Year

1986

Degree Name

Master of Engineering (Hons.)

Department

Department of Civil and Mining Engineering

Abstract

Byarong Creek in the illawarra region is typical of many coastal streams which commence in a predominantly natural escarpment and drain across urbanized lowlands into a coastal lake or directly to the sea. In this present study the variation of suspended sediment and soiute concentrations in the upland catchment of Byarong Creek is presented for ten, well documented storm events. Rainfall and flow were continuously recorded for each storm event and water samples were collected from the beginning to the end of each storm at half hourly intervals and analysed for suspended solids (nonfiltrable residues) and total dissolved solids (electrical conductivity). Because of the small catchment size (4.2 km^) and steepness of the main channel slope (15%), the suspended solids and total dissolved solids concentrations were shown to vary rapidly within a storm event. It was found that the traditional rating curve method using concentration streamflow relationships can provide a reasonable prediction for total dissolved solids but did not enable a good prediction for suspended solids concentrations. A more reliable prediction was obtained for suspended solids by regression analysis of the total suspended solids load on a storm event basis. This technique minimized errors caused by the hysteretic effects within each storm event and for practical purposes can provide a more reliable estimate of the total suspended solids load discharged during any given storm. Additionally the results of the present study will provide baseline data for similar catchments which may be subject to further urbanization.

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