Climate-water quality relationships in three Western Victorian (Australia) lakes 1984-2000

Abstract

To achieve robust simulations of past and future climate and their effect on aquatic biota, it is desirable to integrate results from palaeolimnology, contemporary monitoring and process modelling. Here we analyse over 15 years of water quality monitoring data from three lakes, Purrumbete, Colac and Bullen Merri from Western Victoria, Australia and their relationship to climate. In the context of a large number of limnological and palaeoenvironmental studies from the region, we seek to refine understanding of the primary forcing mechanisms that explain present, past and potentially future water quality variability in the lakes. Our analysis shows that there are strong relationships between climate and water quality in these lakes of varied size and salinity (average conductivity range 740–14,000 μS cm−1). The strongest climate–water quality relationship exists between air and water temperature, particular during the colder months. Strong relationships also exist with air temperature and other parameters, most notably nutrient concentrations. Effective precipitation also appears to exert a strong influence on water quality in these lakes. This influence is, by contrast with the influence of air temperature, less direct. Nevertheless, these lakes of varying salt concentration exhibit a coherent pattern of conductivity response to variation in effective precipitation, particularly during times of high moisture stress.