Monitoring Overview

The following monitoring is being carried out at MU55 and the other drained subcatchments – CG42, MK41, BG4, MU16, JB19, KL34 & BU27. In addition, aquatic invertebrates and microflora has been surveyed in some of the discharge areas, as well as in undisturbed wetlands in the Yarra Yarra saltlake chain. This has been identified as a major gap in our understanding of the system.

Groundwater flow – stainless-steel flume inserted in drain (near outlet); water level logged hourly to calculate flow rate and discharge volume.

Surface-water flow – surface flow channelled and gauging stations installed in two subcatchments near the discharge point to measure runoff.

Groundwater level – at least three transects of six observation bores (spaced at 10, 20, 50, 100, 200, 400 m); 2-5 control bores; depth measurements for at least three months before drain construction, then at two-day intervals for the initial fortnight after drain construction (or until rate of fall slows), then weekly for about a month, then at two-week intervals for about three months, and finally monthly; at least one bore per transect fitted with gauge and depth logged hourly for entire monitoring period.

Groundwater quality – initial sample set from bores and/or pits, then from drain (at fixed collection points); in situ pH, EC and Eh; sampling protocol consistent with Acid Groundwater research project; samples analysed at CSIRO Land & Water labs in Adelaide (Dr Rob FitzPatrick) or at the WA Chem Centre.

• Major anions
• Total (titratable) acidity/alkalinity
• ICP-MS suite of metals
• Rare earths
• Radioelements

Weather – daily rainfall from gauge at local farmhouse; pan evaporation from modelled estimate; temperature from nearest official weather station.

Soil salinity – 1:5 extract from shallow auger holes along existing observation-bore transects; sampled before drain and afterwards at six-monthly intervals.

Gross impacts – at least six photoreference points; photos at six-monthly (spring and autumn) or yearly intervals – from fixed points in pre-determined directions.

Downstream impacts – at and near discharge wetland; monitored at six-monthly or yearly intervals (depending on subjective impression of change)

• Chemistry of discharge sediment (as for ‘water quality’ above)
• Chemistry of discharge water (as above)
• Photoreference points
• Fixed belt-transects for terrestrial vegetation

Drain precipitates – mineralogy and geochemistry; opportunistic sampling; analysis at Uni of SA and UWA.

The Engineering Evaluation Initiative has made available special funding for some of this monitoring work. A substantial part of existing funds is devoted to monitoring work. Additional funding will be sought from other sources for future drains.

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