Collaborative Research: Investigating Timescales of Hydrologic Transport in Catchments Using Natural Tracer Time Series, Theoretical Models, and Laboratory-Scale Simulations

合作研究：利用自然示踪时间序列、理论模型和实验室规模模拟研究流域水文输送的时间尺度

• 批准号: 0125338
• 负责人: Xiahong Feng
• 金额: $ 3.92万
• 依托单位: Dartmouth College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-03-01 至 2006-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0125338&HistoricalAwards=false
• 关键词: Collaborative; Research; Investigating; Timescales; Hydrologic

0125338Feng The travel time of water through a catchment -- that is, the time it takes for rainfall to reach the stream -- is a fundamental hydraulic parameter controlling the persistence of soluble contaminants, and thus the downstream consequences of pollution episodes. A catchment is characterized by a distribution of travel times, reflecting the diverse flow paths that rainfall can take to the stream. Thus, quantifying catchments' travel time distributions should help to clarify the hydrologic mechanisms controlling flow routing in the subsurface. Understanding the timescales of transport and storage in catchments is also important for predicting how rainfall inputs will be chemically modified by reactions with catchment soils and bedrock. But despite the importance of catchment travel time distributions for watershed hydrology and geochemistry, they have rarely been quantified and the mechanisms controlling them are poorly understood. Catchment travel time distributions can be inferred from long-term time series of inert tracers, such as chloride, in rainfall and streamflow. It has recently been shown that catchment travel-time distributions can have unexpectedly long "tails", implying that they can retain soluble contaminants for much longer than would otherwise be expected [Kirchner, Feng, and Neal, Fractal stream chemistry and its implications for contaminant transport in catchments, Nature, 403, 524-527, 2000]. The proposed research program builds on this recent work, and has four main components:a) analyses of long-term time series of rainfall and streamflow concentrations of chloride (a naturally occurring nonreactive tracer) from humid forested catchments in diverse geological settings, using spectral, autocorrelation, and cross-correlation methods to infer each catchment's characteristic travel time distribution,b) development and testing of alternative conceptual models for the observed travel-time distributions, c) construction of laboratory-scale physical models to simulate the hypothesized mechanisms underlying these conceptual models, andd) analyses of reactive tracer data, to complement the passive tracer (chloride) studies. This integrated program of data analysis, conceptual modeling, and laboratory-scale physical models is designed to clarify the mechanisms that control catchment-scale transport, storage, and mixing of waters and their associated solutes. This project is expected to lead to:a) improved understanding of catchment flowpaths and travel time distributions, and the factors controlling them,b) improved understanding of how catchment flowpaths, and reactions between aqueous and solid phases, affect the mobility of reactive solutes at catchment scale,c) improved tools for using hydrologic and geochemical time series to probe the internal workings of catchments, andd) improved methods for testing catchment flow and routing models through comparisons with field data.

0125338Feng通过集水区的水的旅行时间（即降雨到达溪流所需的时间）是控制可溶性污染物持续性的基本液压参数，因此是污染发作的下游后果。 集水区的特征是旅行时间的分布，反映了降雨可以进入溪流的各种流动路径。 因此，量化流域的旅行时间分布应有助于阐明控制地下流动路由的水文机制。 了解集水区中运输和存储的时间尺度对于预测如何通过与流域土壤和基岩的反应对降雨投入进行化学修改也很重要。 但是，尽管集水区旅行时间分布对于流域的水文学和地球化学很重要，但它们很少被量化，并且控制它们的机制也很少理解。 流域旅行时间分布可以从降雨和水流中的惰性示踪剂（例如氯化物）的长期时间序列推断出来。 最近已经显示，流域旅行时间分布可能会出乎意料的“尾巴”，这意味着它们可以保留可溶性污染物的时间比其他预期的要长得多[Kirchner，Feng和Neal，分形流化学及其对集水区污染物的影响，自然，403，524-527，2000，2000年]。 拟议的研究计划以最近的这项工作为基础，并具有四个主要组成部分：a）分析长期降雨和流量集中的氯化物（一种自然发生的非反射性示踪剂），这些降雨和流域的潮湿集水区域中的潮湿森林集水集中是使用光谱，自相传制和相互交流的概念的分配，从旅行时间分布，c）构建实验室规模的物理模型，以模拟这些概念模型的基于的假设机制，并对反应性示踪剂数据进行分析，以补充被动示踪剂（氯化物）研究。该数据分析，概念建模和实验室规模的物理模型的集成程序旨在阐明控制流域规模运输，存储和水域及其相关溶质的机制。 预计该项目将导致：a）提高对流动流动路径和旅行时间分布的了解，以及控制它们的因素，b）改进对流水流流动路径和固体相之间的反应以及在流域上的反应性和固体阶段之间的反应，会影响流域反应性溶质的迁移率，c）改进了使用水文和地球上的工程序列的工具，并改进了流入的方法，以改进流水的方法。与现场数据进行比较。