Will reductions in groundwater abstractions improve low river flows?

Abstract

AbstractIt is a commonly held view that a reduction in groundwater abstractions in many heavily exploited aquifers is likely to improve low flows in rivers. In most aquifers, but especially in chalk and limestone aquifers, the improvement in flows may only be small compared with the reduction in abstraction. Using conceptual and numerical models, the relevant flow processes in chalk and limestone aquifers are examined with special reference to the impact of pumped boreholes on stream and river flows under conditions of differing transmissivities resulting from high or low groundwater heads. The key response is that much of the winter recharge is lost to high winter river flows with only a small proportion of the recharge being stored in the aquifer and available in the summer. Consequently, the low summer river flows, which depend primarily on the areas local to the rivers, may not be strongly influenced by pumped boreholes unless these are close to the rivers. Case studies are used to illustrate the discussion.