Groundwater recharge assessment and hydrometeorological scenario in the Fetam catchment Upper Blue Nile Basin, Ethiopia.

Abstract

Groundwater serves as a vital freshwater source for communities in Ethiopia, particularly in regions like the Fetam River Catchment within the Upper Blue Nile Basin, where reliance on rainfall recharge is significant. However, the uneven distribution of rainfall influenced the distribution of groundwater. The variability of such factors like altitude and land use practices presents challenges for sustainable groundwater management. This study aims to quantify groundwater recharge rates within the catchment, and assess the land use practices affecting recharge, and determine average annual meteorological conditions. Seven years daily meteorological data, including temperature, humidity, sunshine hours, wind speed, and precipitation were analyzed. Additionally, satellite imagery was utilized to understand land use land cover distribution, with the help of field investigation the area is dominated by cultivated land, grass land bult up, forested and bar lands. Three established methods like chloride mass balance, water balance, and water level fluctuation provides 114.5,165 238 mm/year. The mean annual precipitation over a period of seven years is 1727.2mm/yr and its average temperature varies from 10.4 to 29.6C°. The mean recharge rate calculated across all three methods was found to be 172.5mm/yr slightly lower than Ethiopia’s national average of 200 mm/yr. The dominant land use/cover types identified within the catchment include agricultural fields, grasslands, forests, developed areas, and bare land. Notably, water level fluctuation yielded higher recharge estimates compared to the other methods. Considering the specific physiographic characteristics of the region, the average value derived from all three recharge estimation methods offers the most accurate representation.