ABSTRACT
Water, a major development issue, is currently under pressure
from climate change. This reality can be observed throughout the world,
particularly in Africa in the intertropical zone to which Benin belongs. Faced
with the impacts of these changes on the quantitative and qualitative
availability of water resources, it is important to implement sustainable
participatory management because the water resource that is available today in
Benin and more precisely in the lower Ouémé valley is not
inexhaustible. Its management must therefore be supervised in order to protect
it and preserve its share for future generations. It is in this context that
the present thesis aims to analyse the current management of water resources
for an application of IWRM (Integrated Water Resources Management) in a context
of climate change with the mapping of recent data.
Several types of data have been collected, including
meteorological and hydrological data, SRTM images (Shuttle Radar Topography
Mission), the topographic background, geographic positioning data of DWS
(Drinking Water Supply) and socio-economic works obtained in real environment.
The various treatments leading to the results are based on the use of
statistics, hydrological modeling and spatial modeling.
The climatic variability over the period 1987-2016 shows
breaks in stationarity in the rainfall series used. Comparison of mean rainfall
amounts between the sub-periods 1987-2007 and 2008-2016 reveals an upward trend
in rainfall. At the same time, an increase in temperatures is recorded. The
availability analysis indicates an upward trend in flow and infiltration in
line with the evolution of rainfall. Moreover, the assessment of this
availability highlights significant potential for groundwater over 66% of the
area covered by the study.
The characterization of water uses highlights a diversity of
uses in the lower Oueme valley. These are uses related to domestic and
agricultural work, navigation, fishing and the exploitation of fluvio-lagunar
sand. From a quantitative point of view, 70% of domestic uses and the uses
related to fishing are satisfied. From the qualitative point of view, 90% of
households are satisfied with the quality of the water used against the
totality of the fishing actors who are discouraged by the poor quality of the
water and the drop in fishing yield.
The assessment of the level of implementation of IWRM shows a
low application with a score of 31%. In order to raise this score,
recommendations to be implemented for the effectiveness of IWRM in the lower
Ouémé valley are described.
Keywords: IWRM, climate change, mapping, Oueme
valley, Benin.
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