Muhammad Shiraz Riaz, Sneha Kulkarni, Yohei Sawada
Received 16 April, 2026
Accepted 7 July, 2026
Published online 29 August, 2026
Muhammad Shiraz Riaz1), Sneha Kulkarni1), Yohei Sawada1)
1) Department of Civil Engineering, The University of Tokyo, Japan
Although natural climatic variations often lead to drought, it is a complex phenomenon shaped by both environmental and social factors. In water-scarce regions, human activity near available water resources may influence how drought impacts are experienced. While the effects of drought on migration and human settlement patterns have been widely studied, the spatial relationship between changes in human activity and reported drought-affected regions remains less understood. Here, we investigate whether human activity intensification occurs near rivers during reported drought event years. We use harmonized global Nighttime Light (NTL) data as a proxy for human activity and settlement intensity and analyze its spatial relationship with drought events recorded in the Geocoded Disaster (GDIS) database from 2001 to 2020. For each drought event, we calculate NTL-weighted centroids based on harmonized NTL intensity and assess their distance to nearby river networks. Results show that positively deviated NTL changes occur more frequently near rivers than negatively deviated NTL changes in reported drought event years. This suggests that river-proximal drought-affected areas may experience intensified human activity or settlement intensity, which is relevant for drought vulnerability and water-resource planning. These findings highlight the need to consider human activity patterns near rivers when assessing reported drought impacts.
Copyright (c) 2026 The Author(s) CC-BY 4.0
