Hydrological research in humid tropics is particularly challenging because of highly variable hydrological conditions and high socio-economic stresses caused by rapid population increase, as is the case of Nicaragua. The objective of this research is to understand the surface and subsurface runoff generation processes in a poorly gauged coastal catchment in Nicaragua under variable humid tropical conditions. Specifically, it focuses on identifying geomorphological and hydro-climatic controls on catchment response at different spatio-temporal scales and studies the link between hydrological processes and ecosystem conditions (i.e. mangrove forest). Catchment topography, geology and land use control surface and subsurface runoff generation. Spatio-temporal variability of precipitation affects availability of water resources, determines sources of surface runoff generation and induces changes in groundwater-surface interactions. Sustainable water resources management must prevent drastic alterations in catchment structural characteristics defined by forested areas and tidal sand ridges. Catchment response to hydro-climatic and geomorphologic controls supports the mangrove ecosystem freshwater needs. The outcome of this work is a contribution to the hydrological knowledge of poorly gauged catchment in humid tropics. It also provides scientific hydrological insights to support water resources management on the South Pacific coast of Nicaragua.

The field of ecohydraulics integrates hydrodynamic and eco-dynamic processes. While hydrodynamic processes are usually well described by partial differential equations (PDE's) based on physical conservation principles, ecosystem dynamics often involve specific interactions at the local scale. Because of this, Cellular Automata (CA) are a viable paradigm in ecosystem modelling. All cells in a CA system update their states synchronously at discrete steps according to simple local rules. The classical CA configuration consists of uniformly distributed cells on a structured grid. But in the field of hydrodynamics, the use of unstructured grids has become more and more popular due to its flexibility to handle arbitrary geometries. The main objective of this research is to identify whether the CA paradigm can be extended to unstructured grids. To that end the concept of Unstructured Cellular Automata (UCA) is developed and various UCA configurations are explored and their performance investigated. The influence of cell size was analyzed in analogy with the Finite Volume Method. A characteristic parameter -min distance of UCA- was put forward and tested by numerical experiments. Special attention was paid to exploring the analogies and differences between the discrete CA paradigm and discrete numerical approximations for solving PDE's. The practical applicability of UCA in ecohydraulics modelling is explored through a number of case studies and compared with field measurements.

Climate change on earth is having significant impacts on water resources management in Southeast Asia. Knowledge of climate variations and climate change can be valuable for water resources management in agriculture, urban and industrial water supplies, hydroelectric power generation, and ecosystem maintenance. This book presents the findings of case studies on forecasting climate change and its impacts on water availability, irrigation water requirements, floods and droughts, reservoir inflows and hydropower generation, and crop yield in specific basins of Southeast Asian countries such as Thailand, Myanmar, and Vietnam. All case studies start by forecasting the climate change and investigating its impacts by employing several hydrological reservoir simulations and crop water requirement models. The findings provide sound and scientific advice for water managers on the real impacts of climate change and how to adapt to its many challenges.

Due to the complexity of hydrological systems a single model may be unable to capture the full range of a catchment response and accurately predict the streamflows. A solution could be the in use of several specialized models organized in the so-called committees. Refining the committee approach is one of the important topics of this study, and it is demonstrated that it allows for increased predictive capability of models. Another topic addressed is the prediction of hydrologic models' uncertainty. The traditionally used Monte Carlo method is based on the past data and cannot be directly used for estimation of model uncertainty for the future model runs during its operation. In this thesis the so-called MLUE (Machine Learning for Uncertainty Estimation) approach is further explored and extended; in it the machine learning techniques (e.g. neural networks) are used to encapsulate the results of Monte Carlo experiments in a predictive model that is able to estimate uncertainty for the future states of the modelled system. Furthermore, it is demonstrated that a committee of several predictive uncertainty models allows for an increase in prediction accuracy. Catchments in Nepal, UK and USA are used as case studies. In flood modelling hydrological models are typically used in combination with hydraulic models forming a cascade, often supported by geospatial processing. For uncertainty analysis of flood inundation modelling of the Nzoia catchment (Kenya) SWAT hydrological and SOBEK hydrodynamic models are integrated, and the parametric uncertainty of the hydrological model is allowed to propagate through the model cascade using Monte Carlo simulations, leading to the generation of the probabilistic flood maps. Due to the high computational complexity of these experiments, the high performance (cluster) computing framework is designed and used. This study refined a number of hydroinformatics techniques, thus enhancing uncertainty-based hydrological and integrated modelling.

