Drought risk assessment in pasture arid Morocco through remote sensing

摘要

During the last three decades, Morocco has experienced several stern and extended episodes of drought that severely affected pasture production. To cope with this phenomenon, the policy makers have put emphasis on a reactive short term management approach rather than on pro-active risk-based management measures. The purpose of this study is the assessment of drought by remote sensing, which is an important step in the design and implementation of drought management plan. To reach this objective we used bi-weekly TERRA Moderate Resolution Imaging Spectroradiometer (MODIS 250 m) data in arid pasture of Morocco. A preliminary mapping using Landsat TM5 of major land cover types was carried out to extract the pasture area. A comparison of annual and seasonal Normalised Difference Vegetation Indices (NDVI), Vegetation Condition Index (VCI) and rainfall during the time period of 2000 - 2008 were carried out. Results showed that stronger relationship of NDVI with previous seasonal rainfall as compared to VCI indicating that NDVI variation is a good indicator of vegetation changes and consequently can give a better idea on drought conditions in the study area.