University of Twente Student Theses


Application of a satellite based rainfall-runoff model for large scale flood simulation : a case study of Cuvelai basin in Namibia

Mabande, Pricila Ketai (2011) Application of a satellite based rainfall-runoff model for large scale flood simulation : a case study of Cuvelai basin in Namibia.

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Abstract:Distributed hydrological models are an effective tool for analysing catchment response to extreme rainfall events. However, most distributed models require extensive parameterisation and calibration, which increases model prediction uncertainty. The aim of this study is to develop a satellite based rainfall-runoff model for flood simulation in Cuvelai basin, Namibia.This study adapts the structure and format of the LISFLOOD hydrological model. LISFLOOD is a spatially distributed hydrological model that is partly physically-based. It is embedded within a PCRaster GIS environment and runs on a Python interface. The model simulates river discharges in drainage basins as a function of spatial information on soils, topography and land cover. In this study five key parameters in the model are selected for calibration and sampled using root mean squared error (RMSE) and Nash Sutcliffe coefficients. These parameters are the upperzone time constant (UZTC), lower zone time constant (LZTC), ground water percolation value (GPV), Xinanjiang parameter b (Xb) and power preferential bypass flow (PPF). Calibration of LISFLOOD was carried out by trial and error through manually adjusting the each of the parameters while visually inspecting the agreement between the observed and simulated discharges. The uncertainty of predicted discharges at the Cuvelai-basin are narrow in the peak and broad in the ascension and recession limbs. The results show that the simulation of a flood event from a short time frame of 40 days is possible , but can be improved by better calibration, possibly through replacement of single value parameters with heterogenous maps. Replacement of daily average rainfall with a higher temporal resolution such as 3 hourly rainfall can increase the model‘s accuracy in quantifying discharge. It is recommended that an automatic calibration procedure be used to eliminate bias introduced by manual calibration. Key words: floods, PCRaster, LISFLOOD, hydrological model, Cuvelai basin
Item Type:Essay (Master)
Faculty:ITC: Faculty of Geo-information Science and Earth Observation
Programme:Geoinformation Science and Earth Observation MSc (75014)
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