A Once in a Lifetime Upgrade of the Mayfield hinds Irrigation Scheme

The Mayfield Hinds Irrigation Scheme (MHIS) is situated between the Rangitata and Hinds Rivers in MidCanterbury. The scheme was developed by the Ministry of Works in the 1940s and is the largest privatelyowned irrigation scheme in New Zealand.

The scheme takes water from the Rangitata River via the Rangitata Diversion Race, delivering 16.65m³/s of water to around 33,000ha. The scheme was designed to flood paddocks at a single rate (~230L/s) on a fortnightly roster. Changing to a continuous water supply would allow the scheme to make better use of storage and allow more efficient water use. To this end, the Mayfield Hinds Irrigation Ltd (MHIL) Board of Directors are investigating changing the water distribution system from an open channel system to a predominantly piped distribution system. The company has engaged Beca Ltd to advise them on the environmental and engineering aspects of the upgrade. Many of the current landowners’ grandfathers were inaugural benefactors of the MHIS, so the proposed upgrades are likely to be the most significant in a lifetime.

This paper presents the drivers for upgrading the scheme, the challenges such an upgrade faces, the proposed design concept and how the works have been procured to date.