Utilizing Highly Portable Lidar to Characterize and Model Intra-Annual Saltmarsh Dynamism

Saltmarshes and other coastal ecosystems are important geochemical transfer zones and offer essential ecosystem services. These functions are perturbed by direct anthropogenic factors, as well as physical and geochemical changes associated with global climate change. Satellite and airborne instruments are used to monitor long-term changes in terrestrial ecosystems at meaningful spatial scales and spatial and temporal resolutions. However, characterizing change in coastal ecosystems is challenging due to high magnitude, high frequency changes in area coverage due to tidal cycles and snowfall; and spectral changes resulting from vegetation phenology. Episodic events such as storm surges can have both acute and lasting effects on area cover. In order to utilize potential monitoring tools, such as the Landsat and the Sentinel satellites, the known components of saltmarsh dynamism must be predicted or modelled. Advances in terrestrial lidar and optical imaging permit the rapid classification, characterization and quantification of saltmarsh components including vegetation by salinity-delineated zone, creeks, pools and pannes. The Compact Biomass Lidar (CBL) from University of Massachusetts Boston has allowed the assessment of large areas of saltmarsh within narrow windows of temporal stability determined by atmospheric, wind and tidal conditions around satellite overpasses. Herein we present results and methods from a year-long study of the relationship between Landsat 7 and 8 data and saltmarsh components classified with a combination of optical and lidar data within seven co-located Landsat pixels at Plum Island Long Term Ecological Research Site (MA, USA). Terrestrial data were collected at the same time as satellite overpass occurred. We also present results from quantitative modelling of saltmarsh hydrology, and predictive modelling of water area cover based on tidal height measurements applied to 3D models of saltmarsh creeks constructed from lidar scans.