The complexity and particularity of river problems determine that when studying rivers, especially for some important and complicated problems, it is necessary to adopt comprehensive research methods of model test or model test to establish a comprehensive scientific and technological platform-river model to meet the needs of river problems.
1. General category of model theory
The "river model" mainly repeats and simulates the natural phenomena of a river by means of physical model tests, so as to explore the natural laws of a river or water system, provide scientific basis for the decision-making of river or water system management and development planning, and is an important scientific and technological platform to promote the modernization of water control. Physical model test is a scientific method that people simulate a natural phenomenon based on similar concepts and theories, and then prompt the inherent laws of natural phenomena quantitatively or qualitatively to meet the needs of engineering design and theoretical research. Physical model test can master the main influencing factors of the research object, reproduce an evolution or movement process and trend of the research object in a short time, and even demonstrate the influence of an important factor after it changes, and dynamically and intuitively reflect the complex process of some natural phenomena that are difficult to simulate by mathematical methods. Under the current severe flood control situation, only by building a "demonstration river" with complete functions and perfect system can we give full play to the role of modern scientific experiments, further promote the transformation of science and technology into real productive forces, and thus provide strong scientific and technological support for the comprehensive management and development of rivers.
2. Preliminary study on the theory of "model river course"
2. 1 "model river" construction system. The tasks of "model river" project construction mainly include infrastructure construction, measurement and control system facilities construction, solid model system construction and so on. 2. 1. 1 infrastructure construction project. Infrastructure construction projects mainly include model test hall and test area facilities. 2. 1.2 measurement and control system engineering. The measurement and control system project is mainly composed of measurement and control subsystems such as mountain model, reservoir model, wandering cross-section river model, meandering cross-section river model, etc., with the measurement and control center as its connection hub, it is integrated with the digital river to form a "bridge" linking the model river and the digital river. Through the construction of measurement and control system, real-time data monitoring and simulation control are carried out for each monitoring point of "model river", and relevant data statistics and analysis are carried out, so as to establish the engineering information database of "model river", combine the engineering information database with the geographic information database, couple the relevant data of "digital river" and "prototype river", establish various three-dimensional models, and realize "model river" 2./kloc-with the support of advanced software technology. In view of the main problems existing in river courses, the construction of "model river course" system should include four aspects, namely, soil erosion area model, reservoir model, wandering river course model and meandering river course model. 2. 1.3. 1 model of soil erosion area There are some differences in microclimate characteristics, topography, landforms, soil and other factors in different areas of soil erosion area, so physical models can be established for a sand-making area. Firstly, the erosion mechanism is analyzed and simulated, the basic law of erosion is found out, and various possible control schemes are tested. On this basis, the ditch is put forward. 2. 1.3.2 The reservoir model determines the operation mode of the upstream reservoir, carries out experimental research under different inflow conditions, different operating water levels and different outflow conditions, and puts forward the engineering layout of river regime change and its control below the reservoir area. The vertical and horizontal development and adjustment, influence scope, siltation pattern in the reservoir area, open flow sediment discharge conditions, camera lowering water level to scour the reservoir, rainfall scouring generalization experimental study and its influence on the downstream river course are studied under different boundary conditions, the siltation pattern in the reservoir area is optimized, the scientific model of reservoir operation in different periods is demonstrated, and the research on the application of small and medium flow scouring is strengthened in particular. 2. 1.3.3 wandering cross-section river model The main purpose of establishing wandering cross-section river model is to analyze and study the evolution law of river bed, determine the river regulation scheme, predict the flood peak discharge and flood level along the river, and predict the inundation area of beach area. The key research contents mainly include the evolution law of river bed; River regulation scheme of wandering reach; Key technologies of river dredging and regulation; Experimental study on the evolution of upstream scour and siltation in the late stage of sediment retention in Yuecheng Reservoir: preview and forecast of river flood evolution, etc. In the process of previewing the flood evolution, we can also predict the inundation range, inundation depth and inundation duration of the downstream beach or flood detention area, and provide scientific basis for the safe construction of the beach or flood