The use of remote sensing product to monitor meteorological drought in east Africa
Most drought studies have been dependent on limited rainfall data that is available in most parts of Africa. The new developments in space technology, especially satellite derived products now provide new opportunities that can be used to study space-time characteristics of drought. Thus the main objective of this study is to assess the potential of using satellite-derived products to enhance the monitoring of meteorological drought within the East Africa. This involved the validation of the satellite products using some available rainfall records. Rainfall data used in this study was obtained from IGAD Climate Prediction and Application Centre (ICPAC) and was from 2000 to 2009 for East Africa. The other data is a (10-day) dekadal composite of Normalized Difference Vegetation Index (NDVI) images of the East Africa obtained from VGT4Africa website. It contains a spatial resolution of 1 kilometer by 1 kilometer with an accuracy of 300m and runs from year 2000 to 2009 for the east Africa region. The methods used in this study included the calculation of satellite based drought indices using Vegetation Productivity Index from Normalized Difference Vegetation Index (NDVI) values. These were then compared with drought severity index CDSI) derived from rainfall records using some standard statistical methods. The study has shown that drought indices based on Vegetation Productivity Index can provide some realistic estimates of drought indices. There were however some challenges in some stations where vegetation cover are not mainly dependent on rainfall but relied on irrigation. The study has therefore provided some alternative methods that could be used for regional drought monitoring.