Applicability of artificial recharge of groundwater in Mojo, Ethiopia

Abstract

Like in many other towns in Ethiopia, population in Mojo town is growing fast every year. The population growth results in excessive use of the existing water supply sources. In Mojo the water supply sources are boreholes. Some industries located in the town are also depending on groundwater. Water level measurements taken over several years show that groundwater decline is felt throughout the area: some wells in the town have even ceased to be productive and therefore have been abandoned. Therefore, to correct the existing problem at an early stage and to cover the growing water demand of the town, artificial recharge of groundwater was chosen to be studied as main remedy option for the area. Study of artificial recharge applicability was done in the wellfield area of Mojo for about four months. Various tests were conducted to determine aquifer parameters as infilitration rate, porosity, transmissivity etc. and recharge water quantity and quality. Infiltrometer and sprinkler tests were done in different pits and plots to determine the infiltration rate. The well field hydrogeological studies, the existing drill logs of the wells and test pumping data were analysed to find out the aquifer type and groundwater flow condition. The storage capacity ofthe aquifer and the recharge waterquality were also analysed. The most reasonable water source for the recharge is the Mojo river. The river water quality is changing rapidly especially during the rains. Thus some kind of pretreatment, like horizontal roughing filtering is recommended to reduce peak turbidities. /Kir10