This dataset contains the Digital Elevation Model (DEM) for Africa from the Hydrologic Derivatives for Modeling and Analysis (HDMA) database. The DEM data were developed and distributed by processing units. There are 19 processing units for Africa. The distribution files have the number of the processing unit appended to the end of the zip file name (e.g. af_dem_3_2.zip contains the DEM data for unit 3-2). The HDMA database provides comprehensive and consistent global coverage of raster and vector topographically derived layers, including raster layers of digital elevation model (DEM) data, flow direction, flow accumulation, slope, and compound topographic index (CTI); and vector layers of streams and catchment boundaries. The coverage of the data is global (-180º, 180º, -90º, 90º) with the underlying DEM being a hybrid of three datasets: HydroSHEDS (Hydrological data and maps based on SHuttle Elevation Derivatives at multiple Scales), Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010) and the Shuttle Radar Topography Mission (SRTM). For most of the globe south of 60º North, the raster resolution of the data is 3-arc-seconds, corresponding to the resolution of the SRTM. For the areas North of 60º, the resolution is 7.5-arc-seconds (the smallest resolution of the GMTED2010 dataset) except for Greenland, where the resolution is 30-arc-seconds. The streams and catchments are attributed with Pfafstetter codes, based on a hierarchical numbering system, that carry important topological information.
This dataset contains the Digital Elevation Model (DEM) grid for the Asian continent from the Hydrologic Derivatives for Modeling and Analysis (HDMA) database. The DEM data were developed and distributed by processing units. There are 19 processing units for Asia. The distribution files have the number of the processing unit appended to the end of the zip file name (e.g. as_dem_3_2.zip contains the DEM data for unit 3-2). The HDMA database provides comprehensive and consistent global coverage of raster and vector topographically derived layers, including raster layers of digital elevation model (DEM) data, flow direction, flow accumulation, slope, and compound topographic index (CTI); and vector layers of streams and catchment boundaries. The coverage of the data is global (-180º, 180º, -90º, 90º) with the underlying DEM being a hybrid of three datasets: HydroSHEDS (Hydrological data and maps based on SHuttle Elevation Derivatives at multiple Scales), Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010) and the Shuttle Radar Topography Mission (SRTM). For most of the globe south of 60º North, the raster resolution of the data is 3-arc-seconds, corresponding to the resolution of the SRTM. For the areas North of 60º, the resolution is 7.5-arc-seconds (the smallest resolution of the GMTED2010 dataset) except for Greenland, where the resolution is 30-arc-seconds. The streams and catchments are attributed with Pfafstetter codes, based on a hierarchical numbering system, that carry important topological information.
This data set consists of a set of 136 ESRI formatted GRID data sets representing elevations in meters for the state of Arizona. Each file covers a half degree block and as a collection they cover the entire State of Arizona. The data were created by processing U.S.Geological Survey 30 meter Digital Elevation Model files for all of the 7.5 minute quadrangle map areas in Arizona. The processing produced ESRI formatted lattices (GRIDs) for each quadrangle. These were then merged into the half degree blocks.
The Dauphin County, PA 2016 QL2 LiDAR project called for the planning, acquisition, processing and derivative products of LIDAR data to be collected at a nominal pulse spacing (NPS) of 0.7 meters. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base LIDAR Specification, Version 1.2. The data was developed based on a horizontal projection/datum of NAD83 (2011) State Plane Pennsylvania South Zone, US survey feet; NAVD1988 (Geoid 12B), US survey feet. LiDAR data was delivered in RAW flight line swath format, processed to create Classified LAS 1.4 Files formatted to 711 individual 5,000-foot x 5,000-foot tiles. Tile names use the following naming schema: "YYYYXXXXPAd" where YYYY is the first 3 characters of the tile's upper left corner Y-coordinate, XXXX - the first 4 characters of the tile's upper left corner X-coordinate, PA = Pennsylvania, and d = 'N' for North or 'S' for South. Corresponding 2.5-foot gridded hydro-flattened bare earth raster tiled DEM files and intensity image files were created using the same 5,000-foot x 5,000-foot schema. Hydro-flattened breaklines were produced in Esri file geodatabase format. Continuous 2-foot contours were produced in Esri file geodatabase format. Ground Conditions: LiDAR collection began in Spring 2016, while no snow was on the ground and rivers were at or below normal levels. In order to post process the LiDAR data to meet task order specifications, Quantum Spatial established a total of 84 control points (24 calibration control points and 60 QC checkpoints). These were used to calibrate the LIDAR to known ground locations established throughout the project area.
