Hydrologic dynamics and geochemical responses within a floodplain aquifer and hyporheic zone during Hurricane Sandy
Hydrologic dynamics and geochemical responses within a floodplain aquifer and hyporheic zone during Hurricane Sandy
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DOI：
10.1002/2013wr015101
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发表时间：
2014-06
影响因子：
5.4
通讯作者：
A. Sawyer;L. Kaplan;O. Lazareva;H. Michael
中科院分区：
文献类型：
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作者：
A. Sawyer;L. Kaplan;O. Lazareva;H. Michael
风暴主导着集水区的溶质输出预算，并驱动近流环境中的水文地球化学变化。我们通过使用压力传感器、氧化还原探针和孔隙水采样器对克里斯蒂娜河流域临界区观测站（Christina River Basin Critical Zone Observatory）的白色粘土溪（White Clay Creek）的河岸-潜流带断面进行测量，在强风暴（2012年10月的飓风桑迪（Hurricane Sandy））期间捕获了近流水文地球化学动态。在洪泛区含水层，优惠的垂直流动路径，如大孔隙促进快速渗透早期的风暴。地下水位迅速上升，促使地下水不断向河流排泄。洪泛区-山坡地形控制了暴雨后含水层的排水速率，因为西部广阔的洪泛区含水层的排水速度比邻近陡峭山坡的东部狭窄洪泛区含水层慢。地下水流的这些变化驱动了河漫滩含水层和潜流带的非均质地球化学响应。河漫滩和潜流交换的垂直渗透增加DOC和氧气输送到微生物活性沉积物，这可能增强了呼吸作用。由此产生的地球化学扰动在风暴后持续了数天至数周。我们的观察表明，在暴雨期间，地下水携带的溶质输送到溪流取决于独特的相互作用的垂直渗透沿着优先途径，扰动地下水地球化学，地形控制排水率。
Storms dominate solute export budgets from catchments and drive hydrogeochemical changes in the near‐stream environment. We captured near‐stream hydrogeochemical dynamics during an intense storm (Hurricane Sandy, October 2012), by instrumenting a riparian‐hyporheic zone transect of White Clay Creek in the Christina River Basin Critical Zone Observatory with pressure transducers, redox probes, and pore water samplers. In the floodplain aquifer, preferential vertical flow paths such as macropores facilitated rapid infiltration early in the storm. Water table rose quickly and promoted continuous groundwater discharge to the stream. Floodplain‐hillslope topography controlled poststorm aquifer drainage rates, as the broad, western floodplain aquifer drained more slowly than the narrow, eastern floodplain aquifer adjacent to a steep hillslope. These changes in groundwater flow drove heterogeneous geochemical responses in the floodplain aquifer and hyporheic zone. Vertical infiltration in the floodplain and hyporheic exchange in the streambed increased DOC and oxygen delivery to microbially active sediments, which may have enhanced respiration. Resulting geochemical perturbations persisted from days to weeks after the storm. Our observations suggest that groundwater‐borne solute delivery to streams during storms depends on unique interactions of vertical infiltration along preferential pathways, perturbations to groundwater geochemistry, and topographically controlled drainage rates.