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Dean B. Gesch

Publications and source records attributed to Dean B. Gesch.

50 records · Page 3Linked to original sources
USGS2011

ASTER Global Digital Elevation Model Version 2 - summary of validation results

On June 29, 2009, NASA and the Ministry of Economy, Trade and Industry (METI) of Japan released a Global Digital Elevation Model (GDEM) to users worldwide at no charge as a contribution to the Global Earth Observing System of Systems (GEOSS). This “version 1” ASTER GDEM (GDEM1) was compiled from over 1.2 million scenebased DEMs covering land surfaces between 83°N and 83°S latitudes. A joint U.S.-Japan validation team assessed the accuracy of the GDEM1, augmented by a team of 20 cooperators. The GDEM1 was found to have an overall accuracy of around 20 meters at the 95% confidence level. The team also noted several artifacts associated with poor stereo coverage at high latitudes, cloud contamination, water masking issues and the stacking process used to produce the GDEM1 from individual scene-based DEMs (ASTER GDEM Validation Team, 2009). Two independent horizontal resolution studies estimated the effective spatial resolution of the GDEM1 to be on the order of 120 meters. A second version of the ASTER GDEM (GDEM2) is scheduled for release by NASA and METI in mid-October, 2011. Improvements in the GDEM2 result from acquiring 260,000 additional scenes to improve coverage, a smaller correlation kernel to yield higher spatial resolution, and improved water masking. As with the GDEM1, the GDEM2 validation was performed by the U.S. and Japanese partners. Vertical accuracy assessments included a comparison of the GDEM2 against absolute geodetic references over the Conterminous US (CONUS), against national elevation grids over the US and Japan, against the Shuttle Radar Topography Mission (SRTM) 1 arc-second elevation grids over the US and 20 sites around the globe, and against space borne laser altimeter data globally. Horizontal accuracy assessments were conducted as part of the Japan and the global SRTM studies, and horizontal resolution studies were conducted in both Japan and the US. Each group documented changes in artifacts in GDEM2 due to processing improvements. The absolute vertical accuracy study found the GDEM2 to be within -0.20 meters on average when compared against 18,000 geodetic control points over the CONUS, with an accuracy of 17 meters at the 95% confidence level. The Japan study noted the GDEM2 differed from the 10-meter national elevation grid by -0.7 meters over bare areas, and by 7.4 meters over forested areas. Similarly, the CONUS study noted the GDEM2 to be about 8 meters above the 1 arc-second NED over most forested areas, and more than a meter below NED over bare areas. The global altimeter study found the GDEM2 to be on average within 3 meters of altimeter-derived control, and also documented sensitivity to tree canopy height. The Japan study noted that the horizontal displacement in GDEM1 of 0.95 pixels was reduced to 0.23 pixels in GDEM2. Both teams noted improvements in horizontal resolution, between 71 and 82 meters, comparable to the SRTM 1 arc second elevation model, but at the cost of some increased noise. The number of voids and artifacts noted in GDEM1 were substantially reduced in GDEM2, and in some areas virtually eliminated. Based on these findings, the GDEM validation team recommends the release of the GDEM2 to the public, acknowledging that, while vastly improved, some artifacts still exist which could affect its utility in certain applications.

Report↗
USGS2009

Mapping and Visualization of Storm-Surge Dynamics for Hurricane Katrina and Hurricane Rita

