Climate Change and Water Recharge on Eyre Peninsula.
The official water managers on EP; the EP NRM Board, SA Water, and DEWNR have separately and together used the excuse of climate change to explain what has been happening to the various water basins on Eyre Peninsula, especially since 2000 when the Water Allocation Plans commenced.
In particular, Polda Basin, which has been virtually sucked dry by SA Water, is said to have reached that condition because of the impact of climate change and can in no way be attributed to over-extraction. (John Ringham Chief Executive, SA Water stated—“ The agency is aware of claims that lower water levels in Polda Basin have been caused by over-pumping from the Basin. SA Water totally disagrees with those views”. (Page 121 NRC Parliamentary Report 2013). Of course, it is also claimed that the demise of the basin can attributed to lack of rainfall and a corresponding decrease in recharge.
Regrettably, this argument has been accepted by some decision-makers, including the Minister, and has resulted in an inexcusable misunderstanding of what has been happening in the water basins on EP.
What follows is a shortened history of the various claims involving climate change as it has supposedly affected the water levels in the basins on EP. It covers the period 2000 – September 2013, when the Final Report of the Parliamentary Inquiry was produced.
2000 “In order to meet the needs of underground water dependent ecosystems it is necessary to maintain the natural discharge processes that make water available to these ecosystems. If the storage component is allowed to diminish then these discharge processes will be affected, therefore the storage component must be maintained. Maintaining sufficient water for discharge processes will also assist to buffer variations in storage due to climate induced fluctuating recharge.”
(WAP Southern Basins Prescribed Wells Area 31/12/2000).
2006 (June) 3.2 Management of Water Resources
The existing plan addresses the current capacity of the resource and future demand for reticulated water supply, irrigation, industries and stock and domestic use in the community. In addition to this, the WAP makes reference to the provision of water for the WDEs and the potential future impacts of long term variation in climate.
(EPNRM— Southern Basins and Musgrave Water Allocation Plan Review)
3.3 Water Allocation Criteria
The water allocation criteria are designed to ensure the sustainable use of the groundwater resources. The criteria aim to define allocations that are equitable and do not place stress on, or impact on water dependant ecosystems (WDEs). The existing WAP addresses the capacity of the resource, the demand for water within the community, the future impact of potential climatic variation and principles for allocating a volume for WDEs.
(EPNRM —Southern Basins and Musgrave Water Allocation Plan Review)
2009 (May 2009) “Rainfall in the usually wetter months has been significantly below
average in recent years (Table 6.1)
(EP NRM Region Natural Resources Management Plan 2009).
The following table above highlights the lack of any change to the recent recharge rate (2002/3 until 2008/9 for Uley South) used in the Southern Basins water allocations during this period identified by EP NRM of “significantly below average (rainfall) in recent years”.
The table above further highlights the mis-management of the Polda Basin by the FACT that there was a lack of ANY change of the “recent recharge rate” used to determine allocations during this period (2002/3 until 2007/80) identified by EPNRM of “significantly below average (rainfall) in recent years.
In both the documents cited, no attempt is made AT THIS TIME to invoke the possible impact of climate change, nor make any changes to calculating allocation volumes in recognition of any climate change occurring. More than that, the DfW has claimed that the sustainability of the limestone (quaternary) lenses is safeguarded through a built-in mechanism in the WAP that requires licensed allocations to be reviewed each year based on the average annual rainfall over the previous ten years. It is illogical for the DfW to claim that climate change is the cause of falling water levels and rising salinity, because reduced rainfall should have been reflected in reduced allocations from year to year.
In the same Report, the annual rainfall extremes were presented, along with the statement:
This variation in rainfall extremes and the distinct variations between seasons, makes the preparation of water budgets, water resource management and the development of water dependent enterprises in the region difficult. Safety margins must be built into any plans for water use to allow for low rainfall years.
No changes in water allocation calculations were made to build such margins into the plans. The Report then went on:
“Most predictions of global climate change suggest that temperatures will increase in southern Australia and that seasons will become more variable, with more extreme episodic events (ie droughts and storms) accompanied by more hot days, with increased evaporation, and lower average rainfall. The prospect of increased variability and potentially more, hotter droughts suggests that an increased safety margin may be needed in the management of water resources to ensure they are not exhausted by a combination of increased seasonal demand and decreased availability.”
(EP NRM Region Natural Resources Management Plan 2009).
There is no indication in the NRM Plan that changes to increase the water safety margin were required either immediately or in the near future. In fact there is no sense of urgency DESPITE THE FACT THAT POLDA BASIN HAD JUST BEEN CLOSED OFF IT APPEARS BECAUSE OF THE COMPLETE LACK OF WATER AND SALINITY LEVELS. (Prohibition November 2008)
2009 A new report (Green et al 2012) which shows the impact of climate change on the Southern Basins and Musgrave Prescribed Wells Areas is not projected to be as severe as the previous best available information suggested (EPNRMB 2009)
2010 (Feb.) “As outlined in the presentation at Lock the decline in the condition of the Polda Basin is primarily driven by rainfall patterns (page 9 of an unsigned document from Dept. for water).
