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Design of a hydrological model to determine the impact of urbanization on the direct runoff at the hillslope scale in West Java, Indonesia

Warmerdam, M.T.M. (2014) Design of a hydrological model to determine the impact of urbanization on the direct runoff at the hillslope scale in West Java, Indonesia.

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Abstract:Indonesia is coping with a water crisis. Water resources are abundant, but bad governance of these water resources has led to serious troubles with availability of water for irrigation and drinking. On Java the population is still increasing and a continuous urbanization process might pose a threat to the already problematic availability of water resources. This urbanization process has recently also been observed in the vicinity of Labmath-Indonesia. Because the area is very mountainous the effects of this urbanization process on the hydrology is not known. Since the area is also one of the largest water sources for Kota Bandung it is important to determine the effect of this urbanization process at the hillslope scale. During the research at Labmath-Indonesia a hydrological model was developed to determine the effect of urbanization on the direct runoff at the hillslope scale. Data relevant to the study area were not available and no field study was performed. This meant that the model had to be designed using parameters from literature and making rough assumptions based on superficial observations. The model has therefore been developed with the aim to serve a purpose of comparing relative behaviour of the natural system for different urbanization patterns and different climatic conditions. A selection has been made of the key aspects that determine the direct runoff after a precipitation event: precipitation, surface flow, infiltration, soil saturation and evapotranspiration. For the precipitation multiple scenarios have been formulated based on several climate reports. These scenarios aim to show the difference between small precipitation events and extreme precipitation events. Surface flow has been implemented using a numerical model, but based on the analytical derivation of Burger's wave equation. Infiltration and soil saturation have been implemented using Horton's infiltration system because of the lack of available data. Evapotranspiration is based on empirical data and uses a very crude method, which is acceptable due to the relatively small influence on direct runoff. The model has run several urbanization scenarios under different precipitation regimes and for different slope characteristics such as slope length and inclination. A comparison of these scenarios made clear that there is a significant difference between a scattered urbanization pattern and a concentrated pattern. The results show that a scattered urbanization pattern causes a smaller increase in direct runoff than a concentrated urbanization pattern. However the accuracy of the model is questionable. To increase the accuracy of the model results a field study should be performed and the model logic should be improved upon with more realistic hydrological methods such as Green-Ampts infiltration method and the implementation of storm flow.
Item Type:Essay (Bachelor)
Labmath-Indonesia, Indonesia
Faculty:ET: Engineering Technology
Subject:56 civil engineering
Programme:Civil Engineering BSc (56952)
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