Population growth in the Blue Nile Basin has led to fast land-use changes from forest to agricultural land, which resulted in speeding up the soil erosion processes producing highly negative impacts on the local soil fertility and agricultural productivity. The eroded sediment is transported downstream by water and sinks in the lower basin where it significantly reduces reservoir storage and irrigation canals capacity. The only effective solution to mitigate the sedimentation problem is to limit the sediment inputs from upstream by locally implementing erosion control practices. However, given the vastness and remoteness of the involved areas, this first requires the knowledge of the most critical zones. The book identifies the sources of the sediment depositing in the Lower Blue Nile Basin and quantifies the amounts involved providing essential information for the planning and implementation of any interventions aiming at reducing soil erosion. The methods used consist of extensive field work covering most of the basin, watershed, hydrodynamic and morphodynamic modelling and, for the first time, the mineralogical analysis of the sediment at the sources and sinks. The method is successful in indentifying the areas providing most of the transported sediment, where it is recommended to start with erosion control practices.

Climate change, rapid population growth and urbanization are causing water shortage and pollution, especially in arid and semi-arid regions of the world due to the growing demand in different sectors and disposal of inadequately treated wastewater to water bodies. To tackle these challenges, further treatment and reuse of wastewater effluent using soil aquifer treatment (SAT) is an attractive cost-effective and environmentally friendly option that is employed with no intensive use of electricity and chemicals.
This study highlights the prospects of using SAT for treatment and reuse of primary effluent (PE), especially in developing countries where wastewater is not treated to secondary and tertiary effluent levels due to lack of investment and operation costs to run sizable wastewater treatment plants (WWTPs). Coupled with experimental studies that show SAT efficiency to remove suspended solids, bulk organic matter, nutrients and pathogens indicators from PE, the thesis provides step-by-step tools that could be used for development of new SAT scheme. Furthermore, the study provides a water quality prediction model that estimates the potential contaminants removal which could be used to assess the need for reclaimed water post-treatment.
This thesis is envisaged to contribute to the current knowledge on the necessity of water reuse.

Mountains are water towers of our world, but their role in global water resources may be altered due to changing climate. This book provides an integrated assessment of the spatial and temporal variability of both recent and future climate change impacts in the Yellow River source region (YRSR) with specific focus on extremes. The book is structured across four different topics from detecting contemporary hydro-climatic changes, comparing three different statistical downscaling methods, assessing elevation dependency of expected changes in temperature, and projecting future climate-induced hydrologic changes in the YRSR. The detection of historical hydro-climatic changes in recent decades indicates that climate change may already be happening and may pose a serious threat to water availability in this region. However, an ensemble of climate change projections for the periods 2046-2065 and 2081-2100 based on two GCMs and three emission scenarios demonstrates that the future water availability of this region would increase due to climate change. This discrepancy suggests that contemporary hydro-climatic experience based on past records alone may not always provide a reliable guide to the future. This study makes an important contribution toward an improved understanding of climate change impacts in the YRSR. The knowledge generated has major implications for water resources management in the Yellow River and will be instructive for climate change impacts studies in other mountain areas.

Urban informal settlements or slums are growing rapidly in cities in sub-Saharan Africa. Most often, a sewer system is not present and the commonly-used low-cost onsite wastewater handling practices, typically pit latrines, are frequently unplanned, uncontrolled and inefficient. Consequently, most households dispose of their untreated or partially treated wastewater on-site, generating high loads of nutrients to groundwater and streams draining these areas. However, the fate of nutrients in urban slums is generally unknown. In excess, these nutrients can cause eutrophication in downstream water bodies. This book provides an understanding of the hydro-geochemical processes affecting the generation, fate and transport of nutrients (nitrogen and phosphorus) in a typical urban slum area in Kampala, Uganda. The approach used combined experimental and modeling techniques, using a large set of hydrochemical and geochemical data collected from shallow groundwater, drainage channels and precipitation. The results show that both nitrogen-containing acid precipitation and domestic wastewater from slum areas are important sources of nutrients in urban slum catchments. For nutrients leaching to groundwater, pit latrines retained over 80% of the nutrient mass input while the underlying alluvial sandy aquifer was also an effective sink of nutrients where nitrogen was removed by denitrification and anaerobic oxidation and phosphorus by adsorption to calcite. In surface water, nutrient attenuation processes are limited. This study argues that groundwater may not be important as regards to eutrophication implying that management interventions in slum areas should primarily focus on nutrients released into drainage channels. This research is of broad interest as urbanization is an ongoing trend and many developing countries lack proper sanitation systems.

