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河口建闸使河口区沉积动力条件发生剧烈改变,常产生航道淤浅、泄洪不畅的危害。以新洋港河口为例,于2012年8月18-24日在对新洋港闸下河口进行全潮锚系观测,分析水位、流速及悬沙浓度时空变化和悬沙输运特征。结果表明,建闸河口区为不规则半日潮,大潮期间涨潮历时短、潮流强,落潮历时长、流速相对较小;潮周期内沉积物发生强烈的再悬浮和沉降作用,再悬浮通量数量级可达到10-3kg m-2s-1;小潮期间流速、悬沙浓度和再悬浮通量均小于大潮期间的数值。大潮期间的强涨潮流导致水体不但能够产生强烈再悬浮,同时还将高浓度悬沙水体向上游输送、抵达闸下区域,这是造成建闸河口水道淤积的主要原因。在上游开闸初期和后期,存在较强的盐度垂向梯度,水体层化特征显著;但当上游淡水量较大时,流速迅速增强、再悬浮较为显著,水流可将高悬沙水体向外海输送,对河口水深的维持有利。
The construction of the estuary has drastically changed the depositional dynamic conditions in the estuary area, often resulting in the siltation of the waterway and the unfavorable flood discharge. Taking Xin Yang Gang Estuary as an example, the whole tide anchored system observation was conducted on August 18-24, 2012 in Xiaoyangkou Gap Estuary to analyze the spatial and temporal variations of water level, velocity and suspended sediment concentration and the characteristics of suspended sediment transport. The results show that the Jianzha estuary area is an irregular semi-diurnal tide, and the tides during the tide have a short duration, strong tidal current, long ebb tide and relatively small flow velocity. During the tidal cycle, the sediment undergoes intense resuspension and sedimentation, and the amount of resuspension flux Up to 10-3kg m-2s-1. The flow rate, suspended sediment concentration and resuspension flux during the tide were all less than those during the tide. The strong tide during the tide led to the water body not only generating strong resuspension, but also transporting the suspended sediment with high concentration to the area under the gate, which is the main reason for the siltation of the sluice gate estuary. In the early and late opening of the upper reaches, there is a strong vertical gradient of salinity, and the stratification of water bodies is significant. However, when the amount of freshwater in the upper reaches is large, the flow velocity rapidly increases and the resuspension is more significant. Offshore transport, the maintenance of estuary depth of water is beneficial.