Investigating Quantitative Changes of Groundwater in the Semnan Plain

Considering that Semnan Province is in an arid and semi-arid region like other dry parts of the country, it is more vulnerable to a water scarcity crisis, So, Semnan Plain was selected to study groundwater level. In order to study the reduction of water level, 20 observation wells were surveyed during the 20-year statistical period (1994-2013). At first, statistical data from the regional water company of Semnan Province were collected and arranged. After entering the data into GIS, using point maps and Kriging interpolation method, the zoning of surface degradation of groundwater in the study area were prepared. For better display, the resulting data were plotted on the graph in Excel. The results of the study showed that during the statistical period over time, the average groundwater level was reduced by 8.6 meters. Monthly surveys also showed that the highest level of surface water loss was due to the months of September, October and November, which lower rainfall and autumn crop start, and as a result, exploitation of groundwater resources is higher. In order to investigate and identify the sensitive areas and the role of land use on the quantity of water in wells, the specifications mentioned for each type of land use were separately examined. The results showed that the most reduction in groundwater level is related to the residential area. Finally, it can be concluded that the region is in critical condition for groundwater resources, and managing these resources is very essential in the Semnan plain.