保护高山莱茵河谷免受洪水

作者：Renata BarradasGutiérrez

莱茵河是欧洲的主要河流之一，来自格里斯森广州瑞士阿尔卑斯山的来源。高山莱茵河谷（Alpine Rhine Valley）沿着莱茵河（Rhine）从瑞士的来源延伸到90公里，并通过列支敦士登（Liechtenstein）到奥地利。山谷有毁灭性洪水事件的历史，可以追溯到11世纪。如今，大约30万人居住在莱茵河下部和许多公司，包括Leica Geosystems，在该地区蓬勃发展。由于莱茵河谷的强烈人口和重大经济活动，重大洪水事件的破坏潜力估计为100亿欧元。

To protect people, settlements, and as economic activities in the Valley, more room for flood runoff and water retention needs to be given to the Alpine Rhine. Therefore, the flood protection project “Rhein – Erholung und Sicherheit” (“Rhine - Recreation and Safety”) – or shortRhesi- seeks to increase the flow capacity of the Alpine Rhine from 3,100 m³/s to at least 4,300 m³/s on the international stretch between kilometre 65 at the junction of the tributary river Ill and km 91, where the Alpine Rhine discharges into Lake Constance. The project costs, funded equally by Austria and Switzerland, are currently estimated at EUR 1 billion.

“实现洪水protectio的要求水平n, the channel geometry of the Alpine Rhine needs to be altered to enhance flood protection along the project perimeter. In the Rhesi project, a very modern approach has been chosen: instead of raising the river’s levees to take account of the elevated discharge of 4,300 m³/s, the required flow section will be created by increasing the river width from currently 60 – 70 m up to several hundred meters in the future. The river channel, which has at present a very technical shape due to diverse river restoration measures during the last 150 years, will by this means retrieve a near-natural state with conditions that mimic the state of the river system before human intervention,”explains Florian Hinkelammert-Zens, environmental engineer at the Laboratory of Hydraulics, Hydrology and Glaciology (VAW) at the Swiss Federal Institute of Technology Zurich (ETH).

To evaluate the effects of the projected measures and to check the hydraulic calculations and assumptions of the Rhesi project, VAW of ETH Zurich has been commissioned with hybrid model experiments on behalf of the International Rhine Regulation (IRR) body. These investigations consist of two main parts: 1) experiments in a physical hydraulic model and 2) accompanying numerical simulations.

“Two key project sections are replicated consecutively at a scale of 1:50 in extensive hydraulic models. For each section, a flow length of approximately 5 km is replicated (around 110 m in model scale) with watercourse widths ranging from 250 m to 350 m (around 8 m in model scale),”Hinkelammert-Zens说。“At the same time, numerical computer models of the project were created to provide and evaluate the boundary conditions of the hydraulic models, to validate the results and to carry out sensitivity analyses.”

结果，这两种液压模型是有史以来最大的高山河流模型之一，平均尺寸为110 x 9 m。两者都位于奥地利Dornbirn的一栋古老的工厂建筑中，苏黎世Eth设计了一个排放400 l/s的水路。该系统由一个高级水箱，入口和出口盆地，地下室中的水流线和一个深水箱组成，从中，水从中泵回高级水箱（最多400 L/s）。

3D terrain modelling for flood modelling

“During a flood event, a riverbed is subject to significant changes due to high water discharges and flow velocities. Hence, sediment can be deposited at several locations, leading to rising water levels, or can be eroded, e.g. around bridge piers or along the river banks. Both scenarios can be dangerous and have a negative effect on flood protection. To replicate these morphological changes, the hydraulic models are equipped with movable riverbeds.” says Hinkelammert-Zens.

To observe the impact of different sediment loads and various scenarios, a large number of scientific experiments with varying parameters (e.g. water discharge and sediment load) are conducted. By means of a laser scanner, the model topography is measured before and after every single experiment. The acquired data is then used to create terrain models which serve as a basis for the determination of areas where sedimentation and erosion occur in the riverbed.

