A Roadmap to a Seamless Topobathy Surface
Bringing together the resources to simplify coastal digital elevation models
A topobathy digital elevation model (DEM) is a single surface that combines the land elevation with the seafloor surface and which can be used to examine processes that occur across the coastal and nearshore areas. Using a high-accuracy seamless topobathy DEM is essential to understanding where water will move when modeling processes such as sea level rise, hurricane flooding, tsunami inundation, and riverine flooding. This series of products will help users create seamless coastal maps, a task that has been highlighted as an important national need by the National Research Council.
A Roadmap to a Seamless Topobathy Surface (Roadmap) is a series of documents and maps that seeks to improve and streamline the process of creating a seamless topobathy DEM. It aims to make topographic and bathymetric data and reference information accessible and make connections between data set quality and DEM application (such as coastal inundation modeling). Understanding the links between input data quality and application can help create a DEM surface designed for a particular use and help data collectors provide data sets that meet needs. Roadmap resources may also be useful to managers who are involved in activities such as planning a data collection. The Roadmap examines resources and processes associated with DEM creation, including the following:
- Publicly-available data sets and access information
- Processes to generate high-resolution DEMs that minimize error
- Examples of coastal applications of high-accuracy elevation data
Topographic and Bathymetric Data Inventory
The first part of the Roadmap series is a regional inventory of available topographic and bathymetric data resources. The Inventory portrays available resources along the Gulf of Mexico, Southeast Atlantic, and Lake Ontario coasts and is designed to increase awareness and use of existing topographic and bathymetric data sets. It can be used to decrease duplication of effort and strategically targets data collections to fill gaps. The Inventory is a "snapshot" of data availability (completion date varies by region), and it identifies location, collection date, and sources of available data sets, at a minimum. Where additional information about data sets is available, 20 attributes, including vertical accuracy, datums, and point spacing, are provided.
Topographic and Bathymetric Data Considerations
"Topographic and Bathymetric Data Considerations: Datums, Datum Conversion Techniques, and Data Integration (Data Considerations)" is the second part of the Roadmap. It is important for a surface to have data inputs that are positioned in reference to the same metric if it is used to accurately portray the nearshore and coastal areas. The consequences of having mismatched datum references can show up in the DEM grid as a sharp drop-off in the data or as a wall; either of these will have a large impact on how water flows across the land-water interface. This document strives to improve and streamline the process of creating DEMs by providing a review of available datum conversion and integration techniques. It describes the importance of establishing a uniform reference for multiple data sets and techniques for manipulating and joining data sets.
Coastal Applications of High Resolution Elevation Data
The third part of the Roadmap, the Coastal Applications slide show, highlights some common coastal applications that can benefit from a high-accuracy, high-resolution DEM. This reference describes applications of topographic, bathymetric, and topobathy DEMs and how elevation data are used to inform each coastal management decision. Some examples of coastal issues addressed are shoreline delineation, wetland mapping, and inundation modeling.
Additional Resources
Additional on-line topobathy resources can be found on the Additional Topobathy Resources page.
For more information, please contact the NOAA Coastal Services Center.
