Dynamics of Spatio-temporal Occupation of Biological Soils Crusts Using RS and GIS Approach in the Saria Catchment, West-central Region of Burkina Faso

In the semi-arid environments of sub-Saharan Africa, the combined action of climatic factors and human activities degrades the vegetation cover, resulting in soils that are vulnerable to the risk of erosion. This is when micro-organisms of various kinds, known as biological crusts, colonise the soil surface, playing a part in the pedogenetic processes and combating soil degradation. The aim of this study is to investigate the spatio-temporal occupation dynamics of biological crusts in the Saria catchment using remote sensing and geographic information systems. The methodology is based on a geomatics approach that integrates the use of Landsat-8 OLI/TIRS satellite images, geographic information systems and fieldwork. The processing of Landsat-8 OLI satellite images and the pedomorphological and environmental characterization of soils have made possible to map mainly two types of soils i.e. leached tropical ferruginous soils and low-humidity hydromorphic soils with surface pseudogley. After this step, the field work enabled us to identify the land cover units in our study area from which the in-situ observations of soils surfaces revealed that biological crusts are more developed on the soils of the fallow plots (30% - 95%) than the bare (5% - 15%) and field soils (5% - 10%). The results of this study showed that the level of development of soils biological crusts is linked to the plots disturbance and its ages. In conclusion the use of remote sensing and geographic information systems is an effective and less expensive technique for mapping soil types and land cover units covered by biological crusts.