Scottish Fire and Rescue Service (SFRS) - wildfire: incident reporting system - data analyses

1 Introduction

1.1 Background

Globally, over the last 50 years, wildfires have been recorded across many countries and regions. They are particularly common in Australia and Brazil, where known incidents have occurred over extensive areas and have caused destructive environmental harm (Arnell et al, 2021a). Moreover, due to an increasing awareness of wildfire occurrence, as well as concerns about how wildfire incidents could alter the landscape and potentially damage property and infrastructure, wildfires are increasingly an important topic of discussion across the UK (Davies et al, 2008; McMorrow et al. 2006, Arnell et al, 2021a).

Wildfires are commonly classified as semi-natural hazards and, in the Scotland, they are defined as "any uncontrolled vegetation fire which requires a decision, or action, regarding suppression" (Scottish Government, 2013). Their occurrence is likely to be determined by a combination of environmental and climatic influences i.e., temperature and amount of rainfall, but are most often caused by deliberate or accidental human influences (Arnell et al, 2011a). In addition, the distribution of wildfires in Scotland is believed to be non-random in both time and space; in particular, fuel hazard in spring, with abundant dead herbaceous and aerial shrub fuels, is quite different from that in summer where most above-ground fuel is live, while grass fuels are more abundant in the north-west of Scotland (Davies and Legg, 2016).

Most wildland fires in the UK are usually small in nature - usually under a hectare in size (Arnell et al, 2021a) and are most likely to occur in arable, grassland or mountain and heath environments (de Jong et al, 2016, Gazzard et al, 2016, Forestry Commission 2019). Furthermore, wildfires also occur frequently on remote upland peatland environments (Albertson et al, 2010). Although peatlands may be rare globally, covering roughly 2–3% of the Earth's land surface, between 9% and 15% of Europe's peatlands are located in the UK, with 77% of those occurring in Scotland (Bain et al, 2011).

Climate change has been cited as one of the major influences in increased wildfire occurrence globally (Grau-Andres et al, 2018; Arnell et al, 2021b). Specifically for the UK, mean summer temperatures are anticipated to rise by as much as 2.5°C by 2050 increasing wildfire risk, which can be further exacerbated by potential decreases by over 15% in annual rainfall over the same period (Grau-Andres et al, 2018). Increases in the frequency of drought will most likely lead to more frequent wildfires occurring across the UK, which can be more severe in nature, occur more extensively across landscapes and exhibit more variable seasonality (Albertson et al, 2010; Davies et al, 2013).

Wildfires can be destructive for seminatural habitats (Whitehead et al, 2021); they can cause peatland degradation (Carroll et al, 2009; Bain et al, 2011) and reduction of carbon storage; the release of toxic metals into the atmosphere (Turetsky et al, 2006); and extensive damage of sensitive habitats such as Sphagnum vegetation communities (Grant et al, 2012). Overall, it is expected that increased occurrence of wildfires, especially on remote upland area and peatlands, will be costly to fight, cause damage to freshwater catchments and other ecosystem services and require costly restoration (Albertson et al, 2010).

1.2 Project Aims and Objectives

The overall aims of the project entitled: "Provision of Analyses of Scottish Fire And Rescue Service (SFRS) Incident Reporting System (IRS) Data In Relation To Wildfire Incidents" are to a) improve the understanding of how upland wildfires start; b) investigate if wildfire occurrence differs between geographical areas; and c) describe how wildfires exhibit seasonal and temporal trends.

In particular, the principal objectives of the project are to:

• Investigate how wildfires affecting semi-natural habitats can be extracted from SFRS incident data and how can they be best used to provide information about ignition sources (at a broad scale; accident, behavioural, intentional), locations (SFRS areas) and time of year.
• Report on any trends evident from these data.
• Make recommendations on any improvements that could be made to enhance the dataset's usefulness for these purposes.
• Compare the SFRS data to wildfire trends in Europe to examine if there are lessons that can be learnt.

1.3 Report outline

This report is organised in the following sections:

• Section 2 provides the description of the SFRS IRS dataset, including the main fields that were used in the analysis.
• Section 3 presents a brief overview of the methods used in the analysis.
• Section 4 presents the harmonisation of the fire incidents regarding fuel types, and the filtering process devised for identifying and selecting wildfires affecting seminatural habitats.
• Section 5 presents the results of the investigation of different patterns in the filtered wildfires dataset (seasonality, fuel types, motives of ignition, burnt area size and accessibility), analysed at a National and Local Authority level.
• Section 6 presents the results from the comparison of information recorded in IRS wildfires with information derived from burnt area polygons, regarding distances between IRS locations and fire perimeters, fuel type composition and burnt area sizes.
• Section 7 presents the results of the investigation of patterns (temporal, fuel type and burnt area size) in Scotland and other Northern European countries.
• Section 8 presents the results from the Highland LA case study regarding spatial relations between wildfire locations and explanatory variables and ignition risk modelling and mapping.
• Section 9 provides recommendations for improving the IRS dataset for identifying wildfires and using wildfire incident data in wildfire operations and research.