Abstract:
Stream flow variability was evaluated in response to changes in climate, rainfall, and water demands. Water evaluation and planning system with monthly timesteps calculations was used to compute water situation, and parameter estimation tool used in calibration of the model. Model was calibrated using Nash–Sutcliffe efficiency, coefficient of determination, and Percent Bias, attaining values of 0.86, 0.85, and 6.64; while the validation coefficients were 0.90, 0.88, and 1.08, respectively. Climate evaluation scenarios under representative concentration pathway 4.5 and 8.5 predict mean rainfall to be 1420.1 mm and 1332.2 mm, and mean temperatures of 18.8 °C and 19.1 °C, respectively, at the end of 2050. The results show a non-significant increase in rainfall and significant increase in temperatures. Both pathways predict greatly variable decreasing mean discharge by the end of 2050. This variability is attributed to the increase in water demand and temperatures in the face of decreasing rainfall. The best-case and worst-case scenarios predict total water demands to increase to 201,903 and 204,302 billion cubic meters per year, respectively. Water consumption will increase from 77.0
per capita per day in 2021 to 85.2
per capita per day, and a 30% increase in unmet demands in all sectors. Results indicate that climate change will significantly impact water resources under the rising water demands, change of land uses, and varying discharge. Mitigation efforts will result in better flows compared to no intervention. Detailed study linking groundwater to surface water will help to understand the problem better.
