Hydrography 90m Layers¶

The Hydrography 90 layers uses the MERIT Hydro digital elevation model at 3 arcsec (∼ 90 m at the Equator) to derive a globally seamless, standardised hydrographic network, the "Hydrography90m", with corresponding stream topographic and topological information. A central feature of the network is the minimal upstream contributing area, i.e. flow accumulation, of 0.05 km2 (or 5 ha) to initiate a stream channel, which allowed us to extract headwater stream channels in great detail.

The data validation procedures confirmed Hydrography90m as a more accurate representation of stream networks compared to HydroRIVERS, GRWL, and MERIT Hydro–Vector. Improved accuracy was achieved principally by employing a higher resolution DEM, the MD8 flow routing algorithm, and a markedly smaller flow accumulation threshold to initiate stream channels. With these characteristics, Hydrography90m provides a valuable basis for supporting a variety of freshwater-related research disciplines. Find additional details in the paper here. The datasets can be downloaded here. This is one of the highest resolution global hydrography datasets and has multiple applications.

Disclaimer: Whole or parts of the dataset description were provided by the author(s) or their works.

Dataset Preprocessing¶

The hydrography datasets can downloaded here. The folders were renamed based on the descriptions of the papers and are included in the tables below. The parameter name were kept consistent and additional information is provided as need along with units for said parameters.

Paper Citation¶

Amatulli, Giuseppe, Jaime Garcia Marquez, Tushar Sethi, Jens Kiesel, Afroditi Grigoropoulou, Maria M. Üblacker, Longzhu Q. Shen, and Sami Domisch.
"Hydrography90m: A new high-resolution global hydrographic dataset." Earth System Science Data 14, no. 10 (2022): 4525-4550.

Data structure: basin-network-layers¶

Base and network layers of Hydrography90m: flow accumulation, flow direction, drainage basins, outlets, stream segments, subcatchments, regional units, and depression

Output map description	Unit	GEE Collection Name
Flow accumulation (raster)	km2 accumulation=acc	flow_accumulation
Flow direction (raster)	NE–N–NW–W–SW–S–SE–E correspond to 1–2–3–4–5–6–7–8	flow__direction
Drainage basin (raster)	IDs from 1 to 1 676 628	drainage_basin
Outlets (raster)	ID=1 stream_vector=stream threshold=0.05; v.to.rast input=stream	outlet
Depression (raster)	ID = 1	depression
Stream segment (raster)	IDs from 1 to 726 723 221	segment
Sub-catchment (raster)	IDs from basins=sub_catchment	sub_catchment
Regional unit (raster)	IDs from 1 to 116 IDs from 150 to 200	regional_unit

basin-network

Earth Engine snippet: basin-network-layers¶

var flow_accumulation = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/base-network-layers/flow_accumulation");
var flow_direction = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/base-network-layers/flow_direction");
var depression = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/base-network-layers/depression");
var drainage_basin = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/base-network-layers/drainage_basin");
var outlet = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/base-network-layers/outlet");
var regional_unit = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/base-network-layers/regional_unit");
var segment = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/base-network-layers/segment");
var sub_catchment = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/base-network-layers/sub_catchment");

Sample Code: https://code.earthengine.google.com/?scriptPath=users/sat-io/awesome-gee-catalog-examples:hydrology/HYDROGRAPHY90-BASE-NETWORK

Data structure: stream-slope¶

Curvature, gradient (elevation difference divided by distance), and elevation difference raster maps.

Output raster map description	Unit	GEE Collection Name
Maximum curvature between highest upstream cell, focal cell, and downstream cell	m^-1 (scale factor 10^6)	slope_curv_max_dw_cel
Minimum curvature between highest upstream cell, focal cell, and downstream cell	m^-1 (scale factor 10^6)	slope_curv_min_dw_cel
Elevation difference between focal cell and downstream cell	m	slope_elv_dw_cel
Focal cell gradient	Unitless (scale factor 10^6)	slope_grad_dw_cel

stream-slope

Earth Engine Snippet: stream-slope¶

var slope_curv_max_dw_cel = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-slope/slope_curv_max_dw_cel");
var slope_curv_min_dw_cel = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-slope/slope_curv_min_dw_cel");
var slope_elv_dw_cel = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-slope/slope_elv_dw_cel");
var slope_grad_dw_cel = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-slope/slope_grad_dw_cel");

Sample Code: https://code.earthengine.google.com/?scriptPath=users/sat-io/awesome-gee-catalog-examples:hydrology/HYDROGRAPHY90-STREAM-SLOPE

Data structure: stream-outlet-distance¶

Stream or outlet distance and elevation difference raster maps.

Output raster map description	Unit	GEE collection name
Shortest upstream distance between focal grid cell and the nearest sub-catchment drainage divide	m	stream_dist_up_near
Longest upstream distance between focal grid cell and the nearest sub-catchment drainage divide	m	stream_dist_up_farth
Distance between focal grid cell and its nearest downstream stream grid cell	m	stream_dist_dw_near
Distance between focal grid cell and the outlet grid cell in the network	m	outlet_dist_dw_basin
Distance between focal grid cell and the downstream stream node grid cell	m	outlet_dist_dw_scatch
Euclidean distance between focal grid cell and the stream network	m	stream_dist_proximity
Elevation difference of the shortest path from focal grid cell to the sub-catchment drainage divide	m	stream_diff_up_near
Elevation difference of the longest path from focal grid cell to the sub-catchment drainage divide	m	stream_diff_up_farth
Elevation difference between focal grid cell and its nearest downstream stream pixel	m	stream_diff_dw_near
Elevation difference between focal grid cell and the outlet grid cell in the network	m	outlet_diff_dw_basin
Elevation difference between focal grid cell and the downstream stream node grid cell	m	outlet_diff_dw_scatch

