To reconcile its scarce water resources with the ever increasing demand for fresh water, the South African government continues to explore and investigate various demand management and water supply options such as: effluent reuse, interbasin water transfers, rainwater harvesting (RWH), water conservation as well as sea water desalinisation. RWH is an old but underutilised technology that can play a key role in the improvement of rural livelihoods, thus the need to investigate the potential it holds for South Africa. This thesis presents the Rainwater HArvesting Decision Support System (RHADESS) that was developed to facilitate the integration of three streamlined categories of RWH in the management and development of the country’s water resources at the quaternary catchment scale (± 500 km2). Using biophysical and socioeconomic datasets, RHADESS assesses the RWH footprint of any given area of South Africa. Although physical factors are important parameters in the assessment of the RWH suitability of a given area the non‐consideration of ecological and socioeconomic parameters lead to inappropriate targeting of RWH. Once the footprint is determined, the ecohydrological impact of RWH as reduction in river flow can be established. Despite the increasing adoption of RWH, very little is known about its potential ecohydrological impact. This thesis contributes to understanding these impacts for different levels of adoption of RWH at the quaternary catchment scale. Finally, RHADESS sizes the RWH tank per quaternary catchment, assesses its water security and calculates the area of land needed for a household to achieve food security when RWH is implemented. The decision support system was tested in two quaternary catchments which have contrasting rainfall regimes, the semi‐arid C52A and the humid V13D.

In the water utility sector, traditional asset management focusses on the maintenance and provision of physical assets (infrastructure) that allow water companies to deliver their services, meet their customers’ expectations and achieve their economic objectives. Nevertheless, the serviceability of the sector heavily depends on natural elements (e.g. rain, land). The importance of Natural Capital (i.e. the natural systems and their deriving ecosystem services) has been at the core of policy recommendations which have shaped regulatory changes in the water sector of England and Wales. Water companies are now required to explicitly account for and report their inter-dependencies on the natural environment and adopt systems-oriented approaches in their Asset Management Programmes (AMPs). These reforms will enable the sector to become resilient to the environmental and societal challenges faced at urban and rural contexts. Responding to the regulatory demands, the research introduces a novel and structured approach for integrating natural capital in the asset management portfolio of the water industry. The work is built on a transdisciplinary research framework and demonstrates that a new scale needs to be considered for the implementation of Holistic Asset Management: the water basin or catchment. A Catchment Metabolism modelling schema was created, grounded on the principles of Integrated Catchment Management and ecosystems services. The schema is based on the robust synthesis of concepts, tools and methods from a spectrum of disciplines. These include Industrial Ecology, Water Accounting, Environmental Regional Input-Output Analysis, hydrology, software engineering and functional modelling. Catchment Metabolism introduces a holistic perspective in asset management and expands its scope. The schema enables the conceptualisation, modelling and management of catchments as complex asset systems. It, thus, forms the ground for structured collaboration among experts for integrated water resources planning and decision-making. The schema allows for the design and implementation of catchment-based strategies and the assessment of their environmental performance. An industrial case study for a pilot catchment system (Poole Harbour Catchment) is used to demonstrate the application of the Catchment Metabolism. Alternative strategies for nitrogen pollution mitigation are assessed. The application of winter cover crops across the catchment appears to be the optimum strategy. The case study demonstrates the practical and modular implementation of the schema, reveals its methodological strengths and limitations and evaluates its applicability in the asset management planning and decision-making of the water sector.

