Skip to main content
U.S. flag

An official website of the United States government

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

By Rebecca Anderson, Vicki Lukas, and Stephen S. Aichele



Introducing the 3D Hydrography Program

Building on decades of experience developing and managing the National Hydrography Datasets – the National Hydrography Dataset (NHD, the Watershed Boundary Dataset (WBD), and the NHDPlus High Resolution (NHDPlus HR) - the U.S. Geological Survey (USGS) is establishing the 3D Hydrography Program (3DHP) to completely refresh the Nation’s hydrography data and improve discovery and sharing of water-related data. The implementation of the 3DHP marks the beginning of a new era of water data, and the first systematic remapping of the Nation’s hydrography since the original USGS 1:24,000-scale topographic mapping program was active between 1947 and 1992.  

When fully implemented, the 3DHP is estimated to have the potential to provide more than \$1 billion in benefits to Federal, State, Tribal, Territorial, and local governments and to private and nonprofit organizations every year, in addition to myriad societal benefits (Dewberry, 2016, p. 14). The 3DHP initiative would directly support better decision making across myriad applications 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; thus, it will provide 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.

3DHP Figure 1: Improved Alignment and feature density
Figure 1: Graphic showing the improved alignment possible in the 3D Hydrography Program by deriving hydrography data from high-quality 3DEP elevation data. 

The 3DHP will significantly improve the level of detail, currency, and content of hydrography data by deriving (1) three-dimensional (3D) stream network datasets and watersheds from high-quality 3D Elevation Program (3DEP; data and (2) other elevation derivatives to support applications like hydrologic and hydraulic modeling (Figure 1). The 3DHP will improve the ability to track information related to water as it moves through the hydrologic cycle by connecting surface-water features traditionally represented in the National Hydrography Dataset (NHD) to data about wetlands, engineered hydrologic systems, and groundwater; it will also improve the attribution of important hydrologic characteristics like streamflow permanence. 

The 3DHP will support an information infrastructure, or “infostructure,” to share and discover water-related data based on the connectivity and flows represented in the improved stream network. The USGS will develop and implement an operational system, including a modernized data model, to support this vision. In line with the Geospatial Data Act of 2018 ( and Federal Geographic Data Committee (FGDC) guidance (FGDC, 2021), 3DHP datasets and infostructure will emphasize being FAIR—Findable, Accessible, Interoperable, and Reusable.

The 3DHP data and capabilities will allow scientists to more fully model the hydrologic cycle, engineers to make better decisions, water suppliers to improve water quality and availability, disaster response planners to mitigate natural disasters, and natural resource managers to better protect the environment. When 3DHP data are widely available, further private sector and government innovations will follow.


Benefits of Hydrography Data

The “National Hydrography Requirements and Benefits Study” (HRBS; Dewberry, 2016) was conducted to document and analyze 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 nonprofit organizations. Participants identified \$538.5 million in annual benefits from the current National Hydrography Datasets and estimated an additional \$602.55 million in annual benefits if all unmet needs could be satisfied (Dewberry, 2016, page 14, table 5), for a total of over \$1.14 billion in benefits each year. The 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.


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 to update and integrate U.S. Geological Survey (USGS) elevation and hydrography data, and the relationships between them, into a 3D model that delivers higher quality data and supports more sophisticated geospatial analysis than was possible with separate datasets. The 3DNTM, including data from the 3D Hydrography Program (3DHP) and the next generation of the 3D Elevation Program (3DEP), is designed to 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 National Hydrography Program Plus High Resolution (NHDPlus HR) baseline datasets are nearing completion. Several pilot projects to test the integration of hydrography and elevation datasets are underway. Two parts of the 3DNTM Call for Action are being developed: part 1 is focused on hydrography, and part 2 is focused on the next generation of 3DEP. Potential plans for later development phases of the 3DNTM include construction of, and a transition to, a fully integrated 3D data model that will include additional topographic datasets of The National Map ( managed by the USGS National Geospatial Program.


3DHP Datasets

The 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. The 3DHP datasets will be built on high-quality, standardized 3DEP data to ensure spatial and temporal consistency across all derived products. This integration will increase usability of 3DHP datasets for applications like flood modeling and prediction, culvert and bridge engineering design, and stormwater management.

The 3DHP datasets will inherit key attributes of the NHD, WBD, and NHDPlus HR, and they 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 attributions 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 less than 1 meter below, and within 2 meters horizontally, of the water surface where depicted in a high-accuracy elevation surface; these standards will greatly improve the positional accuracy of features compared to the accuracy of 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 as needed. 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.

