Use of high spatial resolution satellite data for monitoring and characterization of drought conditions in the Northwestern Algeria

Over the last decades, Algeria has witnessed intense and persistent drought periods characterized by a significant rainfall deficit. The Northwestern Algeria, such as the most south Mediterranean regions, is marked by alternating wet and dry periods and mixing between Atlantic and Mediterranean airs. In a climate context increasingly disturbed by anthropogenic activities, it is essential to analyze the dry episodes at spatial and temporal scales. In order to understand this problem, this work aims to use the potential of Landsat satellite imagery for monitoring drought conditions in the Cheliff watershed in the northwestern Algeria. As known, the behavior of vegetation is strongly related to climate changes. On this basis, a comparison of the variations in the standardized normalized difference vegetation index (NDVI) and those of the drought indices calculated from meteorological data was implemented. In fact, the rainfall series from fifty meteorological stations were analyzed. The standardized precipitation index (SPI) was calculated for the years 1987, 2000, 2006, 2011 and 2015, corresponding to the acquisition dates of Landsat images. Similarly, an extraction of the NDVI values was performed for each meteorological station. The linear regression between SPI and NDVI showed a good correlation. Thus, the obtained results enabled establishing a new drought index based essentially on satellite data. This index represents the advantage for monitoring spatially the drought phenomena and can solve the problem of climatic data lack.