U.S. Government Workshttps://www.usa.gov/government-works
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These topographic/bathymetric digital elevation models (DEMs) were collected and compiled to characterize erosion and deposition in the Colorado River and in an adjacent zone of laterally recirculating flow (eddy) during both average flow conditions and during a controlled flood that occurred in March 2008. The objectives of the study were to measure changes sandbar morphology that occurred during changes in discharge associated with the controlled flood. These data were collected between February 6 and March 31, 2008 in a 1-mile study reach on the Colorado River within Grand Canyon National Park beginning 44.5 miles downstream from Lees Ferry, Arizona. These data were collected by the USGS Grand Canyon Monitoring and Research Center with cooperators from Northern Arizona University and funding provided by the Glen Canyon Dam Adaptive Management Program. All bathymetric data were collected with a multibeam sonar system (Reson Seabat 8124 sonar with TSS MAHRSS reference system for ...
MIT Licensehttps://opensource.org/licenses/MIT
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The State of Indiana Geographic Information Office (GIO) has published a State-wide Elevation Catalog consisting of Digital Elevation Model (DEM) files from 2005, 2011-2013, and 2016-2020 in Cloud-Optimized GeoTIFF (COG) format on the AWS Registry of Open Data Account. These COG formatted files support the dynamic imagery services available from the GIO ESRI-based imagery solution. The Open Data on AWS is a repository of publicly available datasets for access from AWS resources. These datasets are owned and maintained by the Indiana GIO. These images are licensed by Creative Commons 0 (CC0). Cloud Optimized GeoTIF behaves as a GeoTIFF in all products; however, the optimization becomes apparent when incorporating them into web services.
description: A Digital Elevation Model (DEM) contains a series of elevations ordered from south to north with the order of the columns from west to east. The DEM is formatted as one ASCII header record (A-record), followed by a series of profile records (B-records) each of which include a short B-record header followed by a series of ASCII integer elevations per each profile. The last physical record of the DEM is an accuracy record (C-record). The 7.5-minute DEM (10- by 10-m data spacing, elevations in decimeters) is cast on the Universal Transverse Mercator (UTM) projection (the quads UTM zone can be found in the header record (Record A)) in the North American Datum of 1927. It provides coverage in 7.5- by 7.5-minute blocks. Each product provides the same coverage as a standard USGS 7.5-minute quadrangle, but overedges are published as separate DEM files. Coverage is available for all quads completely contained within New York State, plus some additional ones falling along the borders and containing significant area of the State's land.; abstract: A Digital Elevation Model (DEM) contains a series of elevations ordered from south to north with the order of the columns from west to east. The DEM is formatted as one ASCII header record (A-record), followed by a series of profile records (B-records) each of which include a short B-record header followed by a series of ASCII integer elevations per each profile. The last physical record of the DEM is an accuracy record (C-record). The 7.5-minute DEM (10- by 10-m data spacing, elevations in decimeters) is cast on the Universal Transverse Mercator (UTM) projection (the quads UTM zone can be found in the header record (Record A)) in the North American Datum of 1927. It provides coverage in 7.5- by 7.5-minute blocks. Each product provides the same coverage as a standard USGS 7.5-minute quadrangle, but overedges are published as separate DEM files. Coverage is available for all quads completely contained within New York State, plus some additional ones falling along the borders and containing significant area of the State's land.
