Rainfall Intensity for Sewer Design - Stage 2

Reference: 17/CL/10/17
ISBN: 1 84057 842 4
Published Date: 13/09/2017

This research and its data products make use of a new Met Office 1.5km climate length model simulation of the United Kingdom. This is important because the model can resolve convective processes that produce the heavy rain seen in all seasons which affects the functioning of urban drainage systems. The data products are optimised for use in the planning of urban drainage networks and the analysis of surface water flooding.

The two data products, aimed at urban drainage and storm water management professionals are: 

1.            Estimated changes in design storm uplifts, covering three different regions of the UK.

2.            A time series perturbation tool that allows rainfall time series to be adjusted to reflect estimated future rainfall conditions.

Estimated changes to design storms show similar or higher changes to those currently used by the water industry - this could have significant impacts on the resilience of sewer networks in the future, triggering different adaptive responses to protect customers and communities from flooding. The time series tool allows analysis of future changes to the operation of combined sewer overflows (CSOs) and wet weather loadings on treatment plants. 

Note: The software tool for this project can be downloaded from the 'Supporting Documents' CD.

Price: £250  

Rainfall Intensity for Sewer Design - Technical Guide

Reference: 15/CL/10/16-1
ISBN: 184057 771 1
Published Date: 06/07/2015

UK water and sewerage companies do not have a way of assessing the growing risk of customer flooding and pollution from CSOs. Previous research for UKWIR used UKCIP02 and UKCP09 projections and data. However, short-period rainfall statistics used to assess existing and new sewer systems are largely the result of convective rainfall.  Convective rainfall processes are not well simulated by Regional Climate Models (used in UKCP09 and predecessor projections).
Addressing this issue, this project has produced estimates of rainfall intensity change over different parts of the UK using a combination of climate analogue data and a high-resolution (1.5km) climate model developed by the UK Met Office both approaches capturing or resolving convective rainfall events. The resultant rainfall intensity change estimates are, in general, higher than existing UK guidance suggests.

Sewer flooding frequency and volume, and frequency of pollution events are also investigated for five locations; indicating that these are also likely to increase in the future. It is recommended that further work is undertaken to add confidence to the results produced and to inform future UK guidance.

Price: £50  

Climate Change and the Hydraulic Design of Sewerage Systems Volume IV: Associated Topics; IVB - International Drainage Practices

Reference: 03/CL/10/11
ISBN: 1 84057 365 1
Published Date: 13/12/2004

This report is part of a major study on the impact of climate change on sewerage hydraulic design The project was wide ranging, but with a principle focus on the performance of sewerage systems under future (year 2080) rainfall conditions and what changes might be needed in the hydraulic design of sewerage systems to address any problems that climate change might pose. Other issues include, a summary of international drainage practice and predicted changes in sea levels and river flows.

This report is one of 13 documents collated in 4 volumes. This document is one of four in volume IV - Associated Topics.

The other reports in volume IV cover:

  • An evaluation of the different parameters used in FSR and FEH and their implications with regard to sewerage system design and simulation
  • An overview of high intensity spatial rainfall and the issues relating to climate change and drainage system evaluation

This report provides a summary of current best drainage practices and the possible future direction that drainage design might take is considered.

Price: £50