A water budget model for the tropical Magela flood plain

Abstract

A water budget model is presented for the tropical Magela flood plain, which is located downstream from the Ranger uranium mine in the Northern Territory, Australia. Using input data on rainfall and water discharge from Magela Creek, the model provides daily estimates of the volume of surface water on the flood plain and the rate of discharge at the outlet of the flood plain. Annual variations in the relationship between gauge height and rate of discharge at the outlet are interpreted in terms of a correlation between early wet-season rainfall and seed germination on the flood plain. The daily volume of water on the flood plain can be used to estimate the dilution and subsequent evapoconcentration of any waterborne contaminants that may be transported by Magela Creek from the mine site downstream to the flood plain. The model was validated by testing its ability to predict the measured daily water depth at the outlet channel; comparison of prediction with 12 years' data produced an average error of about 16%.