Water quality variations during a flood event in the Annan River, North Queensland.

Abstract

Variations in water quality (conductivity, pH, suspended solids, Na, K, Ca, Mg, Cl, SO₄, HCO₃ and Si) during a major flood event that occurred in the Annan River, north Queensland, on 21 March 1985 are reported. Factor analysis showed that dilution of base flow concentrations by surface runoff was the dominant influence during the rising stage of the flood event, possibly with some flushing of ions from the surface layers of the catchment soils also occurring. At low river flow, the water quality was dominated by that in ground water and possibly interflow. Heavy metals were mostly transported in particulate forms (Fe 99%; Mn 95%; Pb, Zn, Sn c. 80%; Cu c. 60%). Filterable metal concentrations were low and changed little with flow.