The National Water Act (Act 36 of 1998) provides for an ecological Reserve as the quantity (flow) and quality of water needed to protect aquatic ecosystems. While there are methods available to quantify the ecological Reserve in terms of flow, methods of linking flow to water quality are lacking. Therefore, the research presented in this thesis investigated various modelling techniques to estimate the effect of flow on water quality. The aims of the research presented in this thesis were: Aim 1: Can the relationship between flow and water quality be accurately represented by simple statistical models? Aim 2: Can relatively simple models accurately represent the relationship between flow and water quality? Aim 3: Can the effect of diffuse sources be omitted from a water quality model and still obtain realistic simulations, and if so under what conditions? Aim 4: Can models that solely use historical monitoring data, accurately represent the relationships between flow and water quality? In Chapter 3, simple Q-C regressions of flow and water quality were investigated using Department of Water Affairs (DWA) historical monitoring data. It was found that while flow versus salinity regressions gave good regression fits in many cases, the Q-C regression approach is limited. A mechanistic/statistical model that attempted to estimate the point and diffuse signatures of nutrients in response to flow was developed in Chapter 4 using DWA historical monitoring data. The model was verified as accurate in certain case studies using observed point loading information. In Chapter 5, statistical models that link land cover information to diffuse nutrient signatures in response to flow using DWA historical data were developed. While the model estimations are uncertain due to a lack of data, they do provide an estimation of the diffuse signature within catchments where there is flow and land cover information available. Chapter 6 investigates the extension of an existing mass-balance salinity model to estimate the effect of saline irrigation return flow on in-stream salinity. The model gave accurate salinity estimates for a low order stream with little or no irrigation within its catchment, and for a permanently flowing river within a catchment used extensively for irrigation. Chapter 7 investigated a modelling method to estimate the reaction coefficients involved in nitrification using only DWA historical monitoring data. Here, the model used flow information to estimate the residence time of nutrients within the studied river reaches. While the model obtained good estimations of nitrification for the data it was applied to, very few DWA data sets were suitable for the model. Chapter 8 investigated the ability of the in-stream model QUAL2K to estimate nutrient concentrations downstream of point and diffuse inputs of nutrients. It was found that the QUAL2K model can give accurate results in cases where point sources dominate the total nutrient inputs into a river. However, the QUAL2K simulations are too uncertain in cases where there are large diffuse source inputs of nutrients as the load of the diffuse inputs is difficult to measure in the field. This research highlights the problem of data scarcity in terms of temporal resolution as well as the range of constituents measured within DWA historical monitoring data for water quality. This thesis in addition argues that the approach of applying a number of models is preferable to applying one model to investigate the research aims, as particular models would be suited to particular circumstances, and the development of new models allowed the research aims of this thesis to be explored more thoroughly. It is also argued that simpler models that simulate a few key processes that explain the variation in observed data, are more suitable for implementing Integrated Water Resource Management (IWRM) than large comprehensive water quality models. From this research, it is clear that simple statistical models are not adequate for modelling the relationship between flow and water quality, however, relatively simple mechanistic models that simulate a limited number of processes and water quality variables, can provide accurate representations of this relationship. Under conditions where diffuse sources are not a major factor within a catchment, models that omit diffuse sources can obtain realistic simulations of the relationship between flow and water quality. Most of the models investigated in this thesis demonstrate that accurate simulations of the relationships between flow and water quality can be obtained using solely historical monitoring data.

The effect of altitude on individual storm precipitation in some of the San Dimas experimental watersheds is investigated. It is found that there is a well- defined increase of storm precipitation with altitude for storms greater than one inch. This increase is a linear function of storm depth. Using 41 storms of different magnitudes, a precipitation -altitude relationship is derived for a small area in the San Dimas Experimental Forest. The regionalization of this relationship and its transferability are tested by analyzing differences (errors) between computed and observed storm precipitation values in each case. In testing the regionalization of the precipitation- altitude relationship by computing mean areal storm precipitation over a larger area the standard error of estimate is around 11 percent. In transfering the same relationship the results are not as good and give a standard error of 16 percent. For individual points, however, the error is much higher. A rainfall- runoff model is used as a tool for evaluating the effect of precipitation errors, on simulated streamflow, in a watershed of 4.5 square miles. For annual flows, errors range between 3.4 and 12.3 percent while errors in simulated monthly flows are as high as 22 percent. It is also evident that there is a strong dependence of the error magnitude on the state (wet, dry, etc.) of the preceding year or months, whichever is applicable. An error propagation is observed as a result of consistently over -estimating the precipitation input to the model. This evaluation is more of a qualitative nature and the values of error given should be viewed in this sense.

