Multiple indices-based assessment of agricultural drought: A case study in Gilgel Gibe Sub-basin, Southern Ethiopia

Agricultural drought seriously affects the economies of developing countries due to heavily dependent on rain-fed agriculture. The present study aimed to assess agricultural drought based on vegetation condition index (VCI) and vegetation health index (VHI) using geospatial techniques, the case of Gilgel Gibe sub-basin southern Ethiopia. Landsat images of TM 1990, ETM+ of 2000 and OLI/TIRS of 2020 were used to calculate VCI and VHI for assessing agricultural drought. A normalized difference vegetation index (NDVI) and land surface temperature (LST) were used to estimate agricultural drought through VCI and VHI. The result revealed that NDVI declined from 1990 to 2020 due to expansion of agricultural lands and other socioeconomic activities. The output of VCI values indicates that extreme drought was increased from 0.3 km(2) in 1990 to.4 km(2) and 0.7 km(2) in 2000 and 2020, respectively. In addition, severe drought occurred in 2020 on an area of 6 km (2) (0.1%). Consequently, moderate drought was increased by area of 3.3 km(2) , 22.2 km(2) and 1051.1 km(2) in 1990, 2000 and 2020, respectively, based on VHI in the study area. Thus, to minimize the negative effects of agricultural drought on socioeconomic and well-being of the society in the Gilgel Gibe sub-basin forest and other natural resources conservations are essentials not optional. To alleviate the detrimental consequences of agricultural drought on socioeconomic and well-being, forest and other natural resources conservation is necessary. Moreover, detailed research should be conducted in the study area by using high-resolution satellite data with ground control points.

Automated summary

This study aimed to assess agricultural drought using vegetation condition index (VCI) and vegetation health index (VHI), and found that extreme drought is increasing in the Gilgel Gibe sub-basin. Therefore, protecting forests and other natural resources is essential to alleviate the negative impact of agricultural drought on socioeconomic and well-being.