ASSESSMENT OF IMPACTS OF LAND USE CHANGE ON URBAN HYDROCLIMATE FOR THREE CITIES

The Colorado River and its tributaries contribute to water supply for nearly 40 million people in seven western states. Rapid urbanization and population growth occurring in the arid and semi-arid areas of Colorado River Basin (CRB) make it vulnerable to climate change impacts. Both local and regional climate changes are expected to have massive impacts on the hydrology of Colorado River, thereby accentuating the need of study of hydro-climatic impacts in CRB. In this study, three densely populated urban areas in the CRB—Phoenix, Las Vegas, and Denver—were selected to capture the variable impacts of land use changes on their regional hydroclimate and in general entire CRB. A Weather Research and Forecast (WRF) model, incorporating the latest urban modeling system, is applied for regional climate modeling. This advanced WRF-urban modeling framework is then applied to simulate future land-use change scenarios obtained from Integrated Climate and Land Use Scenarios (ICLUS) from the Environmental Protection Agency with a simulation period from 2010-2040. The future projections for all the cities show significant increase in temperature with maximum increase for A2 emission scenarios (global economic development). This inter-city comparison study assists in identifying both context-specific and generalizable relationships and patterns among the cities and is expected to facilitate urban planning and management in local (cities) and regional scales.