Comments on REM Impact Assessment ReportBy Frank Burden Read the REM Impact Assessment Report [Adobe PDF 4.9 MB] Read the Entire response [Adobe PDF 663 kB] In the time available, it is only possible to provide comments of a general nature. SummaryThe report's authors have an apparent conflict of interest, demonstrate through recorded statements that they have a bias to a deep drain solution, and have views on watertable trends that are inconsistent with Government records. The report fails to consider all mechanisms1 that contribute to dryland salinity and environmental flows, and does not assess the economic and environmental impacts of groundwater drainage. Perception of biasMr Stuart Richardson, a report author, and Mr Donald McCarthy, the report's peer reviewer, both of REM, were employed to represent the Coalition of Concerned Landholders (CCL) in last year's Senate inquiry into the extent and economic impact of salinity. The CCL is a group of farmers that have lobbied the State Government for over a decade for the construction of groundwater drains in the Upper South East. When the report was being finalised, McCarthy's name was listed in the Adelaide hearings' program. The list of witnesses attending the Senate hearing also includes McCarthy's and Richardson's names, and the Hansard transcript of the hearing (page 36) indicates that Richardson produced the CCL's submission for the Senate inquiry. Mr Rasheed is recorded to have said that "Don McCarthy and Stuart Richardson are consultants we are employing to help us with the science side of the issues". McCarthy claimed that groundwater drains are required, because without them, watertables would rise, and cited a CSIRO report (believed to be Cox et al, 2004) as evidence of this. Richardson also wrote (submission 43, page 1) that "Dryland salinity is due to rising groundwater levels", and later claimed that the "Purpose of groundwater drainage is to return groundwater levels back to what they were". However, the attachment to this note indicates that in 2005 watertable levels on the Marcollat Flat and adjacent dune ranges were similar to or lower than when records began, without drains. Watertables are now lower. In some cases, records began nearly 40 years ago, when dryland salinity was not a recorded problem in the region. A conclusion that should be drawn from this observation is that current salinity problems on the Marcollat Flat are not caused by rising groundwater. The CSIRO report, also referred to by Richardson in submission 43, correlated historical
watertable trends with rainfall, and furthermore did not consider the effects on watertable
levels of vegetation or revegetation. CSIRO (Walker, 2005) advised the Upper South East
Program that revegetation of 50-90% of the dunes and associated areas2 with deep-rooted
perennial vegetation, such as lucerne and native vegetation, should restore the groundwater
balance in the region. CSIRO claimed that this would decrease land salinisation, and revert the
land to pre-cleared conditions without recourse to groundwater drains. Richardson, also described the history of the Willalooka Pastoral Company property. He claimed that following clearance of scrub in 1955, stocking rates on the property declined by 50% in the period to 1980, apparently caused by increased soil salinity. He went on to claim that "the watertable gradually rose over the next 20 years [from 1980 to 2000]". This observation is incorrect (see attachment). Richardson went on to describe what he believed to be the causes of dryland salinity, but failed to demonstrate an understanding of the relationship between all mechanisms that contribute to dryland salinity, eg groundwater and surface water interactions, watertables, soil health and structure, vegetation cover, and recharge on the dunes and associated areas. The perception of a deep drains bias (by either REM or the DWLBC) is not addressed in the report's section 1.2. Hydrological TestingThe report (section 2.2) describes the testing method used to measure hydrological data used in REM's modelling. The tests were completed on the 12th and 13th May 2005. The discussion of the measured data identifies a major discrepancy (up to 300-fold) with previously recorded data (section 2.3.2). Furthermore, the period from about October to May is typically when watertables fall to their lowest level. Indeed, the attachment shows that in April and May 2005, watertables on the Flat were below the proposed bed level of the drain (2m). The most representative time to measure aquifer properties for use in drain effectiveness studies is when watertables are close to or at their peak (Leak, 2005), which is generally in August or September. Observations of the Fairview Drain performance indicate that predictions over-estimated groundwater flows by more than five times, presumably because hydrological data used in the modelling had been measured when watertables were at their lowest (April 1992). Temporal changes to soil properties3 were also not considered in REM's analysis. Section 10, paragraph 8 of the REM report states that: "To gain greater confidence in the potential performance of drains in the Upper South East it is recommended that a model be developed for the Fairview Drain that is similar to the models that have been prepared for the proposed Didicoolum Drain. Groundwater monitoring undertaken prior to drain construction and following drain construction at the Fairview Drain site provides