Exploitation of Thermal Signals in Tidal Flat Environments

The overall goal is to identify and understand the physical processes that shape and change coastal environments. Emphasis is on the application of remotely sensed infrared signals that can be compared with in situ observations and assimilated within predictive models. In tidal flat environments, major goals are detection of: geotechnical properties (e.g., sediment strength), morphologic features (e.g., channels), and hydrodynamics events (e.g., plumes). The primary objective of these joint efforts is to develop thermal methods for improved monitoring and prediction of tidal flat environments. Specific objectives are to: 1) Test and apply the Lovell [1985] hypothesis for the porosity of sediment as a function of thermal conductivity, 2) Refine methods to estimate inter-tidal bathymetry using sequential waterline detection, 3) Quantify the importance of channel networks and associated flows. The technical approach is to conduct field experiments using simultaneous remote and in situ observations of thermal signals in tidal flat environments. Infrared images collected from airborne and fixed platforms are being used to study surface temperatures, which are then related to an array of interior (sediment and water) temperature measurements. The experiments are designed to study geotechnical, hydrodynamic, and morphologic aspects of tidal flats. Using a combination of remote infrared imagery and in situ temperature measurements, we have quantified the flow in a tidal channel at low tide and confirmed the source as pore water from mud flats (as opposed to surface water drainage). In addition to a strong correlation of temperatures between the channel outflow and the sub-surface mud, a hydrodynamic analysis shows the low-tide outflow to be distinct from the ebb drainage, consistent with baseflow observed in groundwater studies. This flow is also consistent with the classic Manning equation for open channel flow.
This effort is a contribution to the Tidal Flats Dynamics Departmental Research Initiative of the Office of Naval Research.