<p> In regulated rivers, reservoir operation decisions largely determine downstream river temperature and flow. Computational methods can minimize the risk and uncertainty of making regrettable environmental release decisions and aid operations planning and performance prediction. Mathematical modeling in particular can optimize the timing and magnitude of reservoir release decisions for downstream benefit while accounting for seasonal uncertainty, water storage impact, and competing water demands. This dissertation uses optimization and modeling techniques, modifying traditional optimization modeling to include temporal correlation in outcome variables and incorporating long-term planning and risk management into prescribed reservoir operations. The proposed method is implemented in one case, a) with a state variable that tracks outcome benefits over time (fish population size) and, in another case, b) with a maximin stochastic dynamic program solution algorithm that maximizes net operational benefit and minimizes worst-case outcomes (for cold water habitat delivery). This method is particularly useful for environmental flow management, when the water quality and quantity of the river and reservoir in one time step affect the quantity and quality in the reservoir and the river for later periods. Better solutions with these methods internalize risk and hedge releases at the beginning of an operating season to maximize downstream benefit and reduce the probability of catastrophe for the season and future years. Maximizing the minimum cold-water habitat area over months of a season or multiple years, or maximizing a river indicator variable explicitly, could likely help, for example, maximize an out-migrating salmon smolt population downstream. The method is demonstrated with a case study optimizing environmental releases from Folsom Dam and another optimizing temperature management from Shasta Dam in northern California. These results inform general rules for environmental flow management and temperature management of reservoirs, with specific policy recommendations for both Folsom and Shasta reservoirs. In both cases, the added value from employing hedging rules help reservoir operations minimize the risk of environmental catastrophe and conserve storage both within an operating season and across years.</p><p>

<p> Globally, amphibians have suffered dramatic population declines in the past twenty years with habitat destruction implicated as the primary threat. The Natural Resources Conservation Service&rsquo;s Wetlands Reserve Program (WRP) restores wetlands on marginal agricultural land and is a means to restore the spatio-temporal wetland habitat required by amphibians to prevent, reverse, or stabilize declining population trends. The goal of WRP is &ldquo;to achieve the greatest wetland functions and values, along with optimum wildlife habitat, on every acre enrolled in the program.&rdquo; Functions and values are defined as the hydrological and biological characteristics of wetlands. A key unanswered question is to what extent is this goal being achieved? Amphibians enable quantifying the WRP goal due to their life-history requirements and explicit incorporation of their habitat needs into WRP plans. My research goal was to determine if hydrological and biological wetland characteristics had been restored to WRP sites in the Lower Grand River basin, north-central Missouri, based on distribution, recruitment success, and relative species richness estimates for members of a regional species pool. I identified three design strategies applied to WRP sites over time: walk-away, maximize hydrology, and naturalistic; the latter emphasizing restoring process as well as structure; and evaluated if design strategy was a useful covariate for restoration efforts. I encountered 10 amphibian species representing 59% of the regional species pool. Design strategy was not a predictive site-level covariate as sites within all three design strategies had varying hydrological wetland conditions resulting in greater habitat heterogeneity than anticipated on maximize hydrology and walk-away sites and less than anticipated on naturalistic sites. Amphibian detections occurred across all sites resulting in no difference among design strategy as the degree of heterogeneity in habitat conditions at the within site-scale demonstrated that amphibians were responding to ecological conditions that occur at a finer resolution than site. Results, irrespective of design strategy, indicate seven of the detected species or groups were widely- distributed, two were moderately- distributed, and two were sparsely distributed on WRP sites indicating hydrological wetland characteristics have been restored to sites given the moderate- to wide-distribution of species associated with both seasonal and permanent wetlands. Although species were successfully recruiting young into adult populations, only leopard frogs had high estimates of recruitment success whereas the remaining species had moderately high to moderate to low recruitment estimates indicating biological wetland characteristics are somewhat lacking to lacking for these species. Results from the relative species richness assessment indicate that, whereas 74% of the sites provided some degree of wetland habitat for members of the regional species pool over the course of the field season (7 March &ndash; 19 September), 52% of the sites lacked suitable habitat conditions during the peak of amphibian breeding and larval development (May through July). Targeting management actions that result in suitable seasonal wetland habitat conditions (shallow, vegetated wetlands that gradually dry by mid-to late-summer) throughout the time needed for species to complete their life history requirements is one method to increase the biological wetland value of restored WRP sites. Results show the value of WRP at conserving and restoring river-floodplain amphibians; however, achieving optimum wildlife habitat on every enrolled acre will be difficult at a site-level scale as habitat requirements, although overlapping, vary widely for the full range of species. Providing for all species in the regional species pool requires sites that transverse both the longitudinal and lateral floodplain gradient. If WRP is to realize its full potential, there must be recognition that optimum wildlife habitat can be defined at multiple spatial and temporal scales that match the landscape setting. Optimum wildlife habitat at a wetland scale is not the same as optimum wildlife habitat at the floodplain scale. The intent of WRP is to convert marginal, flood-prone agricultural lands back into wetlands so enrollment of lands located outside the active floodplain may be impracticable or unrealistic. Whereas attaining optimum wildlife habitat on every acre enrolled in the program may not be an achievable objective, providing optimum wildlife habitat for members of a regional species pool within an appropriately defined geography that includes both a longitudinal and lateral gradient represents an objective that is both desirable and attainable.</p><p>

