The Provincetown Center for Coastal Studies is conducting a 3-year, state-funded pilot project for the 'nearshore seafloor mapping and resource characterization' in Cape Cod waters. The agreement also 'acknowledges the need to develop effective mapping strategies for nearshore environments'.

This project, in part, will determine the feasibility of tide-coincident mapping of the interface of the marine and terrestrial nearshore systems at very high resolution. Typically, nearshore mapping occurs in water depths of 10 meters or greater. Closer to shore vessel-based surveying is very labor-intensive, more hazardous and yields data of varying quality. Surveys mapping bathymetry using single-beam sensors on personal water craft capture relatively low-density data and don't include acoustic backscatter data.

The Center will use a state-of-the-art Interferometric Sonar System to map the nearshore marine system (in 2 meters out to 10 meters of water), which will yield coincident swath acoustic backscatter and bathymetric data. The acoustic backscatter data will ensonify or 'take a picture' of the seafloor using sound. This along with sediment samples and underwater imagery and/or video will provide detailed information with regards to the surficial seafloor geology including grain size, composition, bedforms as well as submerged aquatic vegetation and other biota. The bathymetry will provide another layer of detail for establishing baseline data useful for modelers and ongoing and future studies of the area.

This next generation interferometric bathymetry system has the ability to generate an average swath to depth ratio of 10:1, while the typical multi-beam bathymetry systems deliver a 3:1 ratio. Therefore, in water depths of 3 meters our new system could generate a 30 meter swath compared to a 9 meter swath with multi-beam systems. This significantly reduces the time needed to map these shallow water areas with commensurate reductions in both the cost and hazards associated with operating a vessel in the nearshore.

Most past efforts to map the marine/terrestrial interface have used bathymetric data from one survey and terrestrial and shallow water Lidar data from another survey. These surveys were often weeks to months apart. This project will eliminate the uncertainties, or errors, introduced by different: datums, mapping goals, data resolutions/accuracies, or temporally distant surveys. Toward this end, airborne- or terrestrial-based LIDAR (Light Detection And Ranging) will be used to conduct a low-tide survey of the nearshore terrestrial system (beach/dune/bluff ) followed immediately by a high-tide vessel-based survey. This will allow us to overlap spatially and within ~6 hours temporally the marine/terrestrial interface, which will yield a unique dataset for this environment. This area was selected in part for the Areas in Cape Cod Bay to be surveyed have a mean tidal range of ~3 meters.

An enhanced 'proof of methods' survey in Cape Cod Bay will be conducted in the late fall of 2009 and early spring of 2010. A section of the larger study area will be chosen to conduct the initial vessel-based surveys. A full field season of data collection will begin in the late spring and continue into the early fall of 2010. In the fall, winter and early spring of 2010-11 those data will be processed and work will be begin within the Center, and cooperating partners to produce the benthic habitat and seafloor classification maps.