Light From Above
LID AR Applications BY ALVAN KARLIN, EKATERINA FITOS AND GORDON M C CLUNG F rom January to October 2009, flooding in Florida whether from hurricanes, slow-moving weather systems or tornados resulted in more than $22 million in damages and more than $5.4 mil-lion from the Federal Emergency Management Agency to the state for public assistance. The value of accu-rate watershed modeling and floodplain mapping can't be underestimated. Since 2004, the Southwest Florida Water Management District (SWFWMD) has been using highly accurate light detection and ranging (LIDAR) eleva-tion data to construct digital terrain models (DTMs) to assist in floodplain mapping. And during the last five years, the SWFWMD has learned that LIDAR is a blessing in disguise. Previous Methods Watershed modeling and floodplain mapping are among the most visible and evident activities of the Engineering as well as Mapping & GIS Sections at SWFWMD. These functions form the basis of the Watershed Management Program for each of more than 400 watersheds in the 16-county district. Prior to 2002, topographic information in the form of photogrammetrically derived one-foot contour data was the gold standard for water modeling. The lack of relief in southwestern Florida combined with the abundance of surface water during the sea-sonal rains precludes the effective use of two- or five-foot U.S. Geological Survey contours for model-ing purposes. LIDAR (Mostly) Improves Water and Flood Modeling 20 Imagery/LIDAR Special Issue G E O W O R L D / J A N U A R Y 2 O 1 0