Annual Volume
Annual volume is the total amount of water authorised via a water permit over a one year period. For irrigation permits this is determined as being the volume required during an irrigation season, calculated according to Schedule WQN9 version 3.

Schedule WQN9
Schedule WQN9 sets out the way in which a seasonal irrigation demand standard is to be determined. A modification to this schedule, commonly known as WQN9 version 3, has been recommended to the NRRP Hearing Committee in response to submissions on the Plan. This is the version currently in use for calculating annual volumes.

Return Period
Return Period is the time (in days) between successive irrigations.

Profile Available Water (PAW)
Profile Available Water (PAW) reflects the soil's capacity to hold water assessed for the soil profile to a depth of 0.9 metres and expressed as millimetres of water.

Effective Irrigation Season Rainfall
Effective irrigation season rainfall is the amount of rain that will contribute to crop growth over the nominal irrigation season. In determining this amount, provision has been made for:

rainfall that occurs in four out of five years, and
excluding daily rainfall amounts of less than 5 mm, or cumulative rainfall amounts in consecutive days in excess of 50 mm.

Soil Moisture-Effective Rainfall
This is a single layer within GIS that combines the soil PAW layer and the effective irrigation season rainfall layer.

Intensive Pasture
Intensive pasture is land-use relying on perennial pasture production, where yield and quality must be kept high over the major growing period from mid-October to mid-March. In Canterbury, the predominant agricultural activity under this system is dairying, but may include some intensive meat-producing systems that rely on a similarly high level of pasture production such as lamb and beef fattening operations.

Arable (cropping)
Arable (cropping) is where land is cultivated and used predominantly to produce a mix of annual crops being grown in rotation. Arable farms have a mix of crops that usually have a single harvest and the rotation may include process vegetable crops or pasture. The definition does not include perennial bush, vine or tree crops.

Consented System Capacity
Consented system capacity is used to describe what a consent authorises can be applied on to the property on a continuous basis. It is calculated by determining what the maximum authorised (in terms of the resource consent) abstraction equates to in terms of application depth over the consented irrigation area. Consented system capacity is calculated in millimetres per day.

System Capacity Factor
System capacity factor is based on the reduced ability to meet irrigation demand when the consented system capacity is below a specified threshold. Where the consented system capacity is greater or equal to 4.0 mm/day the system capacity factor is assigned a value of 1.0, on the basis that the Total Seasonal Demand can be met at all times, and therefore 100% of the volume calculated using Schedule WQN9 version 3 can be delivered. Where the consented system capacity is below 4.0 mm/day, then the ability to meet the total seasonal demand will be constrained.
ECan has developed an in-house method to determine the system capacity factor using 34 years of daily rainfall and potential evapotranspiration data to calculate the ratio between unconstrained and constrained demand. Due to constraints regarding both the size and the distribution of this data it is not possible for us to make this available on-line however the data can be requested from the National Institute of Water and Atmospheric Research Ltd (NIWA).
If you require a system capacity factor you can either, contact ECan's Customer Services staff and request this be completed, or contact a groundwater consultant who may be able to obtain the climate data.

Consented System Capacity
A consented system capacity of higher than 6.5 mm/day will result in the "consented system capacity" box turning purple which indicates the irrigation system and management should be investigated further. Consented system capacity values above the specified range may indicate incorrect input values.
While no further water will be allocated in terms of the volumes calculated using Schedule WQN9 version 3 for systems that are able to exceed the peak EVT demands, a system capacity of greater than 6.5 mm/day has the potential to result in inefficient use of water. However where such a high system capacity correctly reflects the system design then it is possible that actual seasonal irrigation requirements will be lower than the standard since such systems allow more effective use of irrigation season rainfall through the use of deficit irrigation.

Seasonal Irrigation Demand Standard
Seasonal irrigation demand standard is, for a given land use, soil PAW and effective irrigation season rainfall, the depth of water (measured in millimetres) per hectare per year required to be supplied by irrigation to satisfy plant water demand after allowing for effective irrigation season rainfall. The seasonal irrigation demand standard has two roles in the Natural Resources Regional Plan:

water use for irrigation which complies with the standard is treated as a permitted activity, and
the standard is used to determine effective groundwater allocation in circumstances where annual volumes are not specified as part of the water permit.

Total Seasonal Demand
Total seasonal demand is the total amount of water required to satisfy plant water needs during the main growing period. This demand can be satisfied by rainfall and irrigation. In determining the irrigation component provision has been made for:

an application efficiency of 80%
a system capacity to meet peak demand between 4.0 and 6.5 mm/day
a nominal irrigation season from 1 October to 30 April, and
demand conditions that occur in 4 out of 5 years.