NSDI Description - These data contain georeferenced digital representations of terrestrial surfaces, natural or manmade, which describe vertical position above or below a datum surface. Data may be encapsulated in an evenly spaced grid (raster form) or randomly spaced (triangular irregular network, hypsography, single points). The elevation points can have varying horizontal and vertical resolution and accuracy.
The National Digital Elevation Program (NDEP) has leveraged limited federal and state agency resources to improve national elevation data availability and quality. However, a national strategy and sufficient funds to implement national coverage do not currently exist. Consequently, the majority of U.S. elevation data are more than 30 years old, 10 meters in resolution or coarser, and do not support current and emerging requirements. To more fully understand and better meet federal, state, local, and tribal needs, NDEP is sponsoring a National Enhanced Elevation Requirements and Benefits Assessment. The assessment will provide implementation options for optimizing the balance between cost and benefits in meeting priority national information needs. The assessment will also address these fundamental questions prior to detailed program planning: Is it more cost effective for the government to manage elevation activities within the context of a national program? Are there additional national or agency benefits derived from such a strategy? What does the optimized program look like?
The assessment is inclusive with respect to public and private input since no one sector can speak to all of the business requirements supported by elevation data. The assessment will help discover economies of scale, potential multiple data uses, and common business requirements that can be met through a more comprehensive national strategy for improving elevation data in the United States and its territories, including coastlines.
Theme Uses - Floodplain mapping, site suitability, habitat modeling, forest management, and fire management.
http://atlas.ca.gov/download.html#/casil/elevation/ned
Elevation data, geodetic control and imagery are the fundamental data building blocks of geographic information systems. Together, they create a foundation for interpreting or extracting other data, such as transportation infrastructure, water features and buildings. Without a geospatial foundation anchored by elevation data, it will not be possible to support science and operational decision-making. Specific benefits of improved elevation data include:
• Better floodplain models for insurance rate calculations and emergency response
• Improved delineation of buildings and facilities for property valuation
• Improved decision-making for environmentally sound and economically beneficial infrastructure planning and industrial development
• Improved forest biomass estimates and fire fuels models to access carbon sequestration, forest health and fire risk
• Improved landslide and fault mapping to mitigate risks to people and property
• Improved farming operations and farm assistance for sustainable food production
• Significantly improved geologic mapping and knowledge of energy resources
• Refined land-use maps to support detailed urban and regional planning
• Better surface hydrology information for water management
• Improved soil surveys to support conservation
• Improved siting of wind and solar power activities
Statewide Data Source - USGS Digital Elevation Models (DEM) are the only seamless elevation data covering all of California available in public domain. Many cities and counties have LiDAR or other higher-quality data for specific areas, but these data are not all produced with consistent standards or made publicly available. The new USGS virtual Center for LIDAR Information Coordination and Knowledge (CLICK) was designed to assist users in accessing LIDAR remote sensing data and provide information to help facilitate LIDAR innovation in the scientific community. By having access to data and information that was traditionally cost prohibitive, scientists have the opportunity to incorporate LIDAR data into their applications, thus adding the vertical component to their research. CLICK’s mission is to facilitate data access, user coordination, and educate the science community about LIDAR’s value to their projects. The CLICK web portal (http://lidar.cr.usgs.gov) is a place for all LIDAR users inside and outside the USGS to visit, ask and answer questions, and coordinate with others who are looking for or have data in their study area. The main mission of this virtual center is to invite people in the LIDAR community to come to exchange ideas, information, and even raw point cloud data for scientific (e.g., non-mapping) needs.
Source Description - A DEM is a digital file consisting of terrain elevations for ground positions at regularly spaced horizontal intervals. The US Geologic Survey (USGS) produces five different digital elevation products. Although all are identical in the manner the data are structured, each varies in sampling interval, geographic reference system, areas of coverage, and accuracy; with the primary differing characteristic being the spacing, or sampling interval, of the data. (http://rmmcweb.cr.usgs.gov/elevation/dpi_dem.html)
Status - Existing. The highest available resolution for USGS DEMs is at a 10 - meter sampling interval. However, a 3-meter resolution dataset is in development. DEMs are distributed through: http://data.geocomm.com/dem/demdownload.html
American Recovery and Reinvestment Act funds to USGS for LiDAR will collect data for several areas in California:
Channel Islands
Marin and SF Counties, and part of San Mateo County
SF Bay perimeter (to compliment the NOAA data collection)
Santa Cruz County and parts of Monterey and San Benito Counties
Analysis - The USGS DEMs source data in the public domain is useful to support statewide and regional elevation analysis. As with imagery, there are a number of commercial sources of elevation data that better meet the needs of public and private elevation needs. The trend is for ever increasing levels of accuracy and currency. New data capture techniques such as LiDAR and IFSAR are commercially available for entire statewide geographic coverage. The November 2005 California Geospatial Framework Survey found that there is a strong interest in high accuracy elevation data for use in hydrologic modeling in flood-prone areas.
Standards - Information on the FGDC Content Standard for Framework Land Elevation Data can be found at: http://www.fgdc.gov/standards/projects/FGDC-standardsprojects/ elevation/index_html Information on the USGS Digital Elevation Model Standards can be found at: http://rockyweb.cr.usgs.gov/nmpstds/demstds.html
Potential Data Hosts - A potential host for a seamless statewide data set has not been identified.