An approach to understanding hydrologic connectivity on the hillslope and the implications for nutrient transport

作者：Marc Stieglitz, J. L. Shaman, J. P. McNamara, Victor C. Engel, J. B. Shanley, George W. Kling · 发表于：Global Biogeochemical Cycles · 年份：2003 · DOI：10.1029/2003gb002041 · 被引用次数：299 · 研究领域：Hydrology and Watershed Management Studies、Soil and Water Nutrient Dynamics、Groundwater flow and contamination studies

Hydrologic processes control much of the export of organic matter and nutrients from the land surface. It is the variability of these hydrologic processes that produces variable patterns of nutrient transport in both space and time. In this paper, we explore how hydrologic “connectivity” potentially affects nutrient transport. Hydrologic connectivity is defined as the condition by which disparate regions on the hillslope are linked via subsurface water flow. We present simulations that suggest that for much of the year, water draining through a catchment is spatially isolated. Only rarely, during storm and snowmelt events when antecedent soil moisture is high, do our simulations suggest that mid‐slope saturation (or near saturation) occurs and that a catchment connects from ridge to valley. Observations during snowmelt at a small headwater catchment in Idaho are consistent with these model simulations. During early season discharge episodes, in which the mid‐slope soil column is not saturated, the electrical conductivity in the stream remains low, reflecting a restricted, local (lower slope) source of stream water and the continued isolation of upper and mid‐slope soil water and nutrients from the stream system. Increased streamflow and higher stream water electrical conductivity, presumably reflecting the release of water from the upper reaches of the catchment, are simultaneously observed when the mid‐slope becomes sufficiently wet. This study provides preliminary evidence ...