Global database of river width, slope, catchment area, meander wavelength, sinuosity, and discharge

1.Summary This document describes the database that accompanies the article written by the authors of this dataset and accepted by Geophysical Research Letters (doi: 10.1029/2019GL082027).The database is distributed as a set of shapefiles, containing polylines that define the geometry of river centerlines located between 60°N and 56°S, with attributes described below. The shapefiles are organized according to continent and further broken into major basins to allow for manageable file sizes. A more complete dataset is available in the netCDF format upon request (please email Renato Frasson at [e-mail]). This database was partially funded by the Algorithm Definition Team contract to the Ohio State University, University of North Carolina at Chapel Hill, and Remote Sensing Solutions, Inc. 2.Polyline geometry The centerline geometry is defined by sets of points located approximately every 30 m based on the Global River Widths from Landsat (GRLW) database (Allen & Pavelsky, 2015; 2018). Each line describes a meander and features the following attributes. 3.Attribute description SegmentID: identification number of the river segment (segments are parts of a river delimited by confluences). lakeFlag: 0 – river, 1 – lake, 2 – river under the influence of tide, 3 – canal, 4 – unable to connect GRWL with HydroSHEDs, 5 – dam, -9999 – no data. Width: average width in the meander, disregarding small river widths assigned to locations undetected by Landsat but known to be inundated. Locations where no width could be produced are marked as -9999. Elevation: mean elevation from SRTM (90m) per river meander in meters. SRTM pixels are assigned to equally spaced points (every ~30m) over the river centerlines using the nearest neighbor approach. The average elevation of all valid points per meander is reported here. Locations where no elevation could be produced are marked as -9999. Slope: water surface slope in centimeter per kilometer. Slope is initially computed over 10 km reaches, then used to compute optimum reach lengths using a modified version of the equation proposed by LeFavour and Alsdorf (2005) in the form of RL=2σ /S, where RL is the optimum reach length, σ is the height uncertainty (5.51 m from LeFavour and Alsdorf, 2005) and S the initial slope estimate. Final slopes are computed over the optimum reach lengths using elevations assigned to the 30 m river points using either classic linear regression or the Theil-Sen estimator depending on which method produces the best coefficient of determination. Locations where no slope could be produced are marked as -9999. Meandwave: Meander wavelength in meters. This is computed by first smoothing the 30 m resolution river centerlines using a 5-point moving average and then identifying inflection points on the smoothed river centerlines. Finally, the meander wavelength takes the value of twice the distance between consecutive inflection points according to the definition given by Leopold and Wolman (1960). Sinuosity: Dimensionless sinuosity of each river meander computed the ratio of the length between meander endpoints measured along the river centerline to half the meander wavelength as defined by Leopold and Wolman (1960). catch_area: Catchment area was derived from flow direction and corresponding flow accumulation grids based on HydroSHEDS (Lehner et al., 2008). The flow accumulation grid describes, for any location (i.e. pixel), the number of upstream raster pixels that drain to that particular location. We translated flow accumulation given in number of pixels into catchment area (in m2) by multiplying the number of pixels flowing to a location by the average area of SRTM pixels according to the latitude of the centroid of the river segment. QWBM: mean annual flow estimated with the water balance model WBMsed (Cohen et al., 2014). Strpwr_len: stream power normalized by width (W/m). Strpwr_are: stream power normalized by area (W/m2). Acknowledgements Use of this database should be acknowledged appropriately. The WBM data used in this database were provided by Dr. Albert Kettner at INSTAAR, University of Colorado at Boulder. References Allen, G. H., and T. M. Pavelsky (2015), Patterns of river width and surface area revealed by the satellite-derived north american river width data set, Geophysical Research Letters, 42(2), 395-402, doi: 10.1002/2014gl062764. Allen, G. H., and T. M. Pavelsky (2018), Global extent of rivers and streams, Science, doi: 10.1126/science.aat0636. Cohen, S., A. J. Kettner, and J. P. M. Syvitski (2014), Global suspended sediment and water discharge dynamics between 1960 and 2010: Continental trends and intra-basin sensitivity, Glob. Planet. Change, 115, 44-58, doi: https://doi.org/10.1016/j.gloplacha.2014.01.011. LeFavour, G., and D. Alsdorf (2005), Water slope and discharge in the amazon river estimated using the shuttle radar topography mission digital elevation model, Geophysical Research Letters, 32(17), doi: 10.1029/2005gl023836. Lehner, B., K. Verdin, and A. Jarvis (2008), New global hydrography derived from spaceborne elevation data, EOS, TRANSACTIONS, AMERICAN GEOPHYSICAL UNION, 89(10), 93-94, doi: doi:10.1029/2008EO100001. Leopold, L. B., and M. G. Wolman (1960), River meanders, Geological Society of America Bulletin, 71(6), 769-793, doi: 10.1130/0016-7606(1960)71[769:RM]2.0.CO;2.

