Hydrological modelling of spatial and temporal changes of blue and green water resources in Javanmardi watershed using SWAT model

Comprehensive evaluation of water resources in spatial and temporal scales may provide an effective strategy to understand the renewable water resources and an optimal management of the watersheds. In this study, SWAT model was used to estimate the components of blue and green water resources (green water storage and flow) in Javanmardi watershed. For this purpose, monthly runoff was first simulated using SWAT model and SUFI-2 algorithm was then used for the calibration and validation. Runoff simulation results were satisfactory such that the values of R2 and NS values in the validation step were 0.75 and 0.74, respectively, showing that the model has properly simulated the monthly runoff. The amounts of blue water in the central and eastern parts of the watershed were less than 40 mm per year, whereas in the southern altitudes, northwest and western parts of the watershed, it was more than 60 mm per year. The northern sub-basins of the study area had the lowest values of green water flow (from 400 to 451 mm year-1) and then the central parts had relatively greater values of green water flows than the northern parts. The simulated green water storage in most sub-basins was more than 81 mm where the maximum value of that was 142 mm year-1. The results of the hydrological component estimation provide valuable information about the spatial (in sub-basin scale) and temporal (annual and monthly) distribution of water resources which can be useful for long-term planning and optimal management of the watersheds.