Heat Budget in the Hyporheic Zone of a Large, Gravel-Bed River

该项目是一个基于定量物理学的研究在一条大河的潜流区的热收支。 这与目前研究的河流温度和潜流水通量之间的相互作用有关。 了解潜流区的传热对美国西部的水质及其监管具有重要意义，可能是研究人员，监管机构和水处理专业人员的新工具。 初步结果表明，温暖的河水在砾石坝下的过境过程中经历了潜流冷却。 河流恢复和污染信用交易计划正在围绕着低流冷却战略进行设计，这使得对这一现象的充分理解成为当务之急。 初步假设包括：（1）白天温暖的水在潜流区实际上没有被冷却，但在白天确实排出了夜间凉爽的水，（2）白天温暖的水通过以下方式被显著冷却：a）通过传导到具有较长流动路径的较深地下水并与之混合的热流，B）通过潜热和显热通量到包气带的热流，和/或c）在潜流区的砾石和死区中的临时热存储。 这些假设的初步测试将通过现场仪器和建模的水和热通量下的一个大的，砾石床河，威拉米特河，俄勒冈州的砾石酒吧。 研究地点代表了一个最近沉积的砾石坝，发现这种类型的砾石坝提供了显着的明显冷却。现场勘测和绘图、浅威尔斯井、地震剖面和示踪剂测试的现场数据将表征并促进基底和相关通量的建模。 这种表征和建模将限制后续研究的范围和方法，（1）威尔斯的平台布局是否足以测量横向对流热通量，（2）是否需要额外的威尔斯井来测量更深的热通量和储存，（3）是否需要三维地震数据采集和/或全层析成像分析和波形建模，以确定边界条件。

This project is a quantitative physics-based study of the heat budget in the hyporheic zone of a large river. It is relevant to current research in the interactions between stream temperature and hyporheic water flux. Understanding heat transfer in hyporheic zones has important implications for water quality and its regulation in the western US, and may be a new tool for researchers, regulators, and water treatment professionals. Preliminary results indicate that warm river water undergoes hyporheic cooling during its transit beneath gravel bars. River-restoration and pollution-credit-trading schemes are being designed around hyporheic cooling strategies, and this makes a full understanding of this phenomenon an imperative. Initial hypotheses include: (1) warm, daytime water is not actually cooled in the hyporheic zone but does push out cool, nighttime water during the day, (2) warm, daytime water is significantly cooled by a) heat flow by conduction to and mixing with deeper groundwater with longer flow paths, b) heat flow by latent and sensible heat fluxes to the vadose zone, and/or c) temporary heat storage in gravels and dead zones in the hyporheic zone. Preliminary tests of these hypotheses will be accomplished through field instrumentation and modeling of water and heat fluxes beneath a gravel bar on a large, gravel-bed river, the Willamette River, Oregon. The research site represents a recently deposited gravel bar of the type found to provide significant apparent cooling. Field data from, site surveying and mapping, shallow wells, seismic profiles, and tracer tests, will characterize and facilitate modeling of the substrate and associated fluxes. This characterization and modeling will constrain the scope and methods for a follow-up study of (1) the adequacy of the platform layout of wells to measure laterally advective heat fluxes, (2) the need for additional wells to measure deeper heat fluxes and storage, (3) the need for three-dimensional seismic data acquisition and/or full tomographic analysis and waveform modeling, to determine boundary conditions.