Dynamics of the Inland Valley Occupation in the Oti Watershed in Benin: Diagnosis and Prospective Analysis

The use of inland valley has highly increased in number and area over the last three decades because of their soils fertility and their hydromorphic character. The present research analyzes the dynamics of the occupation and use of inland valley in the south of the Oti watershed in Benin and their future by the years 2030 and 2050. It is based on a combinative approach which integrates spatial Remote Sensing, Geographical Information Systems and Land Use Change Model incorporated in Idrisi Selva software. Landsat TM images of 1988, ETM+ of 2000 and OLI TIRS of 2015 were used for land cover information extraction. The projections’ period was made based on the observed socioeconomic conditions in the study area. The 1988 to 2015 change detection indicates that plant formation (woodlands and savanna) characterized by the inventoried inland valley evolved toward the anthropogenic formations (mosaic of crops, fallows and bare soils). The annual rate of change is estimated at -0,83 %) for the first period and -1,6 % for the second period. The anthropogenic procedure was strongly observed from 1988 to 2015 with a global annual regression of 0,38 % which leads to an extension of the agricultural areas. Considering the three topographic sectors between the period of 1988 and 2015, about 22,01 % of the Atacora massif inland valley, 44,88 % of the wavy interfluves and 30,41 % of the low altitude sector are occupied by crops. This evolutionary trend of agricultural areas comes from the prominent role of the agriculture in the economy of the Oti watershed. By 2030 and 2050, we will probably witness a significant extension of agricultural areas which could respectively go from 105 461,63 hectare in 2015 to 115987 hectare in 2030 and 144182 hectare in 2050.