Coastwide Reference Monitoring System (CRMS) 2021 Site 0501 land-water classification data

Wetland restoration efforts conducted by the Coastal Wetlands Planning, Protection and Restoration Act (CWPPRA) in Louisiana rely on monitoring efforts to determine the efficacy of these efforts. The Coastwide Reference Monitoring System (CRMS) was developed to assist in a multiple-reference approach that uses aspects of hydrogeomorphic functional assessments and probabilistic sampling for monitoring. The CRMS program includes a suite of approximately 398 sites that encompass the range of hydrological and ecological conditions for each stratum. As part of CRMS, land and water classifications are created from Digital Orthophoto Quarter Quadrangles (DOQQs) approximately every three years at all CRMS sites. A DOQQ is a raster image in which displacement in the image caused by sensor orientation and terrain relief has been removed and combines the image characteristics of a photo with geometric qualities of a map. The DOQQs generated for this project consist of 2021 Color Infrared (CIR) Digital Imagery. These images were classified into land and water categories using a threshold of the near infrared (NIR) band, followed by supervised and unsupervised classification. Initial classification results are then reviewed by multiple image analysts to identify and manually recode errors. The final land-water classifications are intended to serve as both geographic and quantitative assessments of landscape composition on the date of acquisition. Five previous assessments have been conducted (2005, 2008, 2012, 2015/2016, and 2018). Once the program creates enough data points for statistical analyses, these data will be used for land area change rate calculation.

美国路易斯安那州实施的《沿海湿地规划、保护与恢复法案》（Coastal Wetlands Planning, Protection and Restoration Act, CWPPRA）所开展的湿地修复工程，需依托监测工作以评估此类修复举措的实施成效。沿海全域参考监测系统（Coastwide Reference Monitoring System, CRMS）正是为支撑多参考基准监测方法而开发，该方法采用水文地貌功能评估与概率抽样技术开展监测工作。CRMS项目共涵盖约398个监测点位，覆盖各分层的水文与生态条件区间。作为CRMS的核心工作之一，项目组将以约每三年一次的频率，依托数字正射影像四分之一象限图（Digital Orthophoto Quarter Quadrangles, DOQQs）为所有监测点位生成水陆分类成果。数字正射影像四分之一象限图（DOQQ）属于栅格影像，其已校正因传感器姿态与地形起伏导致的影像位移，兼具照片的影像表现力与地图的几何精准性。本项目所用的DOQQ数据，均源自2021年采集的彩色红外（Color Infrared, CIR）数字影像。该批影像先通过近红外（near infrared, NIR）波段阈值法完成初步分类，再辅以监督分类与非监督分类算法，最终划分出水陆两类地物。初步分类结果将由多名影像分析师进行复核，以识别并手动修正分类误差。最终生成的水陆分类成果，可作为影像采集当日景观组成的地理空间与定量评估依据。该项目此前已完成五次评估（分别为2005年、2008年、2012年、2015/2016年及2018年）。待项目积累足够多可用于统计分析的数据点后，相关数据将被用于计算陆地面积变化速率。