Pumping well groups on riverbanks: design and optimization by numerical simulation

To ensure sustainable development and utilization of water resources, and to minimize negative impacts on ecological environment, it is necessary to optimize design of pumping well group of riverside water source. With water yield (20×10⁴ m³•d⁻¹) and allowable drawdown of groundwater level (14 m) as objective functions, with proportion of river water captured by wells, area of cone of depression of groundwater level, and theoretical water supply capacity of a single well as constraint conditions, with design parameters (well number, distance between two adjacent wells and distance between well and river) as variables, evolution of groundwater flow field under three exploitation schemes was simulated and predicted with Visual MODFLOW 2010.0. An optimal scheme was obtained by comparison of predicted results. The optimal scheme was found to be: a combination of nine wells, with distance between two adjacent wells at 100 m, and distance between well and river at 50 m. Under optimal conditions, supply capacity of the source was 2.1×10⁵ m³•d⁻¹, 66% of which was from the river; area of depression cone at the groundwater level of the source was 2.8×10⁶ m², corresponding drawdown at groundwater level of the central cone was 11.5 m. This has the least disturbance to environment and the least negative effect on t environment under condition of optimal scheme.