洞庭湖区灾后重建的流域生态管理学思考

洞庭湖中上游水土流失加剧,导致湖区调蓄能力下降,垸高田低,灾害频率上升。为抗御洪水,堤防越筑越高,造成洪水位抬高等副作用。对此,提出流域生态管理对策：①将长江流域生态安全列为国家安全战略体系的重要内容之一；②将非蓄洪性质的围垦调整为蓄洪性质的围垦,正常年份耕种,大洪水时用其蓄洪；将封闭式围垦种植改造成为半封闭型的养殖与留湖调蓄；③环境移民城镇安置,缓解人口对土地、湖泊的压力；④进行避洪、耐渍型生态设计,建立适应水体、湖洲和低湖渍害田的复合高效生态工程；⑤调整丘岗地利用结构与重建山区植被是减灾的治本措施。量大、面广的水土流失发生在丘陵坡地

A CONSIDERATION OF WATERSHED ECOSYSTEM MANAGEMENT RELATED TO REHABILITATION OF FLOODED AREA IN DONGTING LAKE REGION

Dongting Lake drainage basin embraces Xiangjiang,Zishui,Yuanshui,Lishu i rivers and a part of the Yangtze River.Due to neglection of environmental mana gement,soil erosion in the upper and middle reaches of the Yangtze,lake sediment ation,large scale reclamation of marshes,irrational distribution of agriculture and improper cropping system in high water level zone,the flood regulation capa city of the lake was descending,and flood stage was risen and prolonged.Conseque ntly more and more river levees and lake dikes were reinforced almost every year to prevent the disasters,which made flood level go up and flood period last for more days.The frequency of flood and waterlogging disasters rose and their dama ge was enlarged. The countermeasures of watershed ecosystem management were presented as fo llows: (a)In order to publicize knowledge of territory safety, ecological disas ter relief strategy should be placed as an important part of state security system and on the agend a.(b)The reclamation without storing floodwater should be readjusted into new la nd use system with flood storage project.Cultivation and planning can be carried out in normal years.The relaimed land can be used for storing water while a cat astrophic flood takes place.Certain fields acting as a hindrance for flood flow should be merged properly with lakes for fish culture.(c)Environmental migration should be placed in towns so that the tremendous population pressure on land an d lakes can be relieved.(d) To readjust allocation,cropping system and build up high efficiency,multi ecosystem engineering projects which are suitable to the shallow waters,of shores lakes and rivers as well as paddy fields.(e)The adjust ment of hilly land use structure and reconstruction of mountain vegetation wil l serve as fundamental measures for disaster relief.Soil erosion in hilly areas is much more serious,so to set up ecological land use patterns in hilly areas of the upper and middle reaches of the Yangtze is the key project for water and so il conservation.