The damages caused by the storm surges from Hurricane Katrina and Hurricane Rita were significant and occurred over broad areas. Storm-surge maps are among the most useful geospatial datasets for hurricane recovery, impact assessments, and mitigation planning for future storms. Surveyed high-water marks were used to generate a maximum storm-surge surface for Hurricane Katrina extending from eastern Louisiana to Mobile Bay, Alabama. The interpolated surface was intersected with high-resolution lidar elevation data covering the study area to produce a highly detailed digital storm-surge inundation map. The storm-surge dataset and related data are available for display and query in a Web-based viewer application. A unique water-level dataset from a network of portable pressure sensors deployed in the days just prior to Hurricane Rita's landfall captured the hurricane's storm surge. The recorded sensor data provided water-level measurements with a very high temporal resolution at surveyed point locations. The resulting dataset was used to generate a time series of storm-surge surfaces that documents the surge dynamics in a new, spatially explicit way. The temporal information contained in the multiple storm-surge surfaces can be visualized in a number of ways to portray how the surge interacted with and was affected by land surface features. Spatially explicit storm-surge products can be useful for a variety of hurricane impact assessments, especially studies of wetland and land changes where knowledge of the extent and magnitude of storm-surge flooding is critical.

Scientific Investigations Report↗
USGS2009

Coastal sensitivity to sea level rise— A focus on the Mid-Atlantic Region

This Synthesis and Assessment Product (SAP), developed as part of the U.S. Climate Change Science Program, examines potential effects of sea-level rise from climate change during the twenty-first century, with a focus on the mid-Atlantic coast of the United States. Using scientific literature and policy-related documents, the SAP describes the physical environments; potential changes to coastal environments, wetlands, and vulnerable species; societal impacts and implications of sea-level rise; decisions that may be sensitive to sea-level rise; opportunities for adaptation; and institutional barriers to adaptation. The SAP also outlines the policy context in the mid-Atlantic region and describes the implications of sea-level rise impacts for other regions of the United States. Finally, this SAP discusses ways natural and social science research can improve understanding and prediction of potential impacts to aid planning and decision making. Projections of sea-level rise for the twenty-first century vary widely, ranging from several centimeters to more than a meter. Rising sea level can inundate low areas and increase flooding, coastal erosion, wetland loss, and saltwater intrusion into estuaries and freshwater aquifers. Existing elevation data for the mid-Atlantic United States do not provide the degree of confidence needed for local decision making. Systematic nationwide collection of high-resolution elevation data would improve the ability to conduct detailed assessments in support of planning. The coastal zone is dynamic and the response of coastal areas to sea-level rise is more complex than simple inundation. Much of the United States consists of coastal environments and landforms such as barrier islands and wetlands that will respond to sea-level rise by changing shape, size, or position. The combined effects of sea-level rise and other climate change factors such as storms may cause rapid and irreversible coastal change. All these changes will affect coastal habitats and species. Increasing population and development in coastal areas also affects the ability of natural ecosystems to adjust to sea-level rise. Coastal communities and property owners have responded to coastal hazards by erecting shore protection structures, elevating land and buildings, or relocating inland. Accelerated sea-level rise would increase the costs and environmental impacts of these responses. Shoreline armoring can eliminate the land along the shore to which the public has access; beach nourishment projects often increase access to the shore. Preparing for sea-level rise can be justified in many cases, because the cost of preparing now is small compared to the cost of reacting later. Examples include wetland protection, flood insurance, longlived infrastructure, and coastal land-use planning. Nevertheless, preparing for sea-level rise has been the exception rather than the rule. Most coastal institutions were based on the implicit assumption that sea level and shorelines are stable. Efforts to plan for sea-level rise can be thwarted by several institutional biases, including government policies that encourage coastal development, flood insurance maps that do not consider sea-level rise, federal policies that prefer shoreline armoring over soft shore protection, and lack of plans delineating which areas would be protected or not as sea level rises. The prospect of accelerated sea-level rise and increased vulnerability in coastal regions underscores the immediate need for improving our scientific understanding of and ability to predict the effects of sea-level rise on natural systems and society. These actions, combined with development of decision support tools for taking adaptive actions and an effective public education program, can lessen the economic and environmental impacts of sea-level rise.

