Vertical Flow in Heavily Exploited Hard Rock and Alluvial Aquifers

Abstract

ABSTRACTThis paper examines the flow in heavily exploited alluvial and hard rock aquifers and demonstrates that vertical components of flow are of great importance. In a typical example of an alluvial aquifer it is shown that most of the discharge from tube wells originates from the phreatic surface flowing vertically through clay layers to the well screens. A second study of a hard rock aquifer indicates that a tube well in a fractured zone draws water horizontally from the fractured zone but this water is supplied by vertical flow from the weathered zone. The suitability of different types of mathematical models to represent heavily exploited hard rock and alluvial aquifers is also considered.