Effect of Topographic Data Accuracy on Water Storage Environmental Service and Associated Hydrological Attributes in South Florida

摘要

The effects of digital elevation model (DEM) accuracy on terrain attributes and water storage were evaluated by comparing a standard 10-m U.S. Geological Survey DEM and a 10-m DEM derived from Light Detection and Ranging (LIDAR) data, on a ranchland that participated in a water storage environmental services program in South Florida. Elevation differences between the two DEMs ranged from -0.73 m to 1.6 m with a low (31%) correlation. Frequency analysis showed that 64% of the grids in the study area had elevation differences of 0.8 m or greater. Spatial distribution of wetlands and ditches were better represented by the LIDAR than the USGS DEM. Surface water storage in the study area and an isolated wetland was 49% and 21% more, respectively, for the USGS DEM than LIDAR DEM in wet seasons. In dry seasons, the LIDAR DEM resulted in 28% higher storage than the USGS DEM. Annually, the USGS DEM resulted in an average 44% more storage than LIDAR DEM. For a major rainstorm in 2008, the USGS showed 92% inundation of the study area and 44% for the LIDAR DEM. In a selected wetland, the USGS DEM resulted in an average 23% higher annual water storage than LIDAR DEM. In two sub-watersheds in the study area, USGS DEM resulted in an average 40% more pasture inundation than LIDAR DEM. Results indicate the importance of topographic data accuracy in quantified water storage and design of water control structures in water storage environmental services programs.