河道线型设计
河道线型设计即河道总体平面的设计。由于城市用地的紧缺,河道滨水地带不断被侵占,水面越来越少,河宽越修越窄,但是为了泄洪的需要,要保证过水断面,只好将河道取直、河床挖深,这样对驳坎的强度要求就逐步地提高,建设费用逐渐加大,而生态功能逐渐衰退,河道基本成为了泄洪渠道,这与可持续发展的战略相悖。而生态化治理就需要退地还河,恢复滨水地带,拆除原先视觉单调、生硬、热岛效应明显的渠道护岸,尽量恢复河道的天然形态,宜弯则弯,宽窄结合,避免线型直线化。
The design of river alignment is the design of overall river plane. Due to the shortage of urban land, the riverfront area is constantly occupied, the water surface is less and less, and the river width is narrower and narrower. However, in order to meet the needs of flood discharge, we have to take the River straight and dig the river bed deep, so that the intensity of barge is gradually increased, the construction cost is gradually increased, and the ecological function is gradually increased. With the gradual decline, rivers have basically become flood discharge channels, which is contrary to the strategy of sustainable development. The ecological management needs to return the land to the river, restore the waterfront, dismantle the original visual monotony, rigidity, heat island effect obvious channel revetment, try to restore the natural form of the river, should bend, width and narrow combination, avoid linearization.
自然蜿蜒的河道和滨水地带为各种生物创造了适宜的生境,是生命多样性的景观基础。河湾、凹岸处可以提供生物繁殖的场所,洪峰来临时还可以作为避难场所,为生物的生命延续创造条件,而丰富多样的水际边缘效应是其它生态环境所无法替代的,在有条件的河段,还可以增加一些湿地、河湾、浅滩、深潭、沙洲等半自然化的人工形态,既增添了自然美感,又利用河流形态的多样性来改善生境的多样性,从而改善生物群落的多样性。相对于直线化的渠道,自然曲折的河岸设计能够提高水中含氧量,增加曝气量,因此也有利于改善生物的生存环境。
Natural meandering rivers and waterfront zones create suitable habitats for all kinds of organisms and are the landscape foundation of life diversity. Bays and concave banks can provide places for biological reproduction, flood peak can also be used as a refuge to create conditions for the continuation of biological life, and the rich and diverse marginal effects of water are irreplaceable by other ecological environments. In conditional River sections, wetlands, bays, shallows, deep pools, etc. can also be added. Semi-natural artificial forms such as sandbars not only add natural beauty, but also use the diversity of river forms to improve the diversity of habitats, thereby improving the diversity of biological communities. Compared with linear channels, natural tortuous river bank design can increase oxygen content and aeration in water, so it is also conducive to improving the living environment of organisms.
从工程角度,自然曲折的河道线型能够缓解洪峰,消减流水能量,控制流速,所以也减少了对下游护岸的冲刷,对沿线护岸起到保护的作用。退地还河、滨水地带的恢复,使得设计人员在河道断面设计上留有选择的余地,也不需要采用高强度的结构形式对河滨建筑进行保护。顺应河势,因河制宜,无疑在工程经济性方面也是有利的。
From the engineering point of view, the natural tortuous river line can alleviate the flood peak, reduce the flow energy and control the flow speed, so it also reduces the scouring of the downstream revetment and plays a protective role on the coastal revetment. Returning land to rivers and restoring waterfront areas make designers have a choice in the design of river section, and do not need to adopt high-strength structural form to protect Riverfront buildings. It is undoubtedly advantageous in engineering economy to conform to the river regime and adapt to the river conditions.