Measures for river regulation
1. Regulation of mountain and stream rivers
(1) Reservation and Utilization of Beach Land
Beach land is a unique product of mountain and stream rivers. Generally, the river beach is wider and the flood season is flooded, which is conducive to flood discharge and detention. Its function should be retained and fully exploited and utilized. The rivers flowing through the urban area, while maintaining the flood discharge function of the beach, use the beach to set up green land, parks, traffic accessory roads and sports places, develop their leisure and hydrophilic functions, and become a good place for citizens to entertain, exercise and play. In the course of regulation, we should conform to the river regime, adjust measures to the river conditions, retain the beaches and bends, restore the natural form of the river, reduce the slope of the river bed, reduce the flood level and peak pressure, and at the same time reduce the height of the flood dike. In addition, the curved flow is more conducive to biodiversity and creates a suitable living environment for cattle.
(2) Design of Compound Section
Generally speaking, the riverbanks of mountain and stream rivers are open, and the design of river cross-section can adopt the form of compound cross-section. In dry season, the discharge is small, and the flow returns to the main channel; in flood season, the discharge is large, allowing floods to overflow beaches, large cross-section and low flood level, so it is generally not necessary to build tall flood dikes. In dry season, according to the width, topography and topography of the river beach, the function of the river beach can be fully developed according to the local reality: for example, the beach is wider, large-scale or comprehensive sports fields such as golf courses and football fields can be generally developed; for the relatively narrow river beach, small field places, riverside parks or auxiliary roads can be built. Reasonable development and utilization of riverbanks can not only give full play to the function of riverbanks, but also raise flood level due to beach enclosure, thus increasing the pressure of flood control on both sides of the river.
(3) Design of short and plump dikes that can not prevent scouring and flooding
Mountain-stream rivers have the characteristics of steep slope of riverbed and sudden rise and fall of flood, short duration of high water level, concentrated discharge, high flow rate, and serious erosion of dykes and farmland along rivers: through planning, the design of low-fat dikes without flooding prevention is adopted to protect the opening of lower reaches of dikes. The rivers are also provided with space to provide outlets for floods, allowing low-frequency floods to overflow dams, and ensuring that dikes do not collapse. Farmland is washed away but not destroyed. In rural rivers with flood control as the main function, the foundation of dikes has been scoured seriously. Pine pile foundation can be used to improve the integrity and stability of dikes with low investment, good integrity and strong scour resistance.
(4) Biological embankment reinforcement to reduce embankment hardening
For rural field rivers, besides the need to build embankments and slope protection for the severely scoured riverbanks, the original natural features should be maintained as far as possible, the natural forms of beaches, River hearts and shorelines under natural conditions should be maintained, the flood-carrying beaches on both sides of the river should be maintained, the original wetland ecological environment should be maintained, and the damage to the natural features and ecological environment caused by the project should be reduced. In the construction of embankments, large pebbles and dry blocks can be used to revet the banks, so that the riverbanks tend to be natural. Some plants with straight roots, such as Metasequoia glyptostroboides, or lawn slope protection, can be used to protect the interior of the embankment.