detention area and the safe evacuation of the people. (1) Analyze and study the river bed evolution law. The influence of various water and sediment conditions with different duration, different discharge, different sediment concentration and their combinations on riverbed evolution is analyzed, the main boundary conditions and laws of riverbed deformation, river regime change and river pattern change are explored, and the riverbed undercutting, widening or siltation, inclined river, cross river, tumbling river and engineering diversion are predicted. (2) Determine the river regulation scheme. Wandering rivers are not easy to be effectively controlled, with wide and scattered channels, frequent oscillation of the main stream, and the phenomenon of inclined rivers, horizontal rivers and rolling rivers sometimes occurs. Through the river model test, the specific regulation scheme, control and diversion project layout, structural type and other related parameters (such as design flow, flood discharge width, control line, etc.) are determined. ) has been studied and determined. (3) Put forward the scheme of dredging and silting back. According to the riverbed evolution characteristics, river regime change characteristics, regulation project layout and dike standardization construction process in different reaches of the upper reaches, the scheme of dredging the river and silting back to strengthen the dike in a specific reach and its implementation position and opportunity are put forward through model tests. For example, in wandering rivers, the dredging scheme that is most beneficial to improve river regime and strengthen flood control and its implementation opportunity are determined through experiments; In the continuous scouring reach, the scour prevention scheme is put forward through experiments to minimize the suspension of engineering foundation. (4) Siltation law. The occurrence conditions and development process of historical flow path in different stages of Qingshuigou flow path are simulated and analyzed, with emphasis on siltation and scour expansion, and the internal mechanism of river expansion in different flow paths is found out. Simulation of erosion and deposition changes, morphological changes, river swing, flow path duration, flood and sediment discharge capacity changes, land reclamation rate, etc. Along the flow path of Qingshuigou under different water and sediment conditions and different boundary conditions, the relationship between siltation extension and water and sediment and their boundary conditions is found out. 2. 1.3.4 meandering river model. The main characteristics of the meandering section of the river are: serious scouring in the upstream and serious siltation in the downstream; The foundation of the upstream project is seriously suspended, which seriously affects the engineering performance; The upstream flood control situation is grim, and the downstream irrigation drought relief situation is grim. (1) River flood evolution, flood peak discharge and flood level forecast. It is of great practical significance for flood control decision-making to use river model to evolve floods of different magnitudes and predict peak discharge and flood level along the way. In concrete operation, the river model can be combined with the flood warning and forecasting system. When the flood forecasting system puts forward the possible peak flow of a certain section, it can evolve this flow on the river model, so as to predict the peak flow and flood level of each section along the way. (2) Prediction of inundation range of beach area and flood detention area. Using river model test to predict the inundation range, inundation depth and inundation duration of the downstream beach area will provide scientific basis for the safe construction of the beach area and the safe evacuation of the people in the flood season.
2.2 The foundation and conditions needed to carry out the theoretical research of "model river". 2.2. 1 theory supports the theoretical research on the application of mathematical model simulation technology; Theoretical research on measurement and control instrument system: research on information technology system. 2.2.2 Specially study the scale physical erosion model of outdoor slope, ditch, small watershed experimental area and indoor artificial rainfall moving bed; Reservoir solid model, river small watershed solid moving bed model; Basic characteristics and matching method of ultra-fine model sand; Automatic modeling of model terrain based on GIS technology: similarity conditions and simulation technology of rainfall scouring test in Duosha reservoir: theory and method of hydraulic similarity stability and error evaluation of large-scale and long-scale models; Key technology of measurement and control system for river engineering moving bed model test.
3. Establishment of research mechanism of "model river"
The overall design of "model river" project should aim at "analyzing and studying the natural laws of rivers and putting forward scientific river regulation schemes" and take the principle of "scientificity, systematicness, advancement and practicability". Overall planning and step by step. Special attention should be paid to improving the high-tech content in the construction of "demonstration river" project. The formation and display of test equipment (especially all kinds of observation equipment), operation and results should be completed by an efficient, accurate and fast automation system to avoid errors caused by manual observation and operation and improve the scientificity and accuracy of test results.
For more information about project/service/procurement bidding, and to improve the winning rate, please click on the bottom of official website Customer Service for free consultation:/#/? source=bdzd