Sediment supply and transmission via roadside gully pots

Field studies undertaken on the Clifton Grove residential estate, Nottingham, between August 1976 and October 1980, in which the input and release of material to and from roadside gullies and the gully pot liquor quality were monitored, are reported. Factors affecting sediment supply, such as variations in soil moisture deficit, rainfall parameters, runoff volume and catchment characteristics are considered. Sediment retention by gullies and its release in storm flows are assessed in the light of the nature of the sediments found in basal samples from gully pots and in runoff samples obtained downstream in the storm sewer. The effect of sediment input on gully liquor quality and the variation in dissolved oxygen concentration are detailed. The suspended sediment concentration in road surface/gully pot discharges showed no clear tendency to decrease through a storm event and this, coupled with previous findings from storm simulations, strongly suggest that “first flush” effects are a function of the flushing of in-pipe deposits from a previous storm event.