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The 3D National Topography Model Call for Action - Part 1: The 3D Hydrography Program

The implementation of 3D National Hydrography Program marks the beginning of a new era of water data. The public and private sectors that depend on high-quality water data have expressed the need for better information to answer the most demanding water resource management questions. Community-wide coordinated investments contribute toward consistent set of national water data.




A Legacy of Surface Water Mapping

The National Hydrography Datasets depict the Nation’s surface waters of streams, lakes, and watersheds.
Figure 1: The National Hydrography Datasets depict the Nation’s surface waters of streams, lakes, and watersheds.  This figure shows streams and catchments from the NHDPlus High Resolution superimposed on a hillshaded digital elevation model.

For more than 20 years, the USGS and partners have developed and maintained the National Hydrography Datasets as the authoritative mapping of the Nation’s surface water network and watersheds (OMB, 2002). The National Hydrography Datasets consist of the National Hydrograpy Dataset (NHD), the Watershed Boundary Dataset (WBD), and the NHDPlus High-Resolution (NHDPlus HR). These datasets have been integral to a wide range of business uses and mission-critical activities undertaken and managed by government entities, nonprofit organizations, Tribes, and private companies including water quality monitoring, flood risk prediction, infrastructure development, ecosystem management, agricultural resources, and many more. These hydrography data, which are regularly used by a broad variety of users to depict the stream network on maps, provide a consistent framework for geographic analyses and hydrologic modeling, and support scientific research by connecting information from the landscape to the stream network.


Benefits of Hydrography Data

The National Hydrography Requirements and Benefits Study (HRBS; Dewberry, 2016) was conducted to document and understand current and emerging requirements as well as current and future potential benefits of hydrography data. The participants included Federal, state, Tribal, Territorial, and local government associations, private companies, associations, and non-profit organizations. Participants identified \$538.5 million in annual benefits from the current National Hydrography Datasets and estimated an additional \$602.4 million in annual benefits if all unmet needs could be satisfied, for a total of over \$1.14 billion in benefits each year. HRBS results identified many requirements for hydrography data, including better linkage to other water datasets, such as the U.S Fish and Wildlife Service National Wetlands Inventory (NWI), better positional accuracy, better alignment to elevation data, and more frequent updates, among other findings.



The 3D Hydrography Program aims to align hydrography and elevation data.
Figure 2: The Nation needs a system for organizing, sharing, and discovering water data in the context of the stream network that includes network connectivity, flow direction, catchment characteristics and other nearby data.

Building on decades of experience developing and managing the National Hydrography Datasets, the USGS is establishing the 3D Hydrography Program (3DHP) initiative to completely refresh the Nation’s hydrography data and improve discovery and sharing of water-related data.  When fully implemented, 3DHP is estimated to provide more than \$1 billion in benefits to Federal, state, local, Tribal, private, and non-profit organizations every year, in addition to myriad societal benefits.  3DHP would directly support better decision-making regarding water resources by providing more accurate, complete, and integrated information. The next generation of surface water mapping under the new 3DHP will incorporate the most relevant and impactful components of the existing National Hydrography Datasets with greatly improved spatial accuracy and better support for hydrologic modeling and accounting. The resulting products and services will be freely available and freely accessible through modern, widely used open-data standard formats and web services.

The 3DHP will significantly improve the level of detail, currency, and content of hydrography data by deriving 3D stream networks and watersheds from high-quality 3D Elevation Program (3DEP) data, as well as other elevation derivatives to support applications like hydrologic and hydraulic modeling. 3DHP will improve the ability to track information about water as it moves through the hydrologic cycle by connecting surface water features traditionally represented in the NHD to wetland, engineered hydrologic systems, and groundwater data; and improving attribution of important hydrologic characteristics like streamflow permanence.


A New Approach to Water Data

3D National Topography Model

Topography is defined by terrain and water, each influencing and shaping the other. The 3D National Topography Model (3DNTM) is a new initiative that updates and integrates USGS elevation and hydrography data, and the relationships between them, into a 3D model to deliver higher-quality data and support improved geospatial analysis. The 3DNTM, including 3DHP and the next generation of the 3D Elevation Program (3DEP), will provide foundational data to meet the most demanding scientific requirements and enable data-driven decisions across user communities.

