Page 41 - Life & Land Use on the Bahrain Islands (Curtis E Larsen)

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between the Political Agency of the islands and the petroleum company
(unpublished correspondence, Bapco water resource files). By the late 1960s more
detailed assessments were made by the U.K. Geological Service (Wright 1967). A
more recent study was made by Italconsult (1971). Groundwater Development
Consultants Ltd. has submitted a still more detailed report to the Food and
Agriculture Organization of the United Nations (FAO 1981). These reports are of
interest here. Each began with similar source material and arrived at somewhat
different conclusions.
E. P. Wright (1967) set forth the major parameters of the hydrologic
system. The following major points may be made:
1. A distinct gradient exists in the static water levels of the Khobar
aquifer in Bahrain. Figure 4 shows this clearly for 1971. The
highest artesian water levels are at the extreme northwest tip of
the main island and reach a minimum along the southwest coast.
Thus, artesian fresh water is distributed diagonally across the
island from southwest to northeast.
2. As the artesian water level drops to near sea level, intrusion by sea
water through offshore springs occurs, thus contaminating the
adjacent water supply. Therefore, the progressive drop in water
level is associated with progressive salinization of the groundwater
resources.
3. The record of water well levels from 1942-66 shows an increase in
the rate of decline between 1950 and 1966. A similar increase in
the total number of drilled wells occurred during the same period
(see fig. 5).
4. Water in the major aquifers fell as rain in central Arabia during the
Late Pleistocene. There has been little recharge since.
5. An increase in the rate of water-level decline can be seen as a
function of the increased extraction of water by drilled wells. This
is superimposed upon the natural decline caused by continued
spring flow from a finite volume of water with minimal recharge.