Quantification and analysis of water retention ecosystem service and its spatial autocorrelation in North west Iran

The development of human societies has altered the landscape of the watershed through remedial activities, industrialization, and urbanization, causing significant changes in a wide range of hydrological, climatic, ecological, and socio-economic functions. This, in turn, has had significant consequences on resources and ecosystems. Therefore, in this study, the water retention index, one of the indicators of multifunctional ecosystem services, was quantified using InVEST software. For this purpose, variables including rainfall, land use, soil hydrological groups, and curve numbers related to 28 watersheds in Ardabil province were prepared and introduced to InVEST software. Then, an accuracy assessment was conducted using error coefficients, including R2, RMSE, ME, and MAE. Additionally, to analyze auto-spatial correlation and identify runoff hotspots and water retention, global Moran's index and Enslin Moran's index were employed. The results showed that the minimum water retention was observed in residential areas (26.26 m3), and the maximum amount was obtained in the forest (74.43) and grassland (74.46) uses. Moreover, Barogh, Doost Bigloo, Shamsabad, Amoghin, Gilandeh, and Yamchi watersheds were ranked first, while Akbardavod watershed was ranked 28th. Generally, the southern and western parts of the province had a higher water storage capacity compared to the northern parts. Unnatural or artificial land use areas had lower water retention. Comparing the estimated runoff results with InVEST software with observational data from hydrometric stations showed that the software's estimated runoff results were acceptable, provided that the input data was produced with great accuracy. The analysis of Moran's index and hotspots identified patterns of spatial distribution of runoff volume and water retention in most watersheds, indicating significant spatial correlation between the data. The results of this research can provide a theoretical basis for the selection of InVEST software, decision-making, and regional ecosystem management.