Abstract:
Rainfall-induced flooding during the rainy season is a regular phenomenon in Dodola Town. Rapid urbanization, change of rainfall intensity, and inadequate existing drainage system increasing runoff in the study area. The purpose of this study was to develop a adequate drainage system model for Dodola Town, in addition, to simulate the model for future purposes as well. To achieve the aim the catchment characteristics, link-node characteristics, and rainfall were analyzed. The catchment was delineated and drainage network in the catchment was generated using DEM, and sub-catchments characteristics were specified using GIS. The nodes and links input data collected by field survey. The intensity-duration-frequency curve was developed using frequency analysis of rainfall data obtained from the National Meteorological Agency. The rainfall intensity and land use change scenarios were used to estimate the highest runoff quantity to model efficiently after sub-catchments were inputted. The rainfall scenario showed that the peak runoff increased from 23.25m3/s to 62.14m3/s as rainfall intensity increased from 15.63mm/hr to 35.9mm/hr, respectively. The land-use change scenario shown the increased impervious area was 26.73% during the 20 years (2010-2030) caused to increase in the runoff of 59.69%. The combined scenario resulted in the runoff of 47.02m3/s, which is greater than the rainfall and land-use change scenarios of 1.44 and 1.18 times, respectively. Due to the numerous junctions linked to it, the outflow at outfall 3 is higher than others. As per the simulation results, the model of drainage network is efficiently suitable for Dodola Town to solve theflooding over 50 years.
