Using high-resolution climate change information in water management: a decision-makers' perspective

Abstract

The UK Climate Change Act requires the Environment Agency to report the risks it faces from climate change and actions taken to address these. Derived information from projections is critical to understanding likely impacts in water management. In 2019, the UK published an ensemble of high-resolution model simulations. The UKCP Local (2.2 km) projections can resolve smaller scale physical processes that determine rainfall and other variables at subdaily time-scales with the potential to provide new insights into extreme events, storm runoff and drainage management. However, simulations also need to inform adaptation. The challenge ahead is to identify and provide derived products without the need for further analysis by decision-makers. These include a wider evaluation of uncertainty, narratives about rainfall change across the projections and bias-corrected datasets. Future flood maps, peak rainfall estimates, uplift factors and future design storm profiles also need detailed guidance to support their use. Central government support is justified in the provision of up-to-date impacts information to inform flood risk management, given the large risks and exposure of all sectors. The further development of projections would benefit from greater focus and earlier scoping with industry representatives, operational tool developers and end users. This article is part of a discussion meeting issue ‘Intensification of short-duration rainfall extremes and implications for flash flood risks’.

Towards advancing scientific knowledge of climate change impacts on short-duration rainfall extremes

“…This work has enabled access to rainfall extreme metrics for impact researchers and provided a platform for the exploration of the role of storm dynamics in state-of-the-art climate models. However, while progress is evident in model capability, leading to new insights to km-scale atmospheric responses to climate change, the use of CPMs to guide decision-making in a realworld context is still challenging [9]. This is primarily because of under-sampling of either model uncertainty at these finer scales (e.g.…”

“…Cities are particularly vulnerable to floods generated by heavy short-duration rainfall due to ageing drainage infrastructure systems designed to deal with lower historical rainfall intensities and an increase in impermeable surfaces. A better understanding of the impacts of global warming on sub-daily (particularly hourly to 3-hourly) extreme precipitation is therefore crucial for societal adaptation [8], through the management of the water environment (see [9]) and application to design of stormwater drainage infrastructure systems (see [10]), among others.…”

“…However, while progress is evident in model capability, leading to new insights to km-scale atmospheric responses to climate change, the use of CPMs to guide decision-making in a real-world context is still challenging [9]. This is primarily because of under-sampling of either model uncertainty at these finer scales (e.g.…”

Intensification of short-duration rainfall extremes and implications for flood risk: current state of the art and future directions

“…Prein et al [38] show that CPMs can reliably capture the large-scale features of organized convective storms and corresponding climate change signals, including extreme precipitation changes compared to large-eddy simulations (250 m grid spacing). The application of such highresolution modelling efforts in water management is then examined by Orr et al [39] and, as many idealized experiments use temperature forcing to represent anthropogenic climate change, Wasko [40] reviews the application of temperature sensitivities for informing changes to flood extremes with global warming.…”

Climate Change and Rainfall Intensity–Duration–Frequency Curves: Overview of Science and Guidelines for Adaptation

“…About 10 years ago, convection-permitting climate models (CPM) operating at horizontal resolutions ≤4 km emerged as powerful tools that considerably improved the simulation of shorterduration (up to subhourly) rainfall extremes (Meredith et al 2020;Vergara-Temprado et al 2021;Meredith et al 2021), with implications for water management (Orr et al 2021). At such fine spatial resolutions, the deep convection, which is essential for a realistic simulation of rainfall extremes, is explicitly simulated, allowing one to switch off deep convection parameterization in CPMs (Ban et al 2021).…”