Key points are not available for this paper at this time.
Runoff attenuation features ( RAFs ) are low‐cost, soft‐engineered catchment modifications designed to intercept polluted hydrological flow pathways. They are used to slow, store and filter runoff from agricultural land in order to reduce flood risk and improve water quality, specifically by mitigating diffuse water pollution from agriculture. This study focuses on a sub catchment (30 ha) of the Belford Burn catchment (5.7 km 2 ) where the capacity of two RAFs to reduce concentrations of suspended sediment ( SS ), phosphorus ( P ) and nitrate ( NO 3 ) in runoff has been investigated. A field bund RAF , designed to intercept overland flow during storm events, has been shown to retain significant volumes of sediment; however, the underlying field drains are still exporting high concentrations of sediment and nutrients, sometimes exceeding 500 mg SS l −1 , 1 mg TP l −1 and 40 mg NO 3 l −1 . An on‐line sediment pond is accumulating sediment during normal flow conditions, but event sampling has revealed a lack of retention of any pollutants during storm events, which has been attributed to remobilisation of previously deposited material. In order to address these problems and improve the quality of the water leaving the sub catchment, a novel multi‐stage RAF has been constructed in the ditch network. A low‐cost filter trap, using wood chippings, has been installed and will be the focus of on‐going monitoring and investigations. The ability to help tackle flooding and pollution by managing runoff flow pathways does have great potential, despite being somewhat difficult to evaluate.
Barber et al. (Wed,) studied this question.