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Project supporting sustainable expansion of irrigated agriculture and horticulture establishes baseline information


Apr 12, 2018
Author: Goyder Institute

 

The Goyder Institute for Water Research project on Sustainable Expansion of Irrigated Agriculture and Horticulture in Northern Adelaide Plains has made significant progress in recent months, establishing baseline data and models that will provide a basis for ongoing investigations. This has included establishing baseline conditions of the soils; constructing nutrient and chemical fate models; reviewing the quality and quantity of source water options; and comparing different techniques for a rapid method of estimating shallow groundwater depths.

This work will be further developed over the next 12 months and will be used to identify where water can be a trigger for the next generation of agricultural and horticultural development and how water supplies in the Northern Adelaide Plains can meet potential demand. This will include the development of environmental risk maps based on baseline status of the soil and the key water quality constraints for the different sources of water being considered for use. Simply said, the project will identify ‘what can be grown where’ and ‘how environmental issues affecting long term sustainable use can be overcome’.

The project is being led by Prof Jim Cox from PIRSA-SARDI and is a collaboration between PIRSA-SARDI, CSIRO, Flinders University and University of South Australia. Further details on progress for the project tasks can be found below.

Development and optimisation of modelling domain and impact assessment of irrigation expansion on the receiving environment

Progress has included:

  • Baseline soil measurements and determination of soil physico-chemical parameters have been completed (photo, above).
  • Relationships have been established for quick assessment of such soil parameters by means of mid infrared measurements.
  • Measurement of soil hydraulic properties for the five most representative soil groups have been completed; this will allow accurate simulation of the water availability in the soil profile under various irrigation scheduling regimes.

Modelling nutrient and chemical fate, including salinity/sodicity risk, as the basis for identifying longevity of recycled water utilisation and mitigation strategies under current and future climate

  • Conceptual soil models have been developed for the five-key soil groups in the study area, based on existing digital soil data and new soil survey information obtained through this project.  
  • Climatic boundary conditions have been derived for the soil water and soil chemistry balance model HYDRUS-1D by downscaling climate projections for the period 2006-2056.
  • Crop parameters (root water uptake and salinity stress response) have been collated for almonds, vines, potatoes, carrots and onions.
  • Initial test simulations have been undertaken with the HYDRUS-1D simulator to verify its predictive capability by comparison with observed field data. Simulations provide depth distributions of soil water content and soil chemistry parameters (chloride content, sodium adsorption ratio, electrical conductivity, boron concentration, major ions, etc.).
  • Subsequent simulations will establish safe irrigation water quality conditions and scheduling for long-term sustainable irrigation using water source of different quality.

Source water options

A review of the quality and quantity of source water options has been undertaken, with source waters including:

  • Stormwater harvesting from local and regional surface waters for agricultural use;
  • MAR storage;
  • Desalinated waters;
  • Blending options for recycled and bore waters; and,
  • Potential water sources of the region between the Light and Gawler rivers.

 Assessment of Depth to Groundwater (Proof of Concept)

Progress has included the completion of hydrogeophysical field work (photo, below) with frequency and time domain electromagnetic induction (nano-TEM), electrical resistivity tomography (ERT), and ground penetrating radar equipment in two locations.

Initial results suggest that the nano-TEM and ERT surveys map the groundwater conditions better than the other (frequency electromagnetic induction and ground penetrating radar) techniques. The derived depths to groundwater will be used in Task 2 as lower boundary condition for the HYDRUS-1D model.