Riparian zones are key gateways for solutes in watersheds, including nutrients and pollutants moving toward the stream network. In human‐dominated landscapes, they are widely used as buffers to remove pollutants at substantial cumulative cost yet vary widely in their effectiveness, and much is unknown about the detailed processes involved and their controls. Preferential flow is widespread in riparian zones, oriented both horizontally toward the channel (often bypassing beneficial reactions in the soil during baseflow) or vertically (enhancing beneficial reactions by infiltrating surface flow during storms). Preferential flow thus contributes to widespread variability of riparian zone/buffer function, with implications for legacy nutrients stored in upland soils and aquifers. This creates a disconnect between functional riparian definitions based on flow and transport processes and common operational ones based on buffer width. Enhanced field characterization of preferential flow path spatial distribution and connectivity, together with developments in simulating preferential solute transport in soils, would allow better prediction of spatial and temporal variation in riparian zone function. Such prediction in turn would allow improved buffer function by tailoring buffer design to site specific conditions, thereby reconciling functional and operational viewpoints.

中文翻译：

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河岸地下水优先流动：流域溶质迁移的途径及其对水质管理的启示

河岸带是流域中溶质的主要通道，其中包括流向河网的营养物质和污染物。在人为主导的景观中，它们被广泛用作缓冲剂，以较高的累积成本去除污染物，但效果却千差万别，所涉及的详细过程及其控制方式还不为人知。优先流广泛分布在河岸带，水平方向朝向河道（在基流期间通常绕过土壤中的有益反应）或垂直方向（通过在暴风雨期间渗入地面流来增强有益反应）。因此，优先流动导致河岸带/缓冲带功能的广泛变化，并影响到陆地土壤和含水层中存储的传统养分。这在基于流程和运输过程的功能性河岸定义与基于缓冲区宽度的常见操作性定义之间造成了脱节。优先流动路径空间分布和连通性的增强场特征，以及模拟土壤中优先溶质运移的发展，将能够更好地预测河岸带功能的时空变化。这样的预测又将通过使缓冲器设计适应特定地点的条件而允许改进缓冲器功能，从而协调功能和操作观点。可以更好地预测河岸带功能的时空变化。这样的预测又将通过使缓冲器设计适应特定地点的条件而允许改进缓冲器功能，从而协调功能和操作观点。可以更好地预测河岸带功能的时空变化。这样的预测又将通过使缓冲器设计适应特定地点的条件而允许改进缓冲器功能，从而协调功能和操作观点。