IDENTIFYING URBAN FEATURES FROM LIDAR FOR A HIGH-RESOLUTION URBAN HYDROLOGIC MODEL

Light Detection and Ranging (LiDAR), is relatively inexpensive, provides high spatial resolution sampling at great accuracy, and can be used to generate surface terrain and land cover datasets for urban areas. These datasets are used to develop high-resolution hydrologic models necessary to resolve complex drainage networks in urban areas. This work develops a five-step algorithm to generate indicator fields for tree canopies, buildings, and artificial structures using Geographic Resources Analysis Support System (GRASS-GIS), and a common computing language, Matrix Laboratory. The 54 km(2) study area in Parker, Colorado consists of twenty-four 1,500 x 1,500 m LiDAR subsets at 1 m resolution with varying degrees of urbanization. The algorithm correctly identifies 96% of the artificial structures within the study area; however, application success is dependent upon urban extent. Urban land use fractions below 0.2 experienced an increase in falsely identified building locations. ParFlow, a three-dimensional, grid-based hydrological model, uses these building and artificial structure indicator fields and digital elevation model for a hydrologic simulation. The simulation successfully develops the complex drainage network and simulates overland flow on the impervious surfaces (i.e., along the gutters and off rooftops) made possible through this spatial analysis process.