Impact case study database

Our diverse body of pioneering research produced over a number of years had a both broad and deep direct impact on the assessment and management of environmental risks from wildfire. It specifically improved post-fire diagnostics, land management and drinking-water provision in Australia and Europe, with associated environmental and economic benefits.

Water services in Australia:

- WNSW, who supply greater Sydney (>6,000,000 people) commissioned us to quantify ash loads, ash characteristics and predict water contamination potential ( Ra-A& B, [R2-R3]) after a severe fire in their Balmoral catchment in 2013. A key finding was that the contamination potential of arsenic and boron, which were pollutants of concern after previous fires, was relatively low. Phosphorous was a more significant threat, but possible to deal with using the existing water treatment infrastructure. As a direct impact of our report to WNSW, “ no costly modifications to existing water treatment capabilities were required” [ C1, Water Quality Scientist, WNSW].

- The unprecedentedly extensive 2019/2020 Australian wildfires resulted in most of Greater Sydney’s main domestic water supply catchments being burned. Ra-B,D& E allowed us to provide WNSW with (i) ash distribution loads, (ii) expected contaminant concentrations in ash, (iii) a risk analysis of ash and contaminant movement for potential rainfall scenarios, and (iv) the location of ‘hotspots’ where landscape characteristics and thick ash layers cause high erosion risk. These outputs directly guided mitigation measures, such as the installation of fabric curtains across the lake that capture sediment, modifications in the water extraction depth at the dam and location of erosion mitigation barriers on critical hillslope erosion ‘hotspots’ [ C1, C2].

“In this way, the work of Prof. Doerr and his team improved confidence in our assessment of ongoing water quality risks, which was used to inform capacity planning by our major water treatment customer.” [ C1, Water Quality Scientist, WNSW].

A large rainfall event in March 2020 eroded most of the ash from the hillslopes (as predicted by our model), causing large sediment plumes in the reservoir, yet the mitigation measures enabled WNSW to continue supplying safe drinking water to Sydney. “The erosion risk mapping produced by Prof. Doerr’s team was used to guide the placement of erosion mitigation installations. The WEPPcloud-WATAR capabilities represent a significant improvement from our existing fire impact risk assessment methodology implemented at the start of the 2019-2020 fire season. We have adopted the methodologies developed by Prof. Doerr’s team this year into a revised water quality risk assessment process for future fire events” [ C1, Water Quality Scientist, WNSW].

- Following the catastrophic 2019/2020 wildfires, the Water Services Association of Australia (WSAA), who represent 20,000,000 urban water customers, adopted our decision-support framework for risk assessment and mitigation ( Ra-D) in its entirety in their national industry guidelines providing a “ structured approach to identifying mitigating strategies and undertaking risk assessments” [ C3, pg 26; see Fig 7.2 for graphical representation of our framework, pg 27].

UK emergency services and water suppliers:

In 2018, England’s largest wildfire on Saddleworth Moor led to evacuations and burned 1,800ha of water-supply catchments managed by United Utilities. The fire burned deep into peat soils high in metal contaminants, a legacy of emissions from surrounding industrial sites, raising concerns of potential water contamination. Our research findings ([R5], Ra-D) guided the UK Fire and Rescue Services in where to focus hosing to extinguish the fire, reducing peat loss and contaminant release from burning and erosion.

“Work between Prof. Doerr’s team, the Fire and Rescue Services and United Utilities has been a great example of how insights gained from their research have had a direct impact on minimising environmental damage and risk to water resources” [ C4, Tactical Adviser to the UK Fire and Rescue Services].

Using our method ( Ra-A), we identified a substantial water contamination risk from (e.g.) lead, arsenic and mercury. Based on Ra-C&D [R4-6] we guided United Utilities to cover hillslopes adjacent to the reservoir with biodegradable netting which prevented ash and soil eroding into the reservoir. This was the first substantive on-site mitigation treatment for water-contamination risk following a UK wildfire.

“I am pleased to report that the mitigation treatments have been successful in reducing the risk of contaminating raw water prior to treatment. Not only does this reduce the reliance on the treatment process to remove contaminants, but it also assists in ensuring that there are sufficient water resources available for treatment and supply to customers.” [ C5, Integrated Catchment Strategy Manager, United Utilities].

We also provided United Utilities with water-contamination probabilities for future fire scenarios and mitigation recommendations based on our WEPPcloud model ( RaC-E), [R4-R6, C6].

“Prof. Doerr’s team has also provided risk assessments for two other catchments (Chew and Torside) using their model, which we deem as high risk in terms of future fire impacts. This has been very useful in enabling us to focus our wildfire risk and impact reduction measures of resource allocation. These can range from targeted vegetation treatments to reduce landscape-scale flammability and upgrading of filtration capabilities where necessary. … Therefore, by applying the recommendations of the research there is a cost avoidance that could be up to £1 million for every wildfire avoided.” [ C5, Integrated Catchment Strategy Manager, United Utilities].

Improved environmental management in Spain:

The Canary Islands’ steep slopes are particularly vulnerable to post-fire erosion. In direct collaboration with Cabildo de Tenerife (Island Council of Tenerife), we evaluated the effectiveness of log barriers [R4], the traditionally-used hillslope erosion mitigation treatment (~GBP18,000,000 treatment costs between 2007 and 2017). Having determined their low efficacy, we developed alternative methods involving increased ground cover, which reduced soil and contaminant transport by 51-77% based on our monitoring of field plots ( Ra-D, [R4]), but which were comparable in application cost (~GBP1200/ha). These findings led to changes in the post-fire erosion treatment guidelines for the Canary Islands [ C7, C8 pg 16, C9 pg 14], which now incorporate the application of ground cover treatments using locally-obtained forest materials (wood-chip or pine-needle mulch) as recommended in R4. This treatment was adopted as standard practice on the islands and was applied after two fires in 2018 (391ha) and 2019 (9687ha) [C7]. Based on road repair costs alone following the 2009 post-fire erosion damage in the Canary Islands (~GBP7,100,000; GBP1900/ha) [C7], the associated cost savings from avoided infrastructure repairs after the 2018 and 2019 fires can be estimated at GBP760,000 and GBP19,000,000 respectively.