Modeling Land Use Change Impacts on Water-Related Ecosystem Services Using a Policy Support System

Quantifying,anticipation of the impacts of changes in water-related services caused by human activities is a complicated aspect of environmental assessment which can be facilitated by the application of dynamic,spatial models of ecosystem services. This paper aims to examine the application of the WW PSS model in the Sarvelat,Javaherdasht forested landscape in order to calculate the water balance,water- related services of the ecosystem in a baseline condition and, then, to measure the impacts of changes in natural forest cover on the services' quantity,quality based on a scenario developed. The result of running the model indicates that the surfaces covered with dense forest have decreased by 29% in recent 13 years, but the semi-dense,poor forest covers have increased by 14%,15%, respectively. Then, the impacts of such structural changes on water services were measured,this showed an overall decrease in water balance of 1.5 mm,yr,an increase in runoff of 12,197,528 m3,yr which is caused by a reduction in evapotranspiration due to cutting forest trees. In the final stage, the environmental consequences of changes in ecosystem services were quantified by the model which depicts an increase in soil erosion of 0.57 mm,yr on average,exacerbation of the potential of water contaminate distribution across the study landscape.