Study On The Effect Of Cofferdams Dismantled In Baiyangdian Typical Model Area On Connectivity

The disordered dikes and cofferdams in Baiyangdian Lake are a complex and unique system formed by the long-term development and utilization of the people in the lake area,which affects the water connectivity in the lake.Since the establishment of xiong’an New District,higher requirements have been put forward for the ecological environment of Baiyangdian Lake.It is an important content of the ecological environment construction of xiong’an new area to study the influence of dike and dike on Baiyangdian connectivity.Combined with the national "13th five year plan" water special project,taking two typical demonstration areas of Baiyangdian as the research objects,different simulation schemes were formulated,the hydrodynamic mathematical model was established,and the influence of different demolition schemes on improving connectivity was analyzed.The research contents and achievements of this paper are as follows:(1)Based on the collected hydrological data of Baiyangdian Lake,this paper analyzes the variation characteristics of temperature,precipitation,evaporation,customs and water level of Baiyangdian Lake,and prepares the basic data for the establishment of the model.(2)Through participating in the survey of Baiyangdian topography and dike,the author has mastered the structure,type and distribution of the dike and dike,analyzed the current situation during flood discharge and water diversion at normal water level,and clarified the influence of dike and dike on the hydrodynamic force of Baiyangdian Lake,and studied the reasonable removal scheme of dike and dike by establishing mathematical model.(3)According to the geographical location of Liuzhuang and Caipu Tai demonstration areas in central and southern Baiyangdian,the boundary conditions of the model were determined,and the simulation area was divided.Using the water level observation data of the demonstration area,the relevant parameters of the model are calibrated,and the verification results are satisfactory,so that the model can be used for the Scheme Simulation of typical demonstration area.(4)During the simulation of the study area,five kinds of Cofferdam Demolition schemes were determined.Based on the analysis of the simulation results of the five schemes,the changes of water level,velocity and velocity zone after the cofferdam is demolished are calculated.The calculation results show that:when the cofferdam is removed to the lake bottom elevation,the velocity in Nanliuzhuang typical demonstration area is increased from 2mm/s to 4.6mm/s,and the area of stagnant water area is reduced by 77.8%;the velocity in caiputai typical demonstration area is increased from 0.9mm/s to 3.6mm/s,and the area volume of stagnant water area is reduced by 80%.The results show that the priority of demolishing the cofferdam along the flow direction has less disturbance on the water body in Nanliuzhuang area,while the removal sequence of the cofferdam in the Putai demonstration area has no obvious impact on the water disturbance.