Examining the impact of rangeland condition on water conservation by using an integrated modelling approach

Rangelands in the arid and semi-arid regions of Iran are under pressure from frequent degradations and extreme climate conditions, which have affected water conservation and delivery of ecosystem services. The timely and efficient assessment of rangeland state/condition impact on water conservation is crucial in rangeland management. This work represents an integrated modelling approach by linking the Soil and Water Assessment Tool (SWAT) and the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) models. SWAT simulated hydrologic components, while InVEST provided a decision support system for water conservation. The coupled SWAT-InVEST model was used to analyze the impact of different rangeland conditions on water conservation in the Atrak River basin in Iran's arid and semi-arid climatic zones. Increasing runoff is proportional to rangeland degradation. Our analyses show a severe degradation of rangelands in Iran. We found that the basin's average runoff varies between 2 and 294.8 m(3) ha(-1) yr(-1). Based on our modelling results, about 50% of the basin's runoff came from poor rangelands, 22% from moderate rangelands, and 28% from good rangelands. Thus, a significant impact on water conservation could be achieved through rangeland management in this basin. The SWAT-InVEST integrated modelling approach developed here proved useful for better decision-making under uncertainty.