McKinney Butte, a late Tertiary andesite vent and flow complex, is located near the town of Sisters, Oregon, in the upper Deschutes Basin, and is situated along the structural trend that forms the eastern margin of the High Cascades graben (Sisters fault zone and Green Ridge). Rapid development and over appropriated surface water resources in this area have led to an increased dependence upon groundwater resources. A primary concern of resource managers is the potential impact of expanding groundwater use on stream flows and spring discharge. Two sets of springs (McKinney Butte Springs and Camp Polk Springs) discharge to Whychus Creek along the east flank of McKinney Butte, and during low-flow conditions supply a substantial component of the total flow in the creek. Despite their contribution to Whychus Creek, the springs along McKinney Butte are small-scale features and have received less attention than larger volume (> 2 m³/s) springs that occur in the basin (i.e., Metolius Spring and Lower Opal Springs). This study used discharge measurements in Whychus Creek upstream and downstream of the springs, and mixing models using measurements of electrical conductivity and temperature in the springs and Whychus Creek to determine the contribution of the springs to the creek. Isotopic, thermal, and geochemical signatures for the McKinney Butte and Camp Polk Springs, and local streams (Whychus Creek and Indian Ford Creek) and springs (Metolius Spring, Paulina Spring, Alder Springs, and Lower Opal Spring) were assessed to determine the source(s) of the McKinney Butte and Camp Polk Springs. The discharge and hydrochemical data along with hydraulic head data from local wells were used in the development of a conceptual model of groundwater flow for the McKinney Butte area. Discharge from the McKinney Butte Springs supplies the majority of water to Whychus Creek on the east flank of McKinney Butte (~0.20 m³/s), provides up to 46% of the flow in the creek, and is relatively stable throughout the year. Discharge from the Camp Polk Springs is less than 0.05 m³/s. Isotopic, thermal, and geochemical signatures indicate distinct sources for the McKinney Butte and Camp Polk Springs. Groundwater discharged at the McKinney Butte Springs is depleted in heavy stable isotopes (δD and δ¹⁸O) relative to the Camp Polk Springs. Recharge elevations inferred from stable isotope concentrations are 1800-1900 m for the McKinney Butte Springs and 950-1300 m for the Camp Polk Springs. Elevated water temperature in the McKinney Butte Springs relative to the average air temperature at the inferred recharge elevation indicates the presence of geothermal heat and implies deep circulation in the flow system. The temperature in the Camp Polk Springs is not elevated. The Camp Polk Springs, though not the McKinney Butte Springs, contain elevated concentrations of ions Cl, SO₄, and NO₃ that are indicative of contamination. The study results indicate the source of the Camp Polk Springs is shallow groundwater whereas the McKinney Butte Springs discharge water that has circulated deep in the groundwater flow system. Additionally, the hydrochemical traits of the McKinney Butte Springs are similar to Metolius Spring, suggesting discharge from the McKinney Butte Springs is controlled by the structural trend that forms the eastern margin of the High Cascades graben. The significant difference in discharge between the McKinney Butte Springs and Metolius spring may be related to the size of faults that occur locally.

