Source-to-stream connectivity assessment through end-member mixing analysis.
Source-to-stream connectivity assessment through end-member mixing analysis.
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DOI：
10.1016/j.jhydrol.2010.07.049
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发表时间：
2009-05
影响因子：
6.4
通讯作者：
G. Ali;A. Roy;M. Turmel;F. Courchesne
中科院分区：
文献类型：
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作者：
G. Ali;A. Roy;M. Turmel;F. Courchesne
在一个5.1公顷的温带湿润森林集水区（加拿大Laurentians），对各种水文条件下的径流源进行了研究。在该系统中，降雨量和径流量之间的关系是非线性的，从而暗示了涉及关键的、瞬态的源区和不断变化的集水区内部连通状态的复杂过程。多年的每日流化学数据被分解成几个水文情景，反映不同的条件，流流量和前期集水区湿度。通过端元混合分析和质量平衡计算，比较了混合空间的维数（即径流源的数量）在64个不同的水文情景下获得;（2）筛选独立采样的端元（即来源的性质），从空间角度评估流域连通性;以及（3）估计端元对径流的相对贡献，以从体积角度表征水文连通性。混合空间维数没有显着变化的测试水文方案，因为三个端元一般需要占流地球化学的大部分变化。差异显着的测试端成员的能力，以适应在混合空间，例如，穿透水和有机土壤水端成员更好地配合在混合空间与高，而不是低排放。端员对径流的相对贡献随时间变化很大。涉及低排放量和干燥的前期条件的情况下，大多与基流，而涉及高排放量和潮湿的前期条件的情况下，与下游下坡和下游上坡地区的穿透水和有机土壤水的比例增加。这些结果表明，一个单一的混合空间的预测能力方面的水文条件下的径流源的性质进行了谨慎的评估。
Streamflow sources across various hydrologic conditions were examined in a 5.1ha temperate humid forested catchment (Laurentians, Canada). In that system, the relationship between rainfall and runoff is nonlinear, thus hinting towards complex processes involving critical, transient source areas and a changing catchment internal state of connectivity. Multiyear daily stream chemistry data were broken down into several hydrologic scenarios reflecting different conditions with respect to stream discharge and antecedent catchment wetness. End-member mixing analysis and mass balance calculations were performed to: (1) compare the dimensionality of the mixing spaces (i.e. the number of streamflow sources) obtained under 64 different hydrologic scenarios; (2) screen independently sampled end-members (i.e. the nature of sources) to assess catchment connectivity from a spatial perspective; and (3) estimate the relative contributions of end-members to streamflow to characterize hydrological connectivity from a volumetric standpoint. Mixing space dimensionality did not vary significantly among the tested hydrologic scenarios, as three end-members were generally required to account for most of the variance in stream geochemistry. Differences were significant in the ability of the tested end-members to fit in mixing spaces; for instance, throughfall and organic soil water end-members better fitted in mixing spaces associated with high rather than low discharges. The relative contributions of end-members to streamflow were highly variable in time. Scenarios involving low discharges and dry antecedent conditions were mostly associated with baseflow, while scenarios involving high discharges and wet antecedent conditions were associated with increased proportions of throughfall and organic soil water from downstream downslope and downstream upslope areas. These results suggest a cautious evaluation of the predictive power of one single mixing space with regards to the nature of streamflow sources across hydrologic conditions.