Analysing changes in short-duration extreme rainfall events

Abstract

Two approaches are presented for using the UKCP09 weather generator (WG) to assess changes in extreme short-duration rainfall. The first provides change factors for design storms of varying duration and frequency, building on established hydrological techniques and with uncertainty estimation. The second approach characterises and facilitates the selection of WG timeseries for use in impact models. The methods have been tested at ten case study sites around the UK. The results show an increase in the intensity of short-duration (1 h and 12 h) events in winter but a reduction in summer, although the latter is subject to high levels of uncertainty. The number of intense events increases slightly and more significantly for some locations, especially in winter. Generally, it is hard to establish any conclusions geographically, although increases in rainfall intensity and events in the Lake District site stand out. The methods provide practical techniques for utilising the UKCP09 WG to assess the impacts of climate change, in particular for urban drainage and sewer modelling

Editorial

“…Such a variety of topics reveals the undeniable complexity that characterises the management of water on Earth. In this respect, identifying the correct scenarios for extreme rainfall events (Darch et al, 2016) and the deterministic or chaotic behaviour of hydrological processes (Kędra, 2016) is tightly related to the optimal design of reservoirs (Celeste, 2016) and, at a more detailed scale, to the interaction between hydrodynamics and sedimentation that can strongly affect the management of shallow reservoirs (Esmaeili et al, 2016).The first paper (Darch et al, 2016) analyses the use of UK climate projections (UKCP09) weather generation (WG) to infer changes in the magnitude of short-duration extreme rainfall events. The problem is undoubtedly relevant as the UK experienced a two-fold increase in the magnitude of extreme rainfall events in the last 50 years, and UKCP09 projections show a further increase in rainfall and extreme events in winter.…”

“…Such a variety of topics reveals the undeniable complexity that characterises the management of water on Earth. In this respect, identifying the correct scenarios for extreme rainfall events (Darch et al, 2016) and the deterministic or chaotic behaviour of hydrological processes (Kędra, 2016) is tightly related to the optimal design of reservoirs (Celeste, 2016) and, at a more detailed scale, to the interaction between hydrodynamics and sedimentation that can strongly affect the management of shallow reservoirs (Esmaeili et al, 2016).…”

“…The first paper (Darch et al, 2016) analyses the use of UK climate projections (UKCP09) weather generation (WG) to infer changes in the magnitude of short-duration extreme rainfall events. The problem is undoubtedly relevant as the UK experienced a two-fold increase in the magnitude of extreme rainfall events in the last 50 years, and UKCP09 projections show a further increase in rainfall and extreme events in winter.…”