Analyzing agricultural drought using remote sensing indices in the east bale zone, southeastern Ethiopian lowlands

Abstract

The practical applications of satellite data in comprehending the changing environment must take in account quantitative awareness of the uncertainty across different satellite products. However, prior drought research efforts in Ethiopia paid less attention to evaluating satellite products although drought has led to agricultural failures in the lowlands of Ethiopia. This study aimed to evaluate the spatial-temporal distribution of agricultural drought in the lowlands of the Bale zone throughout the crop growing season (March to May) from 2012 to 2022. The dataset utilized in this study was chosen by assessing the performance of enhanced MODerate resolution Imaging Spectroradiometer (eMODIS) and enhanced Visible Infrared Imaging Radiometer Suite (eVIIRS) Normalized difference vegetation index (NDVI) in comparison to observed gridded rainfall, employing the simple linear regression model. The assessment of agricultural drought was conducted using the NDVI anomaly and the vegetation condition index (VCI). The eMODIS exhibited a coefficient of determination of 0.45 with a p-value of 0.02, whereas the eVIIRS had a coefficient of determination of 0.47 with a p-value of 0.01. Thus, eVIIRS NDVI was selected as the best dataset for evaluating agricultural drought in the research site. The findings indicated that in both 2012 and 2022, there were periods of agricultural drought. During these periods, severe to extreme drought conditions were seen in 7.6 % to 54.98 % of the study area, encompassing both lowland and midland regions. The biggest influence was detected in the northern, middle, and southern regions of the research area. Severe and moderate drought dominated study area as depicted by NDVI anomaly while extreme and severe as seen from VCI. Whereas the years 2014 and 2020 were the wettest. The study implies that eVIIRS NDVI might be an alternate approach to give empirical information that would aid stakeholders in limiting the consequences of agricultural drought on farming activities.