Studies And Application Of Flood Diversion Area Characteristics And Regulation In The Lower Reaches Of Hanbei River

Flood control dispatch is an important way to control flood.The terrain of the plain basin is changeable and the river is supported by the water level of the outer river.The relationship between water level and discharge of each flood control control point is complex.It is difficult to meet the accuracy requirement by using traditional flood control dispatching.In order to study the hydraulic characteristics of river course and flood diversion area,the hydrodynamic model of flood routing in river network and the hydrodynamic model of flood routing in active flood diversion area are established.The former is used to analyze the hydraulic characteristics of river course,and the former and the latter are used to analyze the hydraulic characteristics of flood diversion area.Secondly,referring to the reservoir optimization principle and solution method,the optimal dispatching problem of flood diversion area is transformed into the optimal dispatching problem of reservoir.Thirdly,the section flow inversion considering tank storage is used to simplify the "effective" dispatching problem into "no aftereffect" dispatching problem.Finally,the joint dispatching model of single flood diversion area and flood diversion area is established and solved.This research is based on ArcGIS watershed geographic information processing technology and DHI Mike hydrodynamic model calculation software.Firstly,collect and collate the hydrological elements of the underlying surface of the calculation area,establish and calibrate the hydrodynamic model framework;secondly,research and develop Mike 11 model batch processing tool to realize the batch establishment,calculation and result extraction of one-dimensional hydrodynamic model;thirdly,with 2008 full-frequency design flood.The process of the whole Hanbei River basin and the combination of four kinds of top support actions in the lower reaches are 24 boundary conditions to establish the flood routing model of river network,and the active flood diversion model under specific boundary conditions is established with 100 flood diversion conditions in five flood diversion areas as control variables.Then,the logical river channel is proposed and established,taking the flood diversion process as input and the influence of flood diversion on river network as output,to explore the flood of river network.The relationship between evolution and active flood diversion evolution is replaced by the hydrodynamic model of the latter.Finally,the whole inflow of river network is calculated as "reservoir" inflow,the tank storage increment is regarded as "reservoir" reservoir capacity increment,and the flood diversion flow is regarded as "reservoir" discharge.The dispatching model is established according to the constraints,and solved by quasi-gradient and similar sub-optimal substitution improved differential evolution method.The main research results of this paper include:(1)The water level and discharge curves at the control points of Tianmen Station in the lower reaches of Hanbei River are counter-clockwise and rope-like,while the increment curve of water level trough storage is approximate to a value curve,and the water level at the control points can be approximately estimated according to the increment of trough storage.(2)Flood routing in the lower reaches of the Hanbei River has a stable hydraulic relationship under the same inflow conditions.When the boundary conditions of flood routing and the discharge of flood diversion are known,logical river network can be used to deduce the hydraulic elements of the designated control section after flood diversion,thus avoiding data redundancy and simplifying calculation complexity.(3)The flood diversion area dispatching problem in the lower reaches of Hanbei River can be approximately transformed into reservoir dispatching problem,and solved by corresponding methods,with the precondition of short time range and ignoring the supplementary assumption of discharge.(4)The total amount of flood diversion in flood diversion area is close to the excess inflow,which improves the efficiency of flood diversion.The optimal dispatching scheme and hydrodynamic model reflect the effect characteristics of each flood diversion area,which proves that the optimal dispatching model of flood diversion area is feasible in the lower reaches of Hanbei River.(5)According to the characteristics of flood diversion process,the results of optimal operation in flood diversion area can be divided into three stages: flood-facing stage,peakcutting stage and aftershock stage.In the flood-prone stage,the short-term regulation of channel storage is adopted to cope with the upcoming flood peak;in the peak-cutting stage,the peak has arrived,the channel storage has increased rapidly,and the flood diversion area should increase the flood diversion volume according to the target requirement;in the aftershock stage,the main flood peak has weakened,but the incoming flood discharge still fluctuates,resulting in a small change of channel storage and a small adjustment of flood diversion discharge accordingly;...