From data capture to actionable data

Right: 3D terrain model of a section of the Alpine Rhine (viewed in flow direction) /Left: Movable riverbed in the hydraulic model after the conclusion of an experiment

To capture the topographical data before and after each experiment, the research team of ETH Zurich relies on aLeica Scanstation P20，Leica Geosystems目标和Leica TS02总站为了地理参考，激光扫描15个参考点。扫描仪P20安装在移动三脚架上，并部署在四个扫描位置上以捕获整个型号。扫描高度约为2.7 m-如果观看角度太陡并避免死角，则最大程度地减少阴影效果 - 在与设备的径向距离为10 m的径向距离下，分辨率为3 x 3 mm，可以获得具有非常低噪声的高质量数据。

After each experiment, the data is imported into狮子旋风3D点云处理软件以注册数据并合并点云。此时，面积为4000 m²is represented with approximately 250 million points. The point cloud is then ‘trimmed’ using polygons to cut-off the data points outside of the model boundaries. The remaining data points are then transformed into grid cells with a cell size representing 50 cm x 50 cm in real life. Finally, the topographical data is converted into the Swiss National Coordinate System.

右：评估激光扫描后，液压模型中观察到的变化的可视化（红色：曲线外部侵蚀，蓝色：曲线内部的沉积物，在流动方向上观察）/左：激光扫描在实验大厅（以流向查看）

“The 3D point clouds are used to create grid datasets with approximately 15 million grid cells with a resolution of 0.5 x 0.5 m, each of them representing one distinct point of time during the experiments. This data is then further processed in geo-information systems in order to create surface views as well as longitudinal and lateral profiles of the mobile riverbed. This enables us to compare different points in time of the experiment with each other,”explains Hinkelammert-Zens。

引用的网格数据集可以在GIS应用程序中用于各种评估，包括：

• Surface views: The grid values of the scan made at the beginning of the experiment are deducted from those made at the end of the experiment. In this way, theETH teamcreates a view where the relative differences in the height of the model riverbed are visible.

• 横向概要:团队创建交叉的资料es at certain positions, extracting grid values to create lateral profiles. Using the scans before and after the tests, the experts can visualise the observed changes and compare them to the project goals.

• Longitudinal profiles: The extracted cross profiles are averaged for the longitudinal profile. By comparing the averaged riverbed elevations before and after the experiments and by observing the changes in nature, the team of experts can validate the hydraulic model.

中级结果和未来步骤

The investigations by VAW of ETH Zurich already led to significant inputs for the further development of the Rhesi project. At first, the model was calibrated via the replication of past flood events. During this process, the water levels and riverbed topography obtained in the hydraulic model were compared to data captured during those events in full-scale. After successful completion of this step, the hydraulic model was adapted to the future shape of the river, as projected in Rhesi. Since then, various long-term scenarios and high flood events have been simulated to investigate the effects of the Rhesi project on the river morphology and water levels.

的调查仍在进行中,只有强度rmediate results can be cited. Up to today, the results show that the assumptions and projections of the Rhesi project were correct and are a solid basis for the elaboration of future project stages with greater detail. The hybrid model experiments will continue until summer 2022, exploring answers to the following technical questions:

• Where will gravel banks be positioned?
• Where will depressions resp. scours occur and what will be their maximum depth?
• 必须保护河岸的深度，以防止侵蚀和搜查？
• 如何保护桥梁免受侵蚀和冲洗的侵害？
• What is the amount of driftwood clocked at bridges during flood events? What will be the effect on the water levels?

这些科学实验的发现得到了Leica Geosystems的现实捕获技术的支持，是确保可持续的河流规划并确保Rhesi防bob综合app赌博洪项目在技术上和经济上可行的基础。这种综合的洪水风险管理方法将大大降低洪水风险，并改善国际高山莱茵河的生态和娱乐价值。