Assessing the land use/land cover and climate change impact on water balance on Tordzie watershed

Water resources management in watersheds require quantitative knowledge of it in time and space. Water availability in watersheds are influenced by land use/cover (LULC) and climate change. This study relate LULC and projected climate changes to water balance in Tordzie basin using climate scenario of RCP 4.5 with CCCMA Model. SWAT embedded in ArcGIS was used for the water availability assessment after calibration (2000-2003) and validation (2004-2006) using discharge from Tordzinu within Tordzie. The Nash-Sutcliffe Efficiency (NSE), Coefficient of regression (R-2) and Percent bias (PBIAS) were performance evaluators employed to assess model suitability and validity on monthly time scale. The SWAT performance indicator values were 0.74, 0.74, 5.10% respectively for 2003 LULC and 0.88, 0.89 and + 0.30% for 2017 LULC. The simulated surface flow (SURF_Q) under the LULC scenarios increased by 24.65% and water yield (WYLD) decreased by 6.7%. The annual simulated water yield were 132.21 mm and 123.30 mm. We found LULC have significantly impacted the hydrology of Tordzie watershed. Projected water balance (2050) indicated increase in surface flow (19.00%) and decrease in ground water (36.40%), base flow (0.77%) and water yield (6.50%). This was linked to climate change. Further study of the watershed is recommended incorporating the water quality parameters.