Thesis (PhDEng)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: The interaction between moving water and the physical attributes of a river, as displayed by the channel morphology, determines the availability of physical habitat for aquatic species and thus also the condition of the ecosystem. As such, the environmental flow assessment process requires knowledge on how changes in the flow regime will affect both the morphological and hydraulic conditions within a river channel. With the increasing development of water-related infrastructure in mountain regions, knowledge of the morphological and hydraulic characteristics of rivers in the upper catchment areas is very important. Cobble and boulder bed rivers in the Western Cape are typical examples. They are characterized by steep gradients, great variability in sediment size and relatively low flow depths. The bed configuration contains a series of pools, steps, rapids, riffles and plane beds, while energy losses are high as a result of turbulence and hydraulic jumps. Due to their wideranging morphological and associated hydraulic attributes, the physical habitats within these rivers are extremely diverse, both on a spatial and temporal scale. This study addresses the interaction between moving water and the physical attributes of cobble and boulder bed rivers. Empirical, semi-empirical and theoretically based models are developed which define the hydraulic and morphological related characteristics of environmental flow components in cobble and boulder bed rivers. They cover macro scale channel deformation, the scouring of sand from the interstitial spaces between the cobbles as well as velocity-depth relationships, which prove to be key components in the assessment of environmental flow requirements in cobble and boulder bed rivers. / AFRIKAANSE OPSOMMING: Die wisselwerking tussen die vloeiende water en die fisiese eienskappe van 'n rivier, soos beskryf deur die morfologie, bepaal die beskikbaarheid van habitat vir akwatiese spesies en gevolglik ook die welstand van die ekosisteem. Kennis omtrent die impak van 'n veranderde vloei regime op beide die morfologiese en die hidrouliese toestande in 'n rivierloop is dus nodig vir die bepaling van omgewingsvloeibehoeftes. Met die toenemende ontwikkeling van water-verwante infrastruktuur in bergagtige gebiede is 'n grondige kennis van die morfologiese en hidrouliese eienskappe van riviere in hierdie bo-opvanggebiede gebiededend noodsaaklik. Spoelklip riviere in die Wes-Kaap is tipiese voorbeelde van sulke riviere. Hierdie riviere word gekenmerk deur steil hellings, 'n wye verskeidenheid sedimentgroottes, relatiewe lae vloeidieptes en hoë energieverliese as gevolg van turbulensie. Verder bevat die ri vierbed afwisselend poele en stroomversnellings en gevolglik word 'n wye verskeidenheid habitat tipes in hierdie riviere aangetref. Hierdie studie fokus op die interaksie tussen bewegende water en die fisiese eienskappe van spoelklip riviere. Met behulp van empiriese, semi-empiriese en teoretiese modelle word die morfologiese en hidrouliese eienskappe van omgewingsvloeibehoeftes in spoelklip riviere aangespreek. Dit sluit makroskaal kanaal vervorming, die uitskuur van sand tusen die spoelklippe asook die verwantskap tussen vloeisnelheid en vloeidiepte in. Hierdie aspekte kan beskou word as van die sleutel elemente vir die bepaling van omgewingsvloeibehoeftes in spoelklip riviere.

The Klein Berg River catchment is intensely cultivated with orchards, vineyards and wheat, while also ensuring a water supply to the main urban center, Tulbagh, and the two conservation areas (Waterval and Groot Winterhoek). The primary objective of this thesis is to determine channel change over a long and short time period, and to relate these changes to landuse change within the catchment. <br /> <br /> Assessing stability of a selected reach within the catchment was done on a short term basis with the use of erosion pins and cross<br /> profiles, while aerial photographs of over 55 years (acquired during 1942, 1967, 1987 and 1997) which were analysed using Geographic Informations Systems. Rainfall and discharge data, which were available for a period of 49-years were statistically analysed and used to determine trends. Vegetation characteristics were assessed by means of transects within the study reach. The results over the short time period (18 months) indicate noticeable channel change in the form of erosion and deposition within the channel. Bank material composition and riparian invasive alien vegetation play an important role in bank stability. Sand was the dominant grain size of the bank material, and fluvial entrainment occurred during periods of high flow. Woody alien trees prevent the growth of protective ground vegetation, and thus the soil is prone to erosion. Undercutting was also observed with the invasive woody trees, resulting in treefall. Debris dams were also common in the channel and depending on their position in the channel, either cause or prevent bank erosion. Landuse change over the 55-year period illustrated its effects on channel stability. Shrublands within the catchment has been replaced with invasive alien vegetation along the riparian zone, while shrublands along the Obiekwa Mountains, were replaced with cultivated lands. The patterns (shape and size) of lateral and point bars within the study area changed significantly within the 55-year period, which indicates a change in the discharge and sediment dynamics within the catchment. The change in sediment dynamics may be due to agricultural activities and urbanization. The increased trend in rainfall, especially during the winter season within the catchment is also an important catchment control. The study has revealed the integrated nature of variables within the catchment. It is thus recommended that a holistic and integrated approach at a catchment scale is required in the assessment of channel change of a river.