Report↗
USGS2008

An enhanced global elevation model generalized from multiple higher resolution source datasets

Global digital elevation models are routinely used in a variety of earth science applications. GTOPO30, a widely used global elevation model produced by the U.S. Geological Survey, was produced in the mid-1990s from several regional sources of elevation information. Since the time GTOPO30 was developed, new and improved sources of elevation data have become available, and the U.S. Geological Survey and the National Geospatial-Intelligence Agency are collaborating on the development of a notably enhanced global elevation model that will replace GTOPO30 as the elevation dataset of choice for global and continental scale applications. The new model is being generated at three separate resolutions (horizontal post spacings) of 30 arc-seconds (about 1 kilometer), 15 arc-seconds (about 500 meters), and 7.5 arc-seconds (about 250 meters). An additional advantage of the new multiresolution global model over GTOPO30 is that seven new raster elevation products will be available at each resolution. The new elevation products are being produced using the following aggregation methods: minimum elevation, maximum elevation, mean elevation, median elevation, standard deviation of elevation, systematic subsample, and breakline emphasis. The primary source dataset for the new global model is the Shuttle Radar Topography Mission 1-arc-second data. When complete, the new global model will undergo a thorough accuracy assessment against reference geodetic control and a relative comparison against the existing GTOPO30 at the 30-arc-second resolution. Full documentation describing the input datasets, the processing, the characteristics of the new global model product layers, and the accuracy assessment results will be available to users. The development of the new global elevation model is in progress, with completion scheduled for mid-2009.

Conference Paper↗
USGS2006

The global topography mission gains momentum

An accurate description of the surface elevation of the Earth is of fundamental importance to many branches of Earth science. Continental topographic data are required for studies of hydrology, ecology, glaciology, geomorphology, and atmospheric circulation. For example, in hydrologic and terrestrial ecosystem studies, topography exerts significant control on intercepted solar radiation, water runoff and subsurface water inventory, microclimate, vegetation type and distribution, and soil development. The topography of the polar ice caps and mountain glaciers directly reflects ice-flow dynamics and is closely linked to global climate and sea level change.

Eos, Transactions, American Geophysical Union↗
USGS2006

CLICK: The new USGS center for LIDAR information coordination and knowledge

Elevation data is rapidly becoming an important tool for the visualization and analysis of geographic information. The creation and display of three-dimensional models representing bare earth, vegetation, and structures have become major requirements for geographic research in the past few years. Light Detection and Ranging (lidar) has been increasingly accepted as an effective and accurate technology for acquiring high-resolution elevation data for bare earth, vegetation, and structures. Lidar is an active remote sensing system that records the distance, or range, of a laser fi red from an airborne or space borne platform such as an airplane, helicopter or satellite to objects or features on the Earth’s surface. By converting lidar data into bare ground topography and vegetation or structural morphologic information, extremely accurate, high-resolution elevation models can be derived to visualize and quantitatively represent scenes in three dimensions. In addition to high-resolution digital elevation models (Evans et al., 2001), other lidar-derived products include quantitative estimates of vegetative features such as canopy height, canopy closure, and biomass (Lefsky et al., 2002), and models of urban areas such as building footprints and three-dimensional city models (Maas, 2001).

Photogrammetric Engineering and Remote Sensing↗
USGS2005

Collection and analysis of high-resolution elevation data for the Lincoln Lidar Project, Lincoln, Nebraska, 2004

The Lincoln Lidar Project was a partnership developed between the U.S. Geological Survey National Center for Earth Resources Observations and Science (EROS), Lancaster County and the city of Lincoln, Nebraska. This project demonstrated a successful planning, collection, analysis and integration of high-resolution elevation information using Light Detection and Ranging, (Lidar) data. This report describes the partnership developed to collect local Lidar data and transform the data into information useable at local to national levels. This report specifically describes project planning, quality assurance, processing, transforming raw Lidar points to useable data layers, and visualizing and disseminating the raw and final products.

