Climate Change and Flood Risk

EMEA Regional Focus: Safety, Risk and Compliance

Flooding can have a devastating impact on industrial facilities in terms of safety, the environmental, asset damage and operational downtime. In the UK, Flooding is the most frequent and widespread natural hazard, and with climate change this frequency of extreme events is expected to increase.

The UK Climate Projections in 2009 (UKCP09) stated that the UK should expect to see an increase in the frequency of intense rainfall events, and although individual extreme weather events are difficult to attribute to climate change, recently observed flood events are consistent with the UKCP09 predictions. This was further corroborated in the 2018 update of UK climate predictions (UKCP18), which confirmed that the UK should expect:

1. Warmer, wetter winter
2. Hotter, dryer summers, but with increases in the intensity of heavy summer rainfall events, and
3. Increases in frequency and intensity of extreme events.

The implications of increases in rainfall intensity and frequency are of the most concern. Urban drainage systems are typically designed for 1 in 50 year events, so as the frequency of extreme events increases, so will the flood risk, to the point when an extreme event becomes a likely event within the lifetime of a typical facility.

Flood Preparedness is recognised by both Government and industry as high priority, with recent flooding events affecting a number of major hazard establishments that are subject to regulation under the Control of Major Accident Hazards Regulations (COMAH) 2015. Flood preparedness has been designated a strategic topic by the COMAH Strategic Forum.

How Can an Industrial Facility Prepare?

Flood management should be based on a risk management approach, and fundamental to this is a sound understanding of the variables in the risk balance. ABS Group has assisting facility operators for many years in risk assessment, mitigation and emergency response planning for flood risk. Based on our experience the key steps a facility should address are listed below:    

1. It is important that facility operator understands the flood hazard for their location.  Not just the water level, but flow velocity, hydrostatic loads, potential debris, contamination, flood duration etc.  The return period is fundamental to the understanding, but climate change is creating some uncertainty here.  Sensitivity studies can be applied to the hazards to identify potential cliff-edge effects.
2. Map out the expected threat timeline from warning through to floodwaters affecting the site.  This will help establish what mitigation can be implemented beforehand and during. 
3. Understanding the potential consequences, considering the impact on: property, equipment, raw materials, finished products etc.  This requires specific knowledge on water ingress mechanisms, flood defence effectiveness and equipment vulnerability.
4. Estimate potential business interruption by considering: operational downtime,  clean up/decontamination, start-up/commissioning, supply chain issues, workforce availability etc.
5. Estimate safety and environmental impacts such as flood induced losses of containment, unsafe shut-down scenarios, ineffective safety critical equipment etc. Further guidance can be found in the COMAH Competent Authorities Operational Delivery Guide, “Inspection of COMAH Operator Flood Preparedness”
6. If there are potential major accident scenarios related to the flood risk, ensure the risk assessment considers:
   1. the effectiveness of internal and external emergency response,
   2. human factors,
   3. vulnerabilities of fixed piping and plant, mechanical equipment, utilities and EC&I., and
   4. flood barrier effectiveness and cliff edge effects

Flooding can have a devastating impact on industrial facilities and local communities, but the risk can be managed with a good understanding of the hazard, the potential consequences and a sound risk based a methodology.

As Seen in Chemicals Northwest's Elements Magazine: Autumn 2021