<p> Aquifer mergence zones are erosional unconformities that hydraulically join interlaying aquifers. In the East Newport Mesa in Orange County, Southern California, aquifer mergence zones may provide a pathway for potentially impaired low-quality groundwater of the shallow, semi-perched aquifer to migrate into the underlying regional, potable, confined aquifers. Major ion and stable isotope results imply that vertical mixing is occurring locally between the discrete shallow and deep groundwater endmembers. Vertical mixing is suggested by anomalously young radiocarbon age-dates of deep groundwater units. Radon-222 results show that shallow groundwater is discharging from the mesa, and is also actively intruded by surface water. Mixing of shallow and deep waters at these mergence zones may pose a threat to the deeper regional aquifer system. </p><p>

This dissertation presents an examination of the causes and mechanisms underlying the widespread contamination of a shallow groundwater aquifer by fecal bacteria. The context for this study is a field site located in a rural area of Bangladesh that represents a microcosm for the many challenges facing the approximately 2 billion people worldwide who rely upon groundwater for their daily needs. The unique contributions of this work include an improved numerical model for fitting column test results, a conceptual model to explain seasonal patterns of well contamination based on the hydraulic interaction of ponds and irrigation/drainage canals and a new understanding of the important role that such canals might play in predicting the microbial contamination of shallow aquifers in flood-protected areas. The mechanisms responsible for filtration of the fecal indicator bacteria, Escherichia coli, during passage through the fine sand aquifer were first investigated through laboratory column experiments using intact sediment cores from the field site as well as repacked sediment that had been dried and, in some experiments, chemically cleaned. To fit the hyper-exponential spatial profiles of attached bacteria in one third of the experiments, a finite difference two-population model with reversible and irreversible attachment modes incorporating bacterial die-off was developed. Where the two-population phenomenon was observed, one population typically was highly irreversible while the other was reversible with a smaller irreversible attachment rate. When applied to transport in the field, this model predicted only a two-fold reduction in bacterial concentrations over a distance of 10 m and transport was limited mainly by the bacterial die-off rate, which was also measured using microcosm experiments. The occurrence of the second population was associated with larger grain size and lower percentage of fine particles and the attachment rates in general increased linearly with increasing percentage of fines. Transport from contaminated surface water to nearby tubewells was studied in the field through measurements of bacterial infiltration below canals and ponds both inside and outside of the flood control embankment. A two-dimensional finite element model of the field-pond-canal system was built and fitted to heads measured at three monitoring wells and 2 surface water bodies. Using parameters from the field measurements, the model was not able to explain the seasonal pattern of E. coli concentrations in tubewells, even when reversible attachment assumptions from the column test results were applied. An alternative conceptual model that incorporates the seasonal shift in flow direction caused by the canal network was developed using the fitted finite element model and could explain the observed pattern of well contamination. The importance of the irrigation/drainage canals in determining the frequency of tubewell contamination by E. coli at the site was further demonstrated by applying a logistic regression model using the intensity of latrines, canals and ponds as predictors, after applying spatial decay rates drawn from the infiltration literature. The resulting Intensity Model found that population density, unsanitary latrines and canals together could explain 48% of the variation in the frequency of E. coli detection in tubewells, but these parameters were only significant at a low spatial decay rate (0.01 m-1). A less complex Proximity Model provides nearly the same explanatory power but only required population with 25 m and the distance to the nearest canal as predictors. These models could be useful in predicting water-related health risks, evaluating contamination risk for groundwater sources based on the sanitary environment around the well or estimating the potential benefits from improvements to sanitation infrastructure in a given region.

