Urban areas are hot spots that drive environmental change at multiple scales. With rapid worldwide urbanization taking place in recent decades, urban areas are becoming the most vulnerable regions to extreme rainfall and flooding hazards, as well as other environmental risks related to excessive thermal loadings and air/water pollution. Flood hazards over urban areas are results of complex interactions of heavy rainfall (varied at both temporal and spatial scales) and land surface/subsurface heterogeneities (related to urban infrastructures, soil properties, etc.). My research has primarily delved in physical mechanisms of urban flood hazards under the context of urbanization and climate change, with the ultimate goal of improving the understanding of impacts of urban areas on hydrology, hydrometeorology and hydroclimatology. More specifically, my research is motivated by three questions: 

  1. What are the structural and evolution properties of flood-producing storms over urban watersheds?
  2. How does urbanization modify the spatial and temporal distribution of rainfall from flood-producing storm systems?
  3. How does the pattern of urban development, along with space-time structure of heavy rainfall, determine the scale-dependent flood response of urban watersheds?

These questions have been examined comprehensively based on multi-scale, multi-dimension observational datasets (e.g., USGS stream gauging records, long-term high-resolution 3-D radar reflectivity fields, cloud-to-ground lightning network, etc.) combined with state-of-art hydrologic and atmospheric modeling strategies. Instead of treating urban area as an isolated land surface system, my research view it as an integral part of the earth system, expecting to provide a holistic assessment of urban flood hazards that could benefit hydrology, meteorology and regional climate community.