Linking channel hydrology with riparian wetland accretion in tidal rivers
Linking channel hydrology with riparian wetland accretion in tidal rivers
复制标题
DOI：
10.1002/2013jf002737
复制
发表时间：
2014-01
期刊：
影响因子：
--
通讯作者：
S. Ensign;G. Noe;C. Hupp
中科院分区：
文献类型：
--
作者：
S. Ensign;G. Noe;C. Hupp
潮汐影响河道的水文过程和潮汐淡水带内的河岸形态知之甚少，但对于预测海平面上升时沿海河流和湿地的命运至关重要。我们调查了美国马里兰州两条沿海平原河流的非潮区至寡盐区沿岸湿地沿着的沉积物淤积模式，以及流速、水位和河道中的悬浮泥沙浓度（SSC）是如何影响这些模式的。沉积物淤积测量超过1年的时间内使用人工标记层，通道水文测量超过1个月的时间内使用声学多普勒电流剖面仪，并预测声散射SSC。河岸沉积物淤积在非潮汐站点最低（平均值和标准差= 8 ± 8 mm yr−1），在上游潮汐淡水森林湿地（TFFW）最高（33 ± 28 mm yr−1），在中游TFFW较低（12 ± 9 mm yr−1），在寡盐（淡水至微咸水）沼泽较高（19 ± 8 mm yr−1）。在两条潮汐河流上，寡盐区的河道最大涨潮和落潮速度是潮汐淡水区的两倍，这与河道内SSC的差异相对应：寡盐区的SSC是潮汐淡水区的两倍多，并且大于非潮汐计的历史SSC。不同河流之间的潮波特征不同，导致弱收敛潮汐河流河漫滩淹没期间的河道内SSC显著大于强收敛潮汐河流。上游TFFW的高沉积物堆积可能是由于飓风后的高河流流量。
The hydrologic processes by which tide affects river channel and riparian morphology within the tidal freshwater zone are poorly understood yet are fundamental to predicting the fate of coastal rivers and wetlands as sea level rises. We investigated patterns of sediment accretion in riparian wetlands along the nontidal through oligohaline portion of two coastal plain rivers in Maryland, U.S., and how flow velocity, water level, and suspended sediment concentration (SSC) in the channel may have contributed to those patterns. Sediment accretion was measured over a 1 year period using artificial marker horizons, channel hydrology was measured over a 1 month period using acoustic Doppler current profilers, and SSC was predicted from acoustic backscatter. Riparian sediment accretion was lowest at the nontidal sites (mean and standard deviation = 8 ± 8 mm yr−1), highest at the upstream tidal freshwater forested wetlands (TFFW) (33 ± 28 mm yr−1), low at the midstream TFFW (12 ± 9 mm yr−1), and high at the oligohaline (fresh‐to‐brackish) marshes (19 ± 8 mm yr−1). Channel maximum flood and ebb velocity was twofold faster at the oligohaline than tidal freshwater zone on both tidal rivers, corresponding with the differences in in‐channel SSC: The oligohaline zone's SSC was more than double the tidal freshwater zone's and was greater than historical SSC at the nontidal gages. The tidal wave characteristics differed between rivers, leading to significantly greater in‐channel SSC during floodplain inundation in the weakly convergent than the strongly convergent tidal river. High sediment accretion at the upstream TFFW was likely due to high river discharge following a hurricane.