Grapevines require regular watering to supplement the natural annual rainfall. To produce the quality of wine grapes expected for this business, the Kayinga Estate vineyard requires approximately 2.5-3.5 megalitres of water per hectare, given the region’s average rainfall.
Water is supplied to the grapevines through a series of pumps and mainlines according to the irrigation design commissioned for the vineyard. From the mainlines, the irrigation water is then supplied to the grapevines within each row via a network of drippers.
The dripper system is considered the most effective irrigation system for grapevines, as it ensures efficient supply of irrigation water directly to the entire root zone maintaining an optimal level of growth, while minimising the off-target and evaporative losses associated with other forms of irrigation (such as sprinklers of flood irrigation).
The irrigation system is controlled by a computer network which enables the efficient application of water through centralised control.
SOUTH AUSTRALIAN WATER ENTITLEMENTS
South Australian Water entitlements were purchased to provide the necessary irrigation water for the vineyard. KVL owns licences with an entitlement to more than 1000 megalitres of water.
This is comprised of:
700 megalitres of SA River Murray water licence entitlements; and
308 megalitres of underground water licence – (see discussion on desalination plant)
During the millennium drought from 2006 - 2010, irrigators drawing from the Murray-Darling basin had their allocations restricted to various degrees and face the potential prospect of restrictions continuing in future seasons. What is certain is that many irrigated growers, unless they lease additional water or incorporate other water management strategies, will sometimes have insufficient water available for their normal requirements with the resultant likelihood of impaired vine condition and/or reduced yield expectations.
KVL has one of the largest private desalination plants in South Australia. During the drought from 2003 to 2010, it became obvious to the manager and MIS responsible entity that further protection for Kayinga Estate was required.
KVL had the underground water license but was unable to use this water because the salinity of this water was approximately 2,500-3000 mg/L whereas the maximum preferred salinity for irrigation of grapevines is less than 1,200 - 1,500 mg/L.
Because of the high salinity of the groundwater below the vineyard and the increasing salinity of the Lake, in late 2007, FABAL Operations established a reverse osmosis (RO) plant on Kayinga Estate to secure reliability of quality water supply to the vineyard.
RO is the preferred method to reduce water salinity and entails filtering out salts, under high pressure, through membranes. The RO plant allows the vineyard to desalinate underground water from the aquifer.
The underground water, due to its high salinity, is not suitable untreated for long term use for irrigation, but after desalination provides a high quality resource that provides an alternative water supply. After desalination, the water is stored underground as part of the ASR project (see below), or mixed with other water resources and irrigated directly onto the vineyard to be withdrawn and applied as irrigation during the following seasons.
AQUIFER STORAGE AND RECOERY (ASR)
ASR is the pumping of water drawn from a variety of sources (Lake Alexandrina, River Murray or the desalination plant) back down the existing bores to be stored in an underground aquifer and then drawn out for irrigation at a later time. ASR has been practiced for many years in the region and FABAL Operations commenced ASR at Kayinga Estate in the 2006-07 season and has been successful for a number of years.