A thesis submitted in partial fulfillment of The requirements for the degree of Master of Engineeing in Water Engineering and Management

Thesis (M.Eng.) - Asian Institute of Technology, 2017

Nowadays, increasing urbanization has increased flash flooding after sudden rain. Land use and other human activities also influence the peak discharge of floods. The Increase in high- rise buildings brings changes to rainfall-runoff characteristics. In highly developed areas, high-rise and tall buildings are constructed in a small catchment area. The vertical area is greater than the drainage (horizontal) area. It seems that increasing area influences runoff and it does not included in conventional design method which uses the changing of physical conditions for runoff coefficient (C) and time of concentration (t-). This study proposes runoff estimation calculated from the interaction between wind-driven rainfall and high-rise and tall buildings. For rainfall, wind-driven rainfall can be calculated by ISO Standard of hygrothermal performance of building which in semi-empirical method. The discharge is calculated from flow that occurs along the facade of tall building. The developed kinematic wave is used to estimate runoff described by the continuity equation and a uniform flow equation. Nusselt equation for thin film flow is applied momentum equation. The effects of tall building and wind-driven rainfall shows increase in rainfall intensity. The wind speed has the most effect on runoff in the modified kinematic wave model. The second and the least effect occur by changing rainfall intensity with height and wind direction, respectively. The rainfall intensity approximately 20 mmlh with appropriate wind direction and speed lead to runoff greater than that from rational method. Estimated runoff is found to have linear relationship with rainfall intensity. From modeling results, rainfall intensity has significantly affected on time of concentration. The higher intensity gives less time of concentration which means the peak volume of runoff will reach faster while least effect by changing height. Moreover, the runoff from aside of tested building is greater than that from building roof when ratio of facade area and horizontal area over 5 times with rainfall intensity more than 40 mmlh and 5 mls for wind speed. The present study successfully shows that interaction of the high-rise/tall building (high-rise building defined by high while tall building defined by proportion) and meteorological variables bring in increased rainfall intensity and consequently, estimated runoff. The new design concept on urban drainage then must be revisited and revised in order to cope with the development change in highly urbanized area.