Calculation Method And Application Of The "Three Beaches" Control Parameters For The Three Beaches Zoning Governance In The Lower Yellow River

The lower reaches of the Yellow River have a high sediment concentration,and the decrease in sediment carrying capacity caused by the flattening of the downstream channels has resulted in an unfavorable situation for wandering channels and secondary suspended rivers,leading to frequent flooding of floodplains.Due to historical reasons,the floodplain area also serves as a habitat for residents within the levee,and there is a contradiction between the residents’ life and flood control.The existing strategies for controlling sandy rivers,including watershed system management and reservoir joint commissioning,lack the necessary spatial conditions for the lower Yellow River floodplain area,and the high-quality development strategy has put forward higher new requirements for the ecology,human settlement,and development of the beach area in the Yellow River governance.This article takes the floodplain area of the Henan section of the lower Yellow River as the research object.In response to the lack of basis for determining the control parameters of the "three beaches" in the planning and design of the three beaches zoning governance model,theoretical methods such as river dynamics and optimization configuration are applied to study the calculation and optimization methods of the key control parameters of the "three beaches",with sediment resource allocation as the core,And it was applied to the management planning of the beach area in the Changyuan section,and a configuration plan for the "three beaches" of the beach area in the Changyuan section was proposed.The work and main conclusions of the paper are as follows:(1)Based on the characteristics of the lower Yellow River channel,tidal flats,and hydrology,the governance standards for flood control and security,as well as the constraints of water flow and sediment,have been determined.The correlation mechanism between river channel flood discharge and tidal flat flood control,linked by sediment resources,has been studied.The implementation process of "dredging and stabilizing channels,and Shaping Floodplain with Silting Method" has been proposed to shape the calculation methods of control parameters for tender beach,lower beach,and high beach.(2)The control parameters for river dredging in the main river channel have been studied,and the flood peak for increasing flood discharge capacity to a 5-year return period has been determined.The calculation method for cross-sectional area and sand excavation volume has been derived,as well as the determination method for parameters such as the excavation position,length,and cross-sectional shape that meet the requirements of river stability.And the area from the water boundary line to the main river channel is called the tender beach,which jointly carries flood and sediment,and retains the function of the beach area.(3)Taking the area between the levee and the boundary line near the water as the lower beach,the comprehensive siltation and reclamation treatment is proposed,and the calculation method is obtained.The siltation height,range and earthwork required for siltation are jointly determined by controlling the guiding line,the characteristic attributes of the mudflat,and the elevation difference of the lip shoal.The adverse situation of secondary suspended rivers can be eradicated by eliminating the negative horizontal gradient of the shoal.(4)A method for selecting high beach sites near levees for centralized resettlement of immigrants was proposed,and based on the 20-year flood control standard and residential safety construction standard,the calculation method for the area,width,elevation,and earthwork required for sedimentation of the high beach was determined,eliminating the contradiction between flood control and development in the beach area,and promoting communication and integration inside and outside the levee.(5)Based on the overview of the Changyuan pilot project,the application and implementation of research paper methods are determined,planning objectives and configuration constraints are determined,and the extension control and continuation prevention plans are supplemented in combination with regional characteristics.The control and guidance lines and the levee are divided into lower beach and tender beach,and the scope of secondary suspended rivers siltation treatment is determined.Then,high beach centralized resettlement in Wuqiu Township and Miaozhai Town is planned,and the required sediment and soil volume for siltation and siltation construction is calculated.The determination of the governance mode can be achieved by adjusting the input and applying it to the governance of sandy floodplain rivers.The optimization of the configuration practice path has standards to follow,and has feasibility and promotion value for application.