“During the meeting at Lock on 2nd February 2010 , Mr. Steven Barnett. Principal Hydro geologist for the Dept. for Water, Land, Biodiversity and Conservation presented information from the aforementioned Department. During this presentation, Mr. Barnett provided a document stating the rainfall from the Bureau of Meteorology rainfall station at Lock (Terre). This rainfall data, Mr Barnett alleged, showed a correlation between the reduction of rainfall above the recharge area of the Polda lens and the reduction of recharge. Hence he concluded that the lack of rainfall (i.e. climate change) was the cause of the reducing water levels in the basin. Upon questioning, Mr Barnett stated this rainfall data was from the BOM website and could be accessed by the public. We questioned this info as we were the then owners of Terre Station and were not aware of any rainfall station.”
Subsequently, we checked the BOM website and found that the rainfall station was closed in 2002...Furthermore, the data in 2000 and 2001 was incomplete and did not therefore give a final yearly rainfall total. When questioned about this, Mr Barnett then claimed that the missing data in this graph was from another BOM rainfall station (Terrah Winds) some 11km from the recharge area from the lens and that it had "similar" rainfall to Terre Station…When presented with the fact that the data from Terrah Winds…was not the same as the info he presented as it was incomplete, he failed to answer the question. We were informed separately from Mr Jono Clark, EPNRM & Mr Brenton Howe, Hydrogeologist DfW, that the data was a computer model generated from a company in Queensland. It is important to note, that Steven Barnett is still using the Terre / Terrah Winds rainfall in current documents. (page 56 NRC Report 2013)
4.1.1 Inconsistent monitoring of rainfall
“The gauging station used to generate the graph in figure 13 was the subject of a bitter dispute between the owner of the property hosting the station and government agencies. The Bureau of meteorology reportedly closed Terre Station No. 18081 in 2002 and Department of Water used data from another gauging station 11 km distant away together with computer modeling to substitute the missing data:”
(page 56 NRC Report)
“The Department used “patched data” when determining rainfall trends such as cumulative deviation which can be a very useful tool in linking water fall trends to rainfall”. (DEWNR Chief Executive Alan Holmes NRC Report 2013).
5.3 GAPS AND OVERLAPS IN MONITORING
5.3.1 Meteorological Monitoring
”BoM 's precipitation observation network in EP is considered adequate for its designed objectives, such as monitoring of seasonal climate patterns and the provisions of flood warning. However rainfall data is also frequently used to model both surface water and groundwater which require a higher degree of reliability and accuracy." DWLBC(Dept. of Water] REPORT 2005/38—Water Monitoring Review in the Eyre Peninsula Natural Resources Management Region by Li Wen with Prabodh Das and Kate Clarke (EPCWMB) as part of the steering Committee and Jonothan Clark (EPCWMB), Clive Jenkins (EPA) and SA Water among those involved in the consultation.
Despite in 2005 it was identified in a Dept. of Water Report of a combination of Government agencies including SA Water, EPA, and EPCWMB that "rainfall data…..require a higher degree of reliability and accuracy",
Alan Holmes (DEWNR Chief Executive) confesses to the NRC (Parliamentary Inquiry into EP Water) that they only used "patched data" when determining rainfall trends.
2010 (April) “an unsigned document arrived [from DfW] at the EP NRM offices which restated that climate change was the single cause of declining water levels [in Polda Basin]” (NRC Final Report page 116. (2013))
In 2011 the question below was asked of the EPNRM Board-
"Can you please provide evidence that the storage component of the Polda Basin lens and the discharge component has been maintained for the needs of the Groundwater Dependent Ecosystems so they will not be affected? (as per page 3 of the WAP)?
The answer given by the EPNRM Board was.
…………A technical assessment would be required to provide response to this question. The Board are not in a position to undertake the required assessments."
In 1993 Scott Evans, hydrogeologist [and also the WAP, 2001) identified the appropriate management, which included monitoring the storage component as a consideration of the condition of the lens.
In 2010 the DWLBC (Dept. of Water) in an unsigned document given to the EPNRM that stated— “DWLBC granted water allocations in line with the process set out in the Water
Allocation Plan. In undertaking this analysis the department took into account an assessment of recharge and the trend in groundwater levels, storage in the basin and pumped water quality…….”
In 2011 EPNRM Board, nearly 20 years after Scott Evans 1993 report and 10 years after the WAP, have literally confessed NOTHING WAS DONE to monitor the storage component of the Basin, and stated that it needed a technical assessment, which they were not in a position to undertake.
