Interactions Between Streams and Groundwater Along the River Continuum: Scaling up to a Stream Network

9909564 Wondzell我们的研究目的是评估控制潜流交换的因素的相对重要性，并提供必要的数据来完善概念模型，这些模型描述了潜流带的范围及其对河流生态系统的影响，范围从单个河流到整个河流网络。我们将使用广泛的河流调查来表征山区河流网络中河道和谷底地貌特征的变化范围，并使用MODFLOW作为工具来探索地下交换流对地貌特征的敏感性。对现有研究地点进行校准的MODFLOW模拟将作为这些敏感性分析的起点。将分析一系列模拟，以确定交换水流对次级河道的存在和不同、不同的河道曲度、泥沙深度、饱和水力传导度(K)、k的空间非均质性、是否存在原木堵塞以及纵向河道坡度和池阶结构的不同组合的敏感性。模型预测将使用我们调查的溪流的一个子集中的井的溪水的保守示踪时间来验证。我们将研究这些控制因素在不同大小和不同渠道约束程度的溪流中的相对重要性。此外，我们将比较管理森林和荒野地区的溪流范围，以确定土地管理措施对控制地下水流的因素的影响。

9909564Wondzell The objective of our study is to assess the relative importance of the factors controlling hyporheic exchange flow and provide the data needed to refine conceptual models that describe the extent of the hyporheic zone and its influence on stream ecosystems across scales ranging from individual stream reaches to entire stream networks. We will use extensive stream surveys to characterize the range of variability in channel and valley floor morphologic features in mountain stream networks, and use MODFLOW as a tool to explore the sensitivity of hyporheic exchange flows to morphologic features. MODFLOW simulations calibrated to existing study sites will serve as the starting point for these sensitivity analyses. A series of simulations will be analyzed to determine the sensitivity of exchange flows to the presence and absence of secondary channels, differing channel sinuosities, sediment depth, saturated hydraulic conductivity (k), and spatial heterogeneity of k, presence or absence of log jams, and different combinations of longitudinal channel gradient and pool-step structure. Model predictions will be verified using conservative tracer time of stream water to wells in a subset of the stream reaches we survey. We will examine the relative importance of these controlling factors in streams of different sizes and with differing degrees of channel constraint. Further, we will compare stream reaches in managed forests with those in wilderness areas to determine the effect of land management practices on the factors controlling hyporheic exchange flows.