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Climate variability observed since the 1970s has resulted in a drought last thirty years in West Africa in
general and in the Sahelian and humid countries bordering the Gulf of Guinea. It results in severe
reductions in rainfall, groundwater levels and stream flows drop of water. In order to examine the
existence of the climate variability in Côte d'Ivoire, precisely in the region of Abidjan-Agboville, and
highlight its impact on the supply of water, that this study was initiated. To do this, various data and
methods were used. Thus, the methodology involves the calculation of centered reduced indices of
NICHOLSON, testing PETTITT, the Bayesian method of LEE and HEGHINIAN and segmentation of
HUBERT. The region is marked by alternating normal period, wet and dry, with a long period deficit
starting from 1970. The rainfall deficit is between 10 % and 31%, with an average value of 20 %. The
largest deficits were recorded in the southern region, including Alépé (31 %), Adiaké (25 %) and Abidjan
(20 %). Hydrological regimes have also undergone profound changes over the period 1955-2003. The
decline in rainfall has resulted in a reduction of water supplies that pass through the rivers of the region.
This decrease is marked by a very significant breach identified in 1968 at the Agboville station on the
river Agnéby. The lack of flow is very important and is estimated at 41.3 %, double the rainfall deficit
(20 %). At the river Agnéby, coefficients of drying of MAILLET (with flow in m3 s-1 and time in days) are
changing from 0.0314 to 0.106 j-1 before 1968 and from 0.0367 to 0.124 j-1 after 1968. This increase in
the coefficient of drying after 1968 shows a much faster draining aquifers supplying base flow. The mean
values ranged from 0.065 j-1 before 1968 and 0.0814 j-1 after this year. The volume of water mobilized by
aquifer rises to 0.143 km3 for an average depletion coefficient of 0.0653 j-1 during the period 1956-1968
and 0.058 km3 for a coefficient of drying average of 0.0814 j-1 from 1969 to 2003. Volumes mobilized by
aquifer after 1968 fell to 59.45 %, resulting in a considerable reduction of groundwater reserves. The
fluctuation of rainfall isohyets shows that 2300 mm and 2200 mm in the region during the decade 1950-
1959 have disappeared to make room for 1500 mm isohyets during the decade 1990-1999.
Key-words: decrease rainfall, drought, environment, water supply and Abidjan-Agboville, Côte d'Ivoire.