P Dehghan Rahimabadi - P.h.D. Candidate in Combat Desertification, Faculty of Natural Resources, University of Tehran, Tehran,Iran
H Azarnivand - Professor; Faculty of Natural Resources, University of Tehran, Tehran, Iran
A Malekian - Associate Professor; Faculty of Natural Resources, University of Tehran, Tehran, Iran

In arid and semi-arid regions, where the rainfall and surface water are scarce, groundwater plays a vital role toprovide fresh water to vegetation. In these regions, groundwater plays a key role in density of vegetation.Therefore, understanding the relationship between these two environmental factors is very important. The mainaim of this study is to investigate the relationship between vegetation and groundwater level in Semnan Basin,Iran. Normalized Difference Vegetation Index (NDVI) and Groundwater Resource Index (GRI) were adoptedto examine the vegetation cover and groundwater level, respectively, using Landsat OLI ۸ images and monthlydata from ۲۱ piezometric wells during ۶ years, from ۲۰۱۳ to ۲۰۱۸. The results indicated that NDVI had highervalues around urban areas than other areas. GRI had decreasing trend over the studied period and the meanvalue of maps of this index decreased from +۱.۱۷ to -۰.۷۲. The results of the correlation between NDVI andGRI illustrated that agricultural lands had dependence in high level (more than ۰.۷) to groundwater level. Toproperly manage the vegetation and groundwater resources and prevent the destruction of agricultural lands,proceedings to increase the groundwater level must be adopted.

NDVI; GRI; Vegetation; Regression