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| Titel |
Measuring the spatial variation in surface moisture on a coastal beach with
an infra-red terrestrial laser scanner |
| VerfasserIn |
Yvonne Smit, Jasper Donker, Gerben Ruessink |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250123371
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| Publikation (Nr.) |
 EGU/EGU2016-2607.pdf |
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| Zusammenfassung |
| Coastal sand dunes provide essential protection against marine flooding. Consequently, dune
erosion during severe storms has been studied intensively, resulting in well-developed erosion
models for use in scientific and applied projects. Nowadays there is growing awareness that
similarly advanced knowledge on dune recovery and growth is needed to predict
future dune development. For this reason, aeolian sand transport from the beach into
the dunes has to be investigated thoroughly. Surface moisture is a major factor
limiting aeolian transport on sandy beaches. By increasing the velocity threshold for
sediment entrainment, pick-up rates reduce and the fetch length increases. Conventional
measurement techniques cannot adequately characterize the spatial and temporal
distribution of surface moisture content required to study the effects on aeolian transport.
Here we present a new method for detecting surface moisture at high temporal and
spatial resolution using the RIEGL VZ-400 terrestrial laser scanner (TLS). Because
this TLS operates at a wavelength near a water absorption band (1550 nm), TLS
reflectance is an accurate parameter to measure surface soil moisture over its full
range. Three days of intensive laser scanning were performed on a Dutch beach to
illustrate the applicability of the TLS. Gravimetric soil moisture samples were used to
calibrate the relation between reflectance and surface moisture. Results reveal a
robust negative relation for the full range of possible surface moisture contents (0% -
25%). This relation holds to about 80 m from the TLS. Within this distance the TLS
typically produces O(106-107) data points, which we averaged into soil moisture
maps with a 0.25x0.25 m resolution. This grid size largely removes small moisture
disturbances induced by, for example, footprints or tire tracks, while retaining larger
scale trends. As the next step in our research, we will analyze the obtained maps to
determine which processes affect the spatial and temporal surface-moisture variability. |
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