Trends in Rainfall and Temperature in the Murray Mallee and Upper Eyre Peninsula Region of South Australia—Connections to Climate and Land Use Change

Abstract

The Murray Mallee (MM) and Upper Eyre Peninsula (UEP) are two important regions to the South Australian agricultural economy. The UEP is dominated by agricultural land use with a semi-arid Mediterranean-type climate, with low, variable annual rainfall. The climate is similar, with significant farming production around the Murray Mallee, adjacent to the Murray River. When investigating rainfall trends in the UEP region, annual rainfall has decreased considerably in the last 73 years, from 1950 to 2023, at all rain monitoring stations. From the 15 stations in the MM, most of the locations' rainfall is decreasing, but three stations, including Callington, Murray Bridge, and Mannum, show an increasing trend in annual rainfall. Monarto Safari Park station had only recent rainfall records; however, it also shows an increasing trend. The records for MM, particularly for gauges where rainfall has seen an increasing trend, seem to correspond with a revegetation program on the Monarto Plateau during the 1970s, and this may have been significant enough to increase rainfall in the surrounding regions, including Callington and Murray Bridge. Each station's annual rainfall, mean minimum temperature, and mean maximum temperature data are analyzed separately using trend analysis with exponential smoothing and three robust change-point analysis methods in the MM and UEP regions. The significant change points observed in annual rainfall and temperature in each location and the overall reduction in rainfall may be attributed to industrial expansion, climate change, and shifts in land use patterns driven by urbanization, which have likely impacted water resources. This study investigated the relationship between land use and climate change that may impact South Australian rainfall patterns and increases in temperature over the last few decades.