At the end of the First World War, new states were created in the former domains of the Ottoman Empire. In the region between the Tigris and Euphrates Rivers, Britain and France obtained through conquest and international writ new "mandate" territories in Iraq and Syria, while in 1923 a new Turkish republic was founded on the Anatolian peninsula. During the next two decades, governments in these states planned a series of water control projects on the two rivers as part of broad economic development efforts. Many of these projects were eventually constructed after the Second World War, shaping the environment of the river basin with dams, flood control and irrigation works, and hydroelectric power stations. By comparing these states' efforts to exploit natural resources and manage the environment of the basin, this study considers the environmental function in the shift from empire to independent nation-state and in the diverse processes of modern state formation. Through water resource exploitation, Iraq, Syria and Turkey founded modern bureaucracies, centralized control over natural resources, and justified new techniques to manage populations. However, the intentions of Baghdad, Ankara and Damascus, as well as the results obtained, differed in significant ways, providing insight not only into the nature of these states, but also the political dimensions of managing a critical natural resource. This dissertation is based on analysis of archival records in Arabic, English, French and Turkish, collected from institutions in England, France, the United States, India and Turkey.

Conventionally, the question of Egyptian water security focused on state-centric transboundary hydropolitics within the larger context of the Nile basin. The presented research explores 'water security' beyond this 'state-centric epistemology', typically focusing on a singular scale of hydropolitical analysis. This dissertation examines the water (hydro) politics of transnational land-water investments (LWI) within Egypt and the larger context of the Nile river basin. Adopting a multi-site case study methodology, it critically examines the changing role of the state and the engagement of non-state actors in the silent appropriation of land-water resources through investments in farmlands abroad. The research methodology contextualizes how land acquisitions take several shapes and forms within Egypt (Old-New Lands and New Lands/Mega Projects), as well as in other Nile basin countries (e.g. Sudan). They also manifest land-water-food nexus interdependencies for both; profit and larger strategic objectives, through the formation of 'State-Capital alliances'. Deploying a case study of an international Emirati investor in Egypt, it shows how land-water investments are rooted in a larger socio-political project as part of the state's vision of horizontal expansion and land reclamation, to address its ecological-demographic narrative of crisis. The research also draws linkages between Egyptian water security and transnational investments in other Nile basin countries with a particular focus on the case of Sudan as part of its larger vision of the 'breadbasket of the Arab World'. However, while these State-Capital alliances are rooted in narratives of state modernization, security, and profit, they entail various tensions and trade-offs amongst different resources nexi and actors, thus masking larger questions of social justice and equity. These tensions often reflect the manufacture of abundance and translate into water grabs transcending multiple hydropolitical scales. The thesis argues that the changing role of the "entrepreneurial state" and the engagement of non-state actors in transnational land-water investments manifest a transition from the hydraulic mission towards water security mercantilism. I argue that "water security mercantilism" denotes water grabbing, which overrides the conventional understanding of the hydraulic mission (water control by the state); towards a broader understanding of the role of non-state actors and international investors in accessing water, thus creating their own private resources security nexus. Hence, drawing on development studies, hydropolitics, and political economy scholarship, this dissertation broadens out the analysis of Egyptian water security beyond singular-scale state-centric hydropolitical debates; towards a multi-level polycentric analysis of water security, central to which are the farmers, the investors, and the state itself. This implies that transnational land-water investments not only influence small farmers through the reproduction of scarcity on the local level, but also influence the hydraulic mission of the state on the national level, and the larger Nile basin transboundary hydropolitics.

