Evaluation of the optimal resolution for characterising the effect of beach surface moisture

Delgado-Fernandez, Irene, Davidson-Arnott, Robin, Bauer, Bernard O, Walker, Ian J and Ollerhead, Jeff (2013) Evaluation of the optimal resolution for characterising the effect of beach surface moisture. 12th International Coastal Symposium, 8-12 April 2013, Plymouth University, UK.

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Abstract

Patterns of aeolian sand transport on beaches are controlled by changes in wind speed and direction, upwind sources of available dry sediment, and variations in surface moisture amongst other factors. The recent availability of remote sensing systems based on time-lapse photography applied to measuring beach surface moisture allows improved explanations for the spatial and temporal patterns of sediment movement, and the changes in beach surface resulting from scour and deposition. Moisture content, in particular, appears to be not only a control for sand movement but also a result of erosion and accumulation across the foreshore and back beach. An issue that still remains open has to do with quantifying a characteristic moisture value that should be used in explanations of sediment transport as a function of wind, moisture, and fetch distances. This paper explores new possibilities offered by moisture maps obtained from a remote sensing system to evaluate the effect of measuring moisture at different spatial and temporal resolutions. Data was collected during an aeolian event on October 21, 2007 at Greenwich Dunes, Prince Edward Island National Park, Canada, using cameras that were mounted on a mast on the foredune crest at a height of about 14 m above the beach. Maps of beach surface moisture were created based on a calibrated relationship between surface brightness from the photographs, at a temporal (5 minutes intervals) and spatial (0.05 m) resolution that would be difficult to achieve with other sampling techniques such as impedance probes. These fine resolution moisture maps offer the possibility of data aggregation through pixel coarsening and can be used to explore appropriate moisture values for different applications. The initial grids were coarsened both temporally and spatially, using scaling methods such as filtering and resampling. This allows evaluation of questions such as what is the loss of data respect to different spatial resolutions, what is the spatial resolution that best represents beach moisture content, and what are the moisture values that could better explain transport rates measured at a given point over the beach surface.

Item Type: Conference or Workshop Item (Paper)
Subjects: G Geography. Anthropology. Recreation > GB Physical geography
G Geography. Anthropology. Recreation > GC Oceanography
G Geography. Anthropology. Recreation > GE Environmental Sciences
Divisions: Geography, Earth and Environmental Sciences
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Date Deposited: 28 May 2013 10:51
URI: http://repository.edgehill.ac.uk/id/eprint/5119

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