Landscape Dynamics and Impact of Anti-Salt Micro-Dams on Rice Cultivation in the Djiguinoum Sub-Watershed, South Senegal

Abstract

The Lower Casamance region benefits from hydrological and soil conditions favorable to agriculture. Rice-growing plays an important role in the region's culture and dietary habits. It is practiced in lowlands and rice fields exposed to water during the winter. However, the expansion of saline lands caused by the rainfall deficit of the 1970s and 1980s and the dynamics of land use are now taking on increasing proportions, hampering the development of rice cultivation in Lower Casamance. To remedy this situation, a policy of safeguarding and developing lowlands has been initiated. It is in this context that this study was carried out to investigate the impact of anti-salt micro-dams and land-use dynamics on rice cultivation in the Djiguinoum sub-watershed. To achieve this, a cartographic approach was adopted through a diachronic analysis of Landsat 4 satellite images from 1984, Landsat 7 from 2000 and 2010 and Landsat 8 from 2024, socio-economic surveys and analysis of soil parameters. Analysis of land use dynamics shows that the areas of wooded savannah and rice paddies have declined by -34.48% and -63.67% respectively. However, built-up areas (599.27%) and open forests (99.06%) have seen remarkable growth, although open forests have declined by -18.68% between 2000 and 2010. In addition, over 35% of those surveyed reported persistent salinity in managed rice fields and a reduction in rice production. Similarly, over 60% of respondents consider water shortages and inadequate hydro-agricultural structures to be the main factors hampering rice growing in the sub-watershed. Soil analyses have shown that the soil in the sub-watershed is acidic, with a pH ranging from 3.21 to 4.56. Ultimately, people are well aware of the extent of this degradation, and several factors are encouraging the adoption of new restoration measures.