Hillslope-Riparian Zone Reservoir Mixing: A Multi- Catchment Test of a New Methodology for Predicting Stream Chemistry

[805475]要理解和预测水流对气候变化和非点源污染物等扰动的化学响应，需要了解控制水流产生的水文机制和影响溶质运输的生物地球化学机制。尽管在小流域进行了近二十年的深入研究，但还没有出现定量框架来指定描述给定流域特征所需的测量，甚至没有提供解释现场测量的背景。拟议的项目旨在通过建模和实地工作相结合来开发这样一个框架。以往的研究表明，在流域尺度上，山坡-河岸水库混合可能是河流化学的最重要控制因素。我们将在3个集水区（Panola Mountain， Sleeper River和Maimai New Zealand）进行山坡-河岸带混合的实地建模研究，涵盖广泛的地貌和水文条件。我们的研究基于以下认识：(1)在风暴事件期间，山坡可能对河流流量的直接贡献不大；(2)在风暴事件期间，山坡的化学特征在河流中并不明显，从而挑战了我们传统的河流作为集水区集大成者的观点；(3)我们可能无法构建基于河流化学和水文的整体（包括山坡）集水区模型，以预测未来的条件。最终目标是客观地将集水区（基于规定的测量）划分为均质储层，以提供一种通用的方法来解释现场观察结果并开发预测模型。这些水库之间的物理联系决定了集水区的水文流动路径。通过在多个集水区工作，我们希望能够辨别出不是特定于一个集水区的模式。将使用不确定度分析。我们的目标是：(i)开发一种新的基于topmodel的水文地球化学水库混合，以测试我们对流动路径和径流产生机制的感性理解，与水文测量相一致；（ii）使用流域交叉比较确定哪些流域因素决定了山坡对河流化学的影响；（iii）量化山坡水何时成为河岸水；（iv）开发一个基于数据的水库混合模型，具有强大的结构，可广泛应用于高地流域。这项研究代表了一种创新的尝试，将受同位素和地球化学数据约束的储层混合模型与流域尺度上地形驱动的水文模型联系起来。

9805475McDonnellUnderstanding and predicting streamwater chemical response to perturbations such as climate change and non-point source pollutants requires knowledge of the hydrologic mechanisms controlling streamflow generation and biogeochemical mechanisms influencing solutes transport. Despite the nearly two decades of intensive research in small catchments, no quantitative framework has emerged that specifies the measurements necessary to characterize a given catchment or even provides a context for the interpretation of field measurements. The proposed project seeks to develop such a framework through a combined modeling and field effort.Previous research has indicated that hillslope-riparian reservoir mixing may be the most important control on stream chemistry at the watershed scale. We will conduct a field-modeling study of hillslope-riparian zone mixing at 3 catchments (Panola Mountain, Sleeper River and Maimai New Zealand) spanning a wide range of geomorphic and hydrologic conditions. Our research is based on realizations that: (1) the hillslope may not contribute much directly to streamflow during storm events, (2) the chemical signature of the hillslope is not apparent in the stream during events, thus challenging our traditional view of the stream as integrator of the catchment, and (3) we may not be able to construct whole (including the hillslope) catchment models based upon stream chemistry and hydrology for prediction of future conditions. The ultimate goal is objective delineation of catchments (based on prescribed measurements) into homogeneous reservoirs to provide a general methodology to interpret field observations and develop predictive models. The physical connections among these reservoirs define the hydrologic flowpaths in the catchment. By working at multiple catchments, we hope to be able to discern patterns that are not specific to one catchemtn.Uncertainty analysis will be used. Our objectives are to: (i) develop a new TOPMODEL-based hydrogeochemical reservoir mixing to test our perceptual understanding of flow pathways and runoff production mechanism, consistent with hydrometric measurements, (ii) determine what catchment factors determine hillslope influence on stream chemistry using a watershed cross-comparison, (iii) quantify when hillslope water becomes riparian water, (iv) develop a data-based reservoir mixing model with robust structure to apply generally to upland catchments. This study represents an innovative attempt to link a reservoir mixing, model constrained by both isotope and geochemical data within a topographically-driven hydrologic model at the catchment scale.