Water Resources of the Southern Semiarid Area of Madagascar

Abstract

This paper outlines the water resources of the southern area of Madagascar, which is based on the field investigation and several reports concerning with the potable water development plan requested from the government of Madagascar.
The area, under the tropical semiarid climate, is classified geographically into the Mahahaly Plateau, the Karimbola Plateau and the Ambovombe Basin, from the west to the east. The average annual precipitation over the area is about 350∼600 mm and it decreases westward. The Karimbola Plateau and the Ambovombe Basin, where the population density is about 15 per one square kilometer, are underlain by continental sediments ranging in age from Tertiary to Quaternary. The Mahahaly Plateau is occupied by Tertiary limestone which yields little groundwater, so that the plateau is not inhabitable.
European Communities have been giving assistance to construction of a pipeline from the Menarndra River to the Karimbola Plateau for supplying potable water. On the other hand, Japan will support to develop water resources in the Ambovombe Basin. About 87, 000 people living in a hill, coastal side of the basin, are in great trouble from lack of water. Apart from the hill, they manage to gain perched groundwater as well as surface water. It is very difficult to get water in the hill because the groundwater level is deep, mo:e than 100 meters from the surface, and an inplubia easily dries up at summer season.
It is recommended to install more inplubia , to inquire deep groundwater as well as perched groundwater and to increase water wagons for the improvement of water supply. 地質調査所, Geological Survey of Japan.