Assessments of Drought Effects on Plant Production Using Satellite Remote Sensing Technology, GIS and Observed Climate Data in Northwest Morocco, Case of the Lower Sebou Basin

Today in Morocco, early warning and drought monitoring systems are the important step in the assessment of agricultural drought risks, especially in rainfed agriculture. Many operational information systems are mainly based on meteorological indices and others incorporate information on vegetation status (remote sensing indices). The present work aimed to assess agricultural drought and model vegetation health to explore its time series change (1984-2016) at the pixel scale in the Lower Sebou Basin (LSB) using remote sensing indices. Then, we evaluated their performance to explain yield losses (SYRS). Cereals were used as the reference crop. Vegetation Condition Index (VCI), Temperature Condition Index (TCI) and Vegetation Health Index (VHI) as remote sensing indices and Standardized Precipitation Index (SPI), Standardized Precipitation Evapotranspiration Index (SPEI) as meteorological indices were implemented. The results showed the manifestation of remarkable changes in crop health over the time series and particularly at the beginning of the twenty-first century. 7% of the crop area was healthy in the last half decade (2010-2016), compared to about 50% in the period 1984-2000. The results also show a strong response of inter-annual variability in cereal yields to short time scales of drought. SYRS was found to be significantly affected by drought throughout the LSB. The comparison between the drought indices and SYRS suggests that SPEI and TCI are more correlated and sensitive to yield than SPI and VCI. This indicates that yield is more sensitive to temperature changes than to moisture. Consequently, these results obtained in the LSB can be obtained in other agricultural regions with similar climates.