LIDAR MAPPING OF WETLAND AREAS SAGEEP 2015 ABSTRACTS MARCH 22-26, 2015

摘要

To assist in the identification of wetland areas, advanced Global Positioning System (GIS) processing of high resolution topography data was used to assess wetland hydrology along the proposed 23-mile long water canal alignment through Liberty County, Texas. Forested wetland hydrology has been difficult to study with conventional remote sensing methods and the collection of these data in the field is often cost prohibitive. Aerial photographs have typically been used to assist in the identification of wetland areas, but the ability of these data sets to detect hydrology is limited, especially in forested areas. High resolution topography datasets including Light Detection and Ranging (LiDAR), offer a unique view of the topography and hydrology beneath the forest canopy. As part of the preliminary assessment of the water conveyance project, high resolution LiDAR topography data was collected for the proposed alignment between the Trinity River and Lake Houston. This topography data was processed using the 'fill sinks' grid processing tool inside the Arc Hydro extension for ArcGIS version 9.3. The 'fill sinks' function analyzes an elevation grid and identifies depressions or sinks where water collects and is unable to flow downhill. These sinks or depressions are representative of a disjointed wetland hydrology and indicate continually wet soils and the likely presence of wetland ecosystems. The 'fill sinks' function determines the extent of these sinks or depressions by determining the pond elevation and spread inside each sink which would result in the overtopping of the depression and the continued flow of water downhill towards a receiving stream. Areas showing as large depressions represent pervasive wetlands while areas with a dense concentration of small independent sinks represent a more dispersed mosaic wetland.