1. 概述
本文档介绍本数据集作者所撰写、并被《地球物理研究通讯》(Geophysical Research Letters)收录的配套数据库，其DOI为10.1029/2019GL082027。该数据库以矢量形状文件（shapefile）集的形式分发，其中包含用于定义北纬60°至南纬56°之间河流中心线几何形态的多段线，属性说明如下。shapefile集按大洲进行组织，并进一步划分为各大流域，以控制文件体积便于使用。如需获取更完整的网络通用数据格式（netCDF）格式数据集，请致信Renato Frasson，邮箱地址为[e-mail]。本数据库的部分资助来自面向俄亥俄州立大学、北卡罗来纳大学教堂山分校以及Remote Sensing Solutions, Inc.的算法定义团队合同。
2. 多段线几何形态
河流中心线的几何形态基于Landsat全球河流宽度数据库（Global River Widths from Landsat, GRLW）（Allen & Pavelsky, 2015; 2018），由间距约30米的点集定义。每条多段线对应一个河曲，包含如下属性。
3. 属性说明
SegmentID：河流河段的标识编号（河段指以汇流点为边界划分的河流片段）。
lakeFlag：取值规则如下：0代表河流，1代表湖泊，2代表受潮汐影响的河段，3代表运河，4代表无法将GRWL与HydroSHEDS进行关联，5代表水坝，-9999代表无有效数据。
Width：对应河曲的平均宽度，忽略Landsat未识别但已知存在淹没的河段的微小宽度值。无法获取宽度数据的位置将标记为-9999。
Elevation：单个河曲的平均海拔，单位为米，数据来自90米分辨率的航天飞机雷达地形测绘任务（Shuttle Radar Topography Mission, SRTM）。通过最近邻法将SRTM像素匹配至河流中心线上间距约30米的等距点，最终取单个河曲所有有效点的平均海拔作为该属性值。无法获取海拔数据的位置将标记为-9999。
Slope：水面坡度，单位为厘米每千米。坡度首先基于10千米河段计算，随后结合LeFavour与Alsdorf（2005）提出的修正版公式（RL=2σ/S，其中RL为最优河段长度，σ为高程不确定性，取值5.51米，取自LeFavour和Alsdorf, 2005，S为初始坡度估算值）计算最优河段长度。最终坡度基于最优河段长度，通过对30米分辨率河流点的高程数据采用经典线性回归或Theil-Sen估计量（取决定系数最优的方法）计算得到。无法获取坡度数据的位置将标记为-9999。
Meandwave：河曲波长，单位为米。计算方式为：首先采用5点移动平均法对30米分辨率的河流中心线进行平滑处理，随后在平滑后的中心线上识别拐点；根据Leopold和Wolman（1960）的定义，河曲波长为连续两个拐点间距的两倍。
Sinuosity：单个河曲的无量纲蜿蜒度，计算方式为沿河流中心线测量的河曲端点间长度与Leopold和Wolman（1960）定义的河曲波长一半的比值。
catch_area：汇流面积，数据基于HydroSHEDS数据库（Lehner等, 2008）的流向栅格与对应汇流累积栅格计算得到。汇流累积栅格用于描述任意栅格点的上游汇流栅格像素数量。我们通过将汇流累积像素数乘以基于河段质心纬度确定的SRTM像素平均面积，将像素单位的汇流累积量转换为以平方米为单位的汇流面积。
QWBM：通过水平衡模型WBMsed（Cohen等, 2014）估算的年平均径流量。
Strpwr_len：以宽度归一化的水流功率，单位为瓦每米（W/m）。
Strpwr_are：以面积归一化的水流功率，单位为瓦每平方米（W/m²）。
致谢
对本数据库的使用需进行恰当的学术致谢。本数据库所用的WBM数据由科罗拉多大学博尔德分校INSTAAR研究所的Albert Kettner博士提供。
参考文献
Allen, G. H. 与 T. M. Pavelsky (2015), 卫星遥感反演的北美河流宽度数据集揭示的河流宽度与地表面积格局, 《地球物理研究通讯》, 42(2), 395-402, doi: 10.1002/2014gl062764.
Allen, G. H. 与 T. M. Pavelsky (2018), 全球河流与溪流分布范围, 《科学》, doi: 10.1126/science.aat0636.
Cohen, S., A. J. Kettner 与 J. P. M. Syvitski (2014), 1960-2010年全球悬浮泥沙与径流动态：大陆尺度趋势与流域内敏感性, 《全球行星变化》, 115, 44-58, doi: https://doi.org/10.1016/j.gloplacha.2014.01.011.
LeFavour, G. 与 D. Alsdorf (2005), 利用航天飞机雷达地形测绘任务数字高程模型估算亚马孙河水面坡度与径流量, 《地球物理研究通讯》, 32(17), doi: 10.1029/2005gl023836.
Lehner, B., K. Verdin 与 A. Jarvis (2008), 基于星载高程数据生成的新型全球水文地貌数据, 《美国地球物理联合会汇刊》(EOS Transactions, American Geophysical Union), 89(10), 93-94, doi: 10.1029/2008EO100001.
Leopold, L. B. 与 M. G. Wolman (1960), 河流曲流, 《美国地质学会通报》, 71(6), 769-793, doi: 10.1130/0016-7606(1960)71[769:RM]2.0.CO;2.

搜集汇总

背景与挑战

背景概述

该数据集提供了全球范围内河流的多项关键参数，包括宽度、坡度、集水区面积等，适用于河流地貌学和遥感研究。数据以shapefile和netCDF格式组织，便于管理和分析。