考虑侧向出沙的河网非均匀沙输移

引水进入河网可快速地改善水质,同时也会造成泥沙淤积问题。水流在主干河道行进时将挟带泥沙向连通支流扩散,因而计算河网泥沙输移时应考虑侧向出沙问题。根据作者在杭州西部河网若干测站进行的全年实时水位-流量和逐日泥沙实测资料,建立了适用河网的对数型非均匀沙挟沙能力公式,进而结合侧向出流首次导出了考虑时变侧向出沙的河网非均匀沙输移计算方法,据此改进了一维河网输沙微分方程和离散计算模式。经实测资料验证,计算与实测值符合良好。对杭州西部河网进行的输沙计算显示,侧向出沙约占淤积总量的11%,这意味着河网模型不考虑侧向出沙会造成较大的误差。

Nonuniform sediment transport with lateral output in river networks

Water quality in river networks can be quickly and effectively improved by water diversion but the problem of sediment deposition could be also caused at the same time. Laden-sediment flow in main rivers would enter into connected tributaries,therefore the calculation of lateral sediment output in river networks should be taken into account. The observations on real-time water level with discharge and daily sediment in the river network of West Hangzhou were carried out for one year. According to the data,an applicable logarithmic formula for nonuniform sediment transport capacity is established. Then, a new method for calculating sediment transport in river networks is first derived under the consideration of time-dependent lateral sediment output with lateral outflow. The 1-D differential equation for sediment transport in river networks and its discrete model are thus improved. The results of simulation agree well with the measurement. Lateral sediment output calculated accounts for about 11% of total deposition. This means that ignorance of lateral sediment output would cause considerable error,as previous model for river networks did.