Global River Topology (GRIT)

The Global River Topology (GRIT) is a vector-based, global river network that not only represents the tributary components of the global drainage network but also the distributary ones, including multi-thread rivers, canals and delta distributaries. It is also the first global hydrography (excl. Antarctica and Greenland) produced at 30m raster resolution. It is created by merging Landsat-based river mask (GRWL) with elevation-generated streams to ensure a homogeneous drainage density outside of the river mask (rivers narrower than approx. 30m). Crucially, it uses a new 30m digital terrain model (FABDEM, based on TanDEM-X) that shows greater accuracy over the traditionally used SRTM derivatives. After vectorisation and pruning, directionality is assigned by a combination of elevation, flow angle, heuristic and continuity approaches (based on RivGraph). The network topology (lines and nodes, upstream/downstream IDs) is available as layers and attribute information in the GeoPackage files (readable by QGIS/ArcMap/GDAL). Regions Vector files are provided in 6 continental regions with the following codes: AF - Africa AS - Asia EU - Europe NA - North America SA - South America SP - South Pacific/Australia The domain polygons (GRITv04_domain_GLOBAL.gpkg.zip) provide 60 subcontinental catchment groups that are available as vector attributes. They allow for more fine-grained subsetting of data (e.g. with ogr2ogr --where). Network segments Lines between inlet, outlet, confluence and bifurcation nodes. Files have lines and nodes layers. Attribute description of lines layer Name Data type Description cat integer domain internal feature ID global_id integer global river segment ID, same as FID catchment_id integer global catchment ID upstream_node_id integer global segment node ID at upstream end of line downstream_node_id integer global segment node ID at downstream end of line upstream_line_ids text comma-separated list of global river segment IDs connecting at upstream end of line downstream_line_ids text comma-separated list of global river segment IDs connecting at downstream end of line direction_algorithm float code of RivGraph method used to set the direction of line width_adjusted float median river width in m without accounting for width of segments connecting upstream/downstream length_adjusted float segment length in m without accounting for width of segments connecting upstream/downstream in m is_mainstem integer 1 if widest segment of bifurcated flow or no bifurcation upstream, otherwise 0 cycle integer >0 if segment is part of an unresolved cycle, 0 otherwise length float segment length in m azimuth float direction of line connecting upstream-downstream nodes in degrees from North sinuous float ratio of line length and Euclidean distance between upstream-downstream nodes, i.e. 1 meaning a perfectly straight line domain text catchment group ID, see domain index file Attribute description of nodes layer Name Data type Description cat integer domain internal feature ID global_id integer global river node ID, same as FID catchment_id integer global catchment ID upstream_line_ids text comma-separated list of global river segment IDs flowing into node downstream_line_ids text comma-separated list of global river segment IDs flowing out of node node_type text description of node, one of bifurcation, confluence, inlet, coastal_outlet, sink_outlet, grwl_change grwl_value integer GRWL code at node grwl_transition text GRWL codes of change at grwl_change nodes cycle integer >0 if segment is part of an unresolved cycle, 0 otherwise continuity_violated integer 1 if flow continuity is violated, otherwise 0 domain text catchment group, see domain index file Network reaches Segment lines split to not exceed 1km in length, i.e. these lines will be shorter than 1km and longer than 500m unless the segment is shorter. A simplified version with no vertices between nodes is also provided. Files have lines and nodes layers. Attribute description of lines layer Name Data type Description cat integer domain internal feature ID segment_id integer global segment ID of reach global_id integer global river reach ID, same as FID catchment_id integer global catchment ID upstream_node_id integer global reach node ID at upstream end of line downstream_node_id integer global reach node ID at downstream end of line upstream_line_ids text comma-separated list of global river reach IDs connecting at upstream end of line downstream_line_ids text comma-separated list of global river reach IDs connecting at downstream end of line length float length of reach in m sinuousity float ratio of line length and Euclidian distance between upstream-downstream nodes, i.e. 1 meaning a perfectly straight line azimuth float direction of line connecting upstream-downstream nodes in degrees from North domain text catchment group, see domain index file Attribute description of nodes layer Name Data type Description cat integer domain internal feature ID segment_node_id integer global ID of segment node at segment intersections, otherwise blank n_segments integer number of segments attached to node global_id integer global river reach node ID, same as FID upstream_line_ids text comma-separated list of global river reach IDs flowing into node downstream_line_ids text comma-separated list of global river reach IDs flowing out of node domain text catchment group, see domain index file Catchments Catchment outlines for entire river basins (network components, including coastal drainage areas), segments (aka. subbasins) and reaches. Attribute description Name Data type Description cat integer domain internal feature ID global_id integer global catchment ID, same as global_id of segment/reach ID if is_coastal == 0 for respective catchments or the catchment_id for component_catchments, same as FID area float catchment area in km2 is_coastal integer 1 for coastal drainage areas, 0 otherwise domain text catchment group, see domain index file Raster Upstream drainage area, flow direction and other raster-based products are also available upon request.

