10 - Review of Hydrology and Water Resources of Humid Tropical Islands

Summary

ABSTRACT

There are many islands in the humid tropical regions of the world, most of which belong to developing nations. Islands, especially small oceanic islands, are unique in many ways. Island water resources are often very limited. Many have no surface water resources and rely on limited groundwater resources in the form of thin fresh water lenses. The exposure of islands makes them particularly vulnerable to cyclones, storm surges and droughts. This paper examines some of the major hydrological and water resources issues of small islands. The main topics discussed are fresh water occurrence, the water balance, water resource assessment, water use, and water resource development and management. Approaches to resolving some of the major problems are provided.

INTRODUCTION

Many islands in the world lie in the humid tropical region, defined as that region where the mean temperature of the coldest month is above 18°C and where the number of months with rainfall greater than 100 mm exceeds 4.5 (Chang & Lau, 1983). The land portion of many countries in the humid tropics consists entirely of islands. Examples of countries consisting of island archipelagos are Indonesia and the Philippines in South East Asia; the Cook Islands, Kiribati, the Federated States of Micronesia, Fiji, the Marshall Islands, New Guinea, Solomon Islands, Tokelau, Tonga, Tuvalu, Vanuatu and Western Samoa in the Pacific Ocean; the Maldives and Seychelles in the Indian Ocean and the Turks and Caicos and the Bahamas in the Caribbean Sea.