Efficiency measures for water management

摘要

New Zealand's national and regional water policies aim to improve the efficiency of water use and water allocation. These policies classify water efficiencies (and some aims) as: economic (improved economic outcomes); technical (larger water use as a fraction of water taken from the source); and dynamic (movement of water allocation between users). However, efficiency measures, fundamental to the implementation of water efficiency policies, are rarely used for water management in this country. Efficiency measures developed from a longitudinal survey of groundwater use, land use and agricultural production in the Lower Confined Aquifer (LCA) zone, Tasman District, in the period 2004/05 to 2007/08 were relevant to water efficiency policy aims. For example, the LCA economic efficiency measure (annual revenue from production divided by annual groundwater use) increased from 4.8 $/m~3 to 16.8 $/m~3 showing improved economic outcomes from water use principally with the conversion of most dairy land to higher-revenue land uses. In addition, LCA allocation efficiency (groundwater use divided by groundwater allocation) for dairy land use increased from 14% to 31% with this conversion. Uptake of efficiency measures for water management is potentially impeded by the relative complexity of efficiency monitoring and privacy requirements of the productive sector. Future research to reduce these barriers is recommended, with the design and testing of a set of measures that link the needs of water managers (within central and regional government) with those of water users.