4.5.1  Water source depletion

Although water is a renewable resource, excessive extraction of water will result in its depletion. If groundwater is extracted from aquifers more quickly than the water is replenished by recharging, this will lower the water table. Excessive groundwater pumping changes the flow patterns around wells and creates a localised depletion of groundwater stores in the area around the well. If several wells are located close together these zones can overlap. The result is that existing wells and boreholes may dry up and new ones have to be dug deeper and deeper before they reach water. The lowering of the water table also affects rivers and streams, which are normally fed partially by underground water. Over-exploitation of groundwater can also affect springs, which may change from permanent to temporary or even dry up completely.

Water source depletion is also directly linked to reduction in forest cover. With the loss of trees and other vegetation, rainwater runs straight off the surface and does not penetrate into the ground to recharge the groundwater. Added to this are the uncertainty of climate change and the effects of periods of drought which have a serious impact on the availability of surface and groundwater sources.