Page 160 - Life & Land Use on the Bahrain Islands (Curtis E Larsen)

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aquifers reflect a similar condition. The broad synclinal trough that Kassler (1973)
shows along the west coast of the Gulf of Bahrain displays the opposite condition,
where compression related to Zagros folding has sealed fractures and reduced
permeability to retard groundwater flow.

If the joint systems of Bahrain are any indication, faulting related to the
relaxation of orogenic forces probably extends across the surface of the anticline.
Thus, one can anticipate the presence of submerged springs along the fold crest.
TTiese, in turn directly connect the waters of the aquifer system and the sea. Sea
water intrusion occurs along such fractures when hydrostatic pressures diminish
and approximate the pressure of the mass of overlying seawater (Wright 1967,
Italconsult 1971).
Wright and Italconsult disagree on the mechanics of the aquifers. Where
Wright considered a model in which the static water surface decreased in elevation
until an equilibrium condition was approximated, Italconsult claimed there was no
sign of an equilibrium condition although invasion of seawater was certainly taking
place. They saw depletion to be a linear function as displayed in Figure 3. These
data were used to predict that the water levels in most of Bahrain’s springs would
approach sea level near the turn of the century and allow seawater intrusion. A
similar prediction was made for the Arabian coast. Italconsult was able to provide
other useful information as well. Most pertinent was a demonstation of the
differential rates of depletion between Bahrain and the Arabian coast at Qatif.
The recorded decrease in standing water level at Urnm Saban water well #1 and
Budaiya water well #27 on Bahrain showed a rate of decrease of 0.07 m/year
between 1942 and 1970. Observation well WW-2 at Qatif, in contrast, showed a rate
of decrease of 0.15 m/year between 1947 and 1971. Both wells draw from the Khobar
aquifer. At Qatif, however, the elevation of the water surface was ca. 7.5 m
whereas it was only ca. 3.5 m in the Bahrain wells. Thus, while depletion is
pronounced in both places, it is far more rapid near Qatif. For example, gravity
flow irrigation systems fed by springs in Qatif or near Dhahran would be subjected

to more rapid changes than their counterparts in Bahrain, In both cases, drilled
wells with pumps must be relied upon once a spring level falls below the level of

the irrigation canals.