CRS34 Number of registrations for flood warnings/alerts

Since the early 1960s, average annual rainfall has increased by 27% across Scotland, varying considerably between regions and seasons.  Winter rainfall has increased most, especially in the North (51%) and West (45%) compared with the East (24%). A trend of increasing heavy rainfall in winter is also apparent; in particular, North and West Scotland have seen an increase of more than eight days.  The patterns of change are broadly similar to those for total precipitation with a strong east-west gradient in winter months. Most of the west has seen an increase of more than five days of heavy rainfall in winter. Changes in summer months are small but some northern areas have become drier.  For the year as a whole, most western parts of Scotland have become wetter while there has been much less of an increase in eastern parts (SNIFFER, 2014).

The awareness raising envisaged by Objective 2 of the Scottish Climate Change Adaptation Programme (SCCAP) is intended to increase resilience and reduce the physical, economic and psychological impacts from the projected increased flood risks.  The Scottish Environment Protection Agency (SEPA) and the Met Office collate hydrological data from 250 rainfall, river and coastal monitoring stations used to predict the likelihood and timing of flooding events (Scottish Flood Forecasting Service).  This information provides Category 1 and Category 2 Responders (UK Government, 2004) with better indications of flood risk.

SEPA have identified the locations most at risk from flooding and developed enhanced coastal and river forecasting capabilities based on a network of monitoring stations. There are 269 of these Flood Warning Areas which can provide advance notice of flooding in these specific risk areas via the warning service: Floodline (SEPA, 2015).  As well as the more targeted flood warnings available to people in those localities, more general Flood Alerts are available which provide flood messages for a larger geographical area (19 in total).  

The effectiveness of this service depends on uptake, i.e. the number of people signing up to receive flood warnings and alerts by phone. It is particularly important that the uptake is high in those areas at significant risk of flooding.  However, it should also be noted that, during flood events, far greater numbers access SEPA’s flood warning services and products digitally, via both SEPA’s own website and also partner information channels (e.g. Met Office, local authorities and the BBC). Therefore, consideration of Floodline registration figures alone does not fully reflect the number of people who utilise SEPA’s flood information services and who take preparatory action as a result.

Related indicators:

BB1/BB3 Property at risk of flooding (residential/non-residential)

[1]Floodline: http://www.sepa.org.uk/environment/water/flooding/floodline/

Floodline was introduced in 2001 to provide a national passive flood warning information system.  In 2006, SEPA introduced the Flood Early Warning System (FEWS) and new flood warning schemes for the Clyde, Kelvin and Irvine catchments.

In 2011, the introduction of the Floodline direct warning service in Scotland provided an active dissemination system for the public. Category 1 and Category 2 Responders also have access and are identified separately.  Uptake rose by 85% in the first four years to December 2015 (Figure 1).

Figure 1 Floodline uptake March 2011 – December 2015

Floodline can also be accessed on-line and via the phone (Figure 2).  During the period March 2011-December 2015, in response to over 8,902 alerts (3,773) and warnings (5,125 plus 4 severe flood warnings) (Figure 3), there were a total of 1,587,417 web page hits and 18,475 phone calls handled by either the Interactive Voice Recording (IVR) system (10,255) or the Floodline service (8,202).

During Storm Desmond in December 2015, the Floodline website received over 100,000 user sessions (250,000 page views) exceeding the previous record of 95,000 in August 2014.  550 new people registered for the service. The water level web page alone was viewed over 100,000 times and 64 notifications of flooding were notified through ‘Report a Flood’, a feature added recently.  At the height of the event 15 Alerts and 75 Warnings had been issued (including 2 Severe, the first time since the launch of the system that this level of risk had been identified).  Over 70,000 messages were sent via a variety of channels (email, fax, pager, SMS and voice messages).

