Development and application of a watershed-based environmental drought index reflecting water cycle characteristics

Le résumé fourni par la source

Droughts driven by climate change increasingly affect aquatic ecosystems by deteriorating water quality. However, conventional drought indices primarily focus on water quantity, limiting their ability to capture environmental impacts. To address this gap, this study develops the Water Quality Environmental Drought Index (WQEDI), building on the Environmental Drought Index (EDI) originally proposed by Srivastava and Maity (2023) and later adapted by Jo et al. (2024) to include water quality indicators. WQEDI introduces three key innovations, including the integration of water quality indicators alongside hydrological and meteorological variables; data driven variable selection and weighting using Random Forest (RF), with threshold derivation via Decision Tree (DT) models; and watershed- specific drought grading tailored to urban, rural, and forest watershed typologies, thereby enhancing spatial adaptability. Validation results confirmed that WQEDI outperforms the EDI proposed by Jo et al. (2024) in terms of explanatory power, showing stronger correlations with biochemical oxygen demand (BOD) concentrations and more consistent exceedance patterns. Moreover, BOD exceedance rates systematically increased with higher WQEDI drought grades, demonstrating its effectiveness in capturing environmental drought severity. Based on these findings, the study identified watershed-specific priority grades and intervention periods and proposed customized drought management strategies. WQEDI provides a refined and adaptable framework for diagnosing and managing drought induced water quality deterioration. It offers a scientifically grounded basis for environmental drought response and supports the development of evidence-based water management and climate adaptation policies.

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