Assessing the impacts of precipitation on water yield estimation in arid environments: Case study in the southwestern part of Saudi Arabia

Water yield is a vital ecosystem service in basins, particularly in arid and subarid regions around the world. This study mainly focuses on the impact of precipitation variations on the estimation of annual water yield in the arid and subarid environment of the southwest part of Saudi Arabia. The simulation was performed using the Terrset software, based on the Integrated Valuation of Ecosystem Services and Tradeoff (InVEST) model. Eight input data parameters were considered, including Land Use and Land Cover, average annual potential evapotranspiration (ET), average annual precipitation ranging from 2000 to 2012, soil depth, PAWC (plant available water content), biophysical data, and a seasonality factor. The results show a high correlation, with an R 2 value of 0.99, between annual water yield and precipitation during the 2000 -2012 period in the region. The highest amount of water yield was obtained in 2010, with values around 266.67 mm, while the lowest was observed in 2006, with a value of 3.51 mm. The average pixel -level water yield in the region ranges from 46.65 to 154.08 mm, with a mean annual water yield of 96.77 mm. The highest amount of water yield is observed in Al Baha, at 1.3 mm per hectare, while the lowest value is observed in the Makkah region, at approximately 1.07 mm per hectare. The estimation of average annual water yield is crucial for understanding the amount of water production annually in the watershed. This information is particularly important in arid and subarid environments where water scarcity is a concern.