More than 100 years of data analysed by Wheatbelt NRM shows the availability of soil moisture in the Wheatbelt is declining.
The data has been included in the most recent update of our Wheatbelt NRM Dashboard and demonstrates the need to continue our focus on the important issue of the drying catchment.
This has been identified in the Wheatbelt NRM Strategy as a major concern for our community, and it is widely accepted that the average rainfall across south-west WA, particularly in the winter months, has declined over the past decade.
How this impacts on the soil moisture available to plants is more complicated and there are a number of factors to take into account, such as soil type and depth, vegetation cover, evapotranspiration rates and groundwater dynamics.
However, the information has implications for how we manage our agricultural areas.
Farm practices that conserve soil moisture, careful crop variety selection and perennial feed alternatives are becoming more important for agriculture to remain viable in the face of decreasing water availability and climate change.
Wheatbelt NRM has compiled more than 100 years of soil moisture estimates from data sourced from the Bureau of Meteorology.
The Australian Landscape Water Balance grids allow users to explore the modelled soil moisture of Australia through space and time.
At Wheatbelt NRM we use this data to explore broad-scale trends in the root-zone soil moisture.
Our analysis demonstrates a statistically significant decline in average annual root-zone soil moisture availability over 109 years from 1911-2020 in the Avon Arc.
The percentage of available soil moisture has also declined over time in the southern, eastern and central regions of the Wheatbelt, with only the Great Western Woodlands bucking the trend despite lower values in the past two decades.
The long-term change in soil moisture is likely to impact on our native vegetation through water stress and the loss of species whose water requirements are no longer being met.
It also highlights the importance of careful plant selection when revegetating to future-proof our revegetation investments against climate change.
The Wheatbelt NRM Dashboard is located on our NRM Strategy website and provides an environmental snapshot of thresholds of potential concern in the region’s environment.