This book is the outcome of rigorous and continuous research work done by the author over about three decades on the open ecosystem and dynamic environment of the estuarine Sunderbans. The objective of this work is to identify the field and factors changing gradually upon this active delta over the years, decades and centuries. The deltaic Sunderbans yet not mature enough, has been changing in its natural course with time. Further, anthropogenic interferences disturb the environments and accelerate degradation of nature of this fragile ecosystem simultaneously. Roles played by almost all the agents including man and environment and their involvement are identified for the changing environmental scenario of the Sunderbans. The book is befitted for the researchers and students for the post graduate levels. The Sunderbans, a UNESCO World Heritage Site covering parts of Bangladesh and the southern tip of Indian state of West Bengal, is a part of world's largest deltaic plain of fluvio-marine deposit formed by the Ganges and Brahmaputra at the confluence of the Bay of Bengal. It is the largest single block of tidal halophytic mangrove forest in the world, conspicuous for its great size and biodiversity. With an enormous network of channels and creeks, tidal inundation twice daily, Sunderbans mangroves wetland is a dynamic and complex ecosystem, which undergoes continuous processes of erosion and accretion. Natural processes like changes in local hydrology, sediment motion under wind, wave and tidal action, beach dynamics, regional and global processes like sea level rise as well as the impact of human interference in the form of reclamation of forest land, changes in land use patterns, coastal urbanizations etc are the lead factors for the changes in the environmental scenario of Sunderbans.

Despite the mechanisms of reservoir sedimentation being well known for a long time, sustainable and preventive measures are rarely taken into consideration in the design of new reservoirs. To avoid operational problems of powerhouses, sedimentation is often treated for existing reservoirs with measures which are efficient only for a limited time. The today's challenge of dam owners and engineers is to guarantee with adequate mitigation measures the future sustainable use of the vital reservoirs supplying water for drinking, food and energy production. Research and development is still urgently needed to identify efficient mitigation measures adapted to the main sedimentation processes involved in reservoirs. During the seventh International Conference on Fluvial Hydraulics "River Flow 2014" at Ecole Polytechnique Federale de Lausanne (EPFL), Switzerland, scientists and professionals from all over the world addressed the challenge of reservoir sedimentation in a special session and exchanged their knowledge and experiences. Invited and selected contributions, which give an overview on the latest developments and research regarding reservoir sedimentation including case studies, are presented in this book, in the hope that they can contribute to better sustainable use of the vital reservoirs worldwide.

This study investigates the role of coagulation in enhancing hydraulic performance and permeate quality of UF membranes and provides insight into options for minimizing or ideally eliminating coagulation from UF pre-treatment to SWRO. Results show that coagulation improves UF hydraulic performance mainly by reducing non-backwashable fouling of the membranes. This can be achieved at very low coagulant dose ( 0.5 mg Fe/L) by coating the membranes with sub-micron particles.
Additionally, the work highlights the applicability of UF membranes with low molecular weight cut-off as the coagulant free future of SWRO pre-treatment. Major benefits in terms of reduced environmental impact is expected when applying membranes with low molecular weight cut-off, as the need for coagulation is eliminated while ensuring longevity of downstream SWRO membranes. In general terms, the research indicates that coagulant consumption can be significantly reduced in UF pre-treatment of SWRO by optimizing operational parameters and applying alternative solutions.

