Paul et al. (2026) Can aerosols improve urban flood forecasting? A case study of 2015 Chennai extreme event

Identification

• Journal: Natural hazards and earth system sciences
• Year: 2026
• Date: 2026-08-12
• Authors: Oscar Paul, N. Nithila Devi, Rakesh Teja Konduru, Soumendra Nath Kuiry, Kundan Lal Shrestha, Chandan Sarangi
• DOI: 10.5194/nhess-26-3749-2026

Research Groups

• Department of Civil Engineering, Indian Institute of Technology Madras, Chennai, Tamil Nadu, India
• Section 4.4: Hydrology, GFZ Helmholtz Centre for Geosciences, Potsdam, Germany
• Earth Observation Research Center, Japan Aerospace Exploration Agency (JAXA), Tsukuba Space Center, Tsukuba, Ibaraki, Japan

Short Summary

This study investigates the impact of aerosols on urban flood forecasting using a case study of the 2015 Chennai extreme event. The results show that explicit aerosol representation can improve the space-time simulation of rainfall and flooding for the EPF in Chennai and potentially for similar coastal megacities.

Objective

• To evaluate the effect of aerosols on simulated rainfall patterns over urban basins during extreme precipitation events.
• To assess the impact of aerosol-induced changes on flood inundation predictions.

Study Configuration

• Spatial Scale: Urban basin scale (5–15 km^2)
• Temporal Scale: 30 November 00:00 UTC to 2 December 00:00 UTC

Methodology and Data

• Models used: Weather Research and Forecasting (WRF) model, HEC-HMS hydrological model, and HEC-RAS hydraulic model.
• Data sources: IMERG satellite observations, MERRA-2 reanalysis data, and Open Street Map building footprints.

Main Results

• The study found that explicit aerosol representation can improve the space-time simulation of rainfall and flooding for the EPF in Chennai by up to 51%.
• Lower CCN concentrations favored warm-rain processes and increased the amount of precipitation.
• The subsequent evaporation of falling raindrops enhanced evaporative cooling, thereby strengthening cold pool activity near the basin.

Contributions

• This study provides new insights into the role of aerosols in urban flood forecasting and highlights the importance of considering aerosol-cloud interactions in simulating extreme precipitation events.

Funding

• Indian Institute of Technology Madras (IITM)
• Japan Aerospace Exploration Agency (JAXA)

Citation

@article{Paul2026Can,
  author = {Paul, Oscar and Devi, N. Nithila and Konduru, Rakesh Teja and Kuiry, Soumendra Nath and Shrestha, Kundan Lal and Sarangi, Chandan},
  title = {Can aerosols improve urban flood forecasting? A case study of 2015 Chennai extreme event},
  journal = {Natural hazards and earth system sciences},
  year = {2026},
  doi = {10.5194/nhess-26-3749-2026},
  url = {https://doi.org/10.5194/nhess-26-3749-2026}
}