N ame   Threshold depth (m)     Area    (ha)   Débo   Walado   - 2.20    120 000   Toggere   Koumbé   - 2.00    52   000   Kakagnan   - 1.60    28 000   Ténenkou   - 1.40    48 000   Kadial   - 1.60    7 000   Sossobé   - 1.10    5 000   Koubaye   - 1,10    7 000   Moura   - 1.10    22 000   Mopti - nord   -   1,20    9 000   Mopti - sud   - 1.10    6 000   Sebera   -   1,10    52 000   Bani nord    -   1,20    11 000   Baramandougou   -   1,20   5 000   Banifin   -   1,20    4 000   Yongari - Mangari   -   1,10    68 000   Pondori   -   1,10    34 000
       Vegetal landscapes and hydrological basins One   of   the   possible   uses   of   the   model   in   isolines   of   equal   depth   of   flood   consists   in   identifying   the   limits   of   large   vegetal landscapes   units   within   the   Delta,   and   in   seeking   the   existence   of   hydrological   basins   appearing   as   closed   or   almost   closed shapes at certain flood levels 1-The large hydrological basins To   determine   the   main   large   hydrological   basins,   we   looked   at   contour   curves   with   closed   or   "almost   closed"   shapes   with   two additional conditions: - at the level directly above, the contour curve is not closed - at lower levels contour curves are nested one inside the other.
One   of   the   remarkable   characteristics   of   these   basins   is   their   threshold   depth,   which   is   specific   to   each   basin.   The   basins   located upstream   on   the   Niger   (Moura,   Koubaye,   Mopti-sud)   as   well   as   in   the   Bani-Niger   Mesopotamia   (Pondori,   Yongari-Mangari   and Sebera)   start      to   appear   at   the   contour   curve   -   1.10   m,   i.e.   for   a   flood   of   5.50   m   at   the   Mopti   gauge.   The   Pondori   even   takes   shape around   -0.90   m   and   appears   completely   isolated   at   -1.10   m.   The   three   basins   directly   dependent   on   Bani   and   Mopti-nord   have   a threshold contour at -1.20 m. The   basins   of   the   center   of   the   Delta,   Tenenkou   (-1.40   m),   Kakagnan   and   Kadial   (-1.60   m)   are   located   deeper   than   the   southern basins.   Finally,   the   threshold   contour   for   Toggere   Koumbe   is   at   -2.00   m   and   the   Débo-Walado,   which   we   have   not   separated   from   the Konna basin, has a threshold contour at -2.20 m. These   differences   in   threshold   contours   between   basins   are   linked   to   the   morphology   of   the   Delta   and   result   from   the   tectonic move   towards   the   north-east,   which   caused   all   channels   to   move   eastwards   and   resulted   in   the   Peroudji   channels   from   Ouro   Modi   to Dialloubé   being   deserted   and   replaced   by   the   current   Niger   flow   through   Mopti   and   Konna.   This   explains   the   lower   subsidence   of   the southern   part   of   the   Delta   floodplain,   which   is   accompanied   by   a   more   intense   alluvium   deposition,   perfectly   in   agreement   with   the morphological   study   by   Jean   Gallais:   The   Inner   Niger   Delta   and   its   borders:   a   morphological   study ”,   (Memoirs   and   documents   of   the CNRS,   vol.   3,   1967,   54   p.,   5   maps,   p   144)   which   described   the   southern   basins   as   "hanging   basins"   compared   to   those,   deeper,   of   the center of the Delta and, a fortiori , that of Débo-Walado. 2 –The vegetal landscapes: The thresholding of the Veg7k3 matrix also allows us to separate the vegetal landscapes of the Delta into major categories: - the dry lands bordering the Delta and the large islands within the floodplain - the high plains, shallowly flooded (between -0.0 m and -0.60 m) - the moderately flooded plains and channels (between -0.60 m and -1.50 m) - the deeply flooded plains and channels (= <-1.50m) The   flood   depth   contours   oppose   the   floodplains   characterized   by   moderate-to-deep   flooding   of   plains   and   channels,   mainly situated   along   the   Diaka,   and   those   characterized   by   shallow   floods,   mainly   located   in   the   south   (Diafarabé   region),   towards      the upstream   limits   of   the   active   Delta.   In   the   south,   the   flooded   erg   of   Samaye   extends   towards   the   Pondori   and Yongari-Mangari   basins, which   it   contributes   to   separate.   The   erg   of   Femaye   further   extends   to   the   east,   forcing   the   Bani   river   to   bend   its   course.   The   high plains   of   Soye,   north   of   Femaye,   contribute   to   clearly   separate   the   southern   basins   from   the   Bani-Niger   Mesopotamia.   Finally,   a   set   of fossil   levees   form   uplands   along   an   SSW   -   NNE   alignment. They   stretch   from   the   Moura   basin   to   the   south   of   Lake   Débo   and   testify   to the   existence   of   a   former   course   of   the   Niger   which   is   now   fossilized.   This   helps   to   isolate   the   basins   in   the   west   of   the   Delta,   which, from   Ténenkou   onwards,   organize   and   communicate   through   a   set   of   deep   flood   plains   finally   joining   the   Wallado-Débo.   These   deep plains   do   not   exist   in   the   south,   and   are   almost   absent   in   the   east   at   Mopti   and   are   only   found   again   to   a   certain   extent   in   the   northeast, near Konna. Map 1 : The main inner Delta plant landscapes
Landscape.rar content file ArcGis Basin and delta plant landscapes.pdf
Table 1 : the main sixteen basins