Study On Wetland Evolution Characteristics And Driving Factor In West Liao River Basin

Wetland has a significant impact on ecological environment,not only it has abundant natural resources,but also huge economic and ecological benefits.With the progress of rapid development of social economy and technology,more and more attention is paid to the research on wetland conservation,and the study methods are diversity.West Liao river basin located in the farming and animal husbandry staggered areas,most of the study area has a worse natural environment,the ecological environment is extremely fragile.At present,the wetland evolution characteristics in West Liao river basin is lack of study,this paper choose remote sensing images,topographic data,meteorological data,population and social data as basic data,based on RS and GIS professional software platform,extractes the wetland information of West Liao river basin,analyzes wetland evolution characteristics and driving factors of West Liao river basin.The main study content contains:the pretreatment of remote sensing images,extracting of wetland information in 1985,2000 and 2015 in study area,studying evolution characteristics from four aspacts,including:area change,temporal and spatial variation,conversion matrix analysis,landscape pattern analysis;There are two driving factors which are natural environment and social economy,using temperature,precipitation,evaporation,sunshine duration,elevation,slope,population density and GDP as factors to construct driving factor database,therefore,establish statistical model of random forest,to evaluate influence importance of driving factor.The conclusions are as follows:1.In the last thirty years,1985~2000,the wetland area of West Liao river basin increased,2000~2015,the wetland area of West Liao river basin decreased.The wetland total area of West Liao river basin is reduced 3076.79 km~2,among them,from1985 to 2000,the area is increased 534.67 km~2,from 2000 to 2015,the area is reduced 3611.46 km~2.2.The main type of wetland temporal and spatial variation is reduction from all over of the study area,the area accounts for 62.82%of the total;the most of river wetlands along the river is unchanged;the main increased wetland trpe is constructed wetland,large area paddy field which located in Kezuohou Banner and east of Kangping country.3.From the transfer of land cover of study area,the transferred amount of non-wetland is much larger than wetland,most of the wetland convert to agricultural land and grassland;agricultural land convert to constructed wetland,saline land convert to marsh;the main inner change of wetland is from river wetland to constructed wetland,the area is 117.28,followly is from lake wetland to mash,the conversion has a closely related with human factor.4.From the landscape pattern,patch numbe and density of all types of wetland are reduced;wetland couvert to construction and non-construction land,the dominant type of wetland is constructed wetland.While Shannon index is reduced slightly,edge density and interspersion and juxtaposition index drops a lot,contagion index increase,all of this indicate that although landscape fragmentation of wetland is decrease,the landscape pattern change is obviously,with the huge reduction of wtland,the diversity is reduced,spatial connectivity is better,the landscape typis tends to singleness,furthermore,the effective management and protection to wetland have to strengthen.5.Based on random forest model,evaluating the effect weight of all driving factors on wetland evolution quantitatively,the result indicates that the dominate factor is natural factors,temperature,elevation and sunshine hours included;the importance of population density,slope and GDP is lower.