隨著人口增長、社會經(jīng)濟(jì)發(fā)展和城鎮(zhèn)建設(shè)步伐的加快,土地利用需求快速增加。河流流城亦受到過度開發(fā)。圍墾河流洪泛區(qū)、河灘和湖泊消落區(qū)等重要濕地,嚴(yán)重削弱了問流
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生態(tài)系統(tǒng)自然調(diào)節(jié)洪水的能力。傳統(tǒng)河流整治工程措施也極大地破壞了河流生態(tài)系統(tǒng)。傳統(tǒng)的護(hù)坡工程將整個河岸表面封閉起來,隔絕了土壤與水體之間的物質(zhì)交換,原本生長在岸坡上的生物不能繼續(xù)生存,生態(tài)系統(tǒng)的食物鏈斷開,使土壤和水體中的生物失去了賴以生存的環(huán)境。傳統(tǒng)混凝土河道護(hù)坡對生態(tài)的影響主要有:①在兩岸由水泥石料修葺的河道中,具有凈水功能的水生生物生長非常困難,河水自凈能力將大為降低,水質(zhì)惡化;②混凝土砌成的大面積剛性護(hù)砌面,由于缺乏透氣性、透水性,對溫度、濕度的調(diào)節(jié)性能差。不利于維持水中生態(tài)平衡邊坡上寸草不生,一片荒蕪,特別夏季太陽的直接暴曬,在邊坡周邊所形成的“熱島效應(yīng)”,導(dǎo)致了局部氣候的惡化,還容易使傳染病菌草生;③傳統(tǒng)邊坡忽略了河道與岸上生態(tài)系統(tǒng)的有機(jī)聯(lián)系,使得岸上植物難以生長,魚類及兩棲類動物失去了棲息和繁殖的條件,使水中生物減少,岸上又缺乏天然植物,直接影響沿河生物種類生存。據(jù)統(tǒng)計、河道襯砌后,沿河生物種類減少了70%以上,而水生物也只相當(dāng)于原來的50%。此外,傳統(tǒng)的混凝土護(hù)坡在施工中均不同程度地使用了一些添加劑,如早強(qiáng)劑、抗凍劑、膨脹劑等,這些添加劑在水中發(fā)生反應(yīng),對水質(zhì)和水環(huán)境產(chǎn)生不利的影響。岸坡沒有天然植物作為屏障,會使岸邊的垃圾輕易入水,造成污染。這些雖然不是水質(zhì)惡化的主要原因,但它們對水質(zhì)的惡化起到了促進(jìn)作用。同時,沒有綠色的傳統(tǒng)護(hù)坡使河道失去了原有的生機(jī),這與現(xiàn)代人們追求回歸自然的要求不相一致,與建立優(yōu)美環(huán)境相違背,更與人文景觀不相和諧。With the population growth, socio-economic development and the acceleration of urban construction, the demand for land use increases rapidly. River cities are also over developed. Reclamation of important wetlands such as river floodplain, river beach and lake drawdown area has seriously weakened the cross flow
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The ability of ecosystems to naturally regulate floods. Traditional river regulation engineering measures have also greatly damaged the river ecosystem. The traditional slope protection project closes the whole river bank surface and isolates the material exchange between soil and water. The organisms originally growing on the bank slope can not continue to survive, and the food chain of the ecosystem is disconnected, which makes the organisms in soil and water lose their living environment. The ecological impact of traditional concrete river slope protection is mainly as follows: ① in the river repaired by cement and stone on both banks, the growth of aquatic organisms with water purification function is very difficult, the self purification capacity of the river will be greatly reduced and the water quality will deteriorate; ② Due to the lack of air permeability and water permeability, the large-area rigid masonry surface made of concrete has poor regulation performance of temperature and humidity. It is not conducive to maintaining the ecological balance in the water. There is no grass on the slope and it is desolate. In particular, the "heat island effect" formed around the slope due to the direct exposure of the sun in summer leads to the deterioration of local climate and the grass growth of infectious bacteria; ③ The traditional slope ignores the organic connection between the river channel and the shore ecosystem, which makes it difficult for the plants on the shore to grow, the fish and amphibians lose their habitat and reproduction conditions, resulting in the reduction of aquatic organisms, and the lack of natural plants on the shore, which directly affects the survival of biological species along the river. According to statistics, after the river lining, the biological species along the river have been reduced by more than 70%, while the aquatic organisms are only equivalent to the original 50%. In addition, some additives are used in the construction of traditional concrete slope protection to varying degrees, such as early strength agent, antifreeze agent, expansion agent, etc. these additives react in water and have an adverse impact on water quality and water environment. There are no natural plants on the bank slope as a barrier, which will make the garbage on the bank easy to enter the water and cause pollution. Although these are not the main reasons for the deterioration of water quality, they have promoted the deterioration of water quality. At the same time, the traditional slope protection without green makes the river lose its original vitality, which is inconsistent with the requirements of modern people's pursuit of returning to nature, contrary to the establishment of a beautiful environment, and disharmonious with the cultural landscape.