An Introduction To The Central Plains Irrigation Scheme

Stage 1 of the Central Plains Water Scheme will irrigate approximately 20,000 hectares of farmland in the Canterbury Plains in an area bordered by the Rakaia and Hororata Rivers. An intake on the Rakaia River will direct water into a 17km long gravity fed headrace. A network of underground pipes will then distribute water from the headrace to over 20,000ha of farmland. The key components of Stage 1 are: 

• An intake and headworks at the Rakaia River to bring water into the headrace. 
• A headrace alongside and traversing ‘up’ the northern bank of the Rakaia River to the top of the main Rakaia Terrace. 
• A level headrace across the plains to convey water north and into the reticulation system.  Four piped reticulation networks providing irrigation water to all shareholder farms in the scheme area.

The paper will discuss the design and construction of the four reticulation networks.

The key deliverables of the scheme will be presented, followed by an outline of the numerous and complex design challenges inherent in delivering those requirements.

The paper will also touch on the feasibility and planning stages of the whole Central Plains Scheme, as well as some of the innovative construction methods that have been employed.