Predicting the Effect of Hydro-Climatic and Land-Use Dynamic Variables on Watershed Health Status

Abstract

Abstract This study was conducted with the objectives of predicting the effect of changing hydro-climatic variables, predicting the effect of land-use change on the future health status of the Safa-Roud Watershed, and the role of hydro-climatic and land-use variables in the spatial prioritization of sub-watersheds based on watershed health index. To conduct this study, first, key characteristics were extracted based on human, climatic, and hydrological factors for all three indicators of pressure, state, and response. Then, the watershed health index was calculated for the current conditions. After that, watershed health was predicted based on dynamic hydro-climatic and land-use variables for the 10 and 20 years ahead. The health assessment and zoning of the Safa-Roud Watershed showed that the average value and standard deviation of the current pressure index were equal to 0.573 and 0.185, respectively. The lowest value of this index was around 0.290 and related to sub-watershed 5, and the highest value was around 0.840 and related to sub-watershed 11. The initial evaluation of the classification indicated the prevalence of moderate and high-pressure conditions with a range of about 79%. Finally, the physical factors of sub-watersheds (time of concentration with 15.72%) had the most minor role. In general, among the criteria used to calculate the pressure index in the current period, human factors and climatic factors showed the highest percentage of participation in determining the pressure index. The quantification of the current watershed health status and the 10- and 20-year forecast periods showed that the values of the watershed health index were similar. However, the changes in the health index in the sub-watersheds at the beginning of the study period ranged from relatively unhealthy favorable conditions to moderately positive and moderately negative conditions.