Introducing an Efficient Socio-Economically Oriented Data Envelopment Analysis Method for Selecting the Optimum Groundwater Dam Site Location

Groundwater dams are commonly constructed in arid and semiarid regions for subsurface storage of water. In this study, an attempt is made to present a new efficiency-based site selection methodology for constructing groundwater dams based on socio-economic approaches. The site selection process was conducted in a semiarid region in Central Iran. A total of 13 different criteria in four major classes of climate, geology, hydrology, and socio-economy were defined. Nine multi-criteria decision making (MCDM) methods were used for site selection, followed by integrating the results by Borda and Copeland algorithms. The data envelopment analysis (DEA) was employed for selecting the optimum groundwater dam site from the same choices. The DEA method is based on efficiency and it is capable for evaluating the performance of each alternative. Four different scenarios, including the CCR-Input, CCR-Output, BCC-Input, BCC-Output, were used to implement the DEA approach. In addition, the socio-economic-based optimization equation was solved by considering three socio-economic criteria as the output of the DEA model. The results show that the CCR method provides the best results for groundwater dam site selection by maximizing the outputs. Two algorithms, namely the Potential Improvement and Input/output contribution, were used to evaluate the performance of each alternative. These algorithms show the amount of improvement for each selected option. The application of the DEA method, as a new approach for groundwater dam site selection, can increase the performance of the selected option and facilitate dam maintenance throughout its operation time.

Conjunctive Operation of Surface and Subsurface Dams Based on Drought Severity

As an effective water management method to respond to the increasing severity of drought, this study proposed a conjunctive operation using a surface reservoir and subsurface dams. The proposed methodology predicts the probable rainfall according to the drought severity and the water demand, and uses these as the basis for water allocation. Sokcho City, located in South Korea, was used as the study case. Sokcho is a tourist city that has suffered from water shortages for many years due to its excessive dependence on a single groundwater dam. Considering conjunctive operation, drought frequency, and drought duration, a total of 80 cases under four scenarios were generated and simulated to determine the water supply capability over the entire year. The results indicate that domestic water can be supplied throughout the year with appropriate water allocation, even when a once-in-50-year drought lasts for 120 days. Furthermore, the water supply potential, which is the additionally available capacity in a reservoir, was used to assess the effects of conjunctive operation. It was estimated that, for a once-in-10-year drought, up to 318% of the annual water demand was available in the reservoir. As the proposed methodology is relatively simple, it offers a useful water resource management tool for sites with similar social and environmental conditions.