Key elements of the 3DNTM are in place or under active development. The 3DEP and High Resolution NHDPlus baseline datasets are nearing completion.  Several projects piloting the integration of hydrography and elevation datasets are underway.  The 3DNTM Call for Action Part 1, focused on hydrography, and a 3DNTM Call for Action: Part 2, focused on the next generation of 3DEP are being developed. Later development phases of the 3DNTM will include construction of and a transition to a 3D data model that will include additional topographic datasets of The National Map ( managed by the USGS National Geospatial Program.


3DHP Datasets

3DHP Datasets will include a 3D hydrography network, generated from and integrated with 3DEP elevation data to better represent stream gradients and channel conditions, along with waterbodies, hydrologic units, hydrologically enhanced elevation and other surfaces, and more consistent and accurate attributes. 3DHP datasets will be built on high-quality, standardized 3DEP data to ensure spatial and temporal consistency across all derived products. This will increase usability of 3DHP datasets for applications like flood modeling and prediction, culvert and bridge engineering design, and stormwater management.

3DHP Datasets will inherit key attributes of the NHD, WBD, and NHDPlus HR, but also will include new attributes and links to other data such as the NWI, groundwater, and engineered hydrologic systems like stormwater networks.

The modernized 3DHP data model will include both the stream network and hydrologic units with more robust logic rules to ensure data quality. The data model will store a highly detailed and accurate set of derived stream network features, as well as attribution for generalizing the stream network and hydrologic units. The features in the stream network will be connected such that flow models will work correctly across the entire network. The 3DHP stream features are expected to be within one meter vertically, and within two meters horizontally, of the bottom of a channel where depicted in a high accuracy elevation surface, greatly improving the positional accuracy of features compared to existing hydrographic data. Improved spatial accuracy will also make the new hydrography data more consistent with other data such as transportation networks and other infrastructure.

A snapshot of all 3DHP data will be made available annually as a national dataset release with a persistent Digital Object Identifier (DOI) to support citations in scientific research.  These annual snapshots will be archived so that users may reference older versions if necessary. The most current data will be available as individual data layer downloads and accessible as map services between annual data releases. Open data standards will be considered in developing 3DHP Datasets.

3DHP Datasets will be an integrated data stack that includes:

•           A stream network derived from high quality 3DEP elevation data, with attribution to enable generalization and scale-appropriate rendering;

•           Multiple levels of nested hydrologic units derived using the stream network and elevation data;

•           Hydrologically enhanced elevation and other derivative products that align with the stream network and hydrologic units; and

•           Additional attributes that assist with hydrologic and stream network routing and analysis

The 3D Hydrography Program is the surface water component of the 3D National Terrain Model.
Figure 3: The 3D Hydrography Program will better align hydrography and elevation data.


3DHP Infostructure

The Nation lacks a system for organizing, sharing, and discovering water data in the context of the stream network.
Figure 4: The 3D Hydrography Program is the hydrography component of the 3D National Topography Model.​​​​​

3DHP will be designed to provide a set of open and interoperable web-based tools, maps, and data catalogs, creating a robust system for users to reference their information about water collectively referred to as the infostructure. The infostructure will support discovery of data based on the stream network – examples of user data include everything from water levels at stream gages to water temperature to the health of fish and aquatic life in a stream. 3DHP and the Infostructure will provide a foundational geospatial underpinning for the Internet of Water (IoW) (, a community-based effort to modernize tools and technologies to share water data

3DHP hydrographic addressing tools will enable users to link water data to create and share the information as authoritatively managed observations and data linked to the 3DHP network. 3DHP hydrographic addressing tools will provide reference locations on the stream network, similar to street addresses, that can be attached to a user’s data records. 3DHP search and discovery tools will not only help to locate data within the stream network, but also to understand relationships between different records or observations at different locations, such as the distance between water quality observations or how obstacles to fish passage, such as dams, might affect spawning or the spread of invasive species.  Any kind of water-related information can be given a address on the stream network, including hydrology, geomorphology, water quality, biology, regulations, or public access points.


