Remote sensing mapping of the rice fields and vegetal cover in the sub-watershed of Ebinkine (Lower Casamance, Senegal)

Abstract

Rice lowland Lower Casamance is facing a double bind , climate and soil salinization , noticeable in rice areas sub-basin of Ebinkine which covers an area of 2,429.7 ha. This led to the implementation of anti-salt dams and micro-dams in the valleys. The aim of this work is to study the dynamics of paddy fields and vegetation cover in this sub- Watershed from processing and analysis of satellite images. The methodology used is mainly based on a supervised classification of Landsat TM satellite images of 1984, 1992 and Landsat ETM + 2000 and 2010 associated with fieldwork. The analysis of the dynamics of land use show that rice fields occupying 615.0 hectares in 1984; 581.1 hectares in 1992; 402.2 hectares in 2000 and 415.8 hectares in 2010. The sharp decline of rice cropping is caused by a rainfall defect, as well as mismanagement of the water after the establishment of micro-dams in the sub watershed in 1996. These have led to a flood of 123.6 hectares of rice paddies in the upstream areas of the watershed. Meanwhile, an increase in shrub-trees-savannah between 2000 and 2010, it is the result of natural regeneration promoted by the expansion of plantations of Anacardium occidentale. However, recent illegal timber exploitation has increased between 2000 and 2010 in the area.