Velocity measurements from drifter GPS records are assimilated and used in an ensemble-based inversion technique to extract the river bathymetry. The method is tested on a deep meandering reach and a shallow braided reach of the Kootenai River in Idaho, USA. The Regional Ocean Modeling System (ROMS) is used to model numerous statistically varied bathymetries to create an ensemble of hydrodynamic states. These states, the drifter observations, and the uncertainty of each are combined to form a cost function which is minimized to produce an estimated velocity ���eld. State augmentation is then used to relate the velocity ���eld to bathymetry. Our goals are to assess whether ROMS can accurately reproduce the Kootenai River ���ow to an extent that depth inversion is feasible, investigate if drifter paths are sensitive enough to bottom topography to make depth inversion possible, and to establish practical limitations of the present methodology. At both test sites, the depth inversion method produced an estimate of bathymetry that was more accurate and more skillful than the prior estimate. / Graduation date: 2013

As anthropogenic demands on water resources intensify instream flow needs are becoming an increasingly important area of study, particularly over winter months during which time little is known about the behaviour and physiology of fishes. This thesis addresses the implications of water withdrawal from a small in situ stream on brook trout (Salvelinus fontinalis) during the winter of 2007 and 2008 in the Rocky Mountains. Water was withdrawn from one of two stream enclosures reducing the discharge by 50% and 75%, for 4hrs daily. Behaviour was monitored using radio transmitters that were externally attached to the small trout. Changes in physiology were monitored by measuring stress hormone levels and by measuring predicted body composition parameters using bioelectrical impedance analysis. Trout reacted to water withdrawal by being more active, but this change in behaviour did not elicit detectable changes in physiology. / x, 129 leaves : ill. ; 29 cm. --

Problems in the water sector range from degradation and depletion of water resources as a result of the impacts of land based anthropogenic activities, to the impacts of natural hydrological disasters and floods, while inadequate availability of water is at the core of most water related disputes in arid and semi-arid areas at local, regional, national and international levels. In the past, finding practical solutions for these problems fell neatly within the traditional scope of water resources management, which hinged almost entirely on economic viability of engineering oriented endeavors. However, a new set of management challenges has arisen following the high priority nowadays given to equity in water allocation and the protection of the natural environment above other issues. These new challenges have created a need for devising and adopting suitable management approaches, especially that would take social considerations into account. One of the approaches that provides promise relative to the new directions in dealing with contemporary water issues is integrated water resources management (IWRM). One objective of this study was to critically review the definitions and the fundamental principles of IWRM with the view of determining its applicability in developing countries and highlighting difficulties that may be faced regarding the adoption and implementation of this integrated approach. Swaziland is atypical example ofa developing country that is engulfed by the diverse water resources issues highlighted above and is currently engaged in updating water management legislation. Hence, Swaziland's experiences were used to put in perspective the key points and barriers regarding the adoption and implementation of IWRM. The catchment, the recommended spatial unit of IWRM, poses the first practical barrier, as catchments often cross both political and administrative boundaries, thereby creating the need for many water management problems to be solved across catchments with international security issues, cultural issues, different levels of development and different hydroclimatic regimes. The successful implementation of IWRM depends on effective participation of stakeholders. Lack of information flow between stakeholders of different backgrounds limits informed participation. Therefore, it is necessary to develop tools such as decision support systems (DSSs) that will foster easier multilateral information flow and aid decision making. IWRM requires information which itself should be managed in an integrated manner and be readily accessible. This is not always the case in developing countries with shortage of funds for data collection, manipulation and storage as well as adequately trained and experienced staff With the shortage of sufficiently long and reliable hydrological data for water management, the alternative is to synthesize records through hydrological modelling. Another objective of this study was to evaluate and test the suitability of the ACRU modelling system, a daily time-step agrohydrological model, to simulate catchment level hydrological processes and land use impacts as part of the assessment studies which form an integral part of integrated water resources management. ACRU was set up for the Mbuluzi, a 2958 km2 catchment in Swaziland. The catchment was subdivided into 40 sub catchments, after which the model was used for assessing both the impacts of land use and management changes on runoff yields and available water resources by evaluating present and future sectoral water demands, determining whether river flow from Swaziland into Mozambique meets the quantitative requirements of the international agreement existing between the two countries, and evaluating sediment yield and its spatial and temporal variation as well as its response to potential changes in land management. The physical-conceptual structure of the model, its multi-level adeptness regarding input information requirements, coupled with in-built decision support systems and generic default values make ACRU a suitable modelling tool in developing countries, as it makes it possible to obtain reasonable simulations for a range of levels of input information. Together with the model's multi-purpose nature, the ability of simulating ''what if scenarios", which was utilised in this study, makes it useful in the generation of information for IWRM. Future research needs which were identified include finding means of encouraging effective communication between scientists, water managers and other stakeholders, who may be "lay people". There is a need to conduct research that will lead to equipping ACRU with sediment routing and deposition algorithms, as well as routines to account more explicitly for dam operating rules and ecological issues, which would render its output even more useful in IWRM than the model's present structure allows. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.

