Flooding, and management, cost the UK £2.2billion per year. Under current economic pressures, flood policy is shifting from entirely flood defences to broader management strategies. This includes Natural Flood Management (often also denominated Nature Based Solutions (NBS)) which aims to restore the natural functioning of catchments to store water and slow the flow. Examples of NBS, shown in the figure here presented, include tree planting, leaky dams and river restoration, along with agricultural land management. These work with hydrological processes, including increasing infiltration of rainfall into the soil, storing water on the floodplain and increasing the flow resistance to flow within the channel to attenuate the flood peak (taking the top of the peak). These interventions also have multiple benefits for other ecosystem services such as biodiversity, water quality and carbon sequestration.
However, despite gaining popularity with policy makers and flood action groups, a lack of evidence on its effectiveness and advice about how to go about implementing such an innovative approach are limiting its success.
There are two gaps in current knowledge relating to the effectiveness of NBS. First, at the intervention scale, we do not have a full understanding of how much the natural processes which are modified by the features do alter ecosystem service provision. Second, at the larger sub-catchment scale, we have limited knowledge of how the effect of the interventions combine together and propagate through the river system. The importance of how sub-catchments interact in terms of tributary synchronicity is essential to understand in terms of larger scale scheme design (Pattison et al., 2014). Furthermore, there may be synergies and trade-offs between the different ecosystem services which need to be considered at the landscape scale.
This project aims to develop guidance on how NBS schemes can provide the optimum benefits in terms of ecosystem services at the catchment scale. The research will be focussed on the Allan Water Restoration project working with a wide range of stakeholders.
- Carry out laboratory experiments and field trials to determine how interventions, e.g. leaky dams, channel restoration, effect different ecosystem services.
- Develop models to upscale these impacts to the catchment scale.
- To evaluate the synergies and trade-offs between different ecosystem services at the intervention and catchment scales.