Urban modification of heavy rainfall: a model case study for Bhubaneswar urban region

An increase in urbanization has been witnessed from 1980 to 2019 in Bhubaneswar, Odisha. The impact of this increase in urban areas on rainfall pattern and intensity has been assessed in this study. To evaluate these changes, four heavy rainfall events, such as 0(6th) March 2017, 23(rd) May 2018, 20 - 22 July 2018, and 04 - 08 August 2018, have been simulated with 1980, 2000, and 2019 land use land cover (LULC) obtained from United States Geological Survey imageries. With these two LULC sensitivities, urban canopy model (UCM) experiments have also been carried out. These experiments suggest that incorporating corrected LULC is necessary for simulating heavy rainfall events using the Weather Research and Forecasting (WRF) model. Urbanization increases the rainfall intensity, and the spatial shift was more pronounced along the peripheral region of the city. The vertically integrated moisture flux analysis suggests that more moisture present over the area received intense rainfall. An increase in urbanization increases the temperature at the lower level of the atmosphere, which increases [planetary boundary layer height, local convection, and rainfall over the region. Contiguous Rain Area method analysis suggests that the 2019 LULC with single layer UCM predicts a better spatial representation of rainfall. This combination works well for all the four cases simulated.