This study contributes to the understanding of the mechanisms and processes of sand bypassing in artificial and non-artificial coastal environments through a numerical modelling study. Sand bypassing processes in general is a relevant but poorly understood topic. This study attempts to link the theory and physics of sand bypassing processes which is significantly important in definition of coastal sedimentary budget. The main question is how can we model sand bypassing processes and whether the modelled sand bypassing processes represent the actual sand bypassing processes. In this study, it...

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...

The magnitude and urgency of the need to adapt to climate change is such that addressing it has been taken up by the United Nations as one of the sustainable development goals - Goal 13 (SDG13) in 2015. SDG13 emphasises the need to strengthen resilience and adaptive capacity to climate related hazards and natural disasters. Coping with urban floods is one of the major needs of climate adaptation, where integration of climate change responses into flood risk management policies, strategies and planning at international, national, regional and local levels is now the norm. However, much of this...

Computers are increasingly used in the simulation of natural phenomena such as floods. However, these simulations are based on numerical approximations of equations formalizing our conceptual understanding of flood flows. Thus, model results are intrinsically subject to uncertainty and the use of probabilistic approaches seems more appropriate. Uncertain, probabilistic floodplain maps are widely used in the scientific domain, but still not sufficiently exploited to support the development of flood mitigation strategies. In this thesis the major sources of uncertainty in flood inundation...

Seawater desalination is rapidly growing in terms of installed capacity (~80 million m3/day in 2013), plant size and global application. An emerging threat to this technology is the seasonal proliferation of microscopic algae in seawater known as algal blooms. Such blooms have caused operational problems in seawater reverse osmosis (SWRO) plants due to clogging and poor effluent quality of the pre-treatment system which eventually forced the shutdown of the plant to avoid irreversible fouling of downstream SWRO membranes. As more extra large SWRO plants (>500,000 m3/day) are expected to be...

The prospects for the future are clear. Agriculture will have to respond to changing patterns of demand for food and combat food insecurity and poverty amongst marginalized communities. In so doing, agriculture will have to compete for scarce water with other users and reduce pressure on the water environment. Moreover, water managers have to unlock the potential of agricultural water management practices to raise productivity of water, spread equitable access to water, and conserve the natural productivity of the water resource base. This PhD thesis presents field tests combined with...

Since the 1980s a major change took place in public policies for water resources management. The role of governments shifted under this reform process from an emphasis on investment in the development, operation and maintenance of water infrastructure to a focus on managing water resources systems by stipulating general frameworks and defining key principles for water allocation. This interdisciplinary research examines how this water reform process unfolds within four African waterscapes that are historically constituted by natural and social processes. The study analyzes the interplay...

The Abay / Upper Blue Nile basin contributes the largest share of discharge to the river Nile. However, the basin exhibits large spatio-temporal variability in rainfall and runoff. Moreover, human activities also impact hydrological processes through intensive agriculture, overgrazing and deforestation, which substantially affect the basin hydrology. Thus, understanding hydrological processes and hydro-climatic variables at various spatio-temporal scales is essential for sustainable management of water resources in the region.
This research investigates the hydrology of the basin in depth...

Rip currents are among the most dangerous coastal hazards for the bathing public, and contribute to the highest portion of beach rescues all over the world. In order to help life guards in planning and preparing rescue resources so that casualties can be minimized, information about where and when rip currents may occur is needed. This can be provided by a predictive tool which combines meteorological forecasts, hydrodynamic models and remote-sensed observations. In this thesis, a methodology which can provide rip current forecasts for swimmer safety is developed and tested for Egmond aan Zee...

Many estuaries are located in urbanized, highly engineered environments. Cohesive sediment plays an important role due to its link with estuarine health and ecology. An important ecological parameter is the suspended sediment concentration (SSC) translated into turbidity levels and sediment budget. This study contributes to investigate and forecast turbidity levels and sediment budget variability at San Francisco Bay-Delta system at a variety of spatial and temporal scales applying a flexible mesh process-based model (Delft3D FM). It is possible to have a robust sediment model, which...