A Bayesian Framework to Study the Effects of Hydrological Extremes under Present and Future Climate Conditions

据预测，全球变暖将以云量增加、潜热通量增加、强降水事件和洪水的形式放大水文循环。对水文极端情况的预测现在正得到经验证据的证实。然而，我们对水文因素、形态特征、土地利用以及城市环境和农业活动的空间格局之间复杂的相互作用的理解仍有相当大的差距，这些因素将决定流域内的水流状况、养分和污染物衰减率。拟议的研究计划将提供综合流域接收水体系统的水文极端的影响机制的见解。拟议研究的主要重点将放在南安大略，但测试的假设和得出的结论可以转移，并将刺激在加拿大或世界其他地区的研究。该研究计划的主要目标是（一）根据关键气象变量的历史记录描述极端天气条件，（二）提高我们对极端事件如何影响流域范围内的流态和养分循环的理解，以及（三）检查极端天气事件频率增加对接收水体恢复能力的影响。三个主要的流域接收水体系统将是拟议研究的重点，汉密尔顿港，昆特湾和锡姆科湖。选择这些系统是因为它们的流域存在大量人为压力（城市化、农业）。对水文极端情况调节综合流域-接收水体系统反应的能力的预期了解将提供关于地球科学领域“热门主题”的基本知识。这项研究还解决了对先进建模工具的迫切需求，这些工具可以支持环境管理并做出通常具有相当大的社会经济影响的决策。我们对水文极端作用的进一步理解将通过开发新的贝叶斯模型网络来加以利用，这些模型提供了有关减轻气候变化影响的最佳减缓战略的关键规划信息。贝叶斯推理的应用是唯一适合于拟议的水文极端事件的影响的概率表征，因为它能够严格评估与模型，校准数据和自然变异性相关的不确定性。这项国际领先的研究将对科学界产生巨大影响，并将加强加拿大在流域和淡水生态系统管理领域的能力。

Global warming is predicted to amplify the hydrological cycle in the form of increased cloudiness, latent heat fluxes, intense precipitation events, and flooding. The forecasts of hydrological extremes are now being corroborated by empirical evidence. However, there are still considerable gaps in our understanding of the complex interplay among hydrological factors, morphological features, land uses, and spatial patterns of the urban environment and agricultural activities that will determine flow regimes, nutrient and contaminant attenuation rates in a watershed context. The proposed research program will offer mechanistic insights into the impact of hydrological extremes on integrated watershed-receiving waterbody systems. The main focus of the proposed research will be on Southern Ontario, but the hypotheses tested and conclusions drawn can be transferred and will stimulate research in other regions in Canada or the rest of the world. The main objectives of this research program are the (i) characterization of extreme weather conditions based on historical records of key meteorological variables, (ii) the improvement of our understanding of how extreme events impact flow regimes and nutrient cycling within a watershed context, and (iii) the examination of the implications of the increased frequency of extreme weather events for the resilience of the receiving waterbodies. Three major watershed-receiving waterbody systems will be the focus of the proposed research, the Hamilton Harbour, the Bay of Quinte, and Lake Simcoe. These systems were selected due to the multitude of anthropogenic stressors (urbanization, agriculture) in their watersheds. The anticipated insights into the ability of hydrological extremes to modulate the response of integrated watershed-receiving waterbody systems will offer fundamental knowledge on a "hot theme" in the field of biogeosciences. This research also addresses the urgent need for advanced modelling tools that can support environmental management and make decisions that usually have considerable socioeconomic implications. Our improved understanding of the role of hydrological extremes will be capitalized by the development of novel Bayesian networks of models that offer critical planning information about the optimal mitigation strategies for alleviating the impact of climate change. The application of Bayesian inference is uniquely suitable for the proposed probabilistic characterization of the impact of hydrological extremes due to its ability to rigorously assess the uncertainty associated with models, calibration data, and natural variability. This internationally-leading research will have an enormous impact on the scientific community and will strengthen Canada's ability in the area of watershed and freshwater ecosystem management.