Evaluating InVEST model for simulating annual and seasonal water yield in data-scarce regions of the Abbay (Upper Blue Nile) Basin: implications for water resource planners and managers

In developing countries, hydrological data is one of the limiting factors for evidence-based water resources planning and management. Thus, evaluating the performance of hydrological models that require relatively simple inputs is imperative for using them in the decision-making process. This study aims to evaluate the performance of the Integrated Valuation of Ecosystem and Tradeoff (InVEST) models for simulating annual and seasonal water yields in data-scarce regions of the Abbay (Upper Blue Nile) Basin with a case study in the Gumara watershed. The input data required by the InVEST Water Yield and the InVEST Seasonal Water Yield models were prepared from primary and ancillary data sources. The two InVEST models were calibrated using the calibrated Soil and Water Assessment Tool (SWAT) model outputs, and NSE of 0.86 and 0.91, PBAIS of 2.5% and 20.8%, and RMSE of 16 mm and 7 mm were obtained for the InVEST Water Yield and Seasonal Water Yield models, respectively. The attained performance measures indicated that both models can be used for evidence-based water resources planning and management in data-scarce regions of the Upper Blue Nile Basin. However, due attention is needed for calibrating the models since they are sensitive to the calibrating parameters.