Evaluation of vegetation indices for agricultural drought monitoring in East Amhara, Ethiopia

Seyoum Melese Eshetie; Getachew Berhan Demisse; K. V. Suryabhagavan

Volume : V, Issue : X, October - 2016

Evaluation of vegetation indices for agricultural drought monitoring in East Amhara, Ethiopia

Seyoum Melese Eshetie, Getachew Berhan Demisse, K. V. Suryabhagavan

Abstract :

Remote sensing data and models for drought monitoring and early warnings must be validated and caliated before they become operational to specific region and hydro–climatic conditions. The main objective of this research was to evaluate vegetation indices for agricultural drought monitoring. In order to achieve the objective of the study, a relationship between a 3 month Standardized Precipitation Index (SPI) and the respective growing season vegetation indices were first modeled using ordinary least square to vegetation conditions respond to rainfall variability. The coefficient of determination indicates the relationship was highest with Drought Severity Index (DSI) (R2 =0.85) while it was lowest with VCI (R2 =0.53). Relationships between four known MODIS vegetation indices products (NDVI, DSI, VCI an Eta) and crop yield were examined to compare the performances of vegetation indices for drought detection and monitoring. DSI was found to be the best to define agricultural drought phenomena among the four indices (R2=0.76). DSI is followed by VCI, NDVI and Eta. DSI was an efficient and reliable drought index among the four indices analysed. Consequently, drought vulnerable areas were identified and characterized. The results indicate that the study area can be classified into no stress, low stress and high stress agricultural drought risk sub–zones covering 34.94%, 43.18% and 21.88% of the total area, respectively. The present findings, would help to fill the gap by contributing evidences of effectiveness of vegetation indices in monitoring agricultural drought.