The 3D Hydrography Program (3DHP) will have datasets in an integrated data stack that will include the following:

  • A stream network derived from high-quality elevation data of the 3D Elevation Program (3DEP), with attributions 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
  • Additional attributes that assist with hydrologic and stream network routing and analysis


3DHP Infostructure

3DHP Figure 2: Hydrographically addressed water data visualization
Figure 2: Conceptual graphic illustrating how observations about the Nation’s waters – water-quality information, fish occurrence, flow, bed material, and so on – can be attached to points along the stream network (as shown by the blue pins), or along lengths of the stream network as shown by the magenta pins and line

The 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; the system elements are 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 streamgages to water temperature to the health of fish and aquatic life in a stream. The 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. 

The 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. These tools will provide reference locations on the stream network, similar to street addresses, that can be attached to a user’s data records. The 3DHP search and discovery tools will locate data within the stream network, and they will also help users to understand relationships among different records or observations at different locations, such as the distance between water-quality observations or possible effects of obstacles to fish passage, such as dams, on spawning or the spread of invasive species.  Any kind of water-related information can be given an address on the stream network, including hydrology, geomorphology, water quality, biology, regulations, or public access points (fig. 2).


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 the 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 meet published specifications (U.S. Geological Survey, 2022) regarding the derivation of hydrography features from 1-meter digital elevation models (DEMs) derived from lidar data for the conterminous United States and Hawaii and 5-meter DEMs derived from interferometric synthetic aperture radar (IfSAR) data for Alaska. The 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 the USGS or reported by users will be corrected by USGS data editors; a 3DHP maintenance goal will be to correct errors 1–2 months after they are reported. The stream network will be reviewed on a regional basis every 4–5 years, and regional updates will be applied as needed. In the future, change detection based on either the elevation data or hydrography may trigger updates to 3DHP data. 

The 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 (box 1?). The 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. 

Box 1.  3DHP Data Captures Hydrologic Features

  • Stream network—The stream network will be derived from two types of digital elevation models (DEMs): (1) for the conterminous United States and Hawaii, the 3D Elevation Program (3DEP) data will be from 1-meter standard product DEMs derived from light detection and ranging (lidar) data, and (2) for Alaska, the data will be from 5-meter DEMs derived from interferometric synthetic aperture radar (IfSAR) data. The data 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. 

  • Topobathymetry—The U.S. Geological Survey. (USGS) is researching how to create a continuous topobathymetric surface derived from high-resolution elevation and bathymetry. Plans to advance inland bathymetry towards a more systematic national approach will be addressed in the next generation of 3DEP.

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

  • Groundwater connections—Connections between surface-water 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. 

  • Wetlands - Collaborative mapping of the stream network and the National Wetlands Inventory (NWI) will enable the two datasets to function together as a whole and to accurately depict the inland waters of the United States.

  • Engineered Hydrologic Systems—The 3D Hydrography Program (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.

  • Culverts—Culvert data acquired during the process of deriving hydrography from elevation data will be made available.

  • Addressed data—The 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.

Designing the Program

Program Scenarios

Figure 3: Comparison of three scenarios for the 3D Hydrography Program
Figure 3: Chart comparing three scenarios for the 3D Hydrography Program (3DHP). The U.S. Geological Survey’s vision for 3DHP is based on Scenario 2, which is outlined in yellow in the chart. The scenarios were based on data in Dewberry (2016).  DEMs, digital elevation models.

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

Scenario 1 (status quo) continues management of the current hydrography data with minimal incremental improvements. While the 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 9-year period with data derived from 3DEP-quality lidar data for the conterminous Ulnited States and Hawaii or IfSAR-derived data for Alaska.  This scenario includes 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…. Currently, QL1 data are not readily available across the country, making this scenario difficult to achieve, but it 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 (fig. 3) 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 the HRBS and has the potential to achieve more than \$1.047 billion in annual benefits.


3DHP Potential Community-Wide Nine-Year Costs

Figure 4: Graph showing the proposed community-wide 9-year costs broken out by category for the 3D Hydrography Program (3DHP)
Figure 4: Graph showing the proposed community-wide 9-year costs broken out by category for the 3D Hydrography Program (3DHP).

The 3DHP program of work projects that the 9-year effort will begin in fiscal year 2024 (FY 2024), will have moderate growth for FY 2025, and will have accelerated growth primarily through partnerships in subsequent years. Investments by Federal, State, Tribal, Territorial, and local government entities 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 investment of \$685 million will be required between FY 2024 and FY 2032; the timeframe includes 1 year of preparation, 6 years of delineating hydrography data from 3DEP elevation data, and 2 additional years to complete data validation, processing, and publication after the acquisition period. 

