Degefaw, Amare (2007) Application of Remote Sensing for Delineation of Drought Vulnerable Areas in Amhara Region. Masters thesis, Addis Ababa University.
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PDF (Application of Remote Sensing for Delineation of Drought Vulnerable Areas in Amhara Region)
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Abstract
Drought is the most complex but least understood of all natural hazards. It is broadly defined as “severe water shortage”. Low rainfall and fall in agricultural production has mainly caused droughts. A droughts impact constitutes losses of life, human suffering and damage to economy and environment. Droughts have been a recurring feature of the Ethiopian climate therefore study of historical droughts may help in the delineation of major areas facing drought risk and thereby management plans can be formulated by the government authorities to cope with the disastrous effects of this hazard. The Amhara region is prone to extreme climate events such as drought. Successive years of low and erratic rainfall have left large areas of the region in severe drought that resulted in crop failure, water shortage and has raised serious food security concerns for the region. Drought assessment and monitoring based on available weather data are tedious and time consuming. Beside that the data are not available in time to enable relatively accurate and timely large scale drought detection and monitoring. But, the satellite sensor data are consistently available, cost effective and can be used to detect the onset of drought, its duration and magnitude. In the present work an effort has been made to derive drought vulnerable areas facing agricultural drought by use of temporal images from NOAA-AVHRR (8km) and MODIS (500m) based Normalized Difference Vegetation Index (NDVI) (1981- 2007) and (2000 to 2003) respectively. A deviation of the current NDVI with the long-term mean NDVI, and the Vegetation Condition Index (VCI) derived from the AVHRR and MODIS used in this study for drought detection, monitoring and real time prediction. The results clearly indicate that the temporal and spatial characteristics of drought in Amhara region detected and mapped by the DEVNDVI, and VCI indices. These results were validated by ground truth data such as precipitation and agricultural crop yield. The validation result shows that there is a strong correlation between the satellite derived indices and the ground truth data, both precipitation and agricultural production yield for most of the Zones Amhara region. Correlation and regression analysis was performed between NDVI, drought indices, precipitation and agricultural yield. The NDVI and rainfall was found to be highly correlated in water limiting areas. Apart from this, the highest NDVIrainfall correlation associated with three -month time lag shows rainfall event induced vegetation growth in subsequent periods. The NDVI-rainfall correlation was found to be highly influenced by mean rainfall condition and vegetation types. It is therefore concluded that temporal variations of NDVI are closely linked with precipitation. The inter sensor relationships were also developed based on data from specific months and the monthly models explain up to 95 percent of variability in the data of two sensors.
| Item Type: | Thesis (Masters) |
|---|---|
| Subjects: | G Geography. Anthropology. Recreation > G Geography (General) Q Science > QE Geology T Technology > T Technology (General) |
| Divisions: | Africana |
| Depositing User: | Selom Ghislain |
| Date Deposited: | 19 Jun 2018 14:08 |
| Last Modified: | 19 Jun 2018 14:08 |
| URI: | http://thesisbank.jhia.ac.ke/id/eprint/4708 |
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