The effects of land use land cover change on hydrological flow in Giba catchment, Tigray, Ethiopia

Abstract Tigray regional government has proposed land use land cover (LULC) change due to the 5-year growth and transformation plan (GTP). This LULC change could have an effect on hydrological flow. Hence, quantifying the hydrological flow coming due to the LULC change is important for decision making. Considering this, we set out to assess the impact of LULC change on hydrological flow of Gibe catchment using three LULC scenarios as compared to the base year (2010). The three scenarios were, increasing forest area, plantations/area closure and grass lands by 400, 200, and 200% from the base year, respectively. SWAT model was used to simulate the hydrological flow. The model was run on a daily time series for 7 years: calibrated during the 5 years (1998–2002), and validated during the 2 years (2003–2004). The simulated daily flow showed a good agreement to the observed flow with NSE = 0.81, R2 = 0.78 and PBIAS = −6.85 % for calibration, and NSE = 0.79, R2 = 0.75 and PBIAS = −7.52 for validation. The simulation result of the hydrological flow under the scenarios showed that increasing forest, plantation/area closure, and grass land have reduced the annual flow by 8.61, 4.65, and 1.45%, respectively. Reducing the hydrological flow could increase ground water potential and dry season base flow, which can be used for irrigation. Therefore, it is recommended that the government should strengthen the policy on natural resources management.