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Abbreviations

Acknowledgements

Executive Summary

1 Introduction

2 Methodology

3 Allocations and Areas

4 Comparisons and Trends

5 Surface-water Allocation

6 Water Use

Appendix A: Database Format

Appendix B: Assumptions and Parameters

Appendix C: Consent Database Summaries

Appendix D: Regional Summaries

References

2 Methodology

The following subsections outline key elements of the approach and methods adopted in the study.

2.1 Consent database

The compilation of a database of water take consents was a principal project objective. The database is a compilation of water take consents from all 16 regional authorities (12 regional councils and four unitary authorities).

The collection and compilation of consent records included the following steps:

• request for consent information from councils
• QA of records to identify replicate records, gross errors and missing primary fields
• formatting database fields as per standard format (Appendix A)
• if not stated in consent record calculation of weekly and annual allocations and consented irrigated areas (based on parameters listed in Appendix B)
• summary returned to councils for verification
• finalisation and submission of final consent database.

Key elements and process in development of the consent database were as follows:

• it is based on current consents and expired consents for which a renewal application had been lodged
• it is a compilation of consents for water takes from groundwater and surface-water sources for consumptive water use activities including drinking-water supply, industry, irrigation and stock-water supply
• it excludes consents for temporary activities such as well testing and river diversions
• it excludes consents associated with flood control and protection
• it is based on consent status as of May 2006
• quality control of records included screening for:
  • duplicates
  • exceptionally high allocation rates or volumes
  • missing key fields for water source and primary use
  • location; consent fell within council boundaries
  • use type consistent with allocation rate/volume.
• clarifications; councils were requested to clarify apparent anomalies in records.

Table 2.1 shows the database structure adopted for this study.

Key elements of the database are:

• primary fields for region, identifier, primary source, source catchment, primary use, easting and northing
• secondary fields for source type, source identifier, use type
• source type includes a 'blank' for non-geothermal groundwater and unspecified surface-water source, however, in the analysis by primary source 'blank' surface water takes were deemed by default to be direct run-of-river takes
• location (easting and northing); Nelson City Council consents were identified by national catchment coverage boundaries only, therefore were assigned a common location by catchment mid-point
• region ID is identified by abbreviation of regional authority as listed in the list of abbreviations in this report.

Table 2.1: Database structure

2.2 Surface flows

The analysis of surface-water allocations included the following:

• analysis based on national catchment coverage; 4,427 parent catchments (greater than 100 hectares) and 287 sub-catchments.
• subcontract with NIWA for provision of catchment and flow information including catchment boundaries, flow records (mean annual and mean annual low flow) for sites in NIWA database and as requested from councils. Information provided by NIWA and analysis of consent allocations yielded the following:
  • there are 535 parent catchments with surface-water allocations. These catchments cumulatively account for approximately 95 percent of total surface-water allocations
  • there were a total of 476 and 362 sites with mean annual flow and mean annual low flow records respectively. However, there were multiple sites in a large number of catchments and in many cases on tributary branches of the catchment. The site records were screened to select sites which provide a representative record for the whole catchment
  • there is one or more mean annual flow sites in 128 catchments from which representative sites were selected for 113 catchments
  • there is one or more mean annual low flow sites in 113 catchments from which representative sites were selected in 78 catchments.

2.3 Consented irrigated areas

The analysis of consented irrigated area was based on area reported within consent records and, if not listed, calculated for use type based on peak weekly allocation specific to the region.

In the Otago region, there are approximately 500 former mining water right consents used for irrigation. As discussed in the 2000 report (LE, 2000), these consents were originally issued in the period 1860-1940 as surface-water takes for sluicing activities associated with gold mining. Apart from the take rate and primary use (irrigation), there is no information on the irrigated crop or area. As reported by Otago Regional Council (personal communication), the take rate often exceeds available resource and therefore irrigated area and seasonal duration is limited. The approach to the assessment of irrigated area and take rate was based on estimated cumulative area and take rate for the group of consents and as listed in Appendix B.

2.4 Water use

The purpose of this element of the study was to present examples of water use for indicator catchments. Experience both in New Zealand and internationally with the analysis of actual water use, particularly in the agricultural sector, is that there can be a number of issues associated with the accuracy and completeness of water meter readings.

The approach to the acquisition of water use records and information was therefore based on the following:

• discussion with councils to determine type and extent of water use monitoring activities and specific work on water use. This identified the type and extent of work that had been carried out and the availability of information. The core approach was to tap into existing work and analysis which had been verified and therefore would provide a reasonably accurate assessment of use
• presentation of 'case' examples of water use to provide geographic spread and range of water uses. However, generally the focus on metering programmes is on the agricultural sector, in particular irrigation use.

Water use records and information on water use was received from the following councils:

• Auckland Regional Council consent records included quarterly use records for the period 2002-05 for the Region
• Hawkes Bay Regional Council provided details of water use for 52 consented takes in the Ngaruroro catchment (both surface and shallow groundwater takes) for two irrigation seasons
• Horizons Regional Council has established a telemetry trial in the Upper Manawatu River. Relevant sections of water resource assessment reports for the Rangitikei and Upper Manawatu Rivers were submitted. These presented an outline of metering and water use to 2005
• Taranaki Regional Council has a monitoring programme on irrigation takes (approximately 45) some of which are fitted with data loggers. Water use was reported for the past two irrigation seasons. Taranaki Regional Council provided water use records for consents within four of the high demand irrigation zones
• Tasman District Council provided water use data for three water management zones; Hau, Waimea-Waimea West and Motueka Hau
• Marlborough District Council provided a summary of annual water use based on metered crop water use for the Southern Valley, a water short area to the south-west of Blenheim. Water is sourced from deep aquifers (30-200 m) to irrigate 820 hectares, predominantly in grapes
• Otago Regional Council provided water use records for the 2005-2006 season for the Kakanui Valley.

In addition to the above, Environment Waikato, Environment Bay of Plenty and Environment Southland also indicated they have water use records and analysis of water use. However, records and/or reports were not submitted in time or available in a suitable format for inclusion in this report.

2.5 Study units

The following units for area, volume and flow have been adopted:

• Area
  • Square kilometres (km²)
  • Hectares (ha).
• Volume
  • Cubic metres (m³)
  • Million of cubic metres (Mm³)
  • Billion of cubic metres (Bm³).
• Flow rate
  • Litres per second (l/s)
  • Cubic metres per day (m³/d)
  • Cubic metres per week (m³/wk)
  • Cubic metres per second (m³/s).