Combined statistical and hydrodynamic modelling of compound flooding in coastal areas - Methodology and application

Olbert, Agnieszka I., Moradian, Sogol, Nash, Stephen, Comer, Joanne, Kazmierczak, Bartosz, Falconer, Roger ORCID: https://orcid.org/0000-0001-5960-2864 and Hartnett, Michael 2023. Combined statistical and hydrodynamic modelling of compound flooding in coastal areas - Methodology and application. Journal of Hydrology 620 , 129383. 10.1016/j.jhydrol.2023.129383

Preview

PDF - Published Version Available under License Creative Commons Attribution. Download (23MB) | Preview

Abstract

This paper presents a robust cost-effective framework for assessment of coastal-fluvial flooding due to compound action of multivariate dependent drivers. The methodology is an 8-step process that links statistical and hydrodynamic models to determine probabilities of multiple-driver flood events and associated hazards. The method involves individual and combined extreme value analysis, assessment of dependencies and interactions between flood drivers, multivariate joint probability determination accounting for dependencies, high-resolution hydrodynamic modelling of flood scenarios derived from multivariate statistical analysis, and ultimately mapping of inundation. Using Cork City, on the south coast of Ireland, as a study case, the research shows that the interactions and dependencies between tides, surges and river flows affect flood severity when they occur jointly. Tide-surge interactions have a damping effect on the total water level, while dependence between the surge residual and river flow amplifies the risk of flooding. The multivariate joint exceedance probability occurrence of high discharges and water levels represents a more realistic representation of the spatially variable water surface profiles then the combined univariate marginal scenarios. Multivariate analysis allows also considering multiple combinations of joint probability solutions along RP iso-curves. The results show that the quantification of compound flood impacts must be performed along the entire RP probability curve. This is because the physical/hydrological impacts of multiple-driver same-RP flood events can be very different leading to substantially different characteristics of flooding. The multi-scale nested flood model (MSN_Flood) was used to simulate flood wave propagation over urban floodplains for an ensemble of statistically derived flood scenarios. The hydrodynamic runs provide inundation maps that can be used to draw inferences about flood mechanisms and impacts. Multivariate analysis allows also considering multiple combinations of joint probability solutions along a RP iso-curve. While the RPs iso-curve represents the joint events of the same exceedance probability, the physical/hydrological impact of such events can be very different leading to substantially different characteristics of flooding. For these reasons combining the statistical and hydrodynamic modelling is very important.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Engineering
Publisher:	Elsevier
ISSN:	0022-1694
Date of First Compliant Deposit:	15 March 2023
Date of Acceptance:	6 March 2023
Last Modified:	08 May 2023 01:14
URI:	https://orca.cardiff.ac.uk/id/eprint/157727

Actions (repository staff only)

Edit Item