THE MANAGEMENT OF WATER AND SALINITY IN SOUTH-EAST SOUTH AUSTRALIADr David Mitchell, Charles Sturt University Summary SUMMARYThis brief review, focussing on long-term effects of current drainage proposals, was carried out at the request of a group of landholders and with the concurrence of the Department for Environment and Heritage and the Department of Water, Land and Biodiversity Conservation of South Australia. Every attempt was made to be objective and independent of any strongly held views within government agencies and the community. As much relevant information as possible was gathered in the limited time available, by making a visit to the area, meeting people with different views and consulting the extensive documentation on the situation. There was general unanimity about the need to avoid damage to the natural system of wetlands and its associated biota and to the agricultural productivity in the area. It was obvious to all that this required appropriate management of water in the landscape as a whole. There was agreement that some of the changes made to the landscape and its natural resources, with the intention of increasing agricultural productivity, had also increased the potential for salinisation of a number of areas in the region, though there were differing views about how to deal with this phenomenon. My conclusions are primarily influenced by my ecological training and experience of the behaviour of water in the landscape, with particular respect to wetland systems. However, this knowledge is conditioned by some 30 years of intermittent association with rural landholders and government agencies concerned with the management of water in Australian landscapes and, particularly, my recent experience of the success of Natural Sequence Farming procedures in reversing salinisation and sustaining pastures during the recent prolonged period of relatively low rainfall. My recommendations are drawn from these conclusions and are directed towards strengthening the region's long-term capacity to meet the "triple-bottom-line" criteria of:
CONCLUSIONSI have grave concerns about the current rationale for the construction of further deep drains in the Upper South East and with the haste with which this is being pursued, particularly in view of the considerable extent of unauthorised drains that have been constructed on private land in the area. I believe there is a real danger of drying out large areas of the landscape with salt intact, leading to reduced levels of biological activity, reduced water holding capacity and general loss of the integrity of the soil in a number of places. A delay in proceeding with the proposed Bald Hill and Didicoolum drains would provide an opportunity to undertake intensive evaluation of the efficacy of deep drainage in controlling the rise of saline water and of any adverse impacts on the quality of the drained soils and wetland ecosystems and of the biota they support in both agricultural and natural systems. This delay would also provide an opportunity to design a thorough pre- and post-drainage evaluation of the whole range of consequences of drainage with the intention of putting this in place when any further drains are constructed. I have been surprised by the rather sparse attention paid to previous monitoring of relevant consequences of drainage as a basis for current planning. I make this comment with some diffidence, since I have not had the time or the opportunity for an intensive search of the literature, although similar concerns have been alluded to by others (eg McEwan et al. 2002, Rural Solutions 2002(a), Rural solutions 2002(b)). In any event, this delay would also enable a critical assessment of such information as a basis for future management decisions. My visit to the region and particularly the flight over the area also revealed considerable differences in the quality of asset management of agricultural land. Several of the properties exhibited examples of well developed pastures and other agricultural land in excellent condition, in spite of the recent drought, while others gave cause for concern. A critical examination of the factors which enable some landholders to make better use of the prevailing conditions than others - a feature which is characteristic of every farming community with which I have interacted - would also be of benefit for the design of ongoing sustainable management of the region. RECOMMENDATIONS1. Delay the implementation of the proposed Bald Hill and Didicoolum drains. 2. Institute a thorough, scientifically based assessment of the current condition of soils, groundwater, plant cover (native and introduced, as appropriate), and associated biota, in relation to the stated objectives for a range of selected sites likely to be impacted, positively or negatively, by the installation of the above drains. 3. Institute comparative studies, of the same design and intensity as above, in similar areas that have been affected by drains, which have already been installed, as a basis for completing, or modifying, the drainage program, or for terminating and replacing it with alternative management procedures. 4. Review the results of these investigations as a basis for proceeding with the proposed Bald Hill and Didicoolum drains, or for developing a different strategy. 5. In the event that the drains are installed, continue with the investigations of the already selected sites for possible adverse, or beneficial, impacts of drainage. 6. Undertake comparative studies of pasture and cropping management practices on selected farms that volunteer to participate, in the interests of improving overall agricultural and nature conservation standards in the district as a whole. Read the entire report. |
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