Catchment Morphometric Characterization of the Akaki River in the Upper Awash Sub-Basin, Ethiopia

Abstract

Abstract Morphometry is the measurement and analysis of a catchment in the form of fingerprint characteristics. Morphometric studies play an important role in the areas of soil and water conservation, flood control, pollutant and waste management and socio – environmental protection. In this study, morphometrical data analysis indices are gained from high-resolution (12.5 m X 12.5 m) digital elevation model dataset for the of the Akaki watershed. The techniques performed using spreadsheet, R-programming, and ArcGIS tools. Results designate the Akaki watershed as dendritic drainage with elongated channels and irregular spreading streams ramifications. The big Akaki is the longest distance routing river among tributaries in the watershed. The Akaki watershed is expressed by 25% of steep sloppy coverages of Entoto, Yeka, and Sebeta mountainous areas. The implication on the morphometry of the catchment is to higher lag time of flow to reach its outlet. But the flood risk in the downstream areas can be due to the urban and peri – urban land uses with high pavement structures. In terms of the topographic wetness index (TWI), the higher elevation and river abatements areas have low moisture-holding capacities due to the hypsometrical characteristics of the landforms. High rainfall with lower evaporation rate recordings implies that the watershed has good groundwater recharge with good aquifer characteristics. This study could be a primary source of information for future development projects of watershed management, urban planning, riverside rehabilitation, flood controls and stormwater management practices in the Akaki watershed.