Collaborative Research: Evaluating the Past and Future of Mississippi River Hydroclimatology to Constrain Risk via Integrated Climate Modeling, Observations, and Reconstructions

合作研究：评估密西西比河水文气候学的过去和未来，通过综合气候建模、观测和重建来限制风险

• 批准号: 2147781
• 负责人: Sylvia Dee
• 金额: $ 44.13万
• 依托单位: William Marsh Rice University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-06-01 至 2025-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2147781&HistoricalAwards=false
• 关键词: Collaborative; Research; Evaluating; Past; Future

The Mississippi River drains a continent, gathering water from as far as Pennsylvania and Montana and discharging it into the Gulf of Mexico. The channeling of so much water into a single river naturally raises the stakes for flooding, and the river has one of the most extensive flood mitigation systems in the world. But there are limits to the protection afforded by the current system and we do not know if it will prove adequate as climate warms. The effect of warming on flood risk is determined by a balance between competing effects: warming by itself would likely reduce discharge by increasing the amount of moisture that evaporates from the land rather than running off into streams. Warming also reduces snowpack, leading to a reduction in the springtime streamflow resulting from snow melt. On the other hand warmer air generally holds more moisture, which leads to increases in both mean and extreme precipitation, thus increasing flood risk. This projects seeks to determine the net effect of these competing influences on Mississippi River discharge, which serves as a broad-brush proxy for flood risk. Much of the work involves assessments of Mississippi discharge in climate models, particularly the Community Earth System Model (CESM), which uses a River Transport Model (RTM) for the Mississippi. Preliminary results show river discharge increasing dramatically (by perhaps 130%) over the 21st century under a high greenhouse gas emissions scenario (RCP8.5) but remaining within historical norms under lower emissions (RCP4.5). This contrast suggests that the balance between streamflow increases from precipitation and decreases from evaporation and snow melt could be temperature dependent, with precipitation winning out at higher levels of warming.The project also considers the factors driving Mississippi discharge over the last millennium using a combination of weather and streamflow observing networks, paleoclimate reconstructions, and ensembles of present-day and last millennium climate model simulations. Recent work by the Principal Investigators (PIs) suggests that the warm period of the Medieval Climate Anomaly featured lower discharge than the Little Ice Age, a result that is generally captured by CESM simulations of the last millennium. The result is also in keeping with the moderate warming scenario for the 21st century.The work is of societal interest due to the focus on flood risk, and the PIs are working with stakeholders including the US Army Corps of Engineers and the Mississippi River Cities and Towns Initiative to understand the practical significance of their results and provide decision support. The project also involves education and outreach, supporting summer research experiences for high school students and working with the Girl Scouts of America to encourage girls and young women to consider careers in science. The project provides support and training to a postdoctoral researcher and two graduate students.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

密西西比河流经一个大陆，从远至宾夕法尼亚州和蒙大拿州汇集水，然后排入墨西哥湾。 将如此多的水引入一条河流自然会增加洪水的风险，而这条河拥有世界上最广泛的洪水缓解系统之一。 但目前的系统提供的保护是有限的，我们不知道随着气候变暖，它是否足够。 变暖对洪水风险的影响取决于相互竞争的影响之间的平衡：变暖本身可能会通过增加从土地蒸发而不是流入河流的水分来减少排放。 变暖也减少了积雪，导致春季积雪融化造成的径流减少。 另一方面，温暖的空气通常含有更多的水分，这导致平均和极端降水量增加，从而增加了洪水风险。 该项目旨在确定这些相互竞争的影响对密西西比河流量的净影响，这是洪水风险的粗略代表。 大部分的工作涉及评估密西西比排放的气候模型，特别是社区地球系统模型（CESM），它使用了河流运输模型（RTM）的密西西比。 初步结果显示，在高温室气体排放情景（RCP8.5）下，21世纪河流排放量急剧增加（可能增加130%），但在低排放情景（RCP4.5）下仍保持在历史标准范围内。 这种对比表明，降水增加的径流量与蒸发和融雪减少的径流量之间的平衡可能取决于温度，在更高的变暖水平下，降水量占上风。该项目还考虑了过去一千年来推动密西西比流量的因素，使用天气和径流观测网络，古气候重建，以及当今和上个千年气候模式模拟的集合。 主要研究人员（PI）最近的工作表明，中世纪气候异常的温暖时期比小冰期的排放量低，这一结果通常被上个千年的CESM模拟所捕获。 研究结果也符合21世纪的温和变暖情景。由于关注洪水风险，这项工作具有社会意义，PI正在与包括美国陆军工程兵团和密西西比河城镇倡议在内的利益相关者合作，以了解其结果的实际意义并提供决策支持。 该项目还涉及教育和外联，支持高中生的暑期研究经验，并与美国女童子军合作，鼓励女孩和年轻妇女考虑从事科学职业。 该项目为一名博士后研究员和两名研究生提供支持和培训。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。