Fig. 2. GPR record of Riverside Beach, which forms the border to Kennebec River Inlet on the central Maine coast.

Fitzgerald-etal-CEJ-03
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central Maine coast. The pattern of reflectors demonstrates that the channel has narrowed as the

inlet has reached an equilibrium cross sectional area (from FitzGerald et al., 2002).

exposed at low tide (Costa and Glatzel, 2002). These areas were inaccessable by boat

for traditional boat surveys and were difficult to access by land. The LIDAR survey

provided detailed elevation data and improved the results of the hydrodynamic

circulation model (per. comm. Adele Militello).

In the fall of 1995 and the spring of 1996, Assateague National Seashore was

mapped with the ATM (Krabill et al., 2000). The LIDAR surveys were compared to

conventional ground surveys in order to estimate the accuracy of the LIDAR survey.

The error was estimated as the difference between the elevation of the ground survey

and any LIDAR point falling within one meter of the ground survey transect. The

LIDAR survey was collected in November 1995 and the ground survey was collected

that September. The mean error ranged from 0.01 to 0.15 metres. The average error

for all 10 transects was 0.06 metres.

LIDAR surveys have also been used on the West Coast to document a range

of geomorphic responses to the 19971998 El Nino. Locally, some cliff locations