Modelling input of fine granular sediment into drainage systems via gully-pots

An existing model of sediment wash-off from paved surfaces has been extended to predict fine granular sediment inputs into drainage systems via roadside gully-pots. The model comprises three separate components: (1) a model of sediment accumulation on paved surfaces; (2) a model of sediment wash-off from these surfaces; and (3) a model of sediment deposition and erosion in gully-pots. The first two model components have been previously successfully tested, whereas the third component of the model is presented in this paper for the first time. The model was applied to two small catchments located in Dundee, Scotland, where data on flow rates and sediment concentrations were collected at the inlets into the main drainage systems from the road gullies. It was found necessary to calibrate only the build-up component of the model to achieve good agreement between the simulated and measured data. It was concluded that only two calibration parameters are required to model the input of fine granular sediment into storm drainage systems via gully-pots.