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了灾难性的洪水，造成了超过1000亿美元的损失。与哈维飓风有关的降雨量和河流流量打破了德克萨斯州东南部的记录，但这些记录只持续了近100年。飓风哈维造成的洪水有多不寻常？此类事件再次发生的可能性有多大？仪器水文记录的简洁性目前限制了我们精确回答这个关键问题的能力。该项目将利用水文模型的洪水地质证据，延长水文记录的时间长度，从而改善德克萨斯州东南部极端降水和洪水的风险评估。这些数据将使我们更好地了解像飓风哈维这样的事件再次发生的可能性，并评估气候变化和人类活动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，洪水是最近影响休斯顿大都会地区数百万居民的一种危险。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海滩和海岸中心传播给公众和决策者。基于一个世纪的水文测量的频率分析估计飓风哈维的复发间隔？S降水和流量最大值接近1000年（即0.1%的超出概率），但这些估计具有高度的不确定性，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~ 1000年，重新评估休斯顿大都市区的洪水危害。为此，我们将利用已建立的古洪水水文学技术来重建过去一千年来德克萨斯州东南部两条河流的最大流量，并将这些数据与水文模型相结合，以评估自然和人为力量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市区近期其他灾难性洪水的超出概率的评估，(b)检验洪水灾害中存在的非平定性，以及(c)确定气候变率、土地利用和土地覆盖变化在产生极端流量中的作用。该奖项反映了美国国家科学基金会的法定使命，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。

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.