Abhatoo - Centre Nationale de Documentation

Drought phenomenon is one kind of a disaster that can significantly affect the density of vegetation in any area, especially dry regions. In rangelands of Morocco, it is essential to understand sensitivity of vegetation to soil moisture stress on different classes of land cover and corresponding temporal response to improve prediction of drought and yield anomaly. This study tries to express drought effect on vegetation cover in Moroccan pastoral areas. At first, annual average of soil water index (SWI) derived from MetOp-A /ASCAT data (11 km spatial resolution) and Normalized Difference Vegetation Index (NDVI) derived from Moderate Resolution Spectro-Radiometer eMODIS-TERRA (250 m spatial resolution) was calculated from 2007 to 2017.
Afterward, rangelands were classified into three groups including no vegetation (degraded areas), poor vegetation (sparse), and dense vegetation (shrub). Results showed a high correlation between SWI and NDVI of all rangelands. This relationship is strong for shrub rangeland, there were strong positive correlation coefficients for NDVI and SWI (R² = 0.96). Moderate correlations were explain for degraded and sparse rangeland (R² = 0.54 and 0.52) respectively. Drought monitoring using disaggregating SWI anomaly time series in these rangelands in Morocco offers possibility of operational use of soil moisture data at high resolution. The results of anomalies shows a range high than 90 %, this explains that our method is important for characterizing dryness related to soil moisture stress for all Moroccan rangelands. Remote sensing is important to rangeland drought monitor, from the security of water resources to the mitigation of water hazards in the context of climate change. This dryland ecosystem should be managed in a way that enables them to provide ecosystem services that meet human demands for social development. Prediction drought should provide sufficient motivation to reach a consensus on unified water and vegetation management throughout the region.