The Dauphin County, PA 2016 QL2 LiDAR project called for the planning, acquisition, processing and derivative products of LIDAR data to be collected at a nominal pulse spacing (NPS) of 0.7 meters. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base LIDAR Specification, Version 1.2. The data was developed based on a horizontal projection/datum of NAD83 (2011) State Plane Pennsylvania South Zone, US survey feet; NAVD1988 (Geoid 12B), US survey feet. LiDAR data was delivered in RAW flight line swath format, processed to create Classified LAS 1.4 Files formatted to 711 individual 5,000-foot x 5,000-foot tiles. Tile names use the following naming schema: "YYYYXXXXPAd" where YYYY is the first 3 characters of the tile's upper left corner Y-coordinate, XXXX - the first 4 characters of the tile's upper left corner X-coordinate, PA = Pennsylvania, and d = 'N' for North or 'S' for South. Corresponding 2.5-foot gridded hydro-flattened bare earth raster tiled DEM files and intensity image files were created using the same 5,000-foot x 5,000-foot schema. Hydro-flattened breaklines were produced in Esri file geodatabase format. Continuous 2-foot contours were produced in Esri file geodatabase format. Ground Conditions: LiDAR collection began in Spring 2016, while no snow was on the ground and rivers were at or below normal levels. In order to post process the LiDAR data to meet task order specifications, Quantum Spatial established a total of 84 control points (24 calibration control points and 60 QC checkpoints). These were used to calibrate the LIDAR to known ground locations established throughout the project area.
A highly accurate elevation dataset of ground surface topography, derived from aerial Light Detection and Ranging (LiDAR). This 2m resolution version of the bare-Earth LiDAR DEM can be used for a wide range of applications such as 3D spatial analysis (slope calculations, profile creation, volumetric computations), engineering applications (land developments, road design, flood modelling) and 3D terrain visualizations, just to name a few. To learn more, view the attached metadata PDF documents.
DEM of 1m and 20cm resolution are also available on Cityonline.calgary.ca
Two versions are available for download in separate zip files.
The first contains a citywide DEM file in ESRI ArcGrid ASCII (.asc) format. The compressed file for download is 0.5 GB. The uncompressed file is 4.2 GB.
A second zip file contains the same DEM but it is split into smaller files, tiled by Alberta Township System (ATS) sections. The compressed file for download is 0.6 GB. The uncompressed files are 3.0 GB in total for all sections.
Open Government Licence - Canada 2.0https://open.canada.ca/en/open-government-licence-canada
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The High Resolution Digital Elevation Model (HRDEM) product is derived from airborne LiDAR data (mainly in the south) and satellite images in the north. The complete coverage of the Canadian territory is gradually being established. It includes a Digital Terrain Model (DTM), a Digital Surface Model (DSM) and other derived data. For DTM datasets, derived data available are slope, aspect, shaded relief, color relief and color shaded relief maps and for DSM datasets, derived data available are shaded relief, color relief and color shaded relief maps. The productive forest line is used to separate the northern and the southern parts of the country. This line is approximate and may change based on requirements. In the southern part of the country (south of the productive forest line), DTM and DSM datasets are generated from airborne LiDAR data. They are offered at a 1 m or 2 m resolution and projected to the UTM NAD83 (CSRS) coordinate system and the corresponding zones. The datasets at a 1 m resolution cover an area of 10 km x 10 km while datasets at a 2 m resolution cover an area of 20 km by 20 km. In the northern part of the country (north of the productive forest line), due to the low density of vegetation and infrastructure, only DSM datasets are generally generated. Most of these datasets have optical digital images as their source data. They are generated at a 2 m resolution using the Polar Stereographic North coordinate system referenced to WGS84 horizontal datum or UTM NAD83 (CSRS) coordinate system. Each dataset covers an area of 50 km by 50 km. For some locations in the north, DSM and DTM datasets can also be generated from airborne LiDAR data. In this case, these products will be generated with the same specifications as those generated from airborne LiDAR in the southern part of the country. The HRDEM product is referenced to the Canadian Geodetic Vertical Datum of 2013 (CGVD2013), which is now the reference standard for heights across Canada. Source data for HRDEM datasets is acquired through multiple projects with different partners. Since data is being acquired by project, there is no integration or edgematching done between projects. The tiles are aligned within each project. The product High Resolution Digital Elevation Model (HRDEM) is part of the CanElevation Series created in support to the National Elevation Data Strategy implemented by NRCan. Collaboration is a key factor to the success of the National Elevation Data Strategy. Refer to the “Supporting Document” section to access the list of the different partners including links to their respective data.
