Monitoring of Temporal and Spatial Variation of Groundwater Drought using GRI and SWI Indices (Case Study: Sari-Neka Plain)

Decrease of aquifer recharge, Increased pumping through deep wells for agricultural purposes, increases in temperature and evapotranspiration, climate change and change the type of precipitation induced reduce of water level and water table which is called Groundwater Drought. Identifying, monitoring and characterization of drought is very important for water resources planning. The object of this study is investigating temporal and spatial variations of groundwater drought using Groundwater Resource Index (GRI) and Standardized Water Level Index (SWI) in the plain area of Sari-Neka. For this purpose, groundwater data of 40 piezometric well from 1364 to 1394 were analyzed. Thus, GRI and SWI indices for time scales of 3, 6, 9, 12, 18, 24 and 48 months in Minitab and M.S Excel was calculated. Spatial extent of groundwater drought in the plain using IDW in ArcMap 10.3 was obtained. The results show that the severest drought in 3-month time scale using GRI index in Shahrivar 1394 in the amount of -93.3 and SWI index in Mehr 1394, with value of 86.4 occurred. Drought spatial changes in northern parts of the plain are related to Mordad 1384. Zoning maps indicated that Mordad highest amount of drought and Bahman has lowest value; the most important for this is pumping water from groundwater aquifers for agriculture.