Stream ecosystems are increasingly at risk for thermal impairment as urbanization intensifies, resulting in more heated runoff from impervious cover that is less likely to be cooled naturally. While several best management practices, including bioretention filters, have been able to reduce thermal pollution, success has been limited. The extent of thermal mitigation required to prevent ecological damage remains unknown. A calibrated runoff temperature model of a case study watershed in Blacksburg, VA was developed to determine the cumulative treatment volume of bioretention filters required to reduce thermal impacts caused by runoff from development in the watershed to regulated biologically acceptable levels. A future build out scenario of the study watershed was also analyzed. Results from this study established that runoff thermal pollution cannot be fully reduced to goal thresholds during all storms using bioretention filter retrofits. While retrofitting significantly decreased temperatures and heat exports relative to the controls, increasing treatment volumes did not really enhance mitigation. Alternate thermal mitigation methods that actively remove runoff volume should be considered where more thermal mitigation is required.

中文翻译：

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对流域范围的生物保留雨水改造进行建模，以实现缓解热污染的目标

随着城市化进程的加剧，河流生态系统越来越有遭受热损害的风险，导致不透水的覆盖物产生更多的热径流，因此自然冷却的可能性较小。尽管包括生物滞留过滤器在内的几种最佳管理方法已能够减少热污染，但成功却受到了限制。防止生态破坏所需的热缓解程度仍然未知。开发了弗吉尼亚州布莱克斯堡案例研究流域的校准径流温度模型，以确定将流域发育径流引起的热影响降低到可调节的生物学可接受水平所需的生物滞留过滤器的累积处理量。还对研究分水岭的未来扩建方案进行了分析。这项研究的结果表明，使用生物保留过滤器改造后，在所有暴风雨期间都无法将径流热污染完全降低到目标阈值。相对于对照而言，虽然改造后的温度和热量输出显着降低，但增加处理量并不能真正增强缓解效果。在需要更多热缓解措施的地方，应考虑采用主动减少径流体积的替代热缓解方法。