Longitudinal profile of trends in salinity in the river Murray

Abstract

Statistical analyses have been performed on series of electrical conductivity (EC) measurements taken over the past 16 years from 8 stations on the River Murray to assess changes in salinity along the river and trends over time. Below Euston, N.S.W., salinity has generally increased over time, although the log-linear trends were statistically significant at only three stations: Red Cliffs, Morgan and Mannum. The increase in EC of over 1% p.a. at Red Cliffs was partly removed when it passed to Merbein, and we attribute this to the Lake Hawthorn salinity interception scheme. Both Morgan and Mannum showed increases of over 2% p.a., confirming the results of our earlier analysis of chloride data from Morgan, and current levels there are close to the desirable limit of 800 µS/cm. Thus major adverse effects can be anticipated if the rate of increase over the last 16 years is allowed to continue.