Groundwater-Surface Water Interaction and possible changes due to Climate Change at Tana Basin, Upper Abay River Basin

Abstract

The objective of this thesis is to quantify groundwater-surface water interaction and to detect climate change impact on the interaction of the Tana Basin, Upper Abbay Basin Ethiopia. ArcSwat 2.3.3 model is used for the estimation of surface water balance both for the observed climate stations and future Regional climate Models (RCM) climate output scenarios of time periods (2031–2040 and 2091–2000) .From SWAT outputs developed future climate scenarios have both increasing and decreasing effects in space and time for surface runoff, but decreasing trend in deep aquifer recharges for all sub basins. A three-dimensional transient groundwater flow model ,Modflow 2000,has been used to quantify groundwater-surface water interaction on those major Rivers Gumar,Rib,Megech and Gilgel Abay for both the baseline period and future climate scenarios of the top unconfined aquifer Tana basin .Perturbing groundwater recharge output from SWAT model for climate scenarios the base period (1990s) and future climate scenarios (2030s and 2090s).As that of recharge simulated from SWAT model decreases to the future climates ,groundwater contributing to the streams depicts reduction . Climates exert larger percentage variation on surface runoff compared to groundwater-surface water interaction.