Hydraulic Analysis of Storm Water Drainage System in Alamata Town, South Tigray, Ethiopia

With urbanization impervious surfaces increase, drainage pattern changes, overland flow becomes speedy, flooding and environmental problems such as land degradation increases. The objective of this study is to evaluate the hydraulic performance of storm water drainage system of the study area. The drainage channels are filled with or blocked by silt and garbage, the blockage of drainage structures is due to flat areas and siltation of drainage system which leads to failures on roadways.  Spatial analyses were conducted using Arc GIS, Bentley Flow master, Google Earth pro and Auto CAD software’s as analytical tools. The hydrological analysis was computed by rational method. The existing depth and width of the storm water drainage channel were measured for all sub catchments of the town and used to determine the existing drainage capacity using Bentley Flow master. The existing condition drainage channel depths of sub-catchments 6,7 and 8 increased by 68.40%, 160.20% and 121.07%; and the widths by 55.44%, 116.83% and 100.98%, and the design discharge was also 9.29m3/s, 16.47m3/s and 9.13m3/s, respectively. Therefore, this study recommends improvement in the integration of road and drainage structure; integration of solid waste management system in order to prevent the over flowing of storm water as a result of blockage of drains; the stations of the road requires proper maintenance and suitable measures should be taken in order to make the road and storm water drainage structures serve for the intended purposes sustainably to the stakeholders.