Presenting the hydrological research carried out in the Migina catchment (260 km2), Southern Rwanda with the objective to explore the hydrological trends and climate linkages for catchments in Rwanda (26,338 km2), and to contribute to the understanding of dominant hydrological process interactions. Different Hydro-meteorological instrumentations have been installed for several months in the Migina catchment and measurements have been carried out. The trend analysis is based on Mann-Kendall (MK) test and Pettitt test on times series data varying from 30 to 56 years before 2000. The hydrometric data and modern tracer methods is used for hydrograph separation and show that subsurface runoff is dominating the total discharge even during rainy seasons at Cyihene-Kansi and Migina sub-catchments, respectively. Further, a semi-distributed conceptual hydrological model HEC-HMS is applied for assessing the spatio-temporal variation of water resources in the Migina catchment. The model results are compared with tracer based hydrograph separation results in terms of the runoff components. The model performed reasonably well in simulating the total flow volume, peak flow and timing as well as the portion of direct runoff and baseflow.

Growing population and unregulated access to forest land have exerted high pressure on the land and water resources of the recharge areas of the transboundary Mara river, in the Lake Victoria region leading to changes in land and water use patterns in the basin. This thesis considers the interactions among climate change and variability, water quality, land surface cover, hydrology, and human systems, including societal adaptations to changing environmental conditions. The thesis explores the interaction between trends in climatic variables and the feedback response of vegetation variables. The effect of different land cover types on water quality is addressed, and alternative methods to treat data quality for hydrological model inputs and validation are discussed. The Soil and Water Assessment Tool (SWAT) hydrological model was adapted to the tropical watershed experiencing data scarcity, and used to assess the impacts of changes to the climate, land use and management practices. Different scenarios driven by the prevailing natural trends, strategic national development and economic policies were used to asses the potential impacts of changes.

Freshwater is our planet's most precious resource, and also the least conserved. Freshwater makes up only 3 percent of the total water on the planet, and yet the majority (1.9 percent) is held in a frozen state in glaciers, icebergs, and polar ice fields. This leaves approximately one-half of 1 percent of the total volume of water on the planet as freshwater available in liquid form. This book traces the complex history of the steady growth of humankind's water consumption, which today reaches some 9.7 quadrillion gallons per year. Along with a larger population has come the need for more drinking water, larger farms requiring extensive irrigation, and more freshwater to support business and industry. At the same time, such developments have led to increased water pollution. Three detailed case studies are included. The first looks at massive water systems in locations such as New York City and the efforts required to protect and transport such resources. The second shows how growth has affected freshwater quality in the ecologically unique and geographically isolated Lake Baikal region of eastern Russia. The third examines the success story of the privatized freshwater system in Chile and consider how that country's water sources are threatened by climate change.

Replacing the Traditional Physical Model Approach Computational models offer promise in improving the modeling of shallow water flows. As new techniques are considered, the process continues to change and evolve. Modeling Shallow Water Flows Using the Discontinuous Galerkin Method examines a technique that focuses on hyperbolic conservation laws and includes one-dimensional and two-dimensional shallow water flows and pollutant transports. Combines the Advantages of Finite Volume and Finite Element Methods This book explores the discontinuous Galerkin (DG) method, also known as the discontinuous finite element method, in depth. It introduces the DG method and its application to shallow water flows, as well as background information for implementing and applying this method for natural rivers. It considers dam-break problems, shock wave problems, and flows in different regimes (subcritical, supercritical, and transcritical). Readily Adaptable to the Real World While the DG method has been widely used in the fields of science and engineering, its use for hydraulics has so far been limited to simple cases. The book compares numerical results with laboratory experiments and field data, and includes a set of tests that can be used for a wide range of applications. Provides step-by-step implementation details Presents the different forms in which the shallow water flow equations can be written Places emphasis on the details and modifications required to apply the scheme to real-world flow problems This text enables readers to readily understand and develop an efficient computer simulation model that can be used to model flow, contaminant transport, and other aspects in rivers and coastal environments. It is an ideal resource for practicing environmental engineers and researchers in the area of computational hydraulics and fluid dynamics, and graduate students in computational hydraulics.

