ABSTRACT
The flood management of the city of N'Djamena in general and
that of the municipality of the 7th arrondissement in particular using GIS
software and remote sensing, requires a multicriteria analysis based on four
main factors which are rainfall. (rainwater), soil permeability (pedology),
relief (topography), slope and land use. The study carried out around its
factors attests to us that the flooding in the municipality of the 7th
arrondissement is exclusively of a pluvial order with an annual rainfall
accumulation reaching 200 to 300 mm The topography factor unevenly distributed
and therefore the altitudes oscillate from 295 to 304m with an average of 294m.
The slope is very low and is in the order 0.1 to 2.02% with an average of 1.6%
and which is oriented north-west instead of the south of the town to flow into
the river Chari.
The results observed according to the altitudes of the
municipality of the 7th arrondissement show us that the bank of the Chari river
is higher than the interior of the municipality. The other determining factor
that causes flooding in the municipality is land use with high urbanization
which increased from 13% (926 ha) to 77% (5472) in 2020, an increase of 64%.
The exponential growth of the population and anarchic urbanization leads to the
occupation of lowlands and water runoff paths. The pedological factor should be
noted because the town is built on a soil made up of hydromorphic soils (sandy
clay and black clay), which have a low permeability which does not favor the
infiltration of water towards the water table and generates the flood.
Keywords: flood, 7th arrondissement, GIS, Remote sensing.
Mémoire de Master HydroSIG rédigé par
DJONMBE Hounsala, FSEA, Université de N'Djamena Page ix
Contribution du SIG et de la télédétection
à l'étude des inondations dans la ville de N'Djamena : Cas de la
commune du 7e arrondissement.
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Mémoire de Master HydroSIG rédigé par
DJONMBE Hounsala, FSEA, Université de N'Djamena Page 10
Mémoire de Master HydroSIG rédigé par
DJONMBE Hounsala, FSEA, Université de N'Djamena Page 11
Mémoire de Master HydroSIG rédigé par
DJONMBE Hounsala, FSEA, Université de N'Djamena Page 12
Contribution du SIG et de la télédétection
à l'étude des inondations dans la ville de N'Djamena : Cas de la
commune du 7e arrondissement.
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