Water yield (WY) is a key provisioning ecosystem services that is sensitive to climate and land use changes. This study aimed to evaluate the impacts of climate and land use changes on WY in the Tajan watershed, northern Iran, from 2022 to 2052. Additionally, it investigated the relationship of WY to slope, elevation, and normalized diference vegetation index (NDVI) specifcally in 2022. Land use change was simulated in the TerrSet v19 software using the Land Change Modeler, while climate change was projected based on the CMCC-CM model under RCP45 and RCP85 scenarios using the LARS-WG 6 software. Six scenarios were designed according to climate and land use to evaluate the WY in the InVEST 3.13 software. Statistical analysis was performed using the Getis-Ord (G*) statistic, bivariate local Moran’s I (BLMI), and geographically weighted regression (GWR). The results revealed that WY had hotspots in the northern parts and cold spots in the central parts. The total WY volume ranged from 8.7 to 25.1 Mm3 y−1 based on all scenarios. It was clarifed that land use change increased WY by 2–7%, while climate change decreased it by 47% and 65% under RCP45 and RCP85, respectively. The lowest WY was observed in the forest, while and the highest was in built-up areas. As indicated by the BLMI, the WY had a moderate spatial autocorrelation to elevation and slope, having Moran’s I of −0.53 and −0.62, respectively. In contrast, its spatial autocorrelation with NDVI was weak with Moran’s I of −0.01. The GWR analysis revealed a signifcant spatial correlation of WY to elevation, slope, and NDVI, having R2 values of 0.94, 0.90, and 0.96, respectively. This study showed that climate change has a greater impact on the WY than land use change. Furthermore, WY distribution is infuenced by topography and vegetation. Therefore, it is necessary to implement regional management plans through water conservation policies and dealing with climate and land use changes to conserve the water resources of the Tajan watershed in the future
