Rocky Mountains, and Cascade Mountains in the Pacific Northwest. Low predictability catchments are located mostly in the drier regions of US to the west of Mississippi river. Results suggest that streamflow similarity among nearby catchments is more likely in humid runoff-dominated regions than in dry evapotranspiration-dominated regions. In the third study, my goal is to identify what constitutes the essential information that must be transferred from gauged to ungauged catchments in order to achieve good model predictability. A simple daily time-step rainfall-runoff model is developed and implemented over 756 catchments located across the United States. Results show that the rainfall-runoff model simulates well at catchments in humid low-energy environments, most of which are located in the eastern part of the US, the Rocky Mountains, and to the west of Cascade Mountains. Within these regions, transfer of the parameter characterizing hydrograph recession provides reliable streamflow predictions at ungauged catchments, with a loss in prediction efficiency of less than 10% in most catchments. The results presented in this dissertation show that climate exerts a strong control on hydrologic similarity among catchments. The results further suggest that an understanding of the interaction between climate and topography is essential for quantifying the spatial variability in catchment hydrologic behavior at a regional scale.

<p>Water is a basic necessity for sustaining life and development of society. Proper management, protection and exploitation of water resources are the challenges imposed by population growth, increasing pressure on the water and land resources by competing usage. A good amount of clean water exists on Earth although it is normally inadequate in supply because of anthropogenic activities such as deforestation and land use change. Like many other catchments that provide economic activities for the community’s livelihood, the Chalimbana river catchment in Zambia has been deforested heavily and most of the local communities believe that deforestation could be the main contributing factor to the drying up of Chalimbana River. The objective of this study was to analyse the impact of deforestation on the stream flow of Chalimbana River Catchment with the help of a conceptual hydrological model, HBV. There was a 24% reduction in the annual average rainfall amounts for the deforested period as compared to the period before deforestation. The Qrec/Qsim ratios had revealed that the annual stream flow generation for the period after deforestation (1987 to 1996) for the Chalimbana River had decreased by about 12% as compared to the period with enough forest cover (1975 to 1985). The ratio of annual Qrec/P had indicated that after a 30% forest loss in Chalimbana catchment, there was a 33% increase in the generation of the stream flow. Based on the results that were obtained, a number of recommendations aiming at improving the catchment management were made.</p>

<p><font face="Times New Roman"> <p align="left">The objective of this study was to determine the hydrosalinity fluxes associated with overland and subsurface (vadose zone) flow for different soils and land uses. For this purpose, the following data were collected during 2005 and 2006 in a typical small scale catchment located near the town of Riebeeck-Wes: weather data, hydrological and water quality measurements, soil water contents and chemistry, and vegetation growth. The area is characterized by a Mediterranean climate receiving winter rainfall of approximately 300 mm a <font face="Times New Roman">catchment is conservative, with Na</font> <font face="Times New Roman" size="1"><font face="Times New Roman" size="1">+ </font></font><font face="Times New Roman">and Cl</font><font face="Times New Roman" size="1"><font face="Times New Roman" size="1">- </font></font><font face="Times New Roman">being the dominant ions.</font></p> </font></p>