a unique opportunity to check model predictions against actual performance. It is expected that this type of modelling can support future reviews of drain performance." A thorough evaluation of the performance of the Fairview Drain should have been conducted in 1999 - it was a requirement of the program's Environmental Impact Statement. The Fairview Drain was always meant to be a trial, and it is always good science to validate the predictions of any modelling, most especially when the predictive models are then used to underpin future multi-million dollar public investments. It is scandalous that model validation has never been performed, which is an extremely poor reflection on the professionalism of State Government officials responsible for managing and implementing the drainage program. Work that could have been used to validate the 1992 drain modelling commenced in 2002, but stalled, one can only presume because the initial conclusions did not support the preconceptions of State Government officials on deep drain performance. One conclusion drawn in a draft report (Telfer et al, 2002) was that the 1992 predictions over-estimated groundwater drainage flows by more than five times, presumably because hydrological data used in the modelling had been collected when watertables were at their lowest (April 1992). Lower than expected drainage flows translates to a reduced impact on watertable levels, and hence on the ability of deep drains to control dryland salinity in the region. In turn, if reduced groundwater drain performance had been incorporated into the economic assessment of the program conducted in 2002, it would undoubtedly have resulted in the program being reclassified from barely viable at best, to grossly uneconomic and unsustainable. Public funding would never have been provided with this economic assessment, and Government officials would have been forced to give greater priority to other options for dryland salinity and flood management, such as surface drainage, revegetation, improving soil health etc. Clearly concerned about the accuracy of their modelling, the report's authors (see in particular Section 10, paragraphs 4 and 5 of the REM Executive Summary) stated that: "Further development of this modelling approach should include a more comprehensive assessment of the hydraulic conductivity of the aquifer with a pumping aquifer test"; and "Further structured sensitivity analysis would be useful in assessing the impact of uncertainty and variability in model input parameters". These are reasonable recommendations, but should have been implemented in the late 1990s, well before the current stage of drain construction! The REM report appears to be one selectively cited by State Government officials (including the responsible Minister (Gail Gago)) and some landholders as the source of science that supports the continuation of groundwater drain digging. The Government's interpretation of the "science" has been grossly deficient for well over a decade, which is transparently obvious to anybody who takes the time to read and understand any of the technical reports produced for the program. Related reports and bias to drainsThe Didicoolum Drain Ministerial Submission (MINSUB, 2005) refers to a number of documents and sources of information, including the above REM report, and three reports covering a soil analysis (Durkay, 2004), a hydrogeological assessment (GHD, 2004), and a pasture assessment (Horizon, 2004). The Ministerial Submission dismissed the general conclusion of the three reports that a "deep drain would not be the best outcome for the Marcollat Flat" with the claim that "it was concluded there was inadequate assessment made of the observations and trends in water tables and the consequent dryland salinity risks that have been previously well documented in the USE". The inference was that watertables would continue to rise without drains. The Government's records show the opposite. For more detail, read the entire report. [Adobe PDF 663 kB] Footnotes1 For example, groundwater and surface water interactions, watertables, soil health and structure, vegetation 2 This represents between a fifth and a third of the total land area in the region. 3 For example, drained, previously salt-affected soils become less permeable, and resist drainage. ReferencesCox J, Durkay M, Smitt C, Davies P (2004). Predicting the likely impacts of the Bald Hill Drain CSIRO Land and Water Client Report, Draft, November 2004 Durkay M, 2004. Soils & Groundwater, Marcollat Region USE-SA Liquid Gold Hydrology Services, August 2004 GHD, 2004. Didicoolum Drain/Marcollat Watercourse Assessment GHD Pty Ltd, July 2004 Horizon Farming, 2004. Pasture Report Marcollat Flat Proposed Drain Horizon Farming Pty Ltd, June 2004 Leak M, 2005. Review comments on draft REM Report DWLBC, 20 September 2005 MINSUB, 2005. Upper South East Dryland Salinity and Flood Management Program - Issue: Didicoolum Drain Preferred Option Michael Leak, DWLBC, Submission the Minister, October 2005 Telfer A, White G, Santich M (2002). Upper South East Drains - Effectiveness Trial (Stage 1: Assessment of Impacts). Australian Water Environments, Norwood, SA, report prepared for PIRSA, April 2002 Walker G (2005). Changes in groundwater balance in the Upper South-East region of South Australia. CSIRO Land and Water, Background Paper prepared for the Upper South East Program, November 2005. |
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