Bielahong river basin wetlands study on spatial and temporal variation in recent 50 years

Based on the GIS software and Mathematical model,Study aims at the characteristics and laws of Bielahong River basin's time and space has changed in recent 50 years.The results show that Bielahong River basin area was decreasing gradually in the past 50 years,from downstream to the middle and upstream areas,landscape fragmentation serious.Especially in 1955-1976 years,Large area of wetlands were decreasing but the small area was increasing,Landscape pattern presented fragmentation phenomenon,then landscape's dispersion and space difference was increasing;The speed of wetland area decreased slowly since 1976,Large area of wetland changed gradually to smaller 、the fragmentation and discrete greater landscape pattern transformed,wetland-based landscape change to non-wetland landscape,wetlands was decreased seriously;loosing rate of wetlands reaches a maximum by 2005,except some large area wetland in Sanjiang natural protection zone,Other areas only sporadic distribution.,the study shows that the number and quality of wetland in the area showed a declined changing trend in decreasing,it was caused by two factors: natural and human activities.Correlation analysis showed the impact of primary driving on the loss of wetland area in descending order: Arable land,population,relative humidity,annual average temperature.so the main factor results Bielahong wetland has changed in recent 50 years is Humanities.