Optimum interval of artificial groundwater recharge wells, considering injection rate and economic feasibility.

Artificial recharge of groundwater increases the water level in an aquifer, which can be used for water security in a drought-prone region. This study was conducted to identify the interval of injection wells in a small basin upstream of a watershed. For the pilot test, 11 injection wells were installed, in which individual and simultaneous injections were performed. The rates of the individual and simultaneous injections ranged from 0.49–38.13 and 0.04–11.48 m3/d, respectively. Simultaneous injection resulted in a reduced injection rate of approximately 4.4–95.4% compared to that of individual injection owing to the interference effect of the injection wells. Moreover, the hydraulic conductivity of each well and the radius of influence were used to analyze the interference effect during injection using the Thiem-Dupuit equation. The interference effect between injection wells was evaluated by increasing the space from 2 to 15 m at four recharge lines (total length: 340 m) within the study area, and the expected injection rate was calculated as the rates of 220.85–58.95 m3/d. On the other hand, construction cost for installing injection wells became higher at 2 m interval than at 15 m. Therefore, there was no significant increase in construction cost per 1-m3 injection volume as well as decrease in total injection rate if the well interval was > 5 m and the optimum interval of injection well was suggested to be at least 5 m. Drought-prone areas are generally excluded from water-welfare benefits and are economically fragile; consequently, when developing an artificial recharge facility, injection wells should be designed considering the security of suitable amount of water with economic feasibility. [ABSTRACT FROM AUTHOR]