Appendix 1: Definitions

Available water

The total quantum of water that can be allocated from a resource for consumptive use including both existing and potential authorised uses. It includes uses for reasonable stock and domestic water supplies provided by the RMA section 14(3), as well as small-scale abstractions permitted by regional plans.

Ecological flows and water levels

The flows and water levels required in a water body to provide for the ecological function of the flora and fauna present within water bodies and their margins.

Environmental flows and water levels

The flows and water levels required in a water body to provide for a given set of values which are established through a regional plan or other statutory process.

MALF

The mean annual seven-day low flow.

Consumptive uses

Consumptive uses refers to any use of water that alters the flows and/or levels in a water body on either a temporary or permanent basis, including situations where water is stored and later released downstream.

Flow sharing

Flow sharing is a method usually used at medium to high river flows, or in combination with a minimum flow or other measures for managing low flows. Under flow sharing, a fixed proportion of the natural flow can be removed; the rest must remain in the river. A 50/50 sharing is the mostly commonly used. Flow sharing is a coarse approach to providing for flow variability and more complex approaches such as specific flushing flows are used when a more detailed analysis of the ecological role of flow variability is available.

Minimum flow

A ‘minimum flow’ limits the amount of abstraction during low river flows. A minimum flow determines when consent holders have to reduce, and ultimately stop, abstracting. Minimum flows are applied slightly differently throughout New Zealand, depending on local circumstances and location of flow recorder sites.

WAIORA

A computer-based model (Water Allocation Impacts on River Attributes) that calculates whether a water abstraction or discharge could have adverse impacts on dissolved oxygen, total ammonia, water temperature and habitat for aquatic life. The model is available from NIWA.