Bøger i IHE Delft PhD Thesis Series serien

This research contributes towards a better understanding of how the concentration of Escherichia coli, Bacillus subtilis spores, and MS2 bacteriophages in contaminated shallow water bodies and on different urban surfaces is affected by the environmental conditions.

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.

The challenge of water scarcity as a result of insufficient seasonal rainfall and dry spell occurrences during cropping seasons is compounded by inefficient agricultural practices by smallholder farmers where insignificant soil and water conservation efforts are applied.

User interface is one of the most important components for decision support systems since it directly faces to the end users: decision makers and stakeholders. Implementation of modern visualization and interaction techniques can fill the gap between models and information in order to assist the end user to achieve appropriate knowledge. Web-based interactive maps and construction of virtual environments are mainly described in this research. Combining with several case studies, the advantages and disadvantages of 2D and 3D visualization have been revealed.

This book addresses pressing challenges of policy makers, planners and project managers in the water sector to successfully implement adaptation action. It draws on case studies about water sensitive urban design (WSUD) in Australia and the Room for the River flood protection programme in the Netherlands. The book explains a procedure for establishing effective governance of adaptation and shows how this procedure can be implemented to enhance adaptation projects during different stages of system transformation. In addition, it describes how planned adaptation projects in multi-stakeholder settings can be managed effectively. With this, it links governance for strategic planning and the delivery of adaptation to flooding and drought.

At the interface between terrestrial and aquatic ecosystems, the riparian zone plays an important role in nitrogen removal, despite the minor proportion of the land area that it covers. Very limited studies are carried out in modelling these effects at the river basin scales. The Soil and Water Assessment Tool (SWAT) is a well-known river basin scale model to simulate hydrological processes and nutrient dispersal. So far, SWAT followed a lumped approach that did not take into account the effect of the particular position of the hydrological units and their interaction, which implied that SWAT could not model riparian zones as discrete units and take into account the effects from upland areas.This thesis presents two modifications in SWAT: (i) an approach to represent landscape variability and landscape routing across different landscape units, and (ii) a Riparian Nitrogen Model that simulates the denitrification process in riparian zones. This enhanced landscape SWAT model, referred to as SWAT_LS, was tested on a hypothetical case study and then applied to the Odense river basin, an agriculture-dominated and a densely tile-drained river basin.Case study results show that SWAT_LS is able to evaluate the effect of denitrification in riparian zones, taking into account their specific locations as interfaces between terrestrial and aquatic ecosystems. These modifications enable the SWAT model to be used for flow and nitrogen modelling in riparian zones.

Groundwater is increasingly subjected to excessive over-exploitation and contamination in many parts of the world. It faces the challenge of balancing its multiple functions in a sustainable manner. This thesis explores several specific problems related to contaminant migration, groundwater-surface water interactions and managed aquifer recharge, using a variety of simulation methods and combined simulation-optimization modelling approaches. The validity of these approaches for evaluating groundwater quantity and quality management options is explored. Case studies were performed on field applications in Belgium, Germany and Oman. The results of these studies demonstrate that better insights and improved groundwater resource management can be achieved through a combination of different simulation and optimization methods that take into account data availability and specific site conditions.