Remote Sensing Based Agricultural Drought Assessment: a Case Study in Sire Woreda, Arsi, Ethiopia
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Date
2014-06-06
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Addis Ababa University
Abstract
Drought is one of the major limiting environmental factors for agricultural crop production.
Climate change and climate variability will result in agricultural droughts and associated soil
water deficiency in turn, can lead to crop failure and ultimately threaten food security. Sire
woreda is an Agricultural area where the agricultural sector is highly dependent on climate
conditions. Erratic rains and erosion are problematic and wind erosion became a major problem
in the area. It is affected by the drought and also suffers from high soil degradation, which has
increased risks of desertification in year 2009. Consequently, this study was conducted in this
woreda with the objective of assessing agricultural drought using remote sensing based indices.
Drought Severity Index (DSI), Vegetation Condition Index (VCI) and Standard precipitation
index (SPI) were used in this study to assess and examine spatio-temporal variation of seasonal
agricultural drought patterns and severity. The results clearly indicate that the temporal and
spatial characteristics of Sire woreda can be detected and mapped by the indices. Agricultural
yield data was used to validate the strength of indices in explaining the impact of agricultural
drought. The validation result shows that, NDVI based indices could be the best indices for
assessing and monitoring the drought occurrences, preparing drought maps on a local level and
for studying the spatial pattern of drought occurrences in the study area. The result revealed that
DSI, VCI and SPI indices expresses 96, 85 and 51 percent of variability of the agricultural yield
respectively. Thus, DSI is more sensitive towards the assessment of agricultural drought which
affects the agricultural production. Resultant drought map obtained by integrating DSI, VCI and
SPI indicates the area under study faces agricultural drought in different magnitude and areal
coverage. It was evident from the study that, the lowland areas in north western parts of Sire
woreda are more prone to severe agricultural drought while highland areas of southern parts
faces slight agricultural drought. The research shows motivating results that can be used in early
assessing agricultural drought in order to prepare for corrective measures taken timely to
minimize the reduction in agricultural production in drought prone areas.
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Keywords
Agricultural Drought, DSI, NDVI, Remote Sensing, SPI, VCI