Abstract:
Dar-es-Salaam City gets water supply from
surface water and groundwater. The groundwater is used to
supplement surface water supply and has increasingly
become a major source of water supply in the city. The
study area comprises three major parts: the central coastal
plain with quaternary fluvial–deltaic sediments, the deltaic
Mio-Pliocene clay-bound sands and gravels in the north-
west and southeast and the Lower Miocene fluviatile
sandstones of Pugu Hills in the west of the study area. The
main objective of this study was to quantify the integrated
water balance. The major source of renewable groundwater
in the aquifer is rainfall. Hence, the average recharge of
256.2 mm/year (for the year 2006) to the aquifer was
estimated using the balance method of Thornthwaite and
Mather, which is equal to 99.4 hm 3 /year for the whole
alluvial aquifer. This value was balanced with total
groundwater abstraction of 8.59 hm 3 /year, baseflow to
rivers of 75.7 hm 3 /year and discharge into the sea
(15.11 hm 3 /year).
