Study On The Effect Of Meandering River Cutoff Projects In Fejyun Estuary

The river reach from Xianhuangzhu to Baoxiang is meandering in Feiyun estuary, it is about23kilometers long, but the straight distance is about8kilometers. Mayu and Taoshan plains which are in the upstream of the reache always suffered flood disaster. The method of artificial cutoff is effective ways to solve such problems, however, in view of the baronial and far-reaching of cutoff project, especially, some potential negative effects should be paid more attention. The Feiyun river is strong tide estuary, and the sediment condition is very complex. Therefore, it is very necessary to do some scientific research work about cutoff.Based on about30measured topographic data, the analysis of river-bed evolution in Feiyun estuary and meandering reach was made for cutoff engineering, the river regime and river-bed erosion characteristic in meandering reach were analysed detailed. As numerical simulation is an important means of studying river dynamics, lager range two-dimensional numerical model of tide in the Feiyun estuary was built, its upper boundary set to Zhaoshandu, and the lower boundary simulated to the line of Pipamen-Nanji-Dongtou outside the Feiyun river. For the seven layout schemes of two bends from upstream and downstream, comprehensive study was made about the possible ifluence of flood and tide hydrodynamic and the river-bed change.The results show that each cutoff scheme will lower the upstream flood level and duration at different degree, so it will cause positive effect to flood control. At the same time, for the decrease of tidal influx will show a trend of deposition in the downstream at different amplitude, Then, by a comprehensive consideration of the influence of flood, tide and river regime, the up-bend scheme on the top can be used as the emphasis scheme for carrying out research later.