3DHP Lifecycle

Because of the large volumes of data to be acquired in the first several years, and the expectation that acquisitions will decline to a maintenance level later in 3DHP, much of the work to delineate the stream network from elevation will be completed by the private sector for the USGS or partner organizations. The USGS will ensure that all acquired data meets published specifications (USGS, 2022) regarding the derivation of hydrography features from 3DEP 1-meter lidar-derived Digital Elevation Models (DEMs), or from 5-meter IfSAR-derived DEMs in Alaska. USGS will be responsible for data validation prior to accepting data into national data holdings. Once in national data holdings, individual errors within the 3DHP datasets discovered by USGS or reported by users will be corrected by USGS data editors, with a 3DHP maintenance goal of correcting errors 1-2 months after they are reported. The stream network will be reviewed on a regional basis every 4-5 years with regional updates applied as needed. In the future, change detection based on either the elevation data or hydrography may trigger updates to 3DHP data.

USGS will also be responsible for producing data related to the stream network, such as hydrologic units and some attributes, as well as the general management and delivery of data to the public. USGS will maintain an enterprise system to manage the 3DHP Datasets and Infostructure. The 3DHP Infostructure will be developed, tested, and operationalized to use the 3DHP Datasets as the geospatial foundation.


Enhancements included in the 3D Hydrography Program

Stream network

The stream network will be derived from 3DEP 1-meter standard product digital elevation models (DEMs) created from lidar (5-meter DEMs from IfSAR in Alaska) and will include elevation values on each vertex to enable 3D analysis of the data.

Hydrologically enhanced elevation and other surfaces

Hydrologically enhanced raster DEMs will be created as a part of the stream network derivation process so that the flow of water across the surface is represented accurately. Additional derivative surfaces may be developed and provided as products as the program matures.


USGS is researching how to create a continuous topobathymetric surface derived from high-resolution elevation and bathymetry. Plans to operationalize inland bathymetry will be addressed in the next generation of 3DEP.

Hydrologic units

Hydrologic units will be derived using the stream network and elevation data, while retaining and utilizing important outlet point information from the Watershed Boundary Dataset.

Groundwater connections

Connection between surface and groundwater features will be supported, for example, by identifying gaining and losing stream reaches or providing estimates of groundwater contributions to streamflow, where known.


Collaborative mapping of the stream network and the NWI will enable the two datasets to function together as a whole and to accurately depict the inland waters of the U.S.

Engineered Hydrologic Systems

3DHP will include information on engineered hydrologic systems, with a concerted effort to integrate connection points to, or generalized representations of, stormwater systems in urban areas.


culvert data acquired during the process of deriving hydrography from elevation will be made available

Addressed Data

3DHP will support a hydrographic addressing system such that data produced by users can be assigned a unique location on the network (similar to a street address) and shared across the user community



Program Scenarios

The USGS vision for 3DHP is based on Scenario 2.
Figure 5: The USGS vision for 3DHP is based on Scenario 2.

HRBS highlighted the need for a modernized, 3D-enabled hydrography program to support emergent user and stakeholder applications and provide additional benefits. To help define a modernized program, three scenarios created from HRBS were considered.

Scenario 1 (status quo) retains the current hydrography data with minimal incremental improvements. While USGS would make general progress to update the NHD using current technologies, continued local maintenance programs with a variety of funding sources and priorities would continue to decrease national consistency of the datasets over time.

Scenario 2 replaces all existing hydrography over a nine-year period with data derived from 3DEP-quality lidar data, or IfSAR in Alaska, as well as improvements supported by the HRBS, such as improved accuracy, accounting for more components of the hydrologic cycle, and more effective maintenance of data.

Scenario 3 is similar to Scenario 2, except the source data would be 0.5-meter DEMs created from Quality Level 1 (QL1) or better 3DEP lidar data. For a description of Topographic Data Quality Levels, please see  QL1 data are not readily available across the country, making this scenario currently difficult to achieve, but may be a viable program in the future.

►The USGS vision for 3DHP is based on Scenario 2. A comparison of the three implementation scenarios (Figure 5) shows that the new benefits compared with program costs provide the greatest value in Scenario 2.  This scenario would meet most mission critical activity needs identified in HRBS and achieve more than \$1.047 billion in annual benefits.


