Testing nutrient flushing hypotheses at the hillslope scale: A virtual experiment approach
Testing nutrient flushing hypotheses at the hillslope scale: A virtual experiment approach
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DOI：
10.1016/j.jhydrol.2005.06.040
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发表时间：
2006-03
影响因子：
6.4
通讯作者：
M. Weiler;J. McDonnell
中科院分区：
文献类型：
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作者：
M. Weiler;J. McDonnell
不稳定的营养物质（如NO3，DON和DOC）的传输机制知之甚少。最近的工作已经量化了风暴DOC动态和集水单元的连通性之间的关系，以及风暴前湿度和瞬时地下水NO3冲洗潜力之间的关系。虽然一些研究表明，N和C冲洗在风暴事件的重要机制，在出口DOC和DON在小流域，在山坡尺度的实际机制仍然模棱两可。由于土壤性质的空间变异性、检测土壤内流动路径的能力有限以及其他未知因素，在实地研究中难以分离因果关系。一些山坡表现出优先流的行为，可能会允许传输的山坡径流和不稳定的养分与小矩阵的相互作用，其他人没有。因此，实地研究只是部分有用的等同C和N源与水流和运输。本文提出了一种新的方法来研究水文控制不稳定养分冲刷在山坡尺度。我们提出了虚拟实验，重点是量化的一阶控制流动路径和养分运输在山坡上。我们将虚拟实验定义为数值实验，其模型由集体场智能驱动。我们提出了一个新的分布式模型，描述了横向饱和和垂直非饱和水流从假设的有限营养源在上层土壤层。我们描述了透水和排水孔隙度的深度分布，土壤深度的变异性，以及饱和和非饱和带之间的质量交换影响的动员，冲洗和释放不稳定的养分在山坡尺度。我们认为，这种虚拟实验的方法可能提供了一个有充分依据的基础上定义的一阶控制和水文和地球化学之间的联系，在山坡尺度，并可能形成一个基础，用于预测冲洗和运输的不稳定的养分从高地到河岸带。
The delivery mechanisms of labile nutrients (e.g. NO3, DON and DOC) to streams are poorly understood. Recent work has quantified the relationship between storm DOC dynamics and the connectedness of catchment units and between pre-storm wetness and transient groundwater NO3flushing potential. While several studies have shown N and C flushing during storm events as the important mechanism in the export of DOC and DON in small catchments, the actual mechanisms at the hillslope scale have remained equivocal. The difficulty in isolating cause and effect in field studies is made difficult due to the spatial variability of soil properties, the limited ability to detect flow pathways within the soil, and other unknowns. Some hillslopes show preferential flow behavior that may allow transmission of hillslope runoff and labile nutrients with little matrix interaction; others do not. Thus, field studies are only partially useful in equating C and N sources with water flow and transport. This paper presents a new approach to the study of hydrological controls on labile nutrient flushing at the hillslope scale. We present virtual experiments that focus on quantifying the first-order controls on flow pathways and nutrient transport in hillslopes. We define virtual experiments as numerical experiments with a model driven by collective field intelligence. We present a new distributed model that describes the lateral saturated and vertical unsaturated water flow from hypothetical finite nutrient sources in the upper soil horizons. We describe how depth distributions of transmissivity and drainable porosity, soil depth variability, as well as mass exchange between the saturated and unsaturated zone influence the mobilization, flushing and release of labile nutrients at the hillslope scale. We argue that this virtual experiment approach may provide a well-founded basis for defining the first-order controls and linkages between hydrology and biogeochemistry at the hillslope scale and perhaps form a basis for predicting flushing and transport of labile nutrients from upland to riparian zones.