Thesis (Ph.D.) - Cairo University - Faculty of Science - Department of Astronomy and Meteorology

Drought is one of the most important and complex climatic and environmental extreme event in terms of measuring, monitoring and determining related potential effects and hazards. The complex drought phenomenon can be simplified into a drought index to describe the situation and conditions of drought surrounding any area. VHI is Vegetation Health Index based on remote sensing measurements which used in this study as an index to measure the drought conditions over vegetated areas over Libya. Accordingly, through the results of our experiment that used datasets of season{u2019}s growth during the period (2000-2014), it was found that the average of VHI over the studied area didn{u2019}t exceeded 43%, it means that the country was closer to drought conditions. The country has also experienced three major of drought spells (2000-2002, 2009-2011 and 2012-2014). Through the assessment and analysis of drought risks on Libya, it was found that 82% of the areas had been subjected to drought risk of high and very high classes after applied the developed second model of drought hazards map. Standardized Precipitation{u2013}Evapotranspiration Index (SPEI) is a drought index. It considers the rainfall and evapotranspiration to index drought conditions of the country. Three time series were selected of SPEI to study and assess severity of drought in particular during growing season long term period (1950-2014). Analyzes and findings indicated that the eastern zones were more drought-prone than other zones

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