With advancement of remote sensing techniques, remote-sensing drought indices have been widely used for drought monitoring. However, the monitoring accuracy of a specific drought index regionally varies. This study aims to improve the drought severity index by incorporating additional variables and evaluating its performance in different regions. The results show that the improved index can provide more accurate drought monitoring results, especially in regions with complex terrain. The study highlights the importance of considering regional variability in drought monitoring and the need for more accurate and reliable drought indices.