The hydrological response of riparian buffers at field and catchment scale during storm events

Riparian buffer strips have traditionally been adopted for their ability to reduce diffuse pollution and promote ecological habitat. Hitherto, most research focuses on their water quality and hydraulic roughness functions. More recently however, EU and UK flooding legislation have promoted a sustainable approach to flood management encouraging the use of natural processes and features to reduce flooding (Flood Risk Management (Scotland) Act, 2009). From a theoretical perspective, one would expect riparian buffers to increase: infiltration, interception, evapotranspiration and hydraulic roughness, thereby attenuating runoff. Given that these hydrological behaviours will reduce flood risk, there is reason to consider riparian buffers as a natural flood management (NFM) measure with multifunctional purposes (diffuse pollution, water quality and ecology) (Barlow et al. 2014, Bentley et al. 2014). However, there is a distinct lack of clear data to justify this at the present time. There is also uncertainty regarding: the scale of flood event that riparian buffer strips may be able to attenuate, the optimal width of buffer strips in relation to slope, and the spatial scale across a catchment at which they need to be implemented. There is therefore an urgent need for field data to evidence that riparian buffers can influence hydrology sufficiently to reduce flood risk, and to identify temporal, spatial and event scale thresholds for effectiveness. The aim of this study is to examine the field scale hydrological responses of a riparian buffer strip during storm events and to categorise the hydrological behaviour and rainfall characteristics being responded to. The study uses empirical field data to contribute to the understanding, and evidence base, of how effective riparian buffers are as NFM measures.