Monitoring and simulation of Chennai floods through a high-resolution topographic datasets

This study focuses on the catastrophic flood events in the Chennai region in 2005 and 2015, which resulted in significant loss of life and property. To simulate flood extent and inundation depths, the study uses a three-way coupled MIKE FLOOD approach that integrates MIKE 11 HD for river flows, MIKE URBAN Modelling of Urban Sewers (MOUSE) for urban drainage and MIKE 21 for surface runoff modelling. Together, these models simulate the full range of flood sources, including river, urban runoff and surface runoff. The hydrological simulations were carried out used HEC-HMS, which enabled accurate modelling of rainfall-runoff processes. High-resolution LiDAR Digital Elevation Models (DEMs), obtained through airborne laser scanning, were used to extract river cross-sections, determine the ground elevations of stormwater drainage manholes and generate accurate bathymetric data for MIKE 21. Following the flood events of 2005 and 2015, flood depth measurements were collected across the extensive floodplains of the Adyar River to validate the model predictions. Comparisons between simulated and measured flood depths showed strong model performance, with R² values of 0.772 for the 2005 event and 0.883 for the 2015 event, indicating a high level of accuracy. The study provides a valuable tool for urban flood management and enables more effective assessment of flood risks and potential damages. The integrated modelling approach can also be applied to future flood scenarios to strengthen flood preparedness, mitigation, and response strategies in the Chennai region and similar urban areas.