Investigation of groundwater fluctuations influence of climate change and improved irrigation method (Case Study: Ahar plain)

Ground water management is one of the most basic water management issues on basin level. In recent decades, natural and human factors have created critical conditions in aquifers of the country. In this research, the effects of development of pressurized irrigation systems on groundwater resources of Ahar plain have been investigated with WEAP software during 16 years. After calibration and validation of the model, the present situation of the region was simulated. The simulation results showed that development of pressurized irrigation systems has a significant change in the storage volume of aquifer and caused a drop in groundwater level of the Ahar plain. In order to analyze of conditions and to demonstrate of changes effect in different conditions and prediction for the future, the general circulation models of CGCM3 and HadCM3 were developed under A1B, A2 and B1 emission scenarios. The scenarios results showed that the average annual volume of aquifer increased 25% in the lack of pressurized irrigation development condition in the region. If pressure irrigation did not develop in the region, and instead of, surface irrigation was carried out, Surface runoff and agricultural return flow were more than the current situation in the basin. Also, the future climate scenario showed that with continuing the current situation in the future, the average annual volume of the aquifer will be reduced by 33%, that it will be caused to groundwater destroyed in the future. So pressurized irrigation systems not only do not save water but also lead to destruction of groundwater aquifers in the country. The results of this study emphasize the necessity of basin management studies to adopt proper management strategies, especially in critical areas.