The effects of influence radius and drawdown cone on the areas related to the protection of water wells

Determining a suitable protection zone around the pumping well is necessary to protect the quantity and quality of water. Multiple researchers have facilitated the determination of protective zones around the pumping wells by introducing specific definitions (concepts such as influence zone, capture zone, transport zone, and wellhead protection zone) and developing analytical and numerical methods. However, determining the quantitative and qualitative protection zones is still challenging. The influence zone is a region where the water level decreases due to well discharge. Since most concepts of protective zones depend on the influence zone, the current study focused on investigation of the drawdown cone and influence radius as two characteristics of the influence zone. Investigations were performed using the numerical MODFLOW model and the results were compared with some analytical models including Moench, Neuman, Theis, etc. The entire drawdown cone was considered to deter-mine the protection zones of the pumping well. The influence radius solely represented one of the drawdown cone curves, and when calculated by the uncertain assumptions methods, significant amounts of volume and flow in the drawdown cone are ignored. The influence radius could not be considered as a definitive parameter, as this radial distance strongly depends on the definition.

Automated summary

Determining a suitable protection zone around the pumping well is important for preserving the quality and quantity of water. While various definitions and methods have been developed to determine protective zones, it remains challenging to establish quantitative and qualitative protection zones. This study focused on investigating the drawdown cone and influence radius as characteristics of the influence zone, using the numerical MODFLOW model and comparing the results with analytical models. The influence radius, though a representative parameter, has limitations due to its dependence on definition.