Hydrography Data in the US Require Attention

An extensive Report Card on the US National Spatial Data Infrastructure (NSDI) was published earlier this year by the Coalition of Geospatial Organizations (COGO). One of the seven data themes assessed, the Hydrography Data theme, scored a mediocre grade of C. More work needs to be done to efficiently coordinate data collection and to improve quality control. But the overall picture is rather positive.

The National Hydrography Dataset (NHD) is the surface-water component of the National Map of the United States. This dataset encompasses oceans and coastlines, and it is the primary national hydrography data product for the US. Hydrography is valuable to many applications; many users need hydrographic features as reference or base map data. Other applications, particularly environmentally oriented analyses, need the information to analyse and model water supply, pollution, flood hazard, wildlife and land suitability.

Coordination

Federal leadership for the collection, production and distribution of hydrography data has been provided by the US Geological Survey (USGS) and the Environmental Protection Agency (EPA). “There has been good coordination among the federal agencies that require these data for their program and mission needs and with non-federal entities”, states the Report Card’s panel of experts. But because hydrography data are consistently identified as a critical dataset for a wide variety of uses at all levels of government and within the non-governmental sectors, the panel emphasises that this data theme requires attention. “More work needs to be done to better leverage budgets, coordinate data collection efforts, and collaborate across levels of government.”

There are numerous possibilities to leverage and coordinate data collection efforts. For example, the lead agencies at the Federal level, including both the USGS and EPA, coordinate their efforts with the Spatial Water Data Subcommittee, which has the responsibility to develop water resource components of the NSDI. This subcommittee is sponsored by the Federal Geographic Data Committee, responsible for the National Spatial Data Infrastructure of the US. The Spatial Water Data Subcommittee is also part of the Advisory Committee on Water Information (ACWI), which has to coordinate Water Resources Information. ACWI represents the interests of water-oriented organisations, and has 35 members who are appointed by the Secretary of the Interior. Via the ACWI, these organisations coordinate their programmes and advise the federal government on their activities and plans. Members are selected from among a wide variety of organisations including federal agencies, professional water-related associations, state and county water-related associations, academia, private industry, water utility associations, civil engineering societies, watershed and land conservation associations, ecological societies, lake, coastal, and ocean associations, and environmental and educational groups. Less is more?

Access and Exchange

The NHD provides consistent accessible hydrography data across the nation. Most datasets are publicly available through the National Map, EPA data portals, federal government clearinghouses and other web portals. Further information and downloadable data are available at nhd.usgs.gov. The NHD is also accessible through the NSDI Clearinghouse at the Geoplatform.gov portal.
In 34 states hydrographic data are available through a public state-maintained web mapping service, but only in 17 states are these data publicly available for re-use without restrictions.
US and international standards are accommodating the exchange and integration of hydrography data with other data of the NSDI framework. The Federal Geographic Data Committee has developed the Geographic Information Framework Data Content Standard, endorsed in 2008, and hydrography is one of the parts of this standard. The standard defines the components of networked and non-networked surface water features, and enhances data sharing and applications development when used with standards-based web services or file transfer.
The standard anticipates that multiple representations of hydrographic features exist within specific application communities, and accommodates the exchange of these multiple representations. A Framework Standards Guidance Document is available on the FGDC website to facilitate the process of creating new standardised data or to harmonise and transform existing data to match standardised content.

Quality

The NHD is available nationwide in two seamless datasets. One of these datasets is based on 1:24,000-scale topographic mapping, known as the high-resolution NHD, and the other is based on 1:100,000-scale topographic mapping, known as the medium-resolution NHD. It is also becoming available in select areas based on larger scales such as 1:5,000 mapping.
The National States Geographic Information Council (committed to efficient and effective government through the prudent adoption of geospatial information technologies) did a geospatial maturity assessment in the US and included questions about hydrography data. Of the 50 states in the US, 29 have 96% or greater completeness, but 17 have less. Five states have no programme for developing statewide hydrography data.
The US Geological Survey did some research in 2009 comprising hydrography data. In its ‘National Map Customer Requirements’ hydrography was ranked as the fourth highest requirement. The NHD provides a network that supports the analysis of any type of movement by surface waters, such as navigation, sediment transport and effluent dispersion. However, the level of accurate integration with the National Elevation Dataset was not sufficient to meet analysis or basic mapping needs. The panel of experts stipulates that the National Hydrography Dataset is one of the datasets most often cited as needing better quality control.

To complete the picture, it should be mentioned here that since 2013 the US Geological Survey is indeed providing national management to facilitate the overall maintenance process because “users demand greater accuracy,” as stated on the USGS website. A ‘stewardship’ agency in each state manages the maintenance activities within that state, trained by and under quality assurance of the USGS. Updates to the National Hydrography Dataset are made by the stewards, and processed by the USGS for national distribution.

About COGO

The Coalition of Geospatial Organizations (COGO) is a coalition of 13 national professional societies, trade associations, and membership organisations in the geospatial field, representing more than 170,000 individual producers and users of geospatial data and technology.

Evaluation

This year, the Coalition of Geospatial Organizations (COGO) in the US published a Report Card that is intended to address the condition of the US National Spatial Data Infrastructure, and to spur future progress. The completeness and suitability of data on the basic themes – from cadastral to transportation – was evaluated during 2014 by a seven-member expert panel chaired by former Governor of Wyoming James E. Geringer, who is currently the director of policy and public sector strategies with Esri. The panel also included vice-chairs
Dr. David Cowen, Professor Emeritus of the University of South Carolina, and John J. Moeller, former staff director of the Federal Geographic Data Committee.

More information

www.cogo.pro