Sediment Responses During Storm Events in Small Forested Watersheds

Abstract

Measurements of suspended sediment concentration and discharge during storm events are examined to determine the possible patterns in response of sediment to flow in five small forested watersheds. the examination of sediment response is carried out in two contestx: (a) the response of suspended sediment to total discharge (baseflow and quickflow or stormflow), or in the framework commonly used for sediment prediction modelling. (b) the response of suspended sediment to quickflow, where quickflow is postulated as a possible mechanism of sediment delivery to the channel. In both contexts, hysteresis diagrams are first used to determine the broad patterns between suspended sediment concentration and flow in the time domain. Results indicate that seven different response types are operating in the watersheds. Spectral analysis is then used on the storm event data in an attempt to isolate possible factors which may be causing the different response types. The temporal and spatial variations found to be operating in the watersheds have important implications for both the design of monitoring networks and the associated water sampling techniques; and for the commonly used linear predictive methods of estimating sediment loads.