Collaborative Research: Reevaluating precipitation extremes and flood hazard in the wake of Hurricane Harvey

2017年8月，飓风哈维在德克萨斯州东南部造成灾难性洪水，造成超过1000亿美元的损失。与飓风哈维相关的降雨总量和河流流量打破了德克萨斯州东南部的记录，但这些记录只跨越了过去的100年。飓风哈维引发的洪水有多不寻常，这种事件再次发生的可能性有多大？目前，仪器水文记录的简短性限制了我们准确回答这一关键问题的能力。该项目将通过使用水文模型的洪水地质证据，及时延长水文记录的长度，改善德克萨斯州东南部极端降水和洪水的风险评估。这些数据将使我们能够更好地了解飓风哈维等事件再次发生的概率，并评估气候和人类活动的变化如何影响德克萨斯州东南部的洪水风险。这项研究将改善对洪水风险的评估，洪水最近影响了休斯顿大都市地区数百万人的生活。该项目将吸引本科生和研究生参与研究，其研究结果将通过德克萨斯州海滩和海岸中心传播给公众和决策者。基于世纪水文测量的频率分析估计，飓风哈维的复发间隔？的降水和排放最大值接近1,000年（即，0.1%的概率），但这些估计值具有高度不确定性，95%的置信区间跨越多个数量级。该项目的目标是通过将分析的时间范围从~100年扩展到~1,000年来重新评估休斯顿大都市区的洪水危害。要做到这一点，我们将使用已建立的技术在古森林水文重建流量最大的两条河流在德克萨斯州东南部在过去的千年，并将这些数据与水文模型，以评估自然和人为因素对区域洪水灾害的作用。这些数据将使我们能够（a）改进对飓风哈维和休斯顿大都市地区最近发生的其他灾难性洪水的发生概率的评估，（B）检验洪水灾害中非平稳性的存在，以及（c）确定气候变化和土地利用及土地覆盖变化在产生排放极端事件中的作用。该奖项反映了NSF的法定使命，并被认为值得支持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。

In August 2017, Hurricane Harvey produced catastrophic flooding across southeast Texas that caused over $100 billion in damages. Rainfall totals and river flows associated with Hurricane Harvey shattered records across southeast Texas, but these records span only the last ~100 years. How unusual was the flooding generated by Hurricane Harvey, and what is the likelihood of such an event occurring again? The brevity of instrumental hydrologic records currently limits our ability to precisely answer this critical question. This project will improve risk assessments for extreme precipitation and flooding in southeast Texas by extending the length of the hydrologic record back in time using geological evidence of flooding with a hydrologic model. These data will allow us to better understand the probability of an event like Hurricane Harvey occurring again, and evaluate how variations in climate and human activities affect flood risk in southeast Texas. This research will improve assessments of the risk posed by flooding, a hazard that has recent affected millions of people living in the Houston metropolitan area. The project will engage undergraduate and graduate students in research, and its findings will be disseminated to the public and decision-makers through the Center for Texas Beaches and Shores.Frequency analyses based on a century of hydrological measurements estimate that the recurrence intervals of Hurricane Harvey?s precipitation and discharge maxima approach 1,000 years (i.e., 0.1% exceedance probability), but these estimates are highly uncertain with 95% confidence intervals that span multiple orders of magnitude. The goal of this project is to reevaluate flood hazard in the Houston metropolitan area by extending the temporal range of analysis from ~100 years to ~1,000 years. To do this, we will use established techniques in paleoflood hydrology to reconstruct discharge maxima of the two rivers in southeast Texas over the last millennium, and integrate these data with a hydrologic model to evaluate the roles of natural and anthropogenic forces on regional flood hazard. These data will allow us to (a) improve assessments of the exceedance probability of Hurricane Harvey and other recent catastrophic floods in the Houston metropolitan region, (b) test for the presence of non-stationarities in flood hazard, and (c) identify the roles of climate variability and land use and land cover change in generating discharge extremes.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.