Dry‐season length and runoff control annual variability in stream DOC dynamics in a small, shallow groundwater‐dominated agricultural watershed
Dry‐season length and runoff control annual variability in stream DOC dynamics in a small, shallow groundwater‐dominated agricultural watershed
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旱季长度和径流量控制小型浅层地下水主导农业流域河流 DOC 动态的年度变化
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
P. Durand
中科院分区：
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作者：
G. Humbert;G. Humbert;A. Jaffrézic;A. Jaffrézic;O. Fovet;O. Fovet;Gérard Gruau;P. Durand;P. Durand
地下水动力学作为一种综合气候条件和水文控制河流与陆地溶解有机碳（DOC）源之间联系的现象，控制着河流DOC特征（浓度和通量）的格局。在法国西部的Kervidy-Naizin（5平方公里）的源头流域，评估了13年来地下水位、排放量和气候因素年内变化对DOC浓度和通量的影响。根据地下水波动，每年划分出四个季节性时期（A：再湿润，B：高流量，C：衰退，D：干旱）。年和季节基流与暴雨流DOC浓度定义的基础上每日水文读数。年DOC通量的年际变化很大（5.4-39.5 kg ha−1 yr−1），这表明需要几年的数据来包含水通量的变化，以评估流域的实际DOC输出能力。DOC年平均浓度的年际变化要小得多（4.9-7.5 mg C L−1），浓度每年从约100 mg C L−1开始下降。9.2 mg C L−1 in A to ca. 3.0 mg C L−1，以C计。这表明，流DOC浓度的年内模式控制DOC源特性和地下水动态非常相似的跨年。偏最小二乘回归与多元线性回归相结合的结果表明，旱季的特点（长度和下降）决定了年平均DOC浓度，而年径流量决定了年通量。生产-积累和稀释-消耗的拮抗机制与来自河岸湿地土壤的无限制DOC供应相结合，可以减轻溪流浓度对全球变化和气候变化的响应。
As a phenomenon integrating climate conditions and hydrological control of the connection between streams and terrestrial dissolved organic carbon (DOC) sources, groundwater dynamics control patterns of stream DOC characteristics (concentrations and fluxes). Influence of intra‐annual variations in groundwater level, discharge and climatic factors on DOC concentrations and fluxes were assessed over 13 years at the headwater watershed of Kervidy‐Naizin (5 km2) in western France. Four seasonal periods were delineated within each year according to groundwater fluctuations (A: rewetting, B: high flow, C: recession, and D: drought). Annual and seasonal base flow versus stormflow DOC concentrations were defined based on daily hydrograph readings. High interannual variability of annual DOC fluxes (5.4–39.5 kg ha−1 yr−1) indicates that several years of data are required to encompass variations in water flux to evaluate the actual DOC export capacity of a watershed. Interannual variability of mean annual DOC concentrations was much lower (4.9–7.5 mg C L−1), with concentrations decreasing within each year from ca. 9.2 mg C L−1 in A to ca. 3.0 mg C L−1 in C. This indicates an intra‐annual pattern of stream DOC concentrations controlled by DOC source characteristics and groundwater dynamics very similar across years. Partial least squares regressions combined with multiple linear regressions showed that the dry season characteristics (length and drawdown) determine the mean annual DOC concentration while annual runoff determines the annual flux. Antagonistic mechanisms of production‐accumulation and dilution‐depletion combined with an unlimited DOC supply from riparian wetland soils can mitigate the response of stream concentrations to global changes and climatic variations.