Monitoring Drought Trends Induced Climate Variability over Egypt Using MODIS NDVI Satellite Data and Drought Indices

The Drought is considered as a regional phenomenon because the main causes that can produce it are linked to the regional scale. Empirical studies showed that drought is never the result of a single cause. It is the result of many causes, often synergistic in nature (Magaña et al. 1997, Estrada, 2001, Contreras, 2003, Vicente-Serrano et al., 2012, Rita Man Sze Yu, 2013, Joan Ramon, 2013 and Vicente-Serrano et al., 2014). Climatological events over the past three decades have prompted many researchers to pay closer attention to drought across the arid and semi-arid regions such as Egypt. Climate variability leads to more intense and more frequent droughts in the arid regions especially in Egypt. Drought is a recurring extreme climate event over land characterized by below normal precipitation over a period of several months to several years or even a few decades. The main aim of this research is to monitor the drought trends and classification induced by climate variability over Egypt using Terra-MODIS/ NDVI satellite data in companion with Drought Indices. To achieve the aim of the study the climate variability over Egypt is described by the analysis of temperature and rainfall at annual and seasonal time-scale. The drought trends and classifications, which are approached by the application of the most widely, used drought indices Self-Calibrated of Palmer’s Drought Severity Index (Sc-PDSI) which improves the “original” PDSI, Standardized Precipitation Evapotranspiration Index (SPEI) which is based on the difference between the precipitation and the reference evapotranspiration, and Standardized Precipitation Index (SPI) which is based on precipitation data over Egypt 1940-2014. These climatic indices based on rainfall and temperature data, and it has the advantage of combining multi-scalar character with the capacity to include the effects of the temperature variability on drought monitoring. A trend analysis is carried out on drought time-series in order to understand the behavior of drought conditions. Furthermore, the research was depended on the analysis of temperature and rainfall variability from 1940 to 2014 at annual and seasonal time-scale. Moreover, the trends and their statistical significance are also analyzed. This analysis provides relevant information related to the behavior of the main climate variables of Egypt under the current climate change conditions. Remote sensing NDVI data provided by Moderate Resolution Imaging Spectroradiometer (MODIS) Sensor, and Terra-MODIS/NDVI data available from 2000 until 2016, it was used to monitor drought in Egypt. The results accentuated that SPEI drought index does not work properly in all stations of Egypt due to the lack of rainfall compared to really high potential evapotranspiration causes an optimal calibration of the index and, in consequence, SPEI will not be a good tool to monitor and analysis dry events in Egypt. In a country like Egypt where reliable data are difficult to obtain continuous, remote sensing data proved to be a significant tool in monitoring and detecting drought components.