全球河网拓扑（Global River Topology, GRIT）是一套基于矢量的全球河网数据集，不仅涵盖全球水系网的支流组成部分，还包含分流水系（如多河道河流、运河及三角洲分流河道）。它同时是首套采用30米栅格分辨率制作的全球水文测绘数据集（不含南极洲与格陵兰岛）。

该数据集通过融合基于Landsat的河流掩膜产品（GRWL）与高程生成的水系数据构建而成，旨在确保河流掩膜外区域（宽度约小于30米的河流）的水系密度均匀一致。尤为关键的是，本数据集采用了基于TanDEM-X构建的新型30米数字地形模型（FABDEM），其精度优于传统使用的SRTM衍生产品。

在完成矢量化与修剪操作后，数据集通过结合高程、流向角、启发式算法与连续性方法（基于RivGraph工具）为河网赋予流向属性。河网拓扑结构（包含线要素与节点要素、上下游ID信息）以图层与属性信息的形式存储于地理数据包（GeoPackage）文件中，可通过QGIS、ArcMap或GDAL读取。

区域矢量文件按6个大陆区域划分，对应编码如下：AF - 非洲、AS - 亚洲、EU - 欧洲、NA - 北美洲、SA - 南美洲、SP - 南太平洋/澳大利亚。

域多边形文件（GRITv04_domain_GLOBAL.gpkg.zip）包含60个次大陆流域分组，以矢量属性形式存储，支持对数据集进行更精细的子集划分（例如通过ogr2ogr的--where参数实现）。

## 河网段（Network segments）
指入口、出口、汇流与分流节点之间的线段。数据文件包含线要素与节点要素图层。其线要素图层属性说明如下：
- cat：整数型，域内要素的内部唯一标识
- global_id：整数型，全球河流段ID，与要素FID一致
- catchment_id：整数型，全球流域ID
- upstream_node_id：整数型，线段上游端点的全球河段节点ID
- downstream_node_id：整数型，线段下游端点的全球河段节点ID
- upstream_line_ids：文本型，线段上游端点连接的全球河流段ID逗号分隔列表
- downstream_line_ids：文本型，线段下游端点连接的全球河流段ID逗号分隔列表
- direction_algorithm：浮点型，用于设置线段流向的RivGraph方法编码
- width_adjusted：浮点型，未计入上下游连接河段宽度的河流中位宽度，单位为米
- length_adjusted：浮点型，未计入上下游连接河段宽度的河段长度，单位为米
- is_mainstem：整数型，若为分流河道中宽度最宽的河段，或上游无分流，则取值为1，否则为0
- cycle：整数型，若河段属于未解析的循环水系，则取值大于0，否则为0
- length：浮点型，河段长度，单位为米
- azimuth：浮点型，连接上下游节点的线段方向，以与正北方向的夹角（度）表示
- sinuous：浮点型，线段长度与上下游节点间欧氏距离的比值，取值为1代表完全直线
- domain：文本型，流域分组ID，详见流域索引文件

