TITLE:
Dynamics of Land Use in the Basin of Ancient Lagoons (Toho, Todougba, Ahouangan, Dati, Djonou) in South Benin from 1990 to 2020 and Their Current Vulnerability to Pollution
AUTHORS:
Mardochée Ephraïm Achoh, Hyppolite Agadjihouédé, Luc Gangbè, Romaric Aïzonou, Christelle Claudia Akotossodé, Simon Ahouanssou Montcho, Antoine Chikou
KEYWORDS:
Land Use, Vulnerability, Lagoons, Pollution, Anthropogenic Activity
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.9 No.11,
November
16,
2021
ABSTRACT: The
management of living resources and space requires continuous assessments in
order to adjust deviations as necessary for sustainable use. It is in this
context that the present study was conducted and aims on the one hand to assess
the dynamics of land use in the basin of the five-finger lagoons and on the
other hand to assess the degree of their vulnerability to organic pollution.
Thus, the satellite images were collected in free access on the site http://earthexplorer.usgs.gov/
of the USGS (US Geological Survey) of NASA. Image correction was performed with
ENVI 5.1 software and classification was performed with ArcGIS 10.8 software.
The degree of vulnerability was evaluated through the weighting of different
parameters (slope, land use, type of pass, runoff, and density of the
hydrobiological network) by the multi-criteria method of Saaty (Analytic
Hierarchy Process Methods) and the application of mapping. It is found that for
the dynamics of land use, forests, savannahs and plantations have experienced a
significant reduction in their area (respectively 98.9%, 99.60% and 77.10%)
between 1990 and 2020. As for settlements, water bodies and swamps, they have
increased in area to different proportions. The soils are more denuded (Tc =
1264%). This makes the living space vulnerable and therefore facilitates the
transfer of pollutants to the aquatic environment. The evaluation of the degree
of vulnerability to pollution of the lagoons of the basin showed that the
Toho-and Todougba lagoons are under a very high degree of vulnerability (73% -
100%) and do not augur well for the living resources. The other lagoons,
notably the Dathi and Djonou lagoons, are also under stress from the pressures
of surrounding activities. It is therefore important to assess the level of
pollution of the Toho and Todougba lagoons through pollution indices in order
to make decisions that will allow their sustainable use, especially for
aquaculture.