Designing a Payment for Ecosystem Services (PES) Scheme, Based on Sediment Control function in Shirin Darreh Basin, the Province of North Khorasan

Sediment accumulation is one of the major factors that reduce the beneficial life span of artificial reservoirs. Conservation and improving vegetative cover conditions may reduce sediment accumulation. A framework for implementing the PES was proposed assuming that the cost of soil and vegetation cover conservation may be considered as an investment in water supply through economic incentives, consisting of vegetative cover change projection, erosion and sediment transport modeling, reservoir sedimentation estimation, and the PES scheme design. Based on the results of increasing the amount of total sediment production from 486637.6 m3/yr in the current situation to 564217.5 and 658925.4 m3/yr, respectively over the next 20 years, and reduction of the useful lifespan of the Shirin Darreh reservoir (17.3%), the minimum payment for ecosystem services was considered 104 million Rials/yr. Furthermore, the volume and the total value of sediment control services provided by the vegetative cover was also determined by considering a complete degradation of the vegetative cover scenario and opportunity cost of 740535.5 m3/yr and 3.7 billion Riyals. Furthermore, the maximum payment was also estimated by considering the total value of the sediment control services and the estimated net present value of range conservation to be about 3.9 billion Rials/yr.