12 - Groundwater Systems in the Humid Tropics

Summary

ABSTRACT

Aquifers underlie large areas of the humid tropics. Because of their widespread distribution, they can often be developed close to the location of demand, with modest pumping and reticulation costs, to produce groundwater of excellent chemical and microbiological quality requiring little treatment. These factors are leading to increased interest and rapid development of groundwater resources. Groundwater systems characteristic of the humid tropics fall into five main types, major alluvial formations, basement regoliths, intermontane valley-fill, active volcanic arcs and karstic limestones. The principal features of each of these are described and the main problems which arise in each case in the exploitation and management of groundwater resources are indicated. In the humid tropics, the close association between groundwater and surface water and the generally shallow water table make groundwater a valuable resource which, in some cases, is highly vulnerable to pollution from a range of human activities.

INTRODUCTION

Significance of groundwater

Aquifers underlie geographically large areas of the humid tropics. Because of this widespread distribution, their groundwater resources can often be tapped close to the location of water demand, thereby minimizing reticulation costs, at least for supplies up to moderate volume. Groundwater has other advantages for water supply development. Given adequate protection, it has excellent microbiological and organic quality, and requires minimal treatment. Although certain naturally- occurring dissolved chemical constituents can impart an unacceptable quality or a health risk for domestic supply, groundwater with these characteristics are of limited geographical distribution. The capital cost of groundwater development is thus relatively modest and the land requirements are minimal. Finally, the resource lends itself to flexible development, capable of being phased with rising demand.