(WHY NOT? Is this not part of the EPNRM Board’s role in managing EP water resources).
2011 (April) The Demand and Supply Statement indicated that under a worst case scenario, demand for drinking-quality water was projected to exceed supply in 2017-2018. (Demand and Supply Statement 2009-2010)
2012 (April 18th) Population growth, and potential climate change for 2030, 2050 and 2070 was predicted to be such as to contribute to bring about a demand greater than supply of drinking water in 2023-24 (Demand and Supply Statement 2010- 2011)
2012 (June) The DfW predicted in its technical report of June 2012 that there would be substantial reductions in recharge in both prescribed wells areas because of climate change:
“In the Musgrave PWA the models project that reductions in groundwater recharge resulting from median climate scenarios (as predicted by CSIRO and BoM (2007)) range from 12% in a 2030 climate (median 3.5% reduction in annual rainfall with a high, medium or low emissions scenario) to 49% in a 2070 climate (median 15% in annual rainfall with a medium or high emissions scenario). In the Southern Basins PWA the corresponding projected reductions in groundwater recharge range between 11% and 47% in a 2030 climate and 2070 climate, respectively. “
(Stewart et al 2012, p13) quoted in NRC Final Report 2013 page 17.
2013 (Feb 27th) Based on current population growth and potential climate change
impacts, demand for drinking quality water is projected to exceed supply (earlier) in 2020-2021 (Demand and Supply Statement 2011-2012).
2013 (Feb 27th) SA Water’s total licensed allocations from the Southern Basins
Prescribed Wells Areas will decrease in 2013-2014 based on recharge to the aquifers.
In the second half of 2011 and the beginning of 2012, we had a slightly above average
rainfall in the region. (Demand and Supply Statement 2011-2012)
2013 (Sept) “Members (of NRC) understood that the Southern Basins lenses require
intense rainfall events between March and August in order to be recharged. Whilst
average rainfall may not have greatly changed, summer rainfall has increased and
winter rainfall decreased.” NRC Report 2013 page
2013 (Sept) Committee members from the Parliamentary Inquiry stated—- “However, they concluded that over-extraction was probably just as likely to have caused irreparable harm to Polda Basin” (NRC Parliamentary Report page 27.)
Ultimately Scott Evans (20 years ago) summed up the relationship with climate and water recharge…………
“If water levels are high then consumption during below average rainfall periods could be tolerated down to a base water level.
Conversely if water levels are at, or below a base level, then no consumption should occur.
This would protect the lens from increasing salinity and to allow recovery of water levels to occur, better managing the term integrity of the lens the determination of this base level is of high priority and will necessitate the understanding of the relationships between recharge (effective rainfall), amount of commandable storage and distribution of salinity within the aquifer.
It would be expected that as water levels decline and consumption increases, that the salinity of the extracted water may increase.
From the data currently available there is no obvious relationship between water level and salinity. Similarly the spatial extent of groundwater <1,000mg/L within the Quaternary limestone would be expected to vary, decreasing when water levels declin
Continued monitoring and assessment needs to take place to rectify this data deficiency to allow adequate management of this resource.
And finally in the summary Scott Evans states…. “The most appropriate management option would be to vary consumption based on recent rainfall behavior which controls recharge, with consideration of the condition of the lens, ie, whether water level and hence storage is too low”. (1993 Polda Lens Groundwater Study )
The EP community is faced with the fact that the Water Allocation Plans clearly required the ecologically sustainable management of our groundwater, and the water storage levels were to be maintained, not least as a buffer against any changes in climate induced fluctuation. However, the EP NRM Board and the other agencies involved in water management chose to ignore all this in favour of maintaining a “sustainable” supply of water to meet consumption demand regardless of the impact on the environment. These same agencies are now claiming that any deterioration of our groundwater basins can only be the result of climate change and in no way related to level of extraction that they supported over the years.
At no time has an effort been made to actually measure how much climate change has occurred in the last 10 years. This is because the variation in rainfall on Eyre Peninsula is such that it is NOT possible to distinguish between natural variations over time compared with any recent change brought about by climate change. The impact of climate change is very small compared with “average” rainfall figures. The result is no part of any changes in water level in our groundwater basins can be blamed on climate change. It can only vary because of water extraction and the seasonal variation in rainfall.
Even the NRC have recognized that in recent years the rainfall has decreased only slightly, with perhaps some change in the amount of rain between summer (more) and winter (less). It would appear that even this finding (if significant) has not been analysed in a way that assesses “effective” rainfall as has been suggested to the Parliamentary Inquiry.
Until longer rainfall records are available, combined with records directly related to the basins, the present impact of climate change can only be regarded as “slight” to “non-existent” on our groundwater basins.