The Dynamic Evolution And Environmental Renovation Of The Qilihai Lagoon Wetland In Hebei Province

Lagoon is one of the most important types of coastal wetlands and the important component of ecological environment and the natural resource which are closest with human.And it is the richest biodiversity ecology landscape in nature, with great values in terms of natural resource, tourism, environment and scientific research.It is the excellent place for research carried on the wetland to form , evolve and the wetland degeneration ,Because it is in the region where the flood and field correlate, is influenced bigger by the flood and field power'change and the human activity,and the environment evolves rapidly and the agent is complex.The Qilihai Lagoon is a typical semi-enclosed lagoon which is located in the 20km to the north of the Luanhe Rever and it is one of the modern lagoon only exist in China.It has typical nature and representation and is the lagoon ecosystem composed by the water body, the aquatic organism and the migratory bird, the aquatic bird and so on .By 1940s, the nature wetland has a great deal of decrease and the man-made wetland increases unceasingly ,because it is influenced by a series of high strength humanity development operation , for example , encloses tideland for rice cultivation,producted salt by the lagoon, the basin government, the diking storage, building the pond to raise the shrimp. The area of Qilihai Lagoon withered, the biodiversity sharp declined and has degradated seriously.So the study on lagoonal wetland's formation, evolution, causes of wetland environmental degradation and their effect on eco-environment are very significant for lagoonal wetland resources protection.This paper choosed TM remote sensing images of 1987,1991,1994, 1998,2002,2005,four sets of history maps:1919,1956,1969,1980,and extracted the dynamic change information by using RS and GIS technologies ,and analysed the historical process over the past 100 years. Based on historical statistics information and observation data, analysed the natural factors and the human factors which impact on the evolution of the Qilihai lagoon wetland. According to comprehensive index valuation method, evaluated the extent of degradation of the lagoon during a quantitative. This paper used third-effective to combine ecology-oriented principle, feasibility principle, the principle of scarcity and priority, aesthetic principle as the principle of the rectification.Using the hydrodynamic model , selected the optimal programme about the rehabilitation of the tidal channel .The results showed that:(1) Human's long-term strength development and use caused the nature wetland decreasing and the man-made wetland increasing unceasingly. The natural wetland accounts for the wetland total area proportion by 96% in 1956 deflected 19% in 2005. The area of the breeding pond is 349.3hm2, the area is 1128.4hm2 in 2005 which is increases 2.23 times compared to 1987.(2) The evolution of the lagoon initiated biodiversity reducing, the landscape to be unitary day by day, the ecological environment function to weaken and so on a series of ecological environment question.(3) Using comprehensive index valuation method, this paper analyzed the extent of degradation of the time. The results showed that, the extent of degradation has increased from 1956 to 2005. The main degenerated performance is: the basin was seriously filled up and withered, and the water quality becomes worse. The primary cause is: reclamation, pollution, over fishing and so on.(4) Eliminating the breeding pond to reture for the lake, the desilting to dredge the basin, the opening the tidal channel, and the pollution government and so on is effective action restoring the Qilihai Lagoon to the service function of original ecology, and postponing the degenerated advancement of the lagoon.