Tracing water resources flows by complementary use of hydrological and water accounting models

Abstract

AbstractHistorically, there has been a dispute over water allocation between users and policymakers in Iran's Zayandeh‐Roud Basin (ZRB). In this study, we used the “System of Environmental‐Economic Accounting for Water” (SEEAW) framework in combination with the hydrologic model “Soil and Water Assessment Tool” (SWAT) to achieve the water balance in ZRB. We used SEEAW to combine a wide range of water‐related statistics across stakeholders and SWAT to evaluate the unknown agricultural water use. The SWAT model is calibrated based on the stream flows and crop yields in the basin. The model assess the renewable water of the basin into two components, about 363 and 70 mm as green and blue water, respectively. Also results from the physical water supply and water use tables demonstrates that the agricultural sector uses 78% of the total renewable freshwater, followed by the residential, 16%, and the industrial sector, 6%. The flows of water from source to services in ZRB are traced based on the water supply and water use tables. The flow diagram shows that 8 MCM of industrial reused water was transferred to the agricultural sector, and 137 MCM and 18 MCM of water from the wastewater treatment plants to the agricultural and industrial sectors, respectively. Furthermore, the results show that the index of the basin dependence on groundwater resources is high (61%), the value of water stress is high (0.88) and the dependence of the basin on transboundary water resources is 30%. Therefore, this method is highly beneficial for achieving a conceptual water balance in disputed basins without enough agricultural water uses data.