Surface and Groundwater Resource Evaluation of Upper Guma Sub-Catchment (Bonga)

No Thumbnail Available



Journal Title

Journal ISSN

Volume Title


Addis Ababa Universty


The development of a balanced plan for water resources utilization requires full knowledge of quantity, quality and distribution of water resources and also the changing pattern of land use in the entire water shade of and its influence on the river flows in the study area (Guma Sub Catchment) which is located and is bounded within7010' N- 70 25' N latitude and 360 05’ E - 360 30' E longitude. The total aerial coverage of the study area is about 876 km2study area. Prior to this research work, the contribution of information about the water resources and water budget components were not known.The combined effects of climate and geology on the catchment topography yield an erosion pattern which is characterized by a net work of channels or streams. Topography of the area ranges from flat to mountains and gorges. The average monthly rainfall ranges from about 253.51 mm in the highlands in the northeastern part of the study area and 48.86 mm in the northwestern part of the area. Hydrologic and hydrogeologic investigation and water balance calculation were used to study the surface-ground water interaction in Upper Guma Sub-Catchment with emphasis given to hydrochemistry.Classification of water types in the area according to the tri-linear piper diagram plots show that, most of the hand dug wells are Ca-Na-HCO3 and Ca-Mg-Cl water type where as springs show, Ca-Na-HCO3 and Ca-Mg-HCO3 water type. The borehole result has a water type of Ca-Mg-HCO3 and Na-Ca-HCO3 which signifies the dominancy of volcanic terrain. Based on major cations and anions, the general water quality for public supplies, irrigation and industry are identfied in the study area. Values of net groundwater recharge estimate is determined from water balance calculation and found to be 110.7 MCM annually accounting not greater than ten percent of the annual precipitation indicating that groundwater resources should be wisely exploited giving due attention to the integration of the surface water resources of the area. The result of this study can be used as data source for future sustainable development and management the catchment area.



Guma Sub-Catchment