Research on dike breach risk of the hanging reach under different flood conditions in the Lower Yellow River

The influencing factors of dike beach risk of the hanging reach in the lower Yellow River should involve four aspects,the locomotion of incoming water and sediment load,the regional crustal stability,the evolvement of river regime and the stability of river dikes.The evaluation indexes system of dike breach risk and synthetic model are established from the four aspects.With the support of GIS technology,the evaluation indexes system and the model of multi-hierarchical fuzzy synthetic judgment are applied to estimating the dike breach risk in the lower Yellow River under different flood conditions.The evaluation results show the following distributing regularities:(1) The dike breach risk increases with the increase of flood discharge.(2) Dike breach risk decreases with the channel pattern changes along the river.(3) The reaches with greater dike breach risk are mainly distributed in wandering reaches where the south bank is relativly high.(4) The dike breach risk of the north bank is higher than the south bank in winding reaches.These conclusions can be applied to the practice of flood control and channel regulation in the lower Yellow River.Simultaneously,the evaluation results manifest that the evaluation indexes system and the method can preferably resolve the problem of dike breach risk evaluation.The spatial analysis functions of GIS technology make the dike beach risk in different spatial locations qualified,and reflect the difference of dike beach risk in different spatial locations in the lower Yellow River.It has important practical meaning to direct the practice of flood control and channel regulation.