Agricultural Drought Risk Area Assessment and Mapping Using Remote Sensing and Gis: A Case Study of West Hararge Zone, Ethiopia
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Date
2017-06
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Addis Ababa Universty
Abstract
Remote Sensing and GIS Technologies are currently important and timely for draught risk area assessment and mapping. In countries like Ethiopia, experiencing considerable annual regular period of dry seasons, drought is not a new phenomenon. The real drought problem, however, arises when the rainfalls fail to fit with the normal cropping seasons. As this gap brings about eminent crop failure and high yield reduction, drought can be perceived as the quantitative, spatial and temporal mismatch between rainfall and the cropping season. This study aims to identify, analyzing, determining and signifying the impacts of the virtual drought on the local environment and mapping agricultural drought risk prone areas of West Hararge Zone, Oromia region, Ethiopia. In order to effectively realize this goal, efforts were made to collect the ten years (2005-2014) drought behavior data, regarding its onset time, frequency of occurrence, spatial extent, duration and levels of severity on the local environment. In addition, this study utilizes remote sensing data, GIS technology and field observations data. Accordingly, reliable Geo-spatial and temporal data have been obtained through the use of modern Remote Sensing and Geographical Information System. The practical field observations, consultations and discussions played great roles in enhancing the acquisitions of commendable knowledge and experiences on the objective reality of the situation. These data were examined and analyzed to scale up the intensity level of the prevailing drought impacts on the agricultural activities of the local farmers. The general responses to drought and the particular existing correlations between rainfall and crop performances were confirmed using Normalized Difference Vegetation Index, Standard Precipitation Index and Water Requirement Satisfaction Index. Based on the confirmed drought pattern and frequency maps of the three indices, a comprehensive map was produced that indicates agricultural drought risk prone areas of West Hararge Zone. This map shows that 12.34%, 33.89% and 48.48% of the total geographical area of the Zone were slight, moderate and severe agricultural drought risk areas, respectively. The result map was validated based on ground based field data obtained from organizational documents and local field professional practitioners. The validation result show significant relation with a correlation coefficient of r = 94 or R² =88. This result map was based on the robust and timely methods and could be used as a guide for concerned government and non-government organizations for drought impacts mitigation activities in the Zone.
Key words: Agricultural drought, GIS, NDVI, Remote Sensing, SPI, SPOT WRSI
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Keywords
Agricultural drought, GIS, NDVI, Remote Sensing, SPI, SPOT WRSI