节点图层属性说明如下：
- cat：整数型，域内要素的内部唯一标识
- global_id：整数型，全球河流节点ID，与要素FID一致
- catchment_id：整数型，全球流域ID
- upstream_line_ids：文本型，流入该节点的全球河流段ID逗号分隔列表
- downstream_line_ids：文本型，流出该节点的全球河流段ID逗号分隔列表
- node_type：文本型，节点类型，可选值包括：分流点、汇流点、入口、沿海出口、汇水出口、GRWL变化点
- grwl_value：整数型，节点处的GRWL编码
- grwl_transition：文本型，GRWL变化节点处的GRWL编码变化情况
- cycle：整数型，若节点属于未解析的循环水系，则取值大于0，否则为0
- continuity_violated：整数型，若流向连续性被破坏，则取值为1，否则为0
- domain：文本型，流域分组ID，详见流域索引文件

## 河网河段（Network reaches）
指长度不超过1公里的拆分线段，除非原始河段更短，否则此类线段长度介于500米至1000米之间。同时还提供了节点间无顶点的简化版本。数据文件包含线要素与节点要素图层。其线要素图层属性说明如下：
- cat：整数型，域内要素的内部唯一标识
- segment_id：整数型，所属河网段的全球ID
- global_id：整数型，全球河网河段ID，与要素FID一致
- catchment_id：整数型，全球流域ID
- upstream_node_id：整数型，河段上游端点的全球河段节点ID
- downstream_node_id：整数型，河段下游端点的全球河段节点ID
- upstream_line_ids：文本型，河段上游端点连接的全球河网河段ID逗号分隔列表
- downstream_line_ids：文本型，河段下游端点连接的全球河网河段ID逗号分隔列表
- length：浮点型，河段长度，单位为米
- sinuousity：浮点型，线段长度与上下游节点间欧氏距离的比值，取值为1代表完全直线
- azimuth：浮点型，连接上下游节点的线段方向，以与正北方向的夹角（度）表示
- domain：文本型，流域分组ID，详见流域索引文件

节点图层属性说明如下：
- cat：整数型，域内要素的内部唯一标识
- segment_node_id：整数型，河段交点处的河段节点全球ID，无交点时留空
- n_segments：整数型，附着于该节点的河段数量
- global_id：整数型，全球河网河段节点ID，与要素FID一致
- upstream_line_ids：文本型，流入该节点的全球河网河段ID逗号分隔列表
- downstream_line_ids：文本型，流出该节点的全球河网河段ID逗号分隔列表
- domain：文本型，流域分组ID，详见流域索引文件

## 流域（Catchments）
涵盖全河流流域（河网组成部分，包含沿海汇水区）、河段（又称子流域）与汇水区的轮廓矢量数据。其属性说明如下：
- cat：整数型，域内要素的内部唯一标识
- global_id：整数型，全球流域ID。若对应流域为内陆流域（is_coastal=0），则与河段/汇水区的global_id一致；若为沿海流域，则与component_catchments的catchment_id一致，与要素FID一致
- area：浮点型，流域面积，单位为平方公里
- is_coastal：整数型，沿海汇水区取值为1，内陆汇水区取值为0
- domain：文本型，流域分组ID，详见流域索引文件

## 栅格数据
上游汇水区面积、流向及其他基于栅格的产品可根据需求另行提供。

搜集汇总

背景与挑战

背景概述

Global River Topology (GRIT)是首个30米分辨率的全球河流拓扑数据集，包含分支和分流结构，提供矢量文件、网络段、河段和流域等多种数据类型，覆盖全球六大洲。该数据集基于Landsat河流掩膜和高程生成河流，使用新的30米数字地形模型，确保河流网络的准确性和完整性。