Nebraska↗
USGS2005

Analysis of multi-temporal geospatial data sets to assess the landscape effects of surface mining

Geospatial data sets, especially digital elevation data, have proven useful for characterizing and analyzing land surface conditions. Digital elevation models are routinely used for describing the morphology of the land surface in terms of slope gradient and aspect. Additionally, the elevation data are useful for deriving parameters that describe the local drainage conditions such as watersheds and stream channels. When the element of time is added to the analysis through the use of multi-temporal topographic data, the effects of changes to the physical shape of the land surface may be studied. Such is the case with analysis of historical (pre-mining) and recent (post-mining) topographic and other geospatial data sets, including land cover maps derived from remote sensing. Nationwide geospatial data sets now exist with the required spatial and temporal resolution that allow for assessment of the effects of surface mining operations. Changes to the local landscape morphology are readily identified, and the effects to the surface drainage features are quantifiable, such as changes to local relief and drainage pattern and the total length of affected streams. Additionally, the visual impact of the movement of rock and soil materials may be assessed through viewshed analysis. Examples in both Appalachian and Western coalfields show the usefulness of analyzing detailed historical and recent geospatial data sets to better map and describe the effects of surface mining.

Kentucky↗
USGS2002

The national elevation data set

The NED is a seamless raster dataset from the USGS that fulfills many of the concepts of framework geospatial data as envisioned for the NSDI, allowing users to focus on analysis rather than data preparation. It is regularly maintained and updated, and it provides basic elevation data for many GIS applications. The NED is one of several seamless datasets that the USGS is making available through the Web. The techniques and approaches developed for producing, maintaining, and distributing the NED are the type that will be used for implementing the USGS National Map (http://nationalmap.usgs.gov/).

Photogrammetric Engineering and Remote Sensing↗
USGS1994

Topographic data requirements for EOS global change research

This document is a result of Earth Observing System Data and Information System (EOSDIS) Version 0 activities of the Land Processes Distributed Active Archive Center at the U.S. Geological Survey's EROS Data Center. A relatively small part of the Version 0 funding provided by NASA is used to address topographic data issues related to EOS. These issues include identifying and improving access to existing sources of topographic data, data generation, facilitating the use of topographic data in global change research by demonstrating derivative products, and inventorying the specific topographic data requirements of EOS investigators. There is a clear need for global topographic data in EOSDIS. Only 10 percent of the global land surface is covered by high-resolution data that are available to the global change science community. Alternative sources for new data exist or have been proposed; however, none of them alone can fulfill the data requirements by the launch of the first EOS platform in 4 years. There is no operational provider of all the source data that are required. Even if appropriate global source data existed, a concerted production effort would be necessary to ensure the existence of the requisite topographic data before EOS launch. Additionally, no funding from NASA or any other agency has been appropriated for a new mapping mission or for other means of data acquisition. This effort to document requirements is an initial step toward understanding the severity of the data shortage. It is well beyond the scope of Version 0 funding and capabilities to provide the required data in the proper timeframe. The shortage of data and the lack of a plan for providing the necessary topographic data through EOSDIS in time for launch are issues that must be addressed by the EOS program.

Open-File Report↗
USGS1993

Identification of requirements and sources for global digital topographic data

Many of the physical processes being studied by global change researchers are affects by land surface topography and consequently topographic data are an important requirement for these investigations. Remotely sensed data, especially those that will be collected by the instruments of the Earth Observing System, require significant correction to remove topographic effects. Although some requirements are met by existing topographic data, there are serious data shortages that will affect global change science. The interdisciplinary and multi temporal natural of global change research requires that remotely sensed data be processed using a consistent, highly accurate global topographic database so that information extracted from these data for different areas and times can be compared quantitively. Cartographic and remote sensing sources for the generation of new topographic data exist or are planned and will be helpful for fulfilling these requirements. More consistent use of accuracy statement terminology by data users and producers is necessary to better compare the requirements with existing or future data sets.

Pecora 12 Symposium↗