Proceedings

UK climate change – the low flow challenge

• WWTW design focusses om peak flows – formula A, full flow to treatment, storm water retention etc but little attention is paid to minimum flows
• DWF as 20%ile may not reflect base flow as well as was attempted with the previous DWF definition incorporating precedent conditions
• Prolonged dry spells can result in significant reductions in daily flow below DWF20%
• This can impact WWTW performance
• Sewer transport processes may be affected resulting in more severe storm flush events
• This presentation focusses on those sites where prolonged dry weather result in flows below DWF but is also relevant for prolonged DWF operation