Economic-Environmental Management of Agricultural Lands with Emphasis on Reducing Groundwater Abstraction under Rainfall Uncertainty: A Case Study of Qareh Toghan Region of Neka

In recent years drought and the continuous extraction of water by digging deep wells have led to a drop in groundwater levels. Therefore, in order to manage groundwater consumption for sustainable use of water resources and also to maintain the environmental balance of this important resource, appropriate research and policies are needed. In the present study, in order to make optimal use of groundwater in Qareh Toghan region of Neka, the stochastic multi-criteria decision analysis approach has been used under rainfall uncertainty condition. The required data were collected as a library and GAMS software was used to estimate the results. Based on the results, by increasing the probability of rainfall up to 99%, an increase in gross margin in the region would happen so that in scenarios of 95% and 99% probability of rainfall, the gross margin was increased by about 1.44 and 4.13%, respectively, compared to the condition of 90% rainfall probability. Under these conditions, the amount of groundwater abstraction in various scenarios remained unchanged but the share of groundwater in the total water consumption decreased. In contrast, in the case of reducing the probability of rainfall to 99% compared to the probability of 90%, the gross margin of the proposed cropping pattern decreased by about 33.3%. In this condition, the amount of groundwater abstraction decreased by about 32.8% due to low groundwater level in the region and its unsuitability in terms of salinity. However, the share of groundwater consumption in relation to the existing conditions and in all the mentioned scenarios remained constant. Therefore, due to the high share of groundwater in agriculture in the region, as well as increasing farmers' losses and the possibility of declining groundwater levels in low rainfall years, it is suggested to provide suitable plans for using surface water in the study area for optimal management, and improving the environmental conditions of groundwater in the region while supporting the income status of farmers.