Hidden menace or opportunity - groundwater hydrology, playas and commercial options for salinity in wheatbelt valleys
Document Type
Conference Proceeding
Publication Date
2001
Conference Title
Dealing with salinity in wheatbelt valleys: processes, prospects and practical options
Place of Publication
Merredin
Abstract
Wheatbelt valleys contain evidence of a long history of hydrologic and climatic change. In particular they contain ancient palaeodrainage systems comprising large volumes of saline groundwater. Prior to clearing, these palaeodrainages discharged small amounts of groundwater derived from episodic recharge on the hillslopes and in situ within valleys. However, as a result of significant increases in recharge following clearing, these palaeodrainages are now becoming saturated, and small natural discharge areas such as playas, which previously balanced recharge, are now too small to cope with increased surface and groundwater flows. Discharge areas are expanding and saline land is encroaching on farmland, threatening other assets such as towns, roads and remnant vegetation.
Today between 3 and 15% of the wheatbelt shires, and a higher percentage of valley floor farmland, is saline. A larger area of between 22 and 34% is likely to have shallow watertables with much of it being saline, if current trends in groundwater levels are maintained. In addition, few management options are available to reduce recharge, the area required for effective management is large ( > 50%) and there remains considerable uncertainty as to the effectiveness and economics of discharge based options. Despite this uncertainty, farmers threatened by salinity have recognised that engineering options represent the most likely means of unilaterally managing salinity. Many also realise that discharge areas, saline or with a shallow watertable, are a complex mosaic of land with differing salinity levels and capabilities.
Given current levels of effectiveness of management options, added economic incentives for the use of wheatbelt valleys is required. These may be needed to both partially refund recovery of land where engineering options have been used or as a means to develop a new resource and associated industry. We believe that this incentive, should it exist, may potentially come from the longer-term development of the large (1000 GL/yr) and saline ( > 30,000 mg/L) groundwater resources which lie beneath wheatbelt valleys. While aquaculture, salt harvesting, desalinisation and the production of solar energy are all possible, there remains a considerable economic gap to be filled before many of these new industries become reality and wheatbelt valleys change their current landuse and emphasis on reclamation for agriculture.
Recommended Citation
George, R., Coleman, M., "Hidden menace or opportunity - groundwater hydrology, playas and commercial options for salinity in wheatbelt valleys" (2001)., in Dealing with salinity in wheatbelt valleys: processes, prospects and practical options, Merredin.
Comments
Published by Department of Water and Environmental Regulation.