Climate detection studies point to changes in global surface temperature and rainfall patterns over the past 100 years, resulting from anthropogenic influences. Studies on the analysis of rainfall patterns [1950 – 1999] in southern Africa’s summer rainfall areas show an increase in the duration of late summer dry spells, and this change is in line with expected effects of global warming. Observations of surface temperature increases are consistent with climate projections from General Circulation Models (GCMs), as well as with overall changes in climate over the past century. As such, the alterations in climate conditions have a potential to significantly impact agro-ecosystems. The changes in these climatic patterns are projected to result in a cascade of changes in crop responses, and their associated crop yield-limiting factors through altering water available for agriculture, as well as yield-reduction factors by increasing pest/disease/weed prevalence, both of which may lead to agricultural production being affected severely. The objective of this study is to explore effects of scenarios of climate change on agrohydrological responses in the Limpopo Catchment, with an emphasis on the development and application of statistical modelling and analysis techniques. The algorithms of temperature based life cycle stages of the Chilo partellus Spotted Stem Borer, those for agricultural water use and production indicators, and for net above-ground primary production (an option in the ACRU model) as a surrogate for the estimation of agricultural production. At the time that these analyses were conducted, the downscaled daily time step climate projections of the ECHAM5/MPI-OM GCM, considered to indicate projections that are midway between the extremes from other GCMs for southern Africa, were the only scenarios available at a high spatial resolution which had been configured for South Africa. Further, the statistical analysis techniques conducted in the dissertation include quantitative uncertainty analyses on the temperature and precipitation projections from multiple GCMs (the output of which subsequently became available), as well as validation analyses of various algorithms by comparing results obtained from the GCM’s present climate scenarios with those from historically obtained climates from the same time period. The uncertainty analyses suggest that there is an acceptable consistency in the GCMs’ climate projections in the Limpopo Catchment, with an overall high confidence in the changes in mean annual temperature and precipitation projections when using the outputs of the multiple GCMs analysed. However, the means of monthly projections indicated varied confidence levels in the GCMs’ output, more so for precipitation than for temperature projections. Findings from the Validation analyses of the ECHAM5/MPI-OM GCM’s present climate scenario estimations of agricultural production and the agricultural yield-reduction (Chilo partellus) factor against those from observed baseline climate conditions for the same time period indicated a positive linear relationship and a high spatial correlation. This suggests that the ECHAM5/MPI-OM GCM’s present climate scenario is relatively robust when compared with output from observed climate conditions. ECHAM5/MPI-OM GCM projections show that agricultural production in future might increase by over half in the southern and eastern parts of the Limpopo Catchment compared to that under present climate conditions. Findings from the projections of the yield-limiting factor representing water available for agriculture over the Catchment suggest increases in the agricultural water productivity indicator under future climate conditions, with pronounced increases likely in the eastern and southern periphery. On the other hand, the agricultural water use indicator maintained high crop water use over most of the Catchment under all climate scenarios, both present and future. These positive effects might be due to this particular GCM projecting wetter future climate conditions than other GCMs do. Similar increases were projected for the yield-reduction factor, viz. the development of Chilo partellus over the growing season. These results suggest an increase in the C. partellus development, and thus prevalence, over the growing season in the Catchment, and this correlates spatially with the projected rise in agricultural production. The projected positive effects on agricultural production are thus likely to be reduced by the prevalence in agricultural yield-reduction factors and restricted by agricultural yield-limiting factors. The techniques used in this study, particularly the temperature based development models for the agricultural yield-reduction factor and the agricultural water use/water productivity indicators, could be used in future climate impact assessments with availability of outputs from more and updated GCMs, and in adaptation studies. This information can be instrumental in local and national policy guidance and planning. Keywords: Climate projections (scenarios), agricultural production, agricultural yield-reduction (Chilo partellus) and -limiting factors, uncertainty analysis, validation analysis. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

The intensification of agriculture through Europe has led to a lot of environmental issues. Among these are the increased use of fertilizer and pesticides which also constitutes a risk for many water resources. This is mainly due to the leakage of nitrate and pesticides to the water which makes it unsuitable for drinking. The aim of this study was to investigate whether the nearby agriculture constituted a risk in the catchment of Skottorp. If risks were found, the study was also aiming to evaluate possible measures that could be taken. An additional aim was to find out whether a co-operative agreement between the local authorities responsible for the catchment and the farmers would be a possible solution in case of future problems. For the study, water data related to agriculture was analyzed statistically and interviews were performed with the farmers. The study shows that there are no imminent risks to the water in the catchment related to agriculture, which makes measures unnecessary. If problems would arise in the future the study also shows that co-operative agreements are a suitable course of action.

The research presented in the thesis develops an approach for the estimation and mapping of pollutant spreading in catchments and the associated uncertainty and risk of pollution. The first step in the approach is the quantification and mapping of statistical and geographical distributions of advective solute travel times from pollutant input locations to downstream recipients. In the second step the travel time distributions are used to quantify and map the spreading of specific pollutants and the related risk of water pollution. In both steps, random variability of transport properties and processes is accounted for within a probabilistic framework, while different scenarios are used to account for statistically unquantifiable uncertainty about system characteristics, processes and future developments. This scenario approach enables a transparent analysis of uncertainty effects that is relatively easy to interpret. It also helps identify conservative assumptions and pollutant situations for which further investigations are most needed in order to reduce the uncertainty. The results for different investigated scenarios can further be used to assess the total risk to exceed given water quality standards downstream of pollutant sources. Specific thesis results show that underestimation of pollutant transport variability, and in particular of those transport pathways with much shorter than average travel times, may lead to substantial underestimation of pollutant spreading in catchment areas. By contrast, variations in pollutant attenuation rate generally lead to lower estimated spreading than do constant attenuation conditions. A scenario of constant attenuation rate and high travel time variability, with a large fraction of relatively short travel times, therefore appears to be a reasonable conservative scenario to use when information is lacking for more precise determination of actual transport and attenuation conditions.