城市河道修复合理性评价.pptVIP

河流生态修复合理性评价 城市地区的河道作为重要的景观廊道，除了具有交通运输、行洪排涝等基本功能外，还是城市水源和城市生物多样性保护的重要区域．由于城市化和土地利用结构的变化，工业废水排放、农业生产、郊区畜禽养殖等导致城市河道水体中的N、P等营养元素富集，重金属离子、杀虫剂以及其他污染物浓度不断增加。致使城市水质的污染状况越来越严重． 河道清淤、人工渠回填和自然河道恢复 (2) 河堤去除、河道加宽与河漫滩湿地恢复 (3)河道生境结构与河流水文动态恢复 (4)河道及其河系网络的生态修复 (5)修复与重建工程效果的合理评价 生态修复工程阶段 Ecological restoration is still perceived by many conservationists, and the majority of economists, as a diversion, a delusion, and – far worse – a waste of money. In this paper we point out that restoration is in fact complementary not only to nature conservation but also to sustainable, equitable socio-economic development. This is because restoring and augmenting the natural capital base generates jobs and improves livelihoods and the quality of life of all in the economy.（James ，2006） Not including a few extremely large-scale projects, about $1 billion is spent annually on all types of stream restoration in the United States, and the number of restoration projects is increasing exponentially (Palmer et al., 2007) However, few restoration projects are monitored, and fewer are still evaluated for effectiveness. Some regional analyses have suggested that mitigation projects may fall short of their goals (Booth et al., 2002;Thompson, 2002; Lave et al., 2008), while a recent, more comprehensive review found that conclusive information is lacking to evaluate most techniques (Roni et al., 2008） Target conditions are often based on “reference” sites that may or may not be appropriate (Lester et al., 2006). In other cases, monitored projects exhibit short-term success, but long-term failure (Pezeshki et al., 2007;Shields et al., 2008) or produce equivocal findings (Price and Birge,2005). Restoration of features responsible for hyporheic exchange and other physical elements that are coupled with chemical and physical processes is poorly understood at present (Murdock et al.,2004; Parkyn et al., 2005; Kasahara and Hill, 2008, Hester and Doyle,2008). Do stream restoration projects result in a change in ecolo