CSIRO Land and Water, Floreat, Western Australia, Private Bag 5, Wembley, WA 6913, Australia.
Sci Total Environ. 2012 Jun 1;426:264-71. doi: 10.1016/j.scitotenv.2012.03.021. Epub 2012 Apr 12.
In basins combining flat-sandy valleys and hilly-bedrock sub-catchments, the assessment of nutrient (phosphorus) exports from low-runoff yielding environments is difficult. To overcome this issue hydrological modelling and high frequency phosphorus measurements were simultaneously employed. A coupled surface water-groundwater interaction model (MODHMS) was used to determine runoff from the low-runoff yielding part of the catchment. The modelling results indicated that the lower catchment contributed less than 10% of annual catchment discharge over a number of weeks during mid-winter. High frequency phosphorus (P) measurements showed a threefold increase in P concentration during this period in 2008, which lasted for 3 weeks. Concentration-discharge analysis suggested that the increase in P concentration was associated with runoff generation processes in the low-runoff yielding sub-catchment. It was estimated that this area contributed 32% of the annual P load though only 2% of total annual discharge in 2008. Both runoff and P contributions occurred during the period when the water table rose to the surface causing inundation. It was shown that the P concentrations in discharge from the low-runoff yielding sub-catchment were similar to those observed in the shallow groundwater layers.
在兼具平坦沙质山谷和丘陵基岩子流域的盆地中，评估低径流量环境中营养物（磷）的输出是困难的。为了克服这个问题，同时采用了水文模型和高频磷测量。一个耦合的地表水-地下水相互作用模型（MODHMS）被用来确定集水区低径流量部分的径流量。模型结果表明，在 2008 年的数周内，冬季中期，下游流域的贡献不到年流域排放量的 10%。高频磷（P）测量显示，在此期间 P 浓度增加了三倍，持续了 3 周。浓度-流量分析表明，P 浓度的增加与低径流量子流域的径流产出过程有关。据估计，该区域在 2008 年贡献了 32%的年磷负荷，尽管仅占总年排放量的 2%。径流量和磷的贡献都发生在地下水位上升到地表导致淹没的时期。结果表明，低径流量子流域的排放中 P 浓度与浅层地下水中观察到的浓度相似。
