Multivariate drought indices to analyse spatiotemporal drought propagation in a semi-arid river basin

• Published in: Theoretical and applied climatology 2025, Vol.156 (1), p.36
• Main Authors: Gorugantula, Sai Srinivas, Kambhammettu, BVN P, Lakshmi, Srirangam Jhansi, Regonda, Satish Kumar
• Format: Article
• Language: English
• Subjects: Agricultural drought; Agriculture; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Atmospheric Sciences; Catchment area; Catchments; Climate and land use; Climatology; Drought; Drought characteristics; Drought conditions; Drought index; Earth and Environmental Science; Earth Sciences; Evapotranspiration; Evapotranspiration-precipitation relationships; Groundwater; Groundwater levels; Hydroclimate; Hydrologic drought; Hydrology; Land cover; Land use; Moisture content; Multivariate analysis; Precipitation; Propagation; River basin development; River basins; Rivers; Soil moisture; Stream discharge; Stream flow; Vegetation; Waste Water Technology; Water Management; Water Pollution Control
• ISSN: 0177-798X; 1434-4483
• DOI: 10.1007/s00704-024-05236-7

An accurate characterization of drought and its propagation in the spatiotemporal domain is essential to develop early-stage drought warning and mitigation systems. Conventional univariate indices may not necessarily represent actual drought conditions, as drought is resultant of interactions between multiple processes. This study is aimed at understanding meteorological drought characteristics and its propagation into hydrological and agricultural droughts using multivariate drought indices for the Krishna River Basin, India. In addition to the standardized precipitation evapotranspiration index (SPEI), two new copula-based integrated indices are developed to characterize hydrological drought (by combining streamflows and groundwater levels) and agricultural drought (by combining soil moisture and vegetation condition). Meteorological drought events are identified based on run theory by imposing thresholds on duration (≥ 6 months), intensity (< -1), and severity (< -4.5). Drought propagation was analysed using calculated correlation values between the SPEI-n (with n  = 1,3,6, and 12 months) and the developed multivariate indices. Spatial pattern of correlation values indicated a unique hydrological drought signature that is of short-time (monthly to seasonal) propagation in mountainous catchments and long-time (bi-annual to annual) propagation in lower deltaic catchments. However, agricultural drought has a consistent short-time propagation across the basin acting as a precursor to hydrological drought. Further, hydroclimate factors at sub-basin level were analysed with respect to drought indices to identify the influencing factors of drought propagation. Results conclude that hydrological and agricultural drought propagations are influenced by changes in temperature, precipitation, and land cover respectively. Findings of this study can help in developing contextual plans to deal with drought mitigation in a timely and systematic manner. Research Highlights Developed two new copula based multivariate indices for hydrological and agricultural drought characterization. Upper and lower sub-basins have resulted in different hydrological and agricultural drought propagation times. Revealed the role of climate, storage structures and land use characteristics on hydrological and agricultural drought propagation.