Agricultural drought analysis and its association among land surface temperature, soil moisture and precipitation in Gamo Zone, Southern Ethiopia: a remote sensing approach

Drought is a multifaceted natural hazard that has an impact on various aspects like; agricultural, hydrological, ecological and socio-economic systems. Drought has been a predominant concern for farmers in Gamo Zone over the last decades; hence, monitoring drought is important for soil conservation, water planning and management to mitigate impacts on agriculture in the Zone. The vegetation indices normal difference vegetation index and vegetation condition index are popular since they are based only on satellite images. The present study attempts to monitoring spatiotemporal distribution of agricultural droughts and its association with land surface temperature, precipitation and soil moisture from the period 2000–2020 using remote sensing application method in Gamo Zone. The vegetation condition index (VCI) and Normal difference vegetation index (NDVI) were used to evaluate spatial and temporal distribution of agricultural drought in Gamo Zone. The Pearson correlation method was used to identify Normal difference vegetation index association with land surface temperature, soil moisture and precipitation. The results discovered that severe drought to very severe drought was identified in 2000, 2002, 2004, 2008, 2009 and 2015 with the area coverage 39.7%, 28.8%, 33.4%, 24.5%, 61.3% and 23.0%, respectively. Similarly, the findings show that slight to mild droughts have a great chance of occurrence in Gamo Zone. The data also demonstrate that normal difference vegetation index has a strong relationship with land surface temperature ( R = − 0.95), precipitation ( R = 0.65) and soil moisture ( R = 0.85), indicating that normal difference vegetation index is more sensitive to land surface temperature than soil moisture and precipitation, although soil moisture has a positive relationship with precipitation ( R = 0.60). Therefore, this study revealed that normal difference vegetation index and vegetation condition index indices are suitable for agricultural drought monitoring and they are strongly associated with precipitation, soil moisture and land surface temperature. This study shall be helpful for decision makers to take the necessary measures by considering the drought risk maps for early warning system and future drought management plans.