3DHP Potential Community-Wide Nine-Year Costs

3DHP Proposed Nine Year Costs
Figure 6: 3DHP proposed community-wide nine-year costs broken out by category.

The 3DHP program of work assumes the effort begins in FY2023 with moderate growth for FY2024 and accelerated growth primarily through partnerships in subsequent years. Investments by Federal, state, local, Tribal, and private partners in lidar and IfSAR data collections through 3DEP have made it possible to derive 3DHP features from elevation data for a significant portion of the Nation. For the proposed operational program to be fully realized, a similar community-wide \$685 million investment will be required between FY2023 and FY2031, including one year of preparation, six years of delineating hydrography data from 3DEP elevation data, and two additional years to complete data inspection, processing, and publication after the acquisition period.

Just as 3DEP was successful in building community partnerships with Federal, state, and local agencies; Tribal governments; and private organizations to fund data acquisition, 3DHP will follow a similar collaborative funding model that anticipates significant investments by partner organizations on shared data acquisition costs. Data maintenance and distribution costs, as well as data contracting, validation and processing expenses would be included in the core USGS 3DHP budget. The cost share model (Figure 6) is one potential model and is not intended to allocate cost shares to any organization or to individual government sectors. The actual funding model is expected to evolve and change in the program operations plan.



Leadership and Governance

3DHP governance will be led by senior executives from cooperating agencies through USGS-sponsored executive forums that will oversee the formulation and approval of policies and priorities recommended by the 3DEP and 3DHP Working Groups. The NHI Working Group, created in 2018 as a forum for Federal agencies will become the 3DHP Working Group (3DHP WG). The 3DHP WG will provide input and collaboration on the development of the 3DHP datasets and Infostructure and will take on new responsibilities for data acquisition prioritization and coordination.


Partnering to Acquire Data

Data acquisition will have several phases and follow similar data acquisition processes for both 3DEP and 3DHP.
Figure 7: Data acquisition will have several phases and follow similar data acquisition processes for both 3DEP and 3DHP.

To be successful, 3DHP must build on existing relationships to establish a systematic and unified process for data acquisition partnerships. Dependent on availability of USGS acquisition funding for 3DHP, USGS is planning to use an annual Broad Agency Announcement (BAA) in alignment with the one used for 3DEP data acquisition. When a 3DHP BAA becomes available, partners will be able to propose acquisition projects that use the USGS Geospatial Products and Services Contracts or their own contracts to acquire data that meet the 3DHP specification. Organizations may contribute data that meet 3DHP specifications that were acquired outside of the BAA process, and USGS will implement a standard procedure for reviewing those datasets for inclusion in the 3DHP.

USGS will facilitate the sharing of partner mapping requirements to help identify common areas of interest and leverage funds. The strategy will prioritize acquisitions where there are multiple requirements and a high potential for leveraging funds. Data acquisition will take place by whole hydrologic units, with an emphasis on collection through multi-partner and multi-state funding coalitions.


Collaborating to Build the Internet of Water

Community collaboration and cooperation is a core component of 3DHP, the 3DHP Infostructure, and the Internet of Water. While USGS and partner agencies will provide the overarching structure and functionality of the 3DHP Infostructure, the data searchable through it will be managed by the datasets’ authoritative producers. This federated structure gives data producers control over their information while sharing it with the broader community. In turn, the community of users can efficiently search and access the most authoritative data.


Outreach and Communications

Outreach will be an important aspect of the program, because the success of 3DHP is dependent on a broad base of support and participation from Federal agencies, State and Tribal governments, and other stakeholders. Outreach will continue to be directed toward growing user base for 3DHP products and toward gathering feedback to ensure that the 3DHP is responsive to government and private sector user needs. Equally important is a focus on building support and a community-wide funding base to move the program forward.


