Remote Sensing Monitoring Of Ecological Environment Restorationof Reed Wetland In Liaohe Estuary

The reed wetland in Liaohe Estuary is the largest estuary in Asia.Since the ecological rehabilitation project began in 2012,the spatial change of object type in the wetland is obvious.The main data source of this research was based on the UAV remote sensing,different seasonal ZY-3 satellite and GF-1 remote sensing image,and the field investigation data.In order to extract the information of the typical wetland,this research was using object-oriented classification method and visual interpretation by making full use of object features.Using the GIS spatial analysis with the situation in 2012 as the background,compared the distribution of main objects in the wetland of 2014,2015 and 2016.Finally,the spatial and temporal change of the wetland were obtained.At the same time,the effect of ecological restoration of the reed wetland in Liaohe Estuary was evaluated.The results are as follow:(1)According to the phenology of reed,field observation focused on seasonal feature of main vegetation.The degree of difficulty in different seasons of the UAV image data interpretation,the satellite images spectral information,and the result of classification accuracy all proved that the autumn is the best season of reed wetland monitoring.(2)The effect of ecological restoration of reed wetland in Liaohe Estuary was significant from 2012 to 2016,mainly as follow: Reed is the main constructive species in Liaohe Estuary,its self-stability was always above 85% in this study.The area of the reed has increased about 281.01hm2 since 2012.The main weed in study area is cattail,the total area has decreased 1108.01hm2.The symbiosis area of reed and cattail first increased then decreased.As a result of irrigating sea water,the area of water and sparse vegetation near water was increased by 265.25 hm2?388.31 hm2.(3)The wetland changed at each stage was different.The first stage is during 2012 to 2014.In the period,the reed area increased slightly,while cattail was translated to reed and symbiosis area 384.76 hm2.The reed area was greatly increased since 2014-2015,converted from cattail and symbiosis area 324.44hm2 during this period.At the same time,the cattail gradually became poor with the dead part of 175.72 hm2.The wetland patches were improved obviously during 2015 to 2016.The area of cattail was just 11.1% of 2015,while almost all the symbiosis area were transformed into reed.It was a typical result of late period of ecological rehabilitation.