Assessing Impact of Landscape Characteristics on Urban Hydroclimate

The land use and land cover (LULC) changes due to urbanization play a vital role in local as well as regional climate change. The replacement of the natural surfaces with manmade structures modifies the surface energy and water budgets of the environment and is responsible for the urban climate change. To understand the underlying physics of urban climate modeling, in- depth knowledge on the impact of various urban landscape characteristics on the urban climate is needed. In this study, we selected one of the fastest growing cities in the U.S. that is, metropolitan Phoenix, Arizona as our testbed. We carried out regional climate modeling using the Weather Research and Forecasting (WRF) model while also incorporating the single-layer Urban Canopy Model (UCM).This advanced WRF-UCM modeling framework is then applied to simulate plausible scenarios of urban expansion in the study area, jointly determined by landscape planners and researchers. The results from the model are validated with the field measurements from ground based meteorological observation. The impact of a range of land surface parameters associated with the LULC changes, including urban morphology, hydrothermal properties and anthropogenic heat input are evaluated based on outputs of numerical simulations. Among these parameters, excessive urban warming in the study area is found to depend largely on the areal fraction of built surfaces as well as the urban morphology. The results from this study will help to better adapt/mitigate the influence of climate change on the urban environment.