Roles and Responsibility

The whole water-resources community will have a role to play in 3DHP, from partnerships, to data development, to creating new and unimagined applications (Figure 8). Today, states are major contributors of data and often lead statewide acquisition and maintenance programs through stewardship agreements with the USGS. 3DHP will not include a formalized stewardship program. Rather, 3DHP will focus on cooperative community data acquisition; building a network of users with local knowledge who improve 3DHP data by reporting errors; responding to those reports to improve the stream network. Iterative improvements to the 3DHP datasets to support local needs and requirements will be identified jointly, and the 3DHP Infostructure will be developed to empower users to manage their water-related data to promote sharing and new and emerging applications.

The USGS, federal partners, state and local partners, the private sector, and users all have a role to play in 3DHP.
Figure 8: The USGS, federal partners, state and local partners, the private sector, and users all have a role to play in 3DHP.



Schedule and Milestones

As proposed, the 3DHP effort would begin providing products and services to partners and the public by the end of 2025. The strategy is to leverage funding from partners and to encourage increased contributions from all sources. Because 3DHP depends on private sector mapping firms to collect data, jobs will be created as the funding increases. Additional jobs will result when the new applications are developed and implemented based on the 3DHP data, as documented in the HRBS (Dewberry, 2016). At the full funding level for scenario 2, 3DHP could return more than \$1 billion annually in benefits directly to the private sector and indirectly to citizens through improved government program services (Dewberry, 2016).

The project milestones in Figure 9 represent major and time-sensitive accomplishments leading to the successful implementation of the 3DHP. The schedule is based on assumptions of successfully securing community-wide funding and additional assumptions of products and services as described in the figure.  A critical transition will occur during 2023, as development on the legacy datasets – NHD, WBD, and NHDPlus HR – is brought to a close and data acquisition and production shift to 3DHP.  Static versions of the legacy datasets will be published and continue to be available to support existing applications while 3DHP data are acquired, validated, and published.

The general schedule and implementation milestones for 3DHP (contingent upon funding).
Figure 9: The general schedule and implementation milestones for 3DHP.


Research Requirements

The 3DHP planning process identified numerous issues or questions for which additional assessments, evaluations, or research are required. Operational development will be undertaken by the USGS National Geospatial Program (NGP), National Geospatial Technical Operations Center.  More fundamental geospatial and hydrological research will be carried out by the USGS Center of Excellence for Geospatial Information Science, the USGS Water Resources Mission Area, and the broader community of researchers and users.  The near-term and immediate research requirements have been identified, and the research agenda will be managed as a cohesive activity within the USGS NGP.

To address emerging needs and to test emerging technologies, the development strategy for the 3DHP Infostructure calls for an iterative evolution of products and services. Development teams will advance a core functionality, and through feedback from the community the 3DHP Infostructure will be improved. User community input and collaboration will also be provided by the 3DHP Working Group. Over time, the 3DHP Infostructure will evolve to improve functionality and grow additional partnerships through the community.



In 1884, Congress authorized the U.S. Geological Survey to begin systematic topographic mapping of the United States. The implementation of 3D National Hydrography Program marks the beginning of a new era of water data. The public and private sectors that depend on high-quality water data have expressed the need for much better information to answer the most demanding water resource management questions. USGS proposes to work with partners to share the costs of a new program that will address these needs in approximately nine years, assuming the community funds are available to complete the work. Federal, State, Tribal, and local governments are making independent investments to improve their water information, and without a coordinated effort their investments are not contributing to a consistent set of national water data. Government agencies need to respond to this Call for Action to implement the 3DHP Datasets and Infostructure as the universal geospatial underpinnings for water information. The return on investment is significant. The need to support better water resources decisions cannot be overstated. Together, the community can achieve 3D Hydrography Program.



Dewberry, 2016, National Hydrography Requirements and Benefits Study―Preliminary results: Fairfax, Va., Dewberry, May 20, 2016, 139 p. plus appendixes, accessed January 28, 2022, at

Federal Geographic Data Committee, 2021, FGDC Technical Guidance: and The GeoPlatform Metadata Recommendations Including Guidelines for National Geospatial Data Assets (NGDA), accessed January 28, 2022, at

USGS, 2022, Hydrography Standards and Specifications, accessed January 28, 2022 at

USGS, 2022, What is 3DEP, Accessed January 28, 2022 at


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