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Title |
Development of the Turbidity Sensitivity Index (TSI-BM) for Benthic Macroinvertebrates in Lotic Ecosystems
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Authors |
안종호(Jongho Ahn) ; 최미경(Mikyong Choi) ; 이태환(Taehwan Lee) ; 정세웅(Sewoong Chung) |
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DOI |
https://doi.org/10.15681/KSWE.2026.42.1.47 |
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Keywords |
Benthic macroinvertebrates; Suspended sediment (SS); Turbidity; River ecosystem |
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Abstract |
Reduced streamflow not only stresses freshwater ecosystems but is also closely associated with rising river water temperatures. When low-flow conditions coincide with elevated water temperatures, their combined effects can create complex risks for the health of these ecosystems and for water resource management. However, previous studies have mainly used univariate analyses, examining extreme low-flow or high-temperature events separately. This approach limits the ability to quantify the likelihood of joint extreme events involving interrelated variables. To overcome this limitation, this study employs Copula-based bivariate joint modeling to estimate the conditional exceedance probability of concurrent low-flow and high-temperature events. Monthly streamflow and water temperature data from three upstream sites in the Nakdong River basin were analyzed. For each variable, seven theoretical distributions were tested, and the optimal marginal distribution was chosen using the Kolmogorov-Smirnov test. Subsequently, copulas were fitted, and the best model for each site and month was identified based on the Akaike Information Criterion. The results revealed a significant sensitivity of water temperature to changes in streamflow during specific months and locations, suggesting that thermal response characteristics may vary with spatiotemporal conditions. The proposed Copula-based joint probability modeling approach effectively captures the dependency structure between streamflow and water temperature, offering a solid foundation for high-temperature risk assessment and aiding hydrology-based policy and decision-making amid increasing climate variability.
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