奉化江感潮河段水文变化特征分析

Analysis on Hydrological Variation Characteristics of Tidal Reach of Fenghua River

海潮对感潮河段的水文变化影响较大,而天文潮受到地月引力影响,使感潮河段水流特征产生明显的规律性变化。针对感潮河段水流为非恒定流的特点,对奉化江部分流域进行水文泥沙测验,并对结果进行分析。研究结果显示,该流域流速最大值大多出现在表层及0.2 H层,最小值多出现在底层,大致呈现由表层至底层逐渐减小的趋势;涨潮流速基本大于落潮流速,最大流速均发生在涨潮时的涨急时刻;在河道较窄的上游河段,水深较浅,断面流量整体小于下游断面流量。大潮期间水流流速与含沙量呈周期性变化,断面右岸的含沙量变化滞后于水流速度变化,平均滞后0.9 h;断面主槽处含沙量变化也滞后于水流速度变化,平均滞后0.7 h。

The sea tide has a strong influence on the hydrological variability of the tidal river,while the astronomical tide is influenced by the gravitation of the earth and moon,giving the tidal river a distinctly regular flow feature.In this paper,in response to the feature that tidal rivers belong to unsteady flow,hydrological test and sediment test have been carried out in part of Fenghua River basin.The results show that most of the maximum values of flow velocity in the basin occur in the surface layer and the 0.2 H layer,while the minimum values occur in the bottom layer,showing a gradual decrease from the surface layer to the bottom layer.The velocities of rising tides are generally greater than the ebb tides’and the maximum velocities always occur at rising tide during the rush hour.In the narrower upstream reaches of the riverwithshallowdepth,the section flow is overall less than the downstream’s.During spring tides,the flow velocity and sand content change periodically.Specifically,the change in sand content on the right bank of the section lags behind the change in velocity by an average of 0.9 hours.And the change in sand content at the main channel of the section also lags behind the change in current velocity,with an average lag of 0.7 hours.