How irrigation occurs – three basic steps:
ONE: Get a Permit
A water permit/consent must be granted. All irrigation takes in New Zealand are regulated to ensure the sustainability of our water resources. A water ‘take and use’ describes the site specific conditions that need to be followed. For example, a fish screen is often required before water is allowed to be removed from a river. All takes from New Zealand rivers have a ‘minimum flow‘ applied to them. This means when a river’s flow drops below a certain level (the threshold at which aquatic life is maintained) the water take must stop. The permit also states how much water can be removed at any one time (a maximum rate), and over the irrigation season (a seasonal volume). The permit will also specify what the water is to be used for.
In 2010 a new law was passed which requires measurement of all irrigation takes. Irrigators now have to submit their water use data, and can be fined or prosecuted if they fail to do so or renege on the conditions of their water permit.
TWO: Collect and distribute water
The water needs to be collected and distributed to the land. Irrigators take and store water in a number of ways:
- Groundwater via wells –water is pumped from groundwater/aquifers via a well. Some wells can be over 200m deep
- Run of river via pipes or channels –water is pumped or moved via gravity from the river, River takes can only occur when a river is above its minimum flow
- Large scale storage – water is pumped or moved via gravity into a large dam or man-made reservoir
- On farm storage – water is pumped or moved via gravity into a small storage pond on the farm
- Piped systems – water is moved through an underground network of pipes
- Open channel systems – water is moved through man-made waterways
More than half of the irrigation water supply in New Zealand comes through irrigation schemes. An irrigation scheme provides water to a group of water users, either through pipes or open channels. The largest irrigation scheme in New Zealand, the Rangitata Diversion Race (RDR), supplies water to over 70,000 hectares in Ashburton District.
THREE: Apply the water
The last step is irrigating the land. This stage requires a lot of planning to ensure water is used responsibly and sustainably. Different technologies and irrigator types are used depending on the landscape and crop to be irrigated.
The different ways a farm can irrigate
- Centre pivot and linear move irrigators
- Traveling irrigators
- Spray lines and long lateral
- Solid set sprinklers
- Micro sprinklers
Did you know?
Irrigators have to measure the water they take. New government regulations implemented in 2010 require all large water takes to be measured daily. The data is then provided to the local regional council so they can monitor water trends, and report back to the community.