2022 – New Calibration Method to Improve Extreme Flood Estimates

Tim Rhodes, Hugh Nguyen-Mallen and Kosta Tsourdalakis, SMEC

Extreme flood estimates constitute a key input to dam risk assessments, and they are subject to a high degree of uncertainty due to both a limited understanding of the meteorologic drivers and catchment runoff generation processes. Current estimation methods rely on the application of relatively simple models combined with complex processes for estimating inputs. There are, however, few practical tools available to inform the user of whether the modelled outcomes are reasonable. As a result, extreme rainfall estimates can vary widely with modellers and models, leading to inconsistent quantification of risk across dam assets. A new method is presented here which allows the user to identify a unique hydrograph signature for any streamflow gauge and use it to calibrate hydrology models.