Figure 2 Floodline Access March 2011-December 2015

Figure 3 Alerts and Warnings issued March 2011 – December 2015

In February 2017 SEPA published their plans for the delivery of the flood warning service for the next five years (SEPA, 2017). The Framework is structured around three main aims:

Aim 1- Maintenance of existing and delivery of new flood warning schemes

As part of this aim, fourteen new flood warning schemes have been identified for operational delivery by 2021 (Figure 4)

Aim 2- Development and innovation

Building on their partnership with the Met Office, SEPA aim to utilise new data sources to improve forecasting ability and communication of risk and uncertainty. It is intended that new hazard maps will enable more real time flood mapping which can support decision making during flood events

Aim 3- Engagement with partners and customers

In partnership with local authorities and Scottish Water, SEPA aim to increase flood risk awareness campaigns , with priority in areas with new and existing Flood Warning Areas. They also aim to widen their partnerships to include organisations already active at community level.

The Framework also includes key measures for the success of the service e.g:

• Timely delivery of new flood warning schemes
• Annual customer survey and customer feedback analysis
• Analysis of lessons learnt from significant flood events and exercises

Figure 4 Location of existing and new flood warning schemes (SEPA, 2017)

CREW’s report (Geddes et al, 2017) on the effectiveness of the Floodline service included a number of recommendations to improve the service in the future, including:

• Provide a more effective information portal which combines information from disparate sources which many users also access in response to warnings and alerts (e.g. flood forecasting, monitoring and local authority feeds);
• Review flood warning message content to improve specificity regarding expected severity and extent;
• Examine the potential to provide more tailored content that is more geographically specific than currently available;
• Continue to develop awareness of the service, but also improve clarity regarding what the service does and does not provide;
• Introduce a ‘no warning’ message type to provide reassurance to customers in areas not expected to be affected.

Uptake in Flood Warning Areas is particularly important, and of the registered users in December 2015, 16,673 were located within one of the 269 FWAs located in 15 Flood Alert Areas (FAAs)  (Table 1). However, this aggregated data conceals a wide range of uptake across the individual FWAs from 0% - no registrations in Hunters Grove (Argyll & Bute FAA) or Skelmorlie (Ayrshire & Arran FAA), for example - to 663% in the Shawlands, Langside and Cathcart FWA in the West Central FAA, as a result of changed boundaries.

In December 2015 it was estimated that 66,482 properties were at risk of flooding across all FAAs.  The number of registered users shown in Table 1 suggests around 25% (range 17% to 38%) of those properties were signed up for the service.  However, the data cannot be disaggregated to individual properties so this is likely to be an over-estimation.  Additionally, people following flooding alerts and warnings on social media (Twitter, Facebook, etc.) would not be included in the Floodline registration count.   These users are not tracked currently and therefore no data are available.

Table 1 Registrations per Flood Alert Area, December 2015

Data Quality issues (Dec 2015)

1. The number of properties at risk reported through the FWA dataset differs from the dataset used for the baseline appraisal. The Identified Number of Properties in the FWA appears to overestimate the numbers of properties at risk from a 1 in 10 year return value but underestimates for the 1 in 50 and 1 in 200 year return values, significantly for the latter.

However, the FWA dataset and the baseline dataset have different purposes and have been created differently. The appraisal dataset is used by SEPA as the basis for the published figures of number of properties at risk, Annual Average Damages etc. The flood warning dataset is used specifically for flood warnings. Warning areas have been created based on historical flooding, detailed modelling where this is available and, originally, the old indicative flood map (IFM). An exercise is being undertaken to update the warning areas to take account of the hazard mapping rather than the IFM. The baseline dataset comes from strategic level modelling and mapping.

1. Improved mapping techniques and customer feedback can result in boundary changes where the corresponding increase or decrease in the number of properties included in a FWTA may result in anomalies if the number of registered users in those properties is not adjusted to take account of those changes.
2. People can register for flood warnings in ‘areas of interest’ without necessarily being resident in those areas leading to an overstatement of the level of uptake for the area in question.
3. Floodline web statistics for April, July and August 2015 are unreliable due to changes in the HTK pages, the Floodline platform.

National Food Risk Management Strategy datasheets for LPDs, available at: http://apps.sepa.org.uk/FRMStrategies/index.html