Spatial distribution data set of wetlands in Baiyangdian Basin

As one of the wetland systems in the northern plain of China, Baiyangdian plays a key role in ensuring the water resources security and good ecological environment of Xiong'an New Area. Understanding the current situation of the wetland ecosystem in Baiyangdian basin is also of great significance for the construction of the New Area and future scientific planning. Based on the 10 meter spatial resolution sentinel-2B image provided by ESA in September 2017, combined with Google Earth high resolution satellite image (resolution 0.23m), the network distribution map and water system distribution map of Baiyangdian basin wetland ecosystem in 2017 were drawn by artificial visual interpretation and machine automatic classification It provides the basis for the study of the connectivity (including hydrological connectivity and landscape connectivity). The boundary of Baiyangdian basin in this data set is from the basic geographic information map of Baiyangdian basin provided by Zhou Wei and others. The DEM is the GDEM digital elevation data with 30m resolution. The original image data of wetland remote sensing classification comes from the sentinel-2b remote sensing image provided by ESA on September 20, 2017. This data set uses the second, third, fourth and eighth bands of 10 meter resolution in the image, carries out radiation calibration, mosaic, mosaic and other preprocessing operations in SNAP and ArcGIS 10.2 software, and carries out supervised classification in ENVI 5.3 software. The data used for river channel extraction is based on Google Earth high resolution satellite images. The research and development steps of this dataset include: preprocessing sentinel-2B image, establishing wetland classification system and selecting samples, mapping the latest wetland ecosystem network distribution map of Baiyangdian basin by support vector machine classification; obtaining river network of Baiyangdian basin by visual interpretation based on Google Earth high resolution satellite image (resolution 0.23m). The spatial distribution data set of Baiyangdian Wetland includes vector data and raster data: (1) Baiyangdian basin boundary data (. SHP); Baiyangdian basin river network data (. shp); (2) Baiyangdian basin land use / cover classification data (including the classification data of the study area and the river 3 km buffer) (. tif); Baiyangdian basin constructed wetland and natural wetland distribution map (. shp); Baiyangdian basin slope map (. tif). According to the river network map of Baiyangdian basin obtained by manual visual interpretation, the total length of the river in Baiyangdian basin is about 2440 km and the total area is 514 km2. Among them, there are 177 km2 river channels in mountainous area, 866 km in length, distributed in Northeast southwest direction, mostly at the junction of forest land and cultivated land; and 337 km2 river channels in plain area, 1574 km in length. Baiyangdian basin is divided into eight types of land use / cover: river, flood plain, lake, marsh, ditch, cultivated land, forest land and construction land. The remote sensing monitoring results show that the wetland area of Baiyangdian basin accounted for 13.90 % in 2017. Among all wetland types, the area of marsh is the largest, followed by the area of flood plain, ditch accounts for about 1%, and the proportion of lake and river is less than 0.5%. Combined with the land use / cover classification map and the distribution of slope and elevation, it can be seen that nearly 60% of the area of woodland is distributed in 10 ° to 30 ° mountain area, and the rest of the land use / cover types are mainly distributed in 0 ° to 2 ° area. The elevation statistics show that nearly 80% of the lakes and large reservoirs are distributed in the height of 100 m to 300 m, the distribution of marsh is relatively uniform, mainly in the high altitude area of 20 m to 300 m, the types of construction land, flood area and cultivated land are mainly concentrated in the area of 20 m to 100 m, and rivers and ditches are mainly concentrated in the area of 0 m to 100 m. Based on the classification results of land use / cover within the river, it can be found that the main land use type is wetland. Specifically, the types of swamp, flood area and lake are the most, while the types of ditch and river are less. With the increase of the buffer area, the proportion of non wetland type gradually increased, while the proportion of wetland type gradually decreased. The main wetland types in 1-3km buffer zone on both sides of the river are swamp and flood zone. It is worth noting that nearly one third of the River belongs to cultivated land, that is, the river occupation is serious. In terms of area, about 1 / 3 rivers and 3 / 4 lakes are distributed in the river course. Most of the water bodies in the river course are controlled by human beings, but the marsh area in the river course only accounts for about 3% of the marsh area in the whole river course. River occupation will not only directly reduce the connectivity of wetlands in the basin, but also cause some environmental and economic problems such as water pollution. However, if the connectivity of wetlands is reduced, the ecological and environmental functions of wetlands will be destroyed, which will pose a great threat to the water security of the basin. Taking Baiyangdian basin as a whole, improving the connectivity of wetlands and enhancing the ecological and environmental functions of wetlands in the basin will help to improve the water ecological and environmental security of xiong'an new area and Baiyangdian basin.作为中国北方平原湿地系统之一，白洋淀（Baiyangdian）对保障雄安新区的水资源安全与优良生态环境发挥着关键作用。明晰白洋淀流域湿地生态系统现状，对于新区建设与未来科学规划亦具有重要意义。本数据集基于欧洲空间局（ESA）2017年9月获取的10米空间分辨率哨兵-2B（Sentinel-2B）影像，结合谷歌地球（Google Earth）高分辨率卫星影像（分辨率0.23m），通过人工目视解译与机器自动分类，绘制了2017年白洋淀流域湿地生态系统河网分布图与水系分布图，为流域湿地连通性（包括水文连通性与景观连通性）研究提供了依据。本数据集的白洋淀流域边界源自周伟等提供的白洋淀流域基础地理信息图；数字高程模型（Digital Elevation Model，DEM）采用30米分辨率的GDEM数字高程数据；湿地遥感分类的原始影像数据来自ESA于2017年9月20日获取的Sentinel-2B遥感影像。本数据集使用该影像中10米分辨率的第2、3、4、8波段，在SNAP与ArcGIS 10.2软件中完成辐射定标、镶嵌等预处理操作，并在ENVI 5.3软件中开展监督分类。河道提取所用数据基于Google Earth高分辨率卫星影像。本数据集的研发步骤包括：对Sentinel-2B影像进行预处理；建立湿地分类体系并选取样本；通过支持向量机分类绘制白洋淀流域最新湿地生态系统河网分布图；基于Google Earth高分辨率卫星影像（分辨率0.23m）通过目视解译获取白洋淀流域河网。白洋淀湿地空间分布数据集包含矢量数据（vector data）与栅格数据（raster data）：(1) 白洋淀流域边界数据（.SHP）、白洋淀流域河网数据（.SHP）；(2) 白洋淀流域土地利用/覆被分类数据（包含研究区及河道3公里缓冲区的分类数据，.TIF）、白洋淀流域人工湿地与天然湿地分布图（.SHP）、白洋淀流域坡度图（.TIF）。基于人工目视解译获取的白洋淀流域河网图，白洋淀流域河道总长度约2440千米，总面积514平方千米。其中山区河道面积177平方千米，长度866千米，呈东北-西南向分布，多位于林地与耕地交界处；平原区河道面积337平方千米，长度1574千米。白洋淀流域共分为8类土地利用/覆被类型：河道、洪泛平原、湖泊、沼泽、沟渠、耕地、林地与建设用地。遥感监测结果显示，2017年白洋淀流域湿地面积占比为13.90%。各类湿地中，沼泽面积最大，其次为洪泛平原，沟渠占比约1%，湖泊与河道占比均不足0.5%。结合土地利用/覆被分类图与坡度、高程分布可知，近60%的林地分布于10°~30°的山区，其余土地利用/覆被类型主要分布于0°~2°区域。高程统计结果显示：近80%的湖泊与大型水库分布于100~300米高程区间；沼泽分布相对均匀，主要集中于20~300米的高海拔区域；建设用地、洪泛区与耕地类型主要集中于20~100米区间；河道与沟渠则主要集中于0~100米区间。基于河道内土地利用/覆被分类结果可知，河道内主要土地利用类型为湿地。具体而言，沼泽、洪泛区与湖泊类型占比最高，沟渠与河道类型占比较低。随着缓冲区范围扩大，非湿地类型占比逐渐升高，湿地类型占比逐步降低。河道两侧1~3公里缓冲区的主要湿地类型为沼泽与洪泛区。值得注意的是，近三分之一的河道被耕地占用，即河道侵占现象较为严重。从面积来看，约1/3的河道与3/4的湖泊分布于河道缓冲区范围内。河道内多数水体受人类活动管控，但河道内的沼泽面积仅占全流域沼泽总面积的约3%。河道侵占不仅会直接降低流域湿地连通性，还会引发水污染等环境与经济问题。而湿地连通性下降将破坏湿地生态环境功能，对流域水安全构成严重威胁。整体而言，提升白洋淀流域湿地连通性、增强流域湿地生态环境功能，有助于提升雄安新区与白洋淀流域的水生态环境安全。