Hydrologic modelling of flash floods and their effects

Abstract

Flash floods are ranked on top in the number of people that are affected and amount of damages caused. The sudden nature of this disaster gives less time for the victims to prepare, thereby ending up with a disrupted social, economic and political stature. The study aims at analysing the possible peak discharges with the help of a rainfall–runoff model for the flood events that have occurred in the Harangi River basin in the Kodagu district and estimate the economic damage induced. The SCS curve number method is used for simulating the runoff. Fourteen peak events over the months of July and August of two different years are chosen for the validation and calibration of the model. Discharges are simulated using the HEC-HMS extension in WMS software. The effect of variation of rainfall and land-use practices in the runoff volume is studied. It is observed that the changes in land-use practices have more effect on the runoff volume than the rainfall volume. Rapid urbanization and industrialization has increased the intensity of flood damages. The largest flow was recorded when a natural bund of water collected in the upstream was collapsed. © Springer Nature Singapore Pte Ltd 2021.