Maryland Archived Submerged Aquatic Vegetation 2020
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The 2020 Chesapeake Bay SAV Coverage was mapped from digital multispectral imagery with a 25cm GSD to assess water quality in the Bay. WorldView 2 satellite imagery acquired from Digital Globe through the NGA NextView program was used to augment the aerial imagery for the Susquehanna Flats; the Gunpowder River; the Eastern Neck area of the Chester River; Aquia Creek and a middle section of the Potomac River; Anacostia River and northernmost area of the Potomac River; the New Point Comfort area of Mobjack Bay; and Nassawadox Creek, Hungars Creek, and Mattawoman Creek. Each area of SAV was interpreted from the rectified imagry and classified into one of four density classes by the percentage of cover. The SAV beds were entered into an SDE GIS fetaure class using the quality control procedures documented below. The dataset contains all SAV areas that were identified from the areas flown. Some areas that are presumed to contain no SAV were not flown. Some small beds, particularly along narrow tributaries may not have been distinguishable on the aerial photography. This is an MD iMAP hosted service. Find more information at https://imap.maryland.gov. Feature Service Link: https://mdgeodata.md.gov/archive/rest/services/Biota/MD_ArchivedSubmergedAquaticVegetation/FeatureServer/35
2020年切萨皮克湾沉水水生植被（Submerged Aquatic Vegetation, SAV）覆盖图通过25厘米地面采样距离（Ground Sample Distance, GSD）的数字多光谱影像绘制而成，用于评估该海湾的水质。通过美国国家地理空间情报局（National Geospatial-Intelligence Agency, NGA）NextView计划从数字地球（DigitalGlobe）获取的WorldView-2卫星影像，被用于补充以下区域的航空影像：萨斯奎哈纳浅滩、甘波德河、切斯特河东颈区域、阿夸溪与波托马克河中段、阿纳卡斯蒂亚河与波托马克河最北端区域、莫杰克湾新普特康福特角区域，以及纳萨瓦多克斯溪、亨加尔斯溪与马塔沃曼溪。每一处SAV区域均从经过几何校正的影像中解译，并根据覆盖百分比划分为四个密度等级之一。沉水水生植被床通过下述文档记录的质量控制流程，被导入至空间数据库引擎（Spatial Database Engine, SDE）支持的地理信息系统（Geographic Information System, GIS）要素类中。本数据集包含所有在飞行覆盖区域中识别出的SAV区域。部分被推定无SAV分布的区域未进行飞行拍摄。部分小型植被床，尤其是沿狭窄支流分布的植被床，可能无法在航空影像中被分辨出来。本数据集为马里兰州iMAP（MD iMAP）托管服务。更多信息请访问：https://imap.maryland.gov。要素服务链接：https://mdgeodata.md.gov/archive/rest/services/Biota/MD_ArchivedSubmergedAquaticVegetation/FeatureServer/35
