环境科学论文代写 Opportunities Exist For Their Restoration And Creation
Secondly, bank stabilisation can be used to minimise erosion to streams. Structural materials, bio-engineered products, and stream bank re-grading can all be used to re-enforce the bank (18). Mats of geotextile fabrics can be placed over a bank while plants germinate and root, thus giving it even more natural protection. This technique is very effective in rural freshwater habitats; however is not usually enough for urbanised areas due to high peak flows as a result of storm flows (20).
Thirdly, channel reconfiguration and grade control are two techniques but are often used together because they both involve heavy manipulation to the stream. These techniques aim to repair heavily incised channels, improve water conveyance and improve streambed and bank stability (18). Often the re-structuring of a stream with the intent of moving water in a desired way, perhaps to alleviate pressure on a certain bank, causes structural problems further downstream thus hindering success of many of these projects.
Finally, riparian replanting and management is a technique that has been used for urban and rural freshwater habitat restoration. This first means removing invasive exotic species and will typically require management to keep their populations low. The replanting of plants gives banks more structural stability but also increases aquatic biodiversity (18). Using this technique is great; however in urban areas land is expensive and will incur a higher cost than in rural areas. Land is also limited in urban areas because of pavements and development along river banks, however even small plant restoration is enough for a positive effect (18).
Creating freshwater and wetland habitats is much more difficult than restoring current ones because conditions have to be specific and exact in order to keep them sustained (21). A wetland creation project usually takes six months to complete before showing results, whereas a restoration project is usually two weeks. It requires much more planning and the constructed wetlands are often specific in function, mainly being used as stormwater management and pollution control. Constructed wetlands lack the full range of wetting and drying ranges because their water levels are dominated by surface runoff. This makes it hard for constructed wetlands to support wide species diversity (22).
Wetland and freshwater habitats are an important landscape for many different reasons but still they are disappearing at an alarming rate. Unfortunately there is little research about restoration and creation of both habitats, making the success rates of such projects "hit and miss". It is also very time consuming and expensive. It seems clear that the most effect approach to saving wetland and freshwater habitats is educating the public to their importance and begin preventing degradation and therefore less repair systems will be required.
环境科学论文代写 Opportunities Exist For Their Restoration And Creation