stream-distance

Earth Engine snippet: stream-outlet-distance¶

var outlet_diff_dw_basin = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-outlet-distance/outlet_diff_dw_basin");
var outlet_diff_dw_scatch = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-outlet-distance/outlet_diff_dw_scatch");
var outlet_dist_dw_basin = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-outlet-distance/outlet_dist_dw_basin");
var outlet_dist_dw_scatch = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-outlet-distance/outlet_dist_dw_scatch");
var stream_diff_dw_near = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-outlet-distance/stream_diff_dw_near");
var stream_diff_dw_far = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-outlet-distance/stream_diff_up_farth");
var stream_diff_up_near = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-outlet-distance/stream_diff_up_near");
var stream_dist_dw_near = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-outlet-distance/stream_dist_dw_near");
var stream_dist_proximity = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-outlet-distance/stream_dist_proximity");
var stream_dist_up_farth = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-outlet-distance/stream_dist_up_farth");
var stream_dist_up_near = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-outlet-distance/stream_dist_up_near");

Sample Code: https://code.earthengine.google.com/?scriptPath=users/sat-io/awesome-gee-catalog-examples:hydrology/HYDROGRAPHY90-STREAM-OUTLET-DIST

Data structure: flow-index¶

The compound topographic index (cti), stream power index (spi), and stream transportation index (sti) derived from flow accumu- lation (α) and terrain slope (β)

Output raster map description	Unit	GEE collection name
Stream power index (spi)	Unitless (scale factor 10^3)	spi
Stream transportation index (sti)	Unitless (scale factor 10^3)	sti
Compound topographic index (cti)	Unitless (scale factor 10^8)	cti

flow_index

Earth Engine Snippet: flow-index¶

var cti = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/flow_index/cti");
var spi = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/flow_index/spi");
var sti = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/flow_index/sti");

Sample code: https://code.earthengine.google.com/?scriptPath=users/sat-io/awesome-gee-catalog-examples:hydrology/HYDROGRAPHY90-FLOW-INDEX

Data structure:stream-order¶

Stream order rasters

Output map description	GEE collection name
Strahler’s stream order (raster)	order_strahler
Shreve’s stream magnitude (raster)	order_shreve
Horton’s stream order (raster)	order_horton
Hack’s stream order (raster)	order_hack
Topological dimension of streams (raster)	order_topo

stream-order

Earth Engine snippet: stream-order¶

var order_hack = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-order/order_hack");
var order_horton = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-order/order_horton");
var order_shreve = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-order/order_shreve");
var order_strahler = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-order/order_strahler");
var order_topo = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-order/order_topo");

Sample code: https://code.earthengine.google.com/?scriptPath=users/sat-io/awesome-gee-catalog-examples:hydrology/HYDROGRAPHY90-STREAM-ORDER

Data structure:curvature-gradient¶

Curvature, gradient (elevation difference divided by distance), and elevation change raster maps.

Output raster map description	Unit	GEE collection name
Segment downstream mean gradient between focal cell and the node or outlet	Unitless (scale factor 10^6)	channel_grad_dw_seg
Segment upstream mean gradient between focal cell and the init or node	Unitless (scale factor 10^6)	channel_grad_up_seg
Upstream gradient between focal cell and the next cell	Unitless (scale factor 10^6)	channel_grad_up_cel
Cell stream course curvature of the focal cell	m^-1 (scale factor 10^6)	channel_curv_cel
Segment downstream elevation difference between focal cell and the node or outlet	m	channel_elv_dw_seg
Segment upstream elevation difference between focal cell and the init or node	m	channel_elv_up_seg
Upstream elevation difference between focal cell and the next cell	m (outlet cell value = 99 999)	channel_elv_up_cel
Downstream elevation difference between focal cell and the next cell	m	channel_elv_dw_cel
Segment downstream distance between focal cell and the node or outlet	m	channel_dist_dw_seg
Segment upstream distance between focal cell and the init or node	m	channel_dist_up_seg
Upstream distance between focal cell and next cell	m	channel_dist_up_cel

stream-channel-small

Earth Engine Snippet: curvature-gradient¶

var channel_curv_cel = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-channel/channel_curv_cel");
var channel_dist_dw_seg = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-channel/channel_dist_dw_seg");
var channel_dist_up_cel = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-channel/channel_dist_up_cel");
var channel_dist_up_seg = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-channel/channel_dist_up_seg");
var channel_elv_dw_cel = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-channel/channel_elv_dw_cel");
var channel_elv_dw_seg = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-channel/channel_elv_dw_seg");
var channel_elv_up_cel = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-channel/channel_elv_up_cel");
var channel_elv_up_seg = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-channel/channel_elv_up_seg");
var channel_grad_dw_seg = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-channel/channel_grad_dw_seg");
var channel_grad_up_cel = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-channel/channel_grad_up_cel");
var channel_grad_up_seg = ee.ImageCollection("projects/sat-io/open-datasets/HYDROGRAPHY90/stream-channel/channel_grad_up_seg");

Sample code: https://code.earthengine.google.com/?scriptPath=users/sat-io/awesome-gee-catalog-examples:hydrology/HYDROGRAPHY90-STREAM-CHANNEL

License¶

The dataset is licensed under a Creative Commons "CC BY-NC 4.0" license.

Created by: Amatulli, Giuseppe, Jaime Garcia Marquez, Tushar Sethi, Jens Kiesel, Afroditi Grigoropoulou, Maria M. Üblacker, Longzhu Q. Shen, and Sami Domisch

Curated by: Samapriya Roy

Keywords: Hydrology, Hydrography, Slope, Channel, Stream, Runoff, Flow accumulation, Flow direction

Last updated in GEE: 2022-11-14

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