Collaborative Research: Urban Watershed Evolution - Novel Temporal Perspectives on the Hydrologic Impacts and Positive Unintended Consequences of Failing Municipal Infrastructure

使用老化和故障的基础设施来提供持续的清洁水供应，以及返回和处理废水，越来越多的城市面临挑战，但人们对何时，何地以及如何引发基础设施故障或如何发展知之甚少。该项目有三个主要的科学目标，包括：1）确定城市水离开工程系统进入自然水文系统后的命运，2）揭示基础设施故障何时以及在何种条件下开始，以及3）了解这种故障及其对水资源的影响如何随着时间的推移而发展。项目的主要活动包括利用溪流和树木中的天然化学示踪剂重建水质历史，以及利用历史数据重建基础设施发展历史。我们希望我们的方法可以转移到其他基础设施老化的城市系统。更广泛地说，该项目将利用我们的利益相关者网络，帮助为城市层面的规划工作提供信息，以实施弹性基础设施，同时适应21世纪世纪城市人口的快速增长。该项目的成果将被纳入德克萨斯大学奥斯汀分校的可持续发展课程，其中包括跨学科学位和24门课程，这些课程强调实地经验，每年有800名学生沿着一个拟议的溪流研究地点进行校园环境研究，以及UT奥斯汀和亚利桑那大学的地球科学研究生课程。研究生和本科生的培训将强调包容代表性不足的少数民族。在每个奥斯汀流域的基础设施故障的开始，市政水被引入相对原始的自然水文系统泄漏。我们假设，这些人为水源的独特的化学成分记录在秃柏树在故障发生时，并在随后的几年中失败的进展。该项目包括一个新的应用天然同位素示踪剂，以研究城市化对自然水文和河流生态在三个流域在同一水文地质地形的影响。流域之间的主要变量是城市化程度。我们将分析元素和锶同位素的变化，在溪流中，并制定高分辨率测量的Sr同位素在生长的秃柏树的年轮毗邻这些流。我们认为，树木年轮的生长速度和同位素组成编码的基础设施的逐步失败的水文历史。我们将应用这些数据，使用水文地球化学模型：1）跟踪城市水的演变过程中，通过自然水文循环在生态危害流域传输;和2）使用树木化学变化重建十年来解决的时间变化，城市水输入流。这些结果将首次用于确定基础设施故障发生的时间以及故障的程度和影响的时间变化。我们将比较这一时间记录的市政水输入与城市发展的历史，在同一流域，以确定阈值的城市化程度，以上失败的基础设施的水文和生态影响的表现。该奖项由水文科学、环境可持续性和环境工程项目共同资助。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。

Municipalities are increasingly challenged to use aged and failing infrastructure to deliver a continuous supply of clean water, and to return and treat wastewater, yet little is known about when, where, and how infrastructure failures were initiated or how they progressed. This project has three main scientific goals including: 1) determining the fate of municipal water after it leaves the engineered system and enters the natural hydrologic system, 2) unravel when, and under what conditions, infrastructure failure began, and 3) understanding how this failure and its impacts on water resources have progressed over time. The primary project activities comprise using naturally-occurring chemical tracers in stream water and trees to reconstruct a history of water quality, and using historical data to reconstruct a history of infrastructure development. We expect our approach will be transferrable to other urban systems with aging infrastructure. Most broadly, this project will leverage our network of stakeholders to help inform city-level planning efforts to implement resilient infrastructure while accommodating rapid expansion of urban populations in the 21st century. Results from this project will be incorporated across the sustainability curriculum at the University of Texas at Austin, which includes interdisciplinary degrees and 24 courses that emphasize field experiences and engage 800 students per year in on-campus environmental research along one of the proposed stream study sites, as well as geoscience graduate programs at UT Austin and the University of Arizona. Graduate and undergraduate student training will emphasize inclusion of underrepresented minorities.At the onset of infrastructure failure in each Austin watershed, municipal water was introduced by leakage into relatively pristine natural hydrologic systems. We hypothesize that the distinct chemical compositions of these anthropogenic water sources were recorded in bald cypress trees at the onset of failure and in subsequent years as failure progressed. This project comprises a novel application of natural isotopic tracers to examine the impacts of urbanization on natural hydrology and stream ecology in three watersheds in the same hydrogeologic terrain. The primary variable among the watersheds is the extent of urbanization. We will analyze elemental, and Sr isotope variations in stream water, and develop methods for high resolution measurements of the Sr isotopes in the growth rings of bald cypress trees growing adjacent to those streams. We posit that the growth rate and isotopic composition of the tree rings encode a hydrologic history of the progressive failure of infrastructure. We will apply these data using hydrogeochemical models to: 1) trace the evolution of municipal water during its transmission through the natural hydrologic cycle in anthropogenically compromised watersheds; and 2) use dendrochemical variations to reconstruct decadally-resolved temporal changes in municipal water input to streams. These results will be used to identify, for the first time, both the timing of the onset of infrastructure failure and temporal changes in the magnitude and impacts of the failure. We will compare this temporal record of municipal water input with the history of urban development in the same watersheds to determine the threshold for the extent of urbanization, above which hydrologic and ecological impacts of failing infrastructure are manifested. This award is co-funded by the Hydrologic Sciences, Environmental Sustainability, and Environmental Engineering programs.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.