Gap-filled water quality, Normalized Differenced Vegetation Index, total nitrogen (nitrate and ammonia) deposition, and land cover data trends for the Continental United States

The purpose of this work was to quantify trends in water quality, total nitrogen deposition, vegetation, and land-use trends for the Continental United States (CONUS). This dataset contains gap-filled daily and yearly in-stream carbon (C) and nitrogen (N) concentrations, discharge, and calculated exports from United States Geological Survey (USGS) National Water Information System (NWIS) stations across the United States of six different nitrogen parameters (Supplementary Table A1), one carbon parameter, and temperature (USGS, 2016, 2018) (https://waterdata.usgs.gov/nwis). The final water quality dataset is merged with the normalized differenced vegetation index (NDVI), total deposition (TDEP), landcover, and elevation datasets. All data are available at the CONUS scale as well as at the scale of hydrologic unit codes: (HUC) HUC8, HUC6, HUC4, and HUC2 watersheds. There are two zip files associated with this data package. I split the data into two equal sized zip files to comply with the data size limits, however the datasets are the same within each zip file. All data files can be read in directly into the R software.

本研究旨在量化美国本土（Continental United States, CONUS）的水质、总氮沉降、植被及土地利用变化趋势。本数据集包含经间隙填充处理的日尺度与年尺度河道内碳（C）、氮（N）浓度、径流量，以及来自美国地质调查局（United States Geological Survey, USGS）国家水信息系统（National Water Information System, NWIS）全美站点的计算输出通量，涵盖6类氮参数（补充表A1）、1类碳参数与水温数据，数据来源为USGS 2016、2018年数据集，数据源链接为https://waterdata.usgs.gov/nwis。最终水质数据集已与归一化差分植被指数（Normalized Difference Vegetation Index, NDVI）、总沉降量（Total Deposition, TDEP）、土地覆被及高程数据集完成融合。所有数据可在美国本土尺度，以及水文单元代码（Hydrologic Unit Codes, HUC）的HUC8、HUC6、HUC4与HUC2流域尺度获取。本数据包附带两个压缩文件：为符合数据大小限制要求，本研究将数据集拆分为两个容量均等的压缩包，二者内含的数据集完全一致。所有数据文件均可直接导入R软件进行读取。