Bedforms evolution in the Vistula River mouth during extreme flood event, southern Baltic Sea
Bedforms evolution in the Vistula River mouth during extreme flood event, southern Baltic Sea
复制标题
波罗的海南部极端洪水事件期间维斯瓦河口河床形态的演变
DOI：
10.1016/j.oceano.2021.10.005
复制
发表时间：
2021
期刊：
影响因子：
2.9
通讯作者：
M. Kałas
中科院分区：
文献类型：
--
作者：
A. Lisimenka;A. Kubicki;M. Kałas
水深测量的结果进行检查沙丘的几何形状在维斯瓦河河口之前，期间和之后的极端洪水事件的变化。根据沿沿着约3.3 km长的中心线获得的一系列河床高程剖面，共对2076个沙丘进行了分析。低陡度沙丘的特征是平均背风坡小于β<10°，在低流量时完全占主导地位。相反，在高水文条件下，近50%的沙丘显示β>10°。沙丘的高度和长度基本上是不同步的，随着水流量的逐渐变化，暴露出一个非常明显的逆时针滞后。沙丘尺度变化的明显特征是，在上升和下降流量期间，沙丘陡度H/λ分别增大约3倍和减小约4倍。由于沙丘的存在，床面粗糙度在两个分支期间约有10倍的变化，并且发现在约kdunes =（1/5 <$3/5）H平均值的范围内。在中尺度区域，低水文条件下的光谱遵循“-3幂律”，在中等和高流量期间，光谱斜率更陡，接近“-4”。随着洪水的发展，水流分离现象的可能性增加了约9倍，从洪水开始阶段的2.2%增加到洪峰时的20%。所获得的结果可用于改善水力学数值模型在砂床河流预测底形演变，流动阻力和湍流以及洪水事件期间适当的河流系统管理的水位。
Results of bathymetric surveys conducted to examine changes of sand dunes geometry in the Vistula River mouth before, during and after the extreme flood event are presented. A total of 2076 dunes were analysed based on a series of bed elevation profiles obtained along the centreline of about 3.3 km length. Low-steepness dunes characterized by the mean lee-side slopes milder thanβ<10° are fully dominant at low flows. In contrast, at high hydrology, nearly 50% of dunes indicateβ>10°. Dune height and length are substantially out of phase with progressive changes of water discharge exposing a well-pronounced anti-clockwise hysteresis. Distinct behaviour of dune dimensions reflected in increasing of dune steepnessH/λof about 3-fold and decreasing of about 4-fold were observed during rising and falling discharges, respectively. The bed roughness due to dunes presence showed changes of about 10-fold during the both of limbs and is found to be in range of aboutkdunes=(1/5÷3/5)Hmean. At the mesoscale region, spectra followed sufficiently by the ‘–3 power law’ for low hydrology, with steeper spectrum slopes close to ‘–4’ during moderate and high water discharges. With the development of the flood, potential of flow separation phenomena was increased of about 9-fold, from 2.2% at the flood beginning phase up to 20% at the flood peak. The obtained results could be used for the improvement of the hydraulic numerical models in sand-bed rivers to predict bedforms evolution, flow resistance and turbulence as well as water levels for proper river system management during flood events.