Just as 3DEP was successful in building community partnerships with government agencies and private organizations to fund data acquisition, the 3DHP will follow a similar collaborative funding model that anticipates significant investments by partner organizations for 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 budget for the 3DHP. The cost-sharing model (fig. 4) 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.

Building the Program

Leadership and Governance

Governance of the 3DHP will be led by senior executives from cooperating agencies through the 3DNTM Federal Interagency Coordinating Committee that is being established by the Department of the Interior as part of the National Landslides Preparedness Act.   The committee will oversee the formulation and approval of policies and priorities recommended by the 3DEP and 3DHP Working Groups. The National Hydrography Infrastructure (NHI) Working Group, created in 2018 as a forum for Federal agencies, has transitioned to 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 prioritizing and coordinating data acquisition.


Partnering to Acquire Data

Figure 5: Chart showing phases of data acquisition, processing, and delivery to partners and the public for the 3DHP
Figure 5: Chart showing phases of data acquisition, processing, and delivery to partners and the public for the 3D Hydrography Program (3DHP). The phases are similar to those used for the 3D Elevation Program (3DEP). USGS, U.S. Geological Survey.

To be successful, the 3DHP must build on existing relationships to establish a systematic and unified process for data acquisition partnerships. The 3DHP will use a partnership-based acquisition model, in alignment with the one used for 3DEP data acquisition (fig. 5). When USGS funding is available, partners will be able to propose acquisition projects that use the USGS Geospatial Products and Services Contracts (GPSC) or their own contracts to acquire data that meet the 3DHP specifications. Organizations may also contribute data that meet 3DHP specifications that were acquired independently, and the USGS will implement a standard procedure for reviewing those datasets for inclusion in the 3DHP.
The 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 multipartner and multistate funding coalitions.


Collaborating to Build the Internet of Water

Community collaboration and cooperation are core components of the 3DHP, the 3DHP infostructure, and the Internet of Water. While the 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 the 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 a user base for 3DHP products and toward gathering feedback to ensure that the 3DHP is responsive to the needs of government and private sector users. Equally important is a focus on building support and a community-wide funding base to move the program forward.


Roles and Responsibilities

Figure 6: Chart showing the roles to be played in the 3D Hydrography Program (3DHP)
Figure 6: Chart showing the roles to be played by the U.S. Geological Survey (USGS), Federal partners, State and local partners, the private sector, and users in the 3D Hydrography Program (3DHP). Roles include managing the program, acquiring and validating data, and delivering products to partners and the public.

The whole water-resources community will have a role to play in 3DHP, from partnerships, to data development, to creating new and unimagined applications (fig. 6). Today, States are major contributors of data and often lead statewide acquisition and maintenance programs through stewardship agreements with the USGS. The 3DHP will not include a formalized stewardship program. Rather, the 3DHP will focus on cooperative community data acquisition, and building and responding to a network of users with local knowledge who improve 3DHP data by reporting errors. 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.


As proposed, the 3DHP effort would begin providing products and services to partners and the public by the end of 2023. 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, the 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). 



Figure 7: Chart showing the general schedule and implementation milestones for the 3D Hydrography Program (3DHP)
Figure 7: Chart showing the general schedule and implementation milestones for the 3D Hydrography Program (3DHP). Terms: 3DNTM, 3D National Topography Model; CONUS, conterminous United States; FY, fiscal year; HI, Hawaii; NHDPlus HR, National Hydrography Dataset Plus High Resolution.

The project milestones shown in figure 7 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 maintenance 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. 


Research Requirements

The 3DHP planning process identified numerous issues or questions for which additional assessments, evaluations, and research are required. A 3DNTM research plan that addresses both 3DHP and next generation 3DEP research needs will be completed by the end of Fiscal Year 2024.  Operational development will be undertaken by the USGS 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 by 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.


The implementation of 3D Hydrography Program (3DHP) 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 questions about water-resource management. The USGS proposes to work with partners to share the costs of a new program that will address these needs in approximately 9 years if 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. If government agencies respond to this Call for Action, then the community can implement the 3DHP datasets and infostructure as the National geospatial underpinnings for water information. The return on investment has the potential to be significant. The need to support better water-resources decisions cannot be overstated. Together, the community members can achieve the 3D Hydrography Program.


References Cited


For additional information, contact:

Director, National Geospatial Program
U.S. Geological Survey
Mail Stop 511
12201 Sunrise Valley Drive
Reston, VA 20192

Questions related to 3DNTM - 3DHP