Effects of excessive water extraction on groundwater ecosystem services: Vulnerability assessments using biophysical approaches.

In this research, a systematic, integrated framework was developed to evaluate the biophysical state and vulnerability intensity of groundwater supply ecosystem service (GSES) regarding excessive groundwater withdrawal in the Mashhad plain located in the northeastern of Khorasan Razavi province in Iran. At first, following an indexing approach, the biophysical aspects of the ecosystem, including capacity, flow, and the benefits of GSES, were analyzed. Afterward, the relationship between the capacity and flow ecosystem service (ES) was assessed to identify ecosystem's sustainability status. Furthermore, GSES stability was spatially shown. Finally, GSES vulnerability and its associated ESs was assessed based on 3D model of vulnerability via indexing three components of exposure, sensitivity, and adaptive capacity. The final map spatially indicated the zoning of groundwater ecosystem services' vulnerability intensity in Mashhad Plain. The outcomes indicate a high and very high vulnerability in more than 35% of studying area. The results indicate that about 18%, 30%, and 15% of studying land show moderate, low, and no vulnerability, respectively. Finally, it was observed that due to groundwater's over-extraction, supplying the aquifer ecosystem services was disrupted. This method can be used as a solution for the sustainable management of groundwater resources, especially in the arid and semi-arid countries facing the depletion of water resources.