Remote Sensing and GIS Based Drought Vulnerability Assessment: A case of Afar Regional State, Ethiopia
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Date
2016-06
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Addis Ababa Universty
Abstract
Ethiopia is one of the sub-Saharan countries and highly prone to drought hazards. Drought is
water related natural disaster, which affects a wide range of environmental factors. It is
mainly a climatic phenomenon that cannot be eradicated. In 2015, there was short, poor and
delayed rainfall which caused critical water shortage, livestock death, and decline in milk
production mainly in the pastoral regions of Ethiopia. The present study attempted to
investigate the effectiveness of Remote Sensing based drought indices as an indicator for
drought assessment in arid and semi-arid areas, examined the relation between rainfall and
vegetation indices of drought and identified the most drought–vulnerable areas using Remote
Sensing (RS) and GIS in the Afar Regional State of Ethiopia, which is a drought-prone area.
In this study, 11 years’ time series of decadal SPOT (2005 2013) and PROVA-V
(2014 2015) Normalized Difference Vegetation Index (NDVI) and rainfall data were used.
Vegetation indices; Vegetation Condition Index (VCI) and Drought Severity Index (DSI)
derived from SPOT and PROVA-V used for the study. Standardized Precipitation Index (SPI)
was calculated. For the validation of drought indices, correlation and regression analysis
between NDVI and rainfall (r = 75%), NDVI and crop yield, VCI and rainfall (r = 90%) were
done. Results of this study showed that there was extreme drought in the Region in 2005,
2009, 2011 and 2015. The findings indicated that the study area is highly prone to drought
even if its severity level varied. The result map obtained by integrating NDVI, VCI, DSI and
SPI, showed that about 2% of the region is extremely, 32% is severe, 59% is moderate and
6% is mild vulnerable to drought. For the future, besides delineating drought vulnerable areas
importance of vulnerability assessment could be made more meaningful, if detail study of
these areas in terms of water availability, temperature conditions and crops grown. As well as
remedial actions could be implemented before the occurrence of the drought and timely
updated information about the prevalence of drought is important.
Keywords: Drought Vulnerability, SPOT, Remote Sensing, Drought Indices
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Keywords
Drought Vulnerability, SPOT, Remote Sensing, Drought Indices