Shell Point near mouth of Caloosahatchee Estuary. (Image from sfwmd.gov website.) [larger image]

Investigator: Mark Hansen Metadata

Please note: This project title has changed and can now be found under "High Resolution Bathymetric Mapping of South Florida Estuarine and Coastal Systems.

Summary

This project will collect bathymetric data for the Caloosahatchee Estuary and Estero Bay areas to support the the development of hydrodynamic models of coastal waters in these areas

The areas in and around the Caloosahatchee Estuary and Estero Bay Watershed have undergone dramatic increases in the rate of residential and commercial development as well as population growth during the past 15 years. As a result, a series of initiatives have been proposed to balance development and environmental interests in the region. Several recent initiatives including the development MFL and the Southwest Florida Feasibility Study (SWFFS) necessitate the development of hydrodynamic models of coastal waters in the Caloosahatchee Estuary and Estero Bay areas. One of the important data requirements for these models is the bathymetry. The information available at this time is dated and needs to be upgraded with a new survey. In addition, recommendations of the Estero Bay and Watershed Assessment completed in November of 1999 recommended the development of a Bay hydrodynamic and water quality model. Updated river, bay, and coastal bathymetry is required for these effort.

The plan to acquire bathymetric data for the aforementioned area is to employ two methods which have been developed by the U. S. Geological Survey (USGS) and National Aeronautical and Space Administration (NASA). The USGS method is an acoustic based system named System for Accurate Nearshore Depth Surveys (SANDS), and the NASA method is an airborne LIDAR system named Experimental Advanced Airborne Research Lidar (EAARL).

The USGS has developed a hydrographic survey system specifically designed to map in very shallow water. The system can acquire data in water depths of ~25cm, but in practice boat/motor draft limitations prevent surveying in water depths less than 45cm. Precise differential GPS receivers are used to measure boat position and dynamic elevation, a survey quality 200 kHz depth sounder acquires water depth measurements, and a motion sensor measures heave, pitch, and roll of the boat. A measurement is collected about every 3m along a survey line. The vertical accuracy of the system is +/- 8cm and +/- 4cm inches horizontally.

EAARL is a new airborne lidar that provides unprecedented capabilities to bays, the nearshore shoreface, benthic habitats, coastal vegetation, and sandy beaches. The EAARL sensor suite includes a raster-scanning-water penetrating full-waveform adaptive lidar, a down-looking color digital camera, a hyperspectral scanner, and an array of precision kinematic GPS receivers which provide for sub-meter geo-referencing of each laser and hyper-spectral sample. EAARL has the unique real-time capability to detect, capture, and automatically adapt to each laser return backscatter over a large signal dynamic range and keyed to considerable variations in vertical complexity of the surface target. EAARL limited to water depths greater than 50 cm and can penetrate the water column to approximately 1.5 secchi disk depth. The lidar has a ground footprint of 30cm with vertical and horizontal accuracies equal to the SANDS system. The swath width is 250m which converts to a spatial coverage of approximately 1 laser shot per square meter.

The proposed work would use the EAARL system to map shallow (less than 1.5 secchi depth) and non-turbid areas in Estero Bay and nearshore areas. The SANDS system would be used in deeper areas and those which are turbid which include the Caloosahatchee River.

Metadata

• Bathymetry and Sediment Characterization in Southwest and Western Coastal Systems (project metadata)