This is a tiled collection of the 3D Elevation Program (3DEP) and is 1/3 arc-second (approximately 10 m) resolution. The 3DEP data holdings serve as the elevation layer of The National Map, and provide foundational elevation information for earth science studies and mapping applications in the United States. Scientists and resource managers use 3DEP data for hydrologic modeling, resource monitoring, mapping and visualization, and many other applications. The elevations in this DEM represent the topographic bare-earth surface. The seamless 1/3 arc-second DEM layers are derived from diverse source data that are processed to a common coordinate system and unit of vertical measure. These data are distributed in geographic coordinates in units of decimal degrees, and in conformance with the North American Datum of 1983 (NAD 83). All elevation values are in meters and, over the continental United States, are referenced to the North American Vertical Datum of 1988 (NAVD88). The seamless 1/3 arc-second DEM layer provides coverage of the conterminous United States, Hawaii, Puerto Rico, other territorial islands, and in limited areas of Alaska. The seamless 1/3arc-second DEM is available as pre-staged current and historical products tiled in GeoTIFF format. The seamless 1/3 arc-second DEM layer is updated continually as new data become available in the current folder. Previously created 1 degree blocks are retained in the historical folder with an appended date suffix (YYYMMDD) when they were produced. Other 3DEP products are nationally seamless DEMs in resolutions of 1, and 2 arc seconds. These seamless DEMs were referred to as the National Elevation Dataset (NED) from about 2000 through 2015 at which time they became the seamless DEM layers under the 3DEP program and the NED name and system were retired. Other 3DEP products include one-meter DEMs produced exclusively from high resolution light detection and ranging (lidar) source data and five-meter DEMs in Alaska as well as various source datasets including the lidar point cloud and interferometric synthetic aperture radar (Ifsar) digital surface models and intensity images. All 3DEP products are public domain.
This dataset contains the Digital Elevation Model (DEM) for South America from the Hydrologic Derivatives for Modeling and Analysis (HDMA) database. The data were developed and distributed by processing units. There are 10 processing units for South America. The distribution files have the number of the processing unit appended to the end of the zip file name (e.g. sa_dem_3.zip contains the DEM data for unit 3-2). The HDMA database provides comprehensive and consistent global coverage of raster and vector topographically derived layers, including raster layers of digital elevation model (DEM) data, flow direction, flow accumulation, slope, and compound topographic index (CTI); and vector layers of streams and catchment boundaries. The coverage of the data is global (-180º, 180º, -90º, 90º) with the underlying DEM being a hybrid of three datasets: HydroSHEDS (Hydrological data and maps based on SHuttle Elevation Derivatives at multiple Scales), Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010) and the Shuttle Radar Topography Mission (SRTM). For most of the globe south of 60º North, the raster resolution of the data is 3-arc-seconds, corresponding to the resolution of the SRTM. For the areas North of 60º, the resolution is 7.5-arc-seconds (the smallest resolution of the GMTED2010 dataset) except for Greenland, where the resolution is 30-arc-seconds. The streams and catchments are attributed with Pfafstetter codes, based on a hierarchical numbering system, that carry important topological information.
MIT Licensehttps://opensource.org/licenses/MIT
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This web map leverages the KyFromAbove 5 foot Digital Elevation Model (DEM) ArcGIS Server Image Service and provides a 5K tiling grid with embedded links for downloading individual DEM tiles from Phase 1, Phase 2 and Phase3 collection periods. Each of the Phase1 DEM tiles are provided in an ERDAS Imagine (IMG) format and is zipped up with its associated metadata file in XML format. Phase2 and Phase3 DEM tiles are provided in a GeoTIFF format. The Phase1 data resource was derived from the ground class within KyFromAbove point cloud data and has a 5-foot point spacing. The Phase2 and Phase3 data was derived from the ground class within KyFromAbove point cloud data and has a 2-foot point spacing. DEM data specifications adopted by the KyFromAbove Technical Advisory Committee can be found here. More information regarding this data resource can be found on the KyFromAbove website.
This is a dataset download, not a document. The Open button will start the download.Digital Elevation Model. 10m pixels. Elevation values in feet. Elevation data assembled from merged 7.5-minute DEM blocks (10- by 10-m data spacing).
Open Government Licence 3.0http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/
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The SurfZone Digital Elevation Model (DEM) was produced in 2019. Combining LIDAR and near-shore multibeam SONAR Bathymetry elevation data, it is the best currently available Digital Elevation Model (DEM) covering the inter-tidal zone produced by the Environment Agency.
