Investigating the Groundwater Fluctuations Level in Basin of Halil River, Jiroft

Jiroft Plain with arid and semi-arid climate is one of the plains that experienced a significant increase in groundwater depletion in recent years. In the present study, to investigate the effects of precipitation and climatic conditions on the fluctuations of groundwater level, precipitation data of 6 rain-gage and evaporation stations during 1992-2014 were used and the average amount of precipitation of plain was calculated by Thiessen polygon method using Chirps satellite data. The results of the Pearson correlation between precipitation and level of groundwater showed a correlation of 0.23. However, the Standardized Precipitation Index was used to find the effects of drought and wet periods on the groundwater level. The results of consecutive time series analysis showed that SPI7 with 7 months long term scale has more correlation (0.35) with the groundwater level of plain. Evaluation of the hydrographic data of Jiroft plain in the statistical period of 2003-2014 showed that during this period, the groundwater level dropped by 8.65 meters and the average annual decrease is 0.61 meters. Also, the results of zoning maps using the Kriging method over 5-year intervals showed that the groundwater level decrease in the south and central parts of the plain had more drop. Then, using Ward analysis, Jiroft plain was divided into four clusters, which for cluster 1 Kalroud piezometer, for cluster 2 Saghari piezometer, for cluster 3, Konarsandal piezometer and Finally for cluster 4, Chehre Abad piezometer were selected. The correlation of average precipitation in each cluster with groundwater level fluctuations with the selected piezometers of that cluster were 0.51, 0.37, 0.38 and 0.55 for Kalroud, Saghari, Konarsandal and Chehre Abad respectively. Due to the sharp annual decline and over-depletion of the plain, if serious and effective action is not taken in this regard, this plain will not only by exacerbate environmental consequences but also will face economic and social problems in the future.