In all areas of hydrology, where one or several variables are measured as a function of time, it might be necessary to interpolate the measured variable(s). There is a form of artificial intelligence (AI) called neural networks, which seem to be appropriate for this application. In an environmental project in Bolivia, where, among others, the concentrations of arsenic (As), cadmium (Cd) and lead (Pb) in the polluted Huanuni river was measured, a data set appropriate for application of the neural network method was available. Several neural networks with different configurations were used to interpolate concentration values of the three sampled metals. The neural networks interpolated concentrations at time steps where actual, measured, values existed so that an estimate of the method’s capacity could be obtained. The neural networks’ interpolating capability were compared to that of linear interpolation and linear equations derived by multiple regression. In the case of cadmium, the linear interpolation was the best method, whereas the neural network method was best at interpolating arsenic and lead concentrations. The conclusions of this study are that the neural network method was the most succesful method; that this method was the most complicated to implement; that this method was not fully optimised; and that, to evaluate the neural network method’s general applicability as an interpolation method in hydrology, further studies have to be conducted. / Inom alla områden av hydrologin, där man mäter en eller flera variabler som funktion av tid, kan det finnas ett behov av att interpolera glesa tidsseriedata. Det finns en form av artificiell intelligens (AI) som kallas för neurala nät, vilken verkar vara lämplig att applicera på detta problem. Genom ett miljöprojekt i Bolivia, där bl.a. arsenik-, bly-, och kadmiumkoncentrationer i den förorenade floden Huanuni mättes, blev data lämpliga för applicering av den neurala nätmetoden tillgängliga. Flera neurala nät med olika konfigurationer användes för att interpolera koncentrationsvärden av de tre metallerna. De neurala näten interpolerade värden längs tidssteg där verkliga, uppmätta, koncentrationsvärden fanns, så att en uppskattning av metodens kapacitet kunde göras. Dess kapacitet jämfördes med kapaciteten hos två andra metoder: linjär interpolation och linjära ekvationssystem härledda med hjälp av multipel regression. Den linjära interpolationsmetoden var bäst i fallet kadmium, medan den neurala nätmetoden var bäst i de två andra fallen. Slutsatserna av den här studien är att den neurala nätmetoden var den bästa; att denna metod var den mest komplicerade att använda; att denna metod inte var helt optimerad, och att det krävs ytterligare studier för att utvärdera den neurala nätmetodens allmänna lämplighet som metod att interpolera glesa hydrologiska tidsseriedata.

Vid hydrologiska studier är det ofta nödvändigt att känna till flödesvägar och uppehållstider för markvattnet. Syreisotopen 18O kan användas som ett konservativt hydrologiskt spårämne för att bestämma vattnets rörelse. Vid extrahering av markvatten från jordprover för 18O-analys används ofta en destillationsmetod. En enklare och snabbare metod för att extrahera markvatten är att använda en höghastighetscentrifug. Problemet är att allt markvatten i ett jordprov inte extraheras med denna metod. Det är därför möjligt att vatten extraherat genom centrifugering inte har en 18O-halt som är representativ för markvattnet. I den här undersökningen jämfördes 18O-halterna i vatten extraherat genom centrifugering och destillering. Markvatten extraherades från ostörda jordprover och från torkade jordprover mättade med vatten av känd 18O-halt. Extraktionerna gjordes både genom centrifugering vid olika hastigheter följt av destillation och genom enbart destillation. Samtliga jordprover torkades sedan. Skillnaden i 18O-halt mellan vatten extraherat genom centrifugering vid olika hastigheter var små. 18O-halten för destillaten var, med ett undantag, lägre än för centrifugaten. Torkningen av jordproverna visade dock att allt markvatten inte hade extraherats vid destillationen. Detta kan vara en förklaring till den lägre 18O-halten hos destillaten. På grund av ofullständig destillation kunde inte den här undersökningen avgöra i vilken grad 18O-halterna i centrifugaten var representativa för den del av markvattnet som är hårdast bunden till marken. För att karaktärisera 18O-halten i det rörligaste markvattnet, är dock centrifugering inte bara en snabbare metod, utan också en metod med färre felkällor än destillationsmetoden. / In hydrological studies it is often necessary to know the flow pathways and residence time of soil water. The oxygen isotope 18O can be used as a conservative hydrological tracer to help determine water´s movement. To extract soil water from soil samples for 18O analysis, a distillation method is often used. An easier and faster method for extracting soil water is high speed centrifugation. All soil water, however, is not extracted from a soil sample by this method. It is therefore possible that the water extracted by centrifugation does not have an 18O content that is representative of the soil water. In this study, the 18O values of water extracted by distillation and centrifugation are compared. Soil water was extracted from undisturbed soil samples and from oven-dried soil samples saturated with water of a known 18O content. The extractions were done both by centrifugation at different speeds followed by distillation and by distillation only. All of the samples were then oven-dried. The differences in 18O content between water extracted by centrifugation at different speeds were small. The 18O content in the water extracted by distillation was, with one exception, more depleted in 18O than the water extracted by centrifugation. From the oven-drying it was seen that the distillations did not succeed in extracting all soil water. This might be a reason for the depletion in 18O content of the water extracted by distillation. Due to incomplete distillation, this study was not able to determine how well the 18O content in water extracted by centrifugation represents the water bound most strongly to the soil. For characterizing the 18O content in the least bound soil water, however, centrifugation is not only faster, but also less prone to error than distillation.