Compounding extreme rainfall and drought/heatwaves: how will feedbacks alter flood inundation and affect water quality?

Hayley Fowler (NU), Gemma Coxon (UoB), Stuart Allen (EA)

 

Apply for this PhD here https://applyto.newcastle.ac.uk/ using application studentship code FLOOD244. Please contact Caspar Hewett (caspar.hewett@newcastle.ac.uk) if you have any questions about the application process. 

 

 

Rationale: 

Against a backdrop of increasing hydroclimatic variability with global warming, drought conditions, particularly flash droughts associated with heatwaves, are projected to increase in summer alongside increases in short-duration intense rainfall that causes flash floods. Recent advances in convection-permitting climate modelling (e.g. Kendon et al. 2014) that well capture intense rainfall, and capacity to model hydrological and hydraulic changes at national scales, present an opportunity to answer questions of relevance to managing incident response to flooding and land management at catchment scales.

Recent work shows a clear connection between heatwaves and termination by extreme short-duration rainfall in the mid- to high-latitudes (Sauter et al. 2023). Recent extreme events in summer 2021-2022-2023 show connections between blocking and extreme rainfall from cut-off lows (e.g. Storm Daniel in 2023; Germany floods in 2021). It is important to understand how changing characteristics of extreme rainfall and feedbacks to catchment response might change during drought conditions. We need to know more about how drying of catchments themselves might affect rainfall properties or occurrence, and how flood inundation characteristics might be changed under dry conditions. This plays into incident response, both for quality (flushing events, wastewater problems, sediment, dilution, fish kills, etc.) and for flash flooding.

 

Methodology: 

This project will investigate the changing frequencies and intensities of flash drought/heatwaves and their links to extreme rainfall using object-based datasets developed from reanalysis data to identify the ingredients of these compound extremes, then examine climate model simulations to establish how these events and their impacts on flash flooding etc, might change in a warming climate. Using the latest climate model projections together with a suite of hydrological and hydrodynamic models the student will explore (i) the feedbacks between dry conditions and extreme precipitation in convection-permitting models; (ii) the effect of projected changes on flood inundation; (iii) the impacts on water quality; (iii) the implications for catchment management.

The project is collaborative with the Environment Agency, the UK Met Office Hadley Centre and the National Center for Atmospheric Research in Boulder, Colorado and will use reanalysis data, high-resolution observations and the latest climate model projections. There is the opportunity to use a suite of hydrological and hydrodynamic models to explore case studies of impacts.

Skills which would be developed as part of the training for this project include analysis and use of climate model data; programming, rainfall-runoff modelling, hydrodynamic modelling.

 

Location: 
Newcastle University
Background Reading: 

Kendon et al. 2014; doi:10.1038/nclimate2258

Sauter et al. 2023; DOI: 10.1016/j.wace.2023.100563

 

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