Invloedsschatting van landgebruiksverandering en vernatting op rivierbekkenhydrologie = Assessment of the effect of change in land use and rewetting on catchement hydrology
Rubarenzya, M.H. (2007). Invloedsschatting van landgebruiksverandering en vernatting op rivierbekkenhydrologie = Assessment of the effect of change in land use and rewetting on catchement hydrology. PhD Thesis. Katholieke Universiteit Leuven (KUL): Leuven. ISBN 978-90-5682-875-2. XVI, 215 pp. |
| Available in | Author | | Document type: Dissertation
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| Keywords | Basins > River basins
Catchment area
Earth sciences > Geology > Hydrology
Ecosystems
Inflow > River discharge
Land use
Modelling
Models
Topographic features > Landforms > Valleys > River valleys
Water bodies > Inland waters > Wetlands
Belgium, Grote Nete R. [Marine Regions]; Belgium, Nete Basin
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| Abstract | The increasing awareness and concern about the potential impact of anthropogenic changes on river valley ecosystems have led scientists to realize that mankind’s economic strides made over the last two centuries were at the expense of the earth’s biodiversity, its environment, and the stability of its self-regulatory systems. This is resulting in a number of initiatives being planned to reverse past anthropogenic changes, of which, river valley rewetting is one. In this study, spatially distributed hydrological modeling was used to test for the response of the catchment’s hydrology and peak river discharge to alternative methods of implementing river valley rewetting.
The Grote Nete catchment was taken as the study area. It is a middle-sized catchment located in the northeast of Flanders. The basin area of the outlet limnigraphic station at Varendonk is 385km2. Distributed hydrological modeling of the Grote Nete catchment was undertaken using MIKE SHE. MIKE SHE was chosen for its ability to generate a spatially distributed representation of the catchments’ hydrological processes, which was necessary for undertaking scenario analyses. A multi-criteria calibration protocol was used for model development. The land use modelling and spatial analysis was carried out using the spatial analysis tool, SPAN.
A qualitative identification and evaluation of uncertainty in the context of the distributed hydrological modeling was undertaken, along with a study on the importance of river network representation in model development. A detailed discussion is presented on the unsuitability of most available land use maps for direct use in specific modeling applications, and how this challenge was overcome during this study. An evaluation was undertaken to understand the applicability and limitations that could be expected in the scenario analysis of rewetting. The study generated river valley rewetting scenarios in which consideration was made of the type and location of the wetlands. The study confirmed that different types of wetlands have many possible interactions with hydrology. The study found rewetting by infiltration restoration to be a catalyst for the greatest decrease in total river discharge. This was achieved through a decrease in the paved overland component of river discharge, and an increase in the saturated zone flow component.
The greatest increase in discharge resulted from taking no rewetting action. In the event that no rewetting action is taken in the catchment, the return period of extreme river discharges is expected to reduce by nearly 4% which means that extreme river discharges will become more frequent in the future. It was determined that the scenarios with the two highest changes in return period of extremes are infiltration restoration and upstream valley bottom wetlands, respectively. It was established that the return period of extremes was decreased by 2.8% for upstream headwater wetlands. In analyzing the results the study, it was established that for any given scenario, a positive change in paved overland flow component of river discharge was accompanied with a negative change in baseflow + overland flow. Relationships were also established indicating the change in return period of peak river discharge varied with changes in discharge components, across the various scenarios.
Some recommendations of the study were that: an interdisciplinary study approach continue to be adopted for rewetting studies; a similar procedure be followed in using land use information during future studies; the type and location of the wetlands be considered whenever modeling rewetting by wetlands restoration; research be undertaken into wetland classification methods, and wetlands’ hydrological behavior; and field data be obtained from the Grote Nete catchment for at least two or three years of the simulation period, and used to verify the output of the scenario simulations.
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