A Novel Agricultural Remote Sensing Drought Index (ARSDI) for high-resolution drought assessment in Africa using Sentinel and Landsat data.

Drought poses a significant threat to agricultural productivity in Africa due to climate variability and water scarcity. To improve drought monitoring using high-resolution remote sensing data, this paper proposes a novel Agricultural Remote Sensing Drought Index (ARSDI). Imagery from Sentinel-1(S-1), Sentinel-2 (S-2), and Landsat 8 was utilized to develop a drought monitoring system for 2017-2023, during which Egypt and Kenya experienced significant drought events. In Kenya, particularly from 2021 to 2023, recurrent droughts severely affected agricultural output, necessitating the evaluation of ARSDI's efficiency in capturing drought severity. Similarly, in Egypt, drought-like conditions linked to reduced Nile River flow and rainfall variability posed significant challenges. ARSDI exhibited strong correlations with traditional drought indicators, such as the Soil Moisture Condition Index (SMCI), ranging from 0.64 to 0.88 in Egypt and 0.74 to 0.85 in Kenya. It also correlated well with the Vegetation Health Index (VHI), with values (0.96 to 0.98) in Egypt and (0.53 to 0.98) in Kenya. Furthermore, ARSDI aligned with Standardized Precipitation Index (SPI), ranging (0.44 to 0.71) in Egypt and (0.47 to 0.60) in Kenya. By integrating Sentinel-1 radar data, ARSDI mitigated the limitations of cloud cover, providing more reliable vegetation monitoring. Compared to other indices, such as the Normalized Difference Vegetation Index (NDVI), ARSDI exhibited superior performance, particularly during the drought events 2019 in Egypt and 2020 in Kenya, demonstrating its robustness in assessing soil moisture and vegetation health.