An Integrated System Dynamics Model to Predict the Effects of Management Scenarios on Economic Assessment of Water and Soil Resources in Hableh-Rud River Basin, Iran

Abstract

AbstractSystem dynamics modeling facilitates the integrated and sustainable management of soil and water resources by enhancing the understanding of watershed systems. The Hableh-Rud river basin, an important watershed of Iran located across Tehran and Semnan provinces, was chosen for the present research. Reference diagrams were created to represent causal relationships and feedbacks based on which the conceptual model for the integrated management of soil and water resources of the Hableh-Rud river basin was developed. The conceptual model was then converted into a model of stocks and flows and run in the Vensim software. The model is comprised of by the biophysical and the economic subsystems. The main components of the physical subsystem include water balance, groundwater, erosion, sedimentation and water quality. In the economic subsystem, total costs and benefits were taken into account. Model verification was carried out through extreme condition tests and behavior reproduction tests. Having the Nash–Sutcliffe and R2 coefficients with greater values than 0.62 and 0.63, respectively, model tested. Different scenarios including vegetation management, climate, water resources management and cropping patterns were simulated, and the outputs of each scenario were compared to the outputs of the existing condition. The results of scenario analyses for a 30-year period reveal that payment for 50% of the ecosystem services by the government to expand alternative jobs and reduce damage to natural resources was determined as the best scenario. Scenario of payment for 25% of the ecosystem services by the government to expand alternative jobs and reduce damage to natural resources was chosen as the next best scenario. After evaluating the vegetation management scenarios, it was determined that farm management actions were considered as the best vegetation scenario. The research indicates that the system dynamic model, as an integrated approach for management of water resources in a basin, is pragmatic.KeywordsIntegrated water resources managementSystem dynamicsThe economic situationHableh-Rud river basin