Investigating impacts of urban morphology on spatio-temporal variations of solar radiation with airborne LIDAR data and a solar flux model: a case study of downtown Houston

The heavy concentration of population, economic activities and high-rise buildings have formed a unique and complex urban morphology in the city centre areas of many metropolitan regions. This research exploits high-resolution LIDAR data to quantify three-dimensional urban morphology and its impacts on the spatio-temporal variability of solar radiation in downtown Houston, Texas. Various urban landscape components, including buildings, trees, shrubs and lawns, have been extracted by combining LIDAR data and colour infrared aerial photographs. An efficient solar flux model is re-implemented as an ArcGIS module with extended capabilities. Monthly and seasonal solar radiation fields are computed in terms of radiation intensity and illumination duration. Our analysis suggests that the extensive and dense distribution of tall and large buildings has dramatically changed the spatial pattern of solar radiation and hence imposed significant impacts on other urban landscape components, especially urban vegetation canopy. We have determined three types of vegetation habitats: shade, semi-sunny/partial shade, and sunny habitats. This research represents the first effort to model spatio-temporal variation of solar radiation in an urban built-up environment using high-resolution LIDAR data. The temporal solar radiation maps would benefit the design and selection of appropriate species of trees, shrubs, flowers and lawn grasses for urban vegetation planting and management.