The EA SurfZone DEM 2019 is supplied as a tiled raster dataset in GeoTiff format. Each tile is 5km * 5km and aligned to the Ordinance Survey National Grid. Each pixel represents 2 metres spatial resolution on the ground and elevations are presented in metres to Ordinance Survey Great Britain using the OSGM'15 and OSTM'15 transformation models. Elevations are referenced to Newlyn except for the Isles of Scilly which is referenced to St Marys.
The SurfZone DEM was produced by using a bespoke feathering technique to smooth the overlaps between LIDAR and Bathymetric surveys to produce a merged surface. Where small gaps existed between the LIDAR and Bathymetric surveys these were interpolated using a bilinear interpolation technique.
Please refer to the metadata index catalgoues which show for any location which survey was used in the production of the SurfZone DEM. The Metadata Index Catalogue provides information about the source of the survey data used, either LIDAR or Bathymetry for any area as well as the surface type, coastal monitoring region, geoidal model and transformation models used.
All LIDAR data used in the production of the SurfZone DEM was surveyed by the Environment Agency. Bathymetry data was surveyed by the Environment Agency or sourced from the National Network of Regional Coastal Monitoring Programmes of England from the Channel Coastal Observatory (www.channelcoast.org) website. The National Network of Regional Coastal Monitoring Programmes of England comprises of 6 Regional Programmes. When re-using these data, you must use the copyright statements in the licence to acknowledge the individual regions when reusing this dataset.
This is a tiled collection of the 3D Elevation Program (3DEP) and is one meter resolution. The 3DEP data holdings serve as the elevation layer of The National Map, and provide foundational elevation information for earth science studies and mapping applications in the United States. Scientists and resource managers use 3DEP data for hydrologic modeling, resource monitoring, mapping and visualization, and many other applications. The elevations in this DEM represent the topographic bare-earth surface. USGS standard one-meter DEMs are produced exclusively from high resolution light detection and ranging (lidar) source data of one-meter or higher resolution. One-meter DEM surfaces are seamless within collection projects, but, not necessarily seamless across projects. The spatial reference used for tiles of the one-meter DEM within the conterminous United States (CONUS) is Universal Transverse Mercator (UTM) in units of meters, and in conformance with the North American Datum of 1983 (NAD83). All bare earth elevation values are in meters and are referenced to the North American Vertical Datum of 1988 (NAVD88). Each tile is distributed in the UTM Zone in which it lies. If a tile crosses two UTM zones, it is delivered in both zones. The one-meter DEM is the highest resolution standard DEM offered in the 3DEP product suite. Other 3DEP products are nationally seamless DEMs in resolutions of 1/3, 1, and 2 arc seconds. These seamless DEMs were referred to as the National Elevation Dataset (NED) from about 2000 through 2015 at which time they became the seamless DEM layers under the 3DEP program and the NED name and system were retired. Other 3DEP products include five-meter DEMs in Alaska as well as various source datasets including the lidar point cloud and interferometric synthetic aperture radar (Ifsar) digital surface models and intensity images. All 3DEP products are public domain.
This dataset provides topographic indices derived from 1 m resolution DEMs for sequoia groves in both Sequoia-Kings Canyon and Yosemite National Parks. All mapped sequoia groves in Sequoia-Kings Canyon National Park and two groves from Yosemite National Park, Merced and Mariposa, are included. For each grove, aspect, slope, the stream network, height above nearest drainage (HAND), depth to water (DTW), maximum elevation deviation (DEVmax), and heat load index (HLI) are calculated. These indices were chosen because of their relevance in determining soil moisture across a landscape. Derived topographic parameters were calculated using 1 m DEMs generated in 2016 resampled to 3 m and a combination of ArcGIS Pro Tools, ArcPy Scripts, Whitebox GAT tools, and R scripts. The stream networks, which are further used in the calculation of HAND and DTW, were determined using a flow accumulation threshold of 2000 meters squared based on a literature-accepted range, chosen specifically based on knowledge of the areas of interest. The neighborhood size range for DEVmax was chosen on two scales, allowing for the identification of both local and more global minima and maxima: squares centered at each pixel ranging from 9 to 303 meters and 9 to 1203 meters wide. The neighborhood size chosen by the algorithm at each pixel maximizes the deviation from the average. Files that include the neighborhood size chosen are included for reference. All files are included as GeoTIFF files.