Natural ecosystems are heavily dependent on water, as it is essential to the development of life. The ecology and landscape play an important role in the quality and availability of water. It is no coincidence that exceptional hydrological phenomena are found in protected areas. Such is the case with, for example, the geothermic occurrences (principally, geysers) in America's Yellowstone National Park , the oldest park in the world. The Ramsar wetlands (where the ecosystem's dependency on water is strongly evident), The Iguacu Falls (on the border of Argentina and Brazil), or the Zapata Swamp (the largest of its kind on the Caribbean island of Cuba) further exemplify this point. However, in many cases, the conservation strategies for hydraulic resources in protected areas are ignored, or simply deprived of the attention they require. There are many types of suitable management strategies for planning and protecting our valuable treasures. Hydraulic resource management in protected areas is something that must not be separated from these conservation measures. The first Symposium for the Management of Hydraulic Resources in Protected Areas was intended to be a framework of communication about experiences with water resource management in protected areas. Advances in research and possible solutions to the problems within these areas were discussed. The contributions in this proceedings volume are grouped under seven main themes: Purification and reuse of wastewater in rural communities; Impact of public use on water resources; Vulnerability and risks associated with aquifers, Design and management water resources in protected areas; Research and monitoring of water resources in protected areas; Water and its importance as a source of renewable energy in protected spaces; and Geodiversity and conservation of areas with hydraulic heritage.

In general, groundwater is a preferred source of drinking water because of its convenient availability and its constant and good quality. However this source is vulnerable to contamination by several substances. Acceptable quality limits relative to micropollutant contents in drinking water are becoming increasingly lower and efficient elimination treatment processes are being implemented in order to meet these requirements. Metals contaminants at low concentration are difficult to remove from water. Chemical precipitation and other methods become inefficient when contaminants are present in trace concentrations and the process of adsorption is one of the few alternatives available for such situations. This book describes the adsorption method in the removal of selected heavy metals present as cations (Cd2+, Cu2+ and Pb2+) or oxyanions (Cr(VI) and As(V)) using iron oxide coated sand (IOCS) and granular ferric hydroxide (GFH). The effects of pH, natural organic matter (fulvic acid (FA)) and interfering ions (PO43-, Ca2+) on the adsorption efficiency were also assessed. The sorption reactions that take place at the surface of the adsorbent were also described through the surface complexation modelling for Cd2+, Cu2+ and Pb2+ adsorption. Batch adsorption tests and rapid small scale column tests (RSST) were used as laboratory methods.

Water Wells and Boreholes focuses on wells that are used for drinking, industry, agriculture or other supply purposes. Other types of wells and boreholes are also covered, including boreholes for monitoring groundwater level and groundwater quality. This fully revised second edition updates and expands the content of the original book whilst maintaining its practical emphasis. The book follows a life-cycle approach to water wells, from identifying a suitable well site through to successful implementation, operation and maintenance of the well, to its eventual decommissioning. Completely revised and updated throughout, Water Wells and Boreholes, Second edition, is the ideal reference for final-year undergraduate students in geology and civil engineering; graduate students in hydrogeology, civil engineering and environmental sciences; research students who use well data in their research; professionals in hydrogeology, water engineering, environmental engineering and geotechnical engineering; and aid workers and others involved in well projects.

Originally published in 1969, the contributors to this volume examine the natural and social environments of selected areas in Africa and study in detail some particular problems and their solutions. Climate, landforms, soils and vegetation are discussed as fundamental aspects of the physical environment. The next section discusses the social and political environment: demography, agricultural systems and the legacies of colonial administration. Case studies in Malawi, Nigeria, Sudan, Eswatini and Kenya are analysed. The book is aimed at students of African studies, geographers and agriculturalists.

Industrial activities like textile processing and mining are typical sources of heavy metal-rich wastewaters. The sulfate reducing process has become an attractive method for the production of sulfide to precipitate metals since most of these streams also contain sulfate, which is the electron acceptor and, in less common cases, chemical oxygen demand which is the electron donor of sulfate reducing bacteria. The inverse fluidized bed (IFB) reactor is a system for the production of biogenic sulfide and metal precipitation in the same unit due to its configuration: the biomass floats on top of the reactor, whereas metal sulfide precipitates settle and thus can be recovered at the bottom. The main objective of this thesis was to elucidate the factors affecting simultaneous sulfate reduction and precipitation of heavy metals in an IFB reactor in order to optimize the metal recovery from wastewaters such as acid mine drainage. Therefore, this thesis focused on varying different operational conditions to study their effect on the solid-liquid separation and purity of the metal sulfide precipitates as well as on their effect on the sulfate reducing process. Furthermore, one chapter was focused on the study of strategies for sulfide control in the IFB reactor. In addition, recommendations for further research to improve the recovery of the metal sulfides in bioreactors are given.

