Quantifying Stress of Human Activities on Availability of Groundwater Resources of Karkheh River Basin

In recent decades, dramatic global population growth along with other related factors such as economic and industrial development, land use/cover change has contributed to an overall effects on water security and environmental problems around the world. To sustainable water management, quantifying the impacts of human activities on local hydrological cycle and water yield is essential in order to control balance between water demand and supply and increasing water security. This paper aims to offer a better characterization of human activities on groundwater stress and sustainability. Herein, we presented an approach for evaluation of water budget to facilitate understanding of the entire flow system of the aquifer in order to inform sustainable water resources management. We used a simple approach for quantifying direct human-hydrologic interactions by analyzing the aquifers’ water budget including human withdrawals (Hout) and return flows (Hin) according to water-balance equation and then normalized them relative to the net flux (Net Flux). Based on the normalized values of human inflow and outflow, the water-use regimes can be classified as surcharged (S), depleted (D), natural-flow dominated (Nf), and human-flow dominated (Hf). In addition we determine groundwater overdraft as a ratio between human withdrawals (Hout) and Recharge (RT) in order to evaluate the flow condition relative to the human water use. Finally we considered two adaptation scenarios to investigate probability of shift of aquifers that are located to depleted regime area to natural-flow dominated area. The results show that half of the studied aquifers in the Karkheh River Basin are of natural-flow dominated type while the rest are depleted. The Asadabad aquifer shows the highest amount (471 mm/yr) of human withdrawals (Hout) in this basin; actually highest overdraft relative to natural recharge to aquifer. Based on investigation of adaption scenarios, we explored that considering adaptation scenarios and decreasing human activities between 10 to 30 percent can be very useful for some aquifers in this basin.