One-dimensional Hydrodynamic Model MIKE11 Simulation Research

Construction of weir across Lower river would cause flood level rise in the upstream and change the river bed and river bank geometry in the area surrounding the weir,particularly downstream of weir.thereby increasing the possibility of flooding.To investigate these effects a one-dimensional hydrodynamic model MIKE11 simulation study was conducted.Mathematical Model was used to optimize weir dimension and to predict water level rise due to weir construction.The research is focused on the simulation of discharge carrying capacity of the Lower Var river in France responsible for the major flooding.The MIKE11 model is used to optimize the size of the weir and predict the changes in water level rise and flow increase caused by the change in the structure of the weir during the flooding of the Var River.(1)Set up Model.Collect and organize river network data,section data,runoff time series,basic parameters of weir buildings,etc.of the Lower Var River,divide the channel into several section nodes,complete the simulation of the channel flood by solving the section node data,The river barrage project is added to the model as the inner boundary,and the water-blocking effect of the weir project is calculated by using the formula of the wide crested weir.Based on the HD module of the hydraulic model of the one-dimensional hydrological engineering center-river analysis system(MIKE11),a one-dimensional hydrodynamic model of the Lower Wall section is established.Carry out the calibration and verification of the channel roughness parameters.In the context of modeling,studying the importance of certain input parameters and further studying the numerical accuracy of simulations will help physical experiment verification and model accuracy enhancement.(2)According to the peak flood situation in the past years,determine three simulation scenarios.The 1994 flood event with a peak flow of about 3600 m~3/s,the2011 flood event with a peak flow of about 1000 m~3/s,and the extreme case with a peak flow of 4500 m~3/s were selected.And discuss the flood control strategy of the weir at each point of the river.Simulate and analyze the changes of water level and flow in the channel after weir flooding,the impact of flood on the ecological environment of the channel,the impact of flood on the storage level of the Lower Var River and the entry into the sea,and analyze the amount of flood and the hazards that can occur in different years of water inflow.(3)Analysis of the impact of weir height changes.Lower the No.5,6 and 7weirs of the Lower Var by 2m,4m and 6m respectively to evaluate the impact of different heights of the weir on the flood,and specifically to the impact of the weirs at different topographical locations.In the entire watershed of the study area(including river segments and urbanized areas),select a specific urbanized area where a large amount of submergence is detected in the numerical field because of its attributes(such as the location of the building and the terrain of the paved road surface)is complex than rural areas.By considering the river flow and water level,it is concluded that reducing the height of the weir crest level can reduce the flooding of the surrounding area.The calculation results obtained are close to the actual results and have a high calculation rate;the model is simple and generally available,proving that the modeling technique can be very effectively applied to such studies or other similar hydraulic structures.The main advantage of this technique is that it combines accuracy with computational efficiency,because the runtime of 1D is much less than that of 2D.