Sediment and contaminant delivery to upland reservoirs following severe wildfire

Lead Research Organisation: Durham University
Department Name: Geography

Abstract

The devastating moorland wildfires of June and July 2018 which ravaged large parts of Northern England were the worst peatland wildfires since 1976. Severe wildfires, as distinct from managed burning, can act as a catalyst, resulting in catastrophic change in surface vegetation, soil and water runoff systems. Removal of vegetation by fire, coupled with changes to soil physical and chemical properties, enhances runoff and increases delivery of sediment and other contaminants to drainage systems. Although fire is a significant driver of change in moorland habitats the downstream impacts remain largely unknown. Given that such wildfires are likely to increase in frequency as the climate changes, the recent 2018 fires provide a rare opportunity to capture new data on the impact and response of these burnt moorland catchments in the immediate aftermath of the event. In this project we will quantify sediment and contaminant delivery to upland reservoirs from burnt catchments. We will work with local landowners and responsible authorities to promote recovery of these sensitive catchments by actively facilitating knowledge exchange between researchers and land managers.

The overall objective of the project is to quantify sediment and contaminant delivery from upland catchments in the immediate aftermath of a severe wildfire which affected Northern England in July 2018. The general approach considers the fate of fire-generated 'sediment' from source-to-sink along the upland sediment cascade from eroding moorland hillslopes, through the upland channel network to deposition in downstream reservoirs. We will characterise sediment sources within the catchment so that sediment fingerprinting can be used to trace burnt sediment as it moves downstream. Mapping of the catchment will allow us to determine the pathways eroded sediment takes from the hillslopes, through the stream channels and into the reservoirs. Using a combined approach of trapping sediment in the reservoir and the stream network we will quantify the fluxes of eroded sediment (e.g. total, contaminant, organic, inorganic) from the catchment downstream. By analysing sediment cores for charcoal layers deposited in the Victorian reservoirs we will reconstruct a history of fire events in the local region. This information will be extremely valuable in addressing several fundamental questions including whether catchment erosion rates significantly increased after severe moorland fires and which areas are particularly at risk?; and how significant are the current fires in comparison to the historical record of fires in the area?. By establishing clear pathways of knowledge exchange between researchers, local landowners and restoration teams we will directly assist in the recovery of the catchments from the impacts of the fire.

Planned Impact

Who might benefit from this research?

Our approach to impact is based on the premise that the recovery of severely burnt moorland habitat requires a joint effort that must involve scientific understanding, landowner knowledge and expertise; and the experience and skills of restoration managers. This requires effective knowledge exchange between all parties. The main beneficiaries of this research will be the land owners, water utility companies and restoration managers of moorland catchments. We will work with our particular project partners, Moors for the Future Partnership and United Utilities, to deliver these benefits. However, the results from this project will be of much wider application to all those working to management upland peat moorland environments. This includes National Park Authorities with substantial moorland habitats (e.g. Peak District, North York Moors, Northumberland, Dartmoor, etc.) and the upland UK peatland programmes actively managing moorland habitats, including the IUCN UK Peatland Programme and the many regional; programmes which support this. Potentially, results from the research can also feed into wider initiatives regarding landscape sensitivity and management in the face of wider climate change e.g. Department for Environment, Food and Rural Affairs (Defra) cross-regional research programme 'Adapting to Climate Change'.

How might they benefit from this research?

Through good working relationships with the local landowners, Moors for the Future Partnership and United Utilities we will help to promotes habitat recovery by exchanging knowledge relevant to recovery (e.g. identifying hotspots of erosion) and discussing best practice for managing erosion impacts from the fire (e.g. defining areas where sediment transfer is naturally buffered in the landscape).
We will hold a stakeholder 'Catchment Day' where we invite researchers, landowners and stakeholders in to the field to view 'first -hand' the recovery of the burnt catchments 'one-year-on'. This is an important time to take stock of the catchment response and discuss how the recovery of the moorland can be promoted beyond the immediate readjustment phase. We will also distribute a brochure which summarises the research undertaken in the project and, in conjunction with our project partners, issue a joint statement of best practice for promoting recovery of burnt moorland catchments. Multiple copies will be printed for wider dissemination and also a PDF version will be hosted on the project website.

Publications

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