Identification des zones qui ont tendance à la désertification à l'aide de l'imagerie satellitaire.

Abstract

No resource can be considered more strategic and vital than water. Given the growing demand for water, the variability of precipitation is a very sensitive question. Drought can occur in all climatic regimes. The consequences are dramatic in many strategic areas. An early warning system and proactive drought planning is more than necessary. The objective of this study is to contribute to the monitoring and control of drought risks, using satellite data and standardized indices. The study site is M'Sila (Hodna region), a fragile area exposed to drought vulnerability. The SPI and SPEI drought indices are evaluated on multiple time scales (from 1- to 24-month). The surface albedo, derived from the data of three METEOSAT satellites (5, 6 and 7) and corrected by 6S code, is correlated with three types of drought (meteorological, agricultural and hydrological), in order to examine its sensitivity to drought conditions, with regard the indication of each index. The results show that the surface albedo appears to be more sensitive to drought events at a medium time scale class (6-, 9- and 12-month), that corresponds to the agricultural type of drought. According to the SPEI index, the surface albedo is most sensitive during the period from April to September (period of water resource consumption and plant growth). According to the SPI index, the surface albedo is most sensitive during the period from October to March (period of water resource loading and supply).