Land Capability Assessment - Glenelg Hopkins CMA
Land Capability or Suitability Assessment of the Glenelg Hopkins Catchment is a climate change adaptation project aimed at informing government (Local and State), the agricultural sector and the broader community, of the possible impacts of climate change on key commodities produced across the study region. The information has been developed to
1) Generate and communicate specific long-term data, information and strategic plans that enable Local Government Authorities and the agriculture sector in the Glenelg Hopkins catchment to adapt to climate change effectively with a focus on regional development, infrastructure and agricultural industry transformation
2) Reduce risks of soil degradation through farming practices inappropriate to future warmer, drier climate conditions.
The project was co-funded by the Glenelg Hopkins CMA with the support of the Australian Government National Landcare Programme, Southern Grampians Shire Council and Deakin University. An analysis of the potential implications of regional climate change on cropping, through GIS modelling of broadacre crops barley (autumn sown), red wheat (autumn sown), quinoa (spring and autumn sown), chickpeas (autumn sown), faba beans (autumn sown), mustard seed (autumn sown), sunflower seed (spring sown) and industrial hemp (spring and autumn sown) was implemented. An expert-systems based modelling approach was used that considers climatic, soil and landscape parameters to map expected yield across the region. The models and maps were validated with local farmers, farming groups and agronomists then modified according to their feedback, before running the models again with climate change projection data to understand how projected variability in climate might influence the expected yield and subsequently land suitability. The outputs are intended for strategic, regional-level decision making in relation to agricultural development, infrastructure and water. So, it is important to understand the assumptions and caveats associated with the modelling before interpreting the maps, which are covered in the body of the report. Also, the maps and associated information may assist to inform on-farm adaptation, to guide breeding programs and regional trials, among other more localised issued. But, decisions at such localised or specific levels will need to be informed by additional, more targeted research outside the scope of this project.
According to the available climate projection data, the region will become hotter and drier, particularly in the north-east part of the catchment, the traditional cropping zone. The implications on cropping in the region may be significant. Projected changes to the values of key climatic variables, such as rainfall and temperature, could potentially impact the optimal growth conditions for these commodities. Increased temperatures could have negative impacts in terms of increased heat stress, increased evapotranspiration (and therefore increased irrigation requirements) and changes to phenology that impact on sowing and harvest times.
The modelling indicates a likely shift of the traditional cropping zone from the northeast corner of the catchment further south and west, following the projected rainfall decline. Such a shift may increase suitability in the south, specifically for winter cropping commodities sensitive to waterlogging, but the equivalent decrease of precipitation is likely to cause water shortages and subsequent suitability decline in the traditional cropping zone around Ararat, Tatyoon, Lake Bolac and Streatham. Southward spread of cropping can already be observed, but other high-value land uses (such as dairy or cattle and sheep grazing along the coast) are likely to continue offering larger returns. This report looks at alternative commodities that are summer grown, often more drought and heat resistant than the currently grown species, or that have a high market value, in order to encourage more regional trials and inform adaptation efforts.