Integrated and Sustainable, Urban Drainage System Options using GIS & RS in Adi-Haki Sub-city of Mekelle City, Ethiopia.

Abstract

Mekelle including Adi-Haki sub-city is one of the fastest growing Ethiopian cities. The evolution of land use is much related to urban development. Urbanization covers a large part of the ground surface with hard pavements resulted in decreasing in-site infiltration and increasing surface-runoff. The objective of this study is to provide integrated and sustainable urban drainage system (SUDS) options to control flooding in the study area. This objective can be realized by control measures of both structural and non-structural urban drainage system options scientifically estimated and evaluated. The amount of flood can be estimated scientifically using rational and manning methods, but since both methods are manual operations, it is difficult to estimate for a wide catchments. In this case, Storm Water Management Model (SWMM) software is very important surface-runoff simulation model in terms of time and accuracy. Calibration and validation of values obtained from manual and SWMM software model is important to validate and evaluate the performance of SWMM software model. This performance can be tested using the acceptable values of efficiency performance coefficient (𝑅2), Nash-Sutcliffe Efficiency (NSE) and Relative error (RE). According to the estimated surface-runoff volume the maximum (peak) flow and maximum run off volume are 22 m3/sec and 118*103 m3 respectively. The total runoff-volume has been reduced from 503*103 to 336*103 m3 after Low Impact Developments (LIDs) control options are developed (bio-retention, permeable pavement and rainwater harvesting). The study area’s drainage performance can be improved using non-structural SUDS of LIDs control options. The municipality would participate the local community in implementing and managing of SUDS options to improve the drainage system performance of the study area.