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Jeffrey J Danielson

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Located in the northern tropical Pacific Ocean, Majuro is the capital of the Republic of the Marshall Islands. Majuro Atoll consists of a large, narrow landmass and a set of smaller perimeter islands surrounding a lagoon that is over 100 square miles in size. The waters surrounding the Majuro Atoll land areas are relatively shallow with poorly mapped bathymetry. However, the Pacific Ocean on the exterior of the coral atoll and the lagoon within its interior consist of deep bathymetry with steep slopes. The highest elevation of the Majuro Atoll is estimated at only 3-meters above sea level, which is the island community of Laura located on the western part of the atoll. At the eastern edge of the atoll lies the capital...
Categories: Data; Tags: 3D Elevation Program, 3DEP, American Society of Photogrammetry and Remote Sensing, Base Maps, Bathymetric, All tags...
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U.S. Geological Survey (USGS) scientists completed a multidisciplinary data collection effort during the week of October 21-25, 2019, using new technologies to map and validate bathymetry over a large stretch of the non-tidal Potomac River. The work was initiated as an effort to validate commercially-acquired topobathymetric light detection and ranging (lidar) data funded through a partnership between the USGS and the Interstate Commission on the Potomac River Basin (ICPRB). The goal was to compare airborne lidar data to bathymetric data collected through more traditional means (boat-based sonar, wading Real Time Kinematic Global Navigational Satellite System (RTK-GNSS) surveys) and through unmanned aerial systems...
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Low-lying island environments, such as the Majuro Atoll in the Republic of the Marshall Islands, are particularly vulnerable to inundation (coastal flooding) whether the increased water levels are from episodic events (storm surge, wave run-up, king tides) or from chronic conditions (long term sea-level rise). Land elevation is the primary geophysical variable that determines exposure to inundation in coastal settings. Accordingly, coastal elevation data are a critical input for assessments of inundation exposure and vulnerability. Previous research has demonstrated that the quality of data used for elevation-based assessments must be well understood and applied to properly model potential impacts. The vertical...
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Sea-Level Rise Viewer for American Samoa: A Co-Developed Visualization and Planning Tool
American Samoa is vulnerable to sea-level rise in part due to the steep terrain of its islands. This terrain requires the majority of the islands’ villages and infrastructure to be located along thin strips of coastal land. The situation is worsened by the recently recognized rapid sinking of the islands, which was triggered by the 2009 Samoa earthquake and is predicted to last for decades. This subsidence is estimated to lead to roughly twice as much sea-level rise by 2060 as what is already predicted from climate change alone. As a result, the timeline of coastal impacts in American Samoa will be decades ahead of similar island communities in the Pacific. Despite this urgency, decision-makers in the region lack...
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Collecting Elevation Data to Understand Climate Change Effects in the Marshall Islands
The Intergovernmental Panel on Climate Change reports that low-lying atolls (ring-shaped islands or island chains made of coral) in the Pacific Ocean are extremely vulnerable to high tide events (“king tides”), storm surge, tsunamis, and sea-level rise. The Republic of the Marshall Islands (RMI) spreads over 29 atolls and has a population of over 50,000 people with homes and communities that may be threatened by these climate change-related events. Policy makers, planners, and others within RMI are faced with decisions about how to prepare for the future and need scientific data and information about the vulnerability of Pacific Islands to potential climate change impacts like sea-level rise. Topographic and bathymetric...
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