This thesis describes the development of a decision support tool to be used in the operation of Vanderkloof Dam on the Orange River so that the supply of water to the lower Orange River can be optimised. The decision support tool is based on a hydrodynamic model that was customised to incorporate real time data recorded at several points on the river. By incorporating these data into the model the simulated flows are corrected to the actual flow conditions recorded on the river, thereby generating a best estimate of flow conditions at any given time. This information is then used as the initial conditions for forecast simulations to assess whether the discharge volumes and schedules from the dam satisfy the water demands of downstream users, some of which are 1400km or up to 8 weeks away. The various components of the decision support system, their functionality and their interaction are described. The details regarding the development of these components include: • The hydraulic model of the Orange River downstream of Vanderkloof Dam. The population and calibration of the model are described. • The modification of the code of the hydrodynamic engine so that real time recorded stage and flow data can be incorporated into the model • The development of a graphical user interface to facilitate the exchange of data between the real time network of flow gauging stations on the Orange River and the hydraulic model • The investigation into the effect of including the real time data on the simulated flows • Testing the effectiveness of the decision support system. / Thesis (M.Sc.)-University of Natal, Durban, 2002.

The Klein Berg River catchment is intensely cultivated with orchards, vineyards and wheat, while also ensuring a water supply to the main urban center, Tulbagh, and the two conservation areas (Waterval and Groot Winterhoek). The primary objective of this thesis is to determine channel change over a long and short time period, and to relate these changes to landuse change within the catchment. <br /> <br /> Assessing stability of a selected reach within the catchment was done on a short term basis with the use of erosion pins and cross<br /> profiles, while aerial photographs of over 55 years (acquired during 1942, 1967, 1987 and 1997) which were analysed using Geographic Informations Systems. Rainfall and discharge data, which were available for a period of 49-years were statistically analysed and used to determine trends. Vegetation characteristics were assessed by means of transects within the study reach. The results over the short time period (18 months) indicate noticeable channel change in the form of erosion and deposition within the channel. Bank material composition and riparian invasive alien vegetation play an important role in bank stability. Sand was the dominant grain size of the bank material, and fluvial entrainment occurred during periods of high flow. Woody alien trees prevent the growth of protective ground vegetation, and thus the soil is prone to erosion. Undercutting was also observed with the invasive woody trees, resulting in treefall. Debris dams were also common in the channel and depending on their position in the channel, either cause or prevent bank erosion. Landuse change over the 55-year period illustrated its effects on channel stability. Shrublands within the catchment has been replaced with invasive alien vegetation along the riparian zone, while shrublands along the Obiekwa Mountains, were replaced with cultivated lands. The patterns (shape and size) of lateral and point bars within the study area changed significantly within the 55-year period, which indicates a change in the discharge and sediment dynamics within the catchment. The change in sediment dynamics may be due to agricultural activities and urbanization. The increased trend in rainfall, especially during the winter season within the catchment is also an important catchment control. The study has revealed the integrated nature of variables within the catchment. It is thus recommended that a holistic and integrated approach at a catchment scale is required in the assessment of channel change of a river.