A landscape approach to ‘Keeping Rivers Cool’

‘Keeping Rivers Cool’ is a four year (2012 to 2016) £1M climate change adaptation programme (part-funded by the Environment Agency, England), that integrates scientific evidence and practical landscape planning to increase the adaptive capacity of our freshwater ecosystems.

We are taking action now by erecting fences, planting riparian trees and promoting natural regeneration to create shade and reduce the chance of rivers becoming too warm for some freshwater wildlife over the next 60-70 years.

There is a high degree of certainty the UK will become warmer and we expect inland water temperatures to be significantly altered with potentially profound impacts on freshwater ecosystems (Bates et al., 2008; Murphy et al., 2009). An expanding body of literature suggests that changing riparian land use can reduce water temperatures (Caissie, 2006; Malcolm et al., 2008; Clews et al., 2010). A lowland river study in England found that shade provided by woodland reduced water temperature by up to 5.5°C on hot summer days compared to open grassland sections (Broadmeadow et al., 2010).  Other rivers are already reaching temperatures above the lethal limits for salmonid fish in recent hot, dry summers (Solomon and Lightfoot, 2010).

Our aims are to:

• Promote riparian shade as a strategic measure to create cool refuges and reduce temperatures in salmon and trout headwater streams; and
• Inspire and enable others to create riparian shading by providing evidence, guidance and demonstration projects.

Despite a focus on fish we expect to deliver a range of benefits such as: enhanced riparian habitats; carbon sequestration; pools, riffles, stream narrowing (Woodland Trust, 2013); increased woody debris; and reduced bank erosion and diffuse pollution.

We made innovative use of LiDAR (Light Detection and Ranging) data (Figure 1) normally used for flood modelling to generate ‘Shade Maps’ showing relative shade (produced by vegetation and landmass) over rivers, highlighting areas most exposed to warming. These data have been verified by our ‘demonstration pilot’ partners to strategically target tree planting.

Our approach can be applied across Europe. We published our first Guidance Manual (Environment Agency, 2012) in summer 2012 (Figure 2) and it has since made its way to Norway, Spain and Romania. It describes for the first time how to target fencing or planting, select tree species, access funding, and what local consents, engagement and other environmental aspects to consider.

Our first pilot demonstration with the Ribble Rivers Trust has involved planting some 35,000 trees, erecting 15km of fencing and is inspiring others to overcome practical delivery issues such as managing state aid, liaising with multiple stakeholders, ash-die back, adverse weather/wet-ground conditions and lambing. Three further demonstration pilots are planned for 2013 to 2014 (Figure 3) along with monitoring of river temperature, fish and invertebrate community changes. Keeping Rivers Cool is working at a Water Framework Directive management catchment scale to integrate this measure into future river basin plans.