This dataset contains the Digital Elevation Model (DEM) for Europe from the Hydrologic Derivatives for Modeling and Analysis (HDMA) database. The data were developed and distributed by processing units. There are 11 processing units for Europe. The distribution files have the number of the processing unit appended to the end of the zip file name (e.g. eu_dem_3_2.zip contains the DEM data for unit 3-2). The HDMA database provides comprehensive and consistent global coverage of raster and vector topographically derived layers, including raster layers of digital elevation model (DEM) data, flow direction, flow accumulation, slope, and compound topographic index (CTI); and vector layers of streams and catchment boundaries. The coverage of the data is global (-180º, 180º, -90º, 90º) with the underlying DEM being a hybrid of three datasets: HydroSHEDS (Hydrological data and maps based on SHuttle Elevation Derivatives at multiple Scales), Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010) and the Shuttle Radar Topography Mission (SRTM). For most of the globe south of 60º North, the raster resolution of the data is 3-arc-seconds, corresponding to the resolution of the SRTM. For the areas North of 60º, the resolution is 7.5-arc-seconds (the smallest resolution of the GMTED2010 dataset) except for Greenland, where the resolution is 30-arc-seconds. The streams and catchments are attributed with Pfafstetter codes, based on a hierarchical numbering system, that carry important topological information.
DEM Bare Earth Tile Indexes for each LiDAR project. The “DIRECT_DL” field contains a hyperlink to download the associated IMG files. More information for existing DEM collections can be found at https://gis.ny.gov/nys-dem. Service last updated 7/26/24Feature and map services available:https://elevation.its.ny.gov/arcgis/rest/services/Dem_Indexes/FeatureServerhttps://elevation.its.ny.gov/arcgis/rest/services/Dem_Indexes/MapServer
Please contact NYS ITS Geospatial Services at nysgis@its.ny.gov if you have any questions.
Digital Elevation Models (DEM's) for the 2017 San Mateo LiDAR project covering approximately 578 square miles in San Mateo County, CA. This dataset meets QL2 accuracy and with 4 points per meter pulse density. To acquire detailed surface elevation data for use in conservation planning, design, research, floodplain mapping, dam safety assessments, and hydrologic modeling. LAS and bare earth DEM data products are suitable for 1 foot contour generation. USGS LiDAR Base Specification 1.2, QL2. Project Projection, Datums and Units. Projection - State Plane California III FIPS 0403. Horizontal datum - North American Datum of 1983 (NAD83). Vertical datum - North American Vertical Datum of 1988 (NAVD88) using the latest geoid (Geoid12a) for converting ellipsoidal heights to orthometric heights. Units - US feetThe full metadata file in .xml format can be viewed here: DEM_Metadata
This dataset contains the Digital Elevation Model (DEM) for Africa from the Hydrologic Derivatives for Modeling and Analysis (HDMA) database. The DEM data were developed and distributed by processing units. There are 19 processing units for Africa. The distribution files have the number of the processing unit appended to the end of the zip file name (e.g. af_dem_3_2.zip contains the DEM data for unit 3-2). The HDMA database provides comprehensive and consistent global coverage of raster and vector topographically derived layers, including raster layers of digital elevation model (DEM) data, flow direction, flow accumulation, slope, and compound topographic index (CTI); and vector layers of streams and catchment boundaries. The coverage of the data is global (-180º, 180º, -90º, 90º) with the underlying DEM being a hybrid of three datasets: HydroSHEDS (Hydrological data and maps based on SHuttle Elevation Derivatives at multiple Scales), Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010) and the Shuttle Radar Topography Mission (SRTM). For most of the globe south of 60º North, the raster resolution of the data is 3-arc-seconds, corresponding to the resolution of the SRTM. For the areas North of 60º, the resolution is 7.5-arc-seconds (the smallest resolution of the GMTED2010 dataset) except for Greenland, where the resolution is 30-arc-seconds. The streams and catchments are attributed with Pfafstetter codes, based on a hierarchical numbering system, that carry important topological information.