Dune monitoring: implementing remote sensing techniques

There is an increasing interest for different methodological and conceptual approaches applied in geomorphology. Data collection is becoming more and more efficient, and from remote sensing techniques to the use of very precise anemometry instrumentation, the way in which we sample nature improves our ability to subsequently understand it. However, there are a number of issues associated with the different temporal/spatial scales, and the absence of high-quality data of dune dynamics over long periods keeps holistic approaches away from numerical modeling. The work presented here explores the applicability of remote sensing techniques to the study of coastal dunes, and its potential in establishing links between factors acting at different temporal scales. The monitoring station is located at Greenwich Dunes, PEI National Park, PEI (Canada). We have deployed three cannon digital cameras on a 6m mast on top of an 8m foredune crest, each taking hourly exposures during daylight hours. A 2D sonic anemometer mounted at the top of the mast provides continuous record of wind speed and direction. Sediment transport and deposition/erosion processes are measured using a set of Sabatech saltation probes and pins permanently deployed at the backshore area and at the base of the foredune. Through a combination of ArcMap 9.2 and PCI Geomatica tools the pictures are analyzed following a procedure of several steps, such as image rectification or camera calibration for measuring surface moisture content on the beach surface. The result is a large database including time series of wind speed and direction, transport processes, moisture maps, vegetation cover, shoreline position, fetch distances, and other factors involved in the aeolian system at Greenwich. This database is a primary source of information where the aeolian system at Greenwich can be queried in an easy way, and the basis for subsequent modeling. The monitoring of the magnitude, frequency, and timing of events that deliver sediment to the dune will allow us to understand the relative importance of different variables and events. The overall goal is to assess the applicability of remote sensing techniques in measuring beach/dune aeolian processes, and advance our knowledge in the factors affecting foredune evolution to better assist management projects.