Numerical investigation of flow to pumped wells in heterogeneous layered aquifers using radial flow models

Pumping tests are conducted to examine the performance characteristics of a well and the aquifer flow mechanisms. Numerical models that are able to incorporate all flow mechanisms are important for this purpose. Because of the convergent nature of groundwater flow approaching a pumped well, a threedimensional R-θ-Z numerical model that simulates the groundwater flow behavior in heterogeneous aquifers is developed using the object-oriented programming approach. This programming method greatly simplifies the development of the model. The model is applied in two dimensions to investigate the effect of changing the abstraction rate on the time-drawdown response in a heterogeneous aquifer. It is applied in three dimensions to investigate the effects of horizontal and vertical high permeability zones on groundwater flow. Under these circumstances, analytical approaches fail to produce a solution and the use of numerical models is crucial to understanding the groundwater flow behaviour. Finally, the model is used to interpret the results of a pumping test conducted by Thames Water Utilities Limited (TWUL) in a UK Chalk aquifer. The aim is to investigate the flow processes and to study the impact of a nearby quarry on groundwater movement. Pumping test results show that the influence of the quarry is negligible despite its size and proximity to the pumped wells.