Quantifying Indian Ocean Subtropical High-runoff Relationships a Case Study over Campaspe River

El-Nino Southern Oscillation (ENSO) is one of the factors that widely studied with respect to the variability in rainfall and streamflow. However, there are other factors which also influence the climate variability and patterns of the circulation. This study aims to investigate linkage between Indian Ocean High pressure indices and South Pacific high indices with the Campaspe River streamflow. It was found that the zonal movements of the high-pressure system of South Pacific and Indian Ocean largely affect the flow in the river. A regression model was constructed with Indian Ocean high pressure indices and South Pacific indices that explain 42% of the variability in the flow of the River. A Mann Kendall’s tau test was also applied in order to assess the trends in the data. A significant decreasing trend in the streamflow is correlated with the increasing trend in the Indian Ocean high pressure system.