This collection of papers is a snapshot of modern hydrogeology in which highly technical methods and approaches sit side-by-side with overlapping legal, social, organisational, institutional and governance considerations. Groundwater is integral to many human and environmental systems. Indeed, there appears to be a growing realisation that some of the most pressing physical problems in the field of hydrogeology - over-abstraction, salinization or pollution - can only really be solved by taking a multi-disciplinary approach to the issues that takes all other related professions into account. Whilst a 'technical' solution may be readily deciphered, the larger challenge usually lies in the sustainably-funded and widely-accepted implementation of that measure. This book ranges from discussion and debate on the hot topic of hydraulic fracturing of wells or 'fraccing' for shale gas and its potential to disrupt groundwater systems, to the application of highly technical modelling procedures to help solve complex, real world problems. It is a window on the preoccupations of modern hydrogeologists and an insight into the way in which hydrogeological techniques and methods are being holistically adapted to address problems in the real world. This book is targeted at professional hydrogeologists, sociologists, experts in governance, law and policy as well as ecologists and other professionals that nowadays all sit alongside groundwater understanding. The book will also appeal to politicians, resource managers, regulators and others interested in sustainable water supply.

Urban flood risks and their impacts are expected to increase as urban development in flood prone areas continues and rain intensity increases as a result of climate change while aging drainage infrastructures limit the drainage capacity in existing urban areas. Flood mitigation strategies are required as part of sound urban flood management plans to assess flood risk and identify technically feasible and cost-effective options to reduce the risk. Central to the development of flood mitigation strategies is the efficient prediction of flood propagation characteristics in urban areas. Detailed predictions of flood flows in urban areas require the use of high resolution topographic data. However, due to computational demand topographic data is often generalised to a more manageable resolution and floodplain models are built at much coarser resolutions. The research presented in this thesis addresses the problem of capturing small-scale features in coarse resolution urban flood models with the aim of improving flood forecasts in geometrically complex urban environments. The approach adopted in the research used a two-dimensional surface flow modelling system that can extract and incorporate useful information available in high resolution topographic data into coarse grid models. The thesis also presents modelling of the complex interaction between surcharged sewer and flows associated with urban flooding and incorporation of infiltration process in surface flow modelling tools. Case study results showed that the incorporating volume-depth and flow-area-depth relationships extracted from high resolution topographic data significantly improved the results of coarse grid urban flood models while taking the advantage of reduced computational time to ensure efficient prediction of urban flood characteristics.

A considerable amount of scientific evidence has been collected leading to the conclusion that urban wastewater components should be designed as one integrated system, in order to protect the receiving waters cost-effectively. Moreover, there is a need to optimize the design and operation of the sewerage network and wastewater treatment plant (WwTP) considering the dynamic interactions between them and the receiving waters. This book introduces a method called Model Based Design and Control (MoDeCo) for the optimum design and control of urban wastewater components. The book presents a detailed description of the integration of modelling tools for the sewer, the wastewater treatment plants and the rivers. The complex modelling structure used for the integrated model challenge previous applications of integrated modelling approaches presented in scientific literature. The combination of modelling tools and multi-objective evolutionary algorithms demonstrated in this book represent an excellent tool for designers and managers of urban wastewater infrastructure. This book also presents two alternatives to solve the computing demand of the optimization of integrated systems in practical applications: the use of surrogate modelling tools and the use of cloud computer infrastructure for parallel computing.

Natural organic matter (NOM) generally significantly influences water treatment processes such as coagulation, oxidation, adsorption, and membrane filtration. In addition to aesthetic problems such as colour, taste and odour, NOM also contributes to the fouling of filtration membranes, serves as a precursor for disinfection by-products (DBPs) of health concern during disinfection/oxidation processes, increases the exhaustion and usage rate of activated carbon and may promote microbial growth in water distribution networks. The efficiency of drinking water treatment is affected by both the amount and composition of NOM. Proper NOM characterization enables the targeting of the problematic NOM fractions for removal and transformation. However, the characterization methods used are often laborious, time consuming and may involve extensive sample pre-treatment. High performance size exclusion chromatography and fluorescence excitation-emission matrices were used to characterize NOM relatively quickly and with minimal sample preparation. These and other tools were used to improve our understanding of NOM character and behaviour during drinking water treatment. The study demonstrates the potential of multiple NOM characterization tools for the selection, operation and monitoring of water treatment processes.