Blanket Peat Restoration: Numerical Study of the Underlying Processes Delivering Natural Flood Management Benefits

Abstract

Peatlands cover only 2.84% of the land surface of the planet, yet they provide the human population with a wide range of services, including more than a third of soil carbon storage, river flow regulation, and biodiversity (Xu et al., 2018). These sensitive systems require high precipitation or impeded drainage to develop and remain stable. Industrialization, mechanization, land-use change (e.g., agriculture or forestry) and extraction of peat for horticultural and energy production have all led to degradation of peatlands.Blanket peat, the dominant UK peat type, is unusual among peatlands in that it occurs on slopes up to 15° (Lindsay et al., 1988). When surface vegetation is damaged, their sloping nature means that erosion can rapidly occur (Evans, Allott, et al., 2005;Evans, Warburton, & Yang, 2006). Rapid and extensive peatland degradation has been going on in the UK uplands for at least a century due to increased atmospheric pollution (e.g., Rothwell et al., 2007), drainage, grazing, and wildfire damage (e.g., Evans &Warburton, 2011). Peatland degradation not only poses a severe threat to an important ecosystem, but in some circumstances may also enhance downstream flood risk (Acreman & Holden, 2013). For peat to develop and persist it must be largely saturated for much of the year, thus even intact blanket peatlands are often able to store little water during rainfall events, relative to other landscapes. Blanket peatlands typically exhibit a flashy response to rainfall, dominated by saturation-excess overland flow and/or near surface throughflow with minimal base-flow contribution (Evans, Burt, et al., 1999). Peatland degradation through, for instance, vegetation

Using micro‐catchment experiments for multi‐local scale modelling of nature‐based solutions

“…The new ‘modelled’ woodland is assumed to give rise to changes in a number of hydrological processes from increasing friction to overland and near surface flows (Goudarzi et al, 2021), enhancing infiltration rates due to roots, and enhanced through‐storm wet canopy evaporation (this latter has been studied in detail by Page et al, 2020). Rather than modifying multiple Dynamic Topmodel parameters (listed in Section 2.3) as in the approach of Ferguson and Fenner (2020), all these effects are lumped into the shift in the key sensitive parameter, m , as a percentage of the independently calibrated value for the whole of the Eden.…”

“…The new 'modelled' woodland is assumed to give rise to changes in a number of hydrological processes from increasing friction to overland and near surface flows (Goudarzi et al, 2021), enhancing infiltration rates due to roots, and enhanced through-storm wet canopy evaporation (this latter has been studied in detail by Page et al, 2020).…”

Carbon concentrations in natural and restoration pools in blanket peatlands

“…In some locations, where peatland restoration has been undertaken, pools have been created. These "restoration pools" have most commonly occurred when drainage ditches or gullies have been blocked with dams and artificial pools have formed behind each dam (Goudarzi et al, 2021;Holden et al, 2017;Parry et al, 2014).…”

“…In some locations, where peatland restoration has been undertaken, pools have been created. These “restoration pools” have most commonly occurred when drainage ditches or gullies have been blocked with dams and artificial pools have formed behind each dam (Goudarzi et al, 2021; Holden et al, 2017; Parry et al, 2014). Expansion of the number of peatland pools could be of importance for the peatland C cycle because pools may be large sources of both CO 2 and CH 4 to the atmosphere (Hamilton et al, 1994; Pelletier et al, 2014).…”

Assessing the efficacy of offline water storage ponds for natural flood management

“…To expand on emerging modelling methodologies that assess the impact of NFM structures (e.g., Ferguson & Fenner, 2020;Follett et al, 2020;Goudarzi et al, 2021;Metcalfe et al, 2017Metcalfe et al, , 2018Nicholson et al, 2019;Quinn et al, 2013) and additionally to aid opportunity mapping (Barnsley et al, 2021;Hankin et al, 2017;Lavers & Charlesworth, 2018) the collection of high-resolution empirical data for in-depth event analysis of NFM structures is urgently needed (Black et al, 2021). This will ensure uncertainty and scenario analysis of NFM designs across landscapes are able to quantify their efficacy for flood risk reduction (Dixon et al, 2016;O'Connell et al, 2004;Thomas & Nisbet, 2007).…”