University of Twente Student Theses


Flood Propagation Analysis in an Urban Environment; a Case Study in Yen Bai Vietnam

Alahacoon, Niranga (2010) Flood Propagation Analysis in an Urban Environment; a Case Study in Yen Bai Vietnam.

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Abstract:Fast growth of world population can cause the rapid development and expansion of the cities in developing countries. Furthermore, loss of life and properties in such sites is increasing during the severe flood event which can occur under a typhoon. Therefore asses the flood hazard and risk is important for future developments. 1D2D hydrodynamic model can be used as a tool for simulating severe flood events. Accurate elevation data and historic flood data are the most important parameters for such models. Rapid changes of the topography of cities may cause a problem in updating the topography such in Digital Surface Model (DSM). This thesis is focused to asses the flood risk in Yen Bai city Vietnam. To create a Digital Surface Model (DEM), first the Digital Elevation Model (DEM) was created by integrating the different elevation data. The effect of integration of multi-source elevation data was studied through the geostatistical approach by considering the nugget value. Then the interpolation of elevation data was carried out with Kriging, Polynomial and Triangulated Irregular Network (TIN) interpolation to assess the quality of them by errors. The DEM which was generated with Kriging interpolation and the building heights integrated with that to generate the DSM for further hydrological modelling. The DSM and historic flood data was used to simulate the 5, 10, 25, 50 and 100 year return period of flood with SOBEK 1D2D flood model. Then this model was calibrated for building structure and three sets of manning’s coefficient with flood extent and height data of 2008 super typhoon. The flood hazard of the different scenarios period was assigned in to flood extent map and then categorized them in to hazard classes. Furthermore model results of 1D2D flood model was converted in to different flood parameter maps such as maximum flood depth, velocity, impulse, rate of water level rising and sedimentation. Those parameter maps was integrated with Spatial Multi Criteria Evaluation (SMCE) in ILWIS to create the Multi parameterized flood risk map. Among the different DEM interpolations, the Kriging interpolation has given the best DEM for flood simulation. Integrated 1D2D (SOBEK) flood simulation models can be used to simulate the urban floods in complex topography. The behaviour of flood water flow is affected by the building structures of the area and the solid block representation has given the better performance for flood simulation in Yen Bai city. In the event environment experiencing with lack of flood risk data, Multi parameterized flood risk mapping approach can be applied in valuable manner.
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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