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Mahurangi action plan

Research and monitoring

The Mahurangi Action Plan (MAP) was launched as a proactive response to increasing sedimentation in the Mahurangi Harbour.

Environmental monitoring showed that sedimentation was causing a decline in the overall health of the Harbour. Sediment loss from rural land use activities was considered to be the dominant source of sediment entering the estuary, with forestry activities considered to be an important secondary source.

Research, on the sources of sediment, both natural and human induced, and to quantify the relative contribution various sources make has been a key focus to date.

ARC engaged NIWA to undertake sediment source mapping to identify the sources of catchment soil contributing to sediment disposition in the Harbour.

NIWA also mapped the distribution of the soil sources throughout Mahurangi Harbour from pasture, native forest and exotic pine forest.

The results of this study are contained in the ARC technical publication 321: Sediment Source Mapping in Mahurangi Harbour.

ARC technical publication 321: Sediment Source Mapping in Mahurangi Harbour (June 2006) (1200KB PDF)

The findings include:

  • pastoral farming comprises 70% of the catchment area, contributes 15 - 55% of soil in the river delta and 10 - 30% across much of the rest of the Harbour
  • urban development makes up approximately 4% of the catchment area and contributes little to sediment load
  • native forests which make up approximately 20% of the catchment area also contribute sediment. This source contributes <30% in the river delta and generally less than 10% elsewhere
  • forestry comprises 8% of the catchment area. It contributes a locally high proportion of sediment in the river delta (45 - 80%) and about 14% of the total sediment load across the whole Mahurangi Harbour
  • on average, exotic pine forest land use contributes almost twice as much soil per unit area of catchment as pasture and native forest land. However most of the sediment load comes from pasture and native forest in the small sub-catchments along the side of the harbour
  • if forestry harvesting on steep land exposes bare soil to a storm event, the proportions of sediment from pine forestry will increase dramatically
  • most of the sediment load on Mahurangi Harbour is delivered in a small number of storm events each year.

Evaluation

It is too early to determine whether this ultimate goal has been fully achieved, but it is possible to evaluate whether a series of intermediate and related outcomes are being met and, in doing so, conclude whether MAP is on track.

Using one of MAP’s workstreams as an example, figure one outlines the conceptual model that has been used to set out how we measure progress in MAP.

Figure one:  Conceptual outcome model

The full MAP outcomes model is below: 

MAP evaluation framework (77.4 KB PDF)

It describes the 20 year plus high level outcomes and then details the intermediate and immediate outcomes and short term outputs required to achieve the long term goals.

For a progress report, please reference the Mahurangi Action Plan Evaluation Framework  report to the 17 November 2009 Environmental Management Committee meeting. (2.9MB PDF)

Mahurangi Action Plan documents

Below are a number of documents that provide the policy and research that help guide activities in the project:

  • Mahurangi Action Plan – Beyond 2009: Community engagement and options for the future (April 2008) TR 2009/065
  • Mahurangi – Forestry Context (May 2009) TR 2009/066
  • Mahurangi Action Plan: Research on Landowner Assistance Funds - Best Practice report (September 2008) TR 2009/067
  • Mahurangi Action Plan: Stocktake Assessment (August 2008) TR 2009/068
  • Mahurangi catchment: Background document  TR 2009/069 (draft)
  • Mahurangi Action Plan: End of Pilot report  TR 2009/070 (draft)
  • Mahurangi Action Plan: Telling the story (DVD) TR 2009/071
  • A Knowledge Network Model to Inform Sediment Management Mahurangi: Proof of Concept Phase 2 March 2009
  • Hicks, D.; Hawcridge, E. (2004). A survey of sediment sources on streams in the Mahurangi catchment. Internal Report 2009/002
  • Cummings, V. (2007). Mahurangi Estuary ecological monitoring programme – report on data collected from July 1994 to January 2007. Prepared by NIWA Technical Publication Number 270(ACR07207) for Auckland Regional Council. Technical Publication Number 335
  • Gibbs, M. (2006). Sediment source mapping in Mahurangi Harbour. Prepared by NIWA (ARC06214) for Auckland Regional Council. Technical Publication Number 321
  • Oldman, J.W.; Stroud, M.J.; Cummings, V.J. (1998). Mahurangi land-use scenario modeling. 51 p. Prepared by NIWA (ARC70216/2) for Auckland Regional Council. Auckland Regional Council Technical Report 2009/042.
  • Stroud, M. (2003). Modeling long-term daily sediment loads to the Mahurangi Estuary. Prepared by NIWA (HAM2003-144) for Auckland Regional Council. Technical Report 2009/043
  • Stroud, M.J.; Cooper, A.B. (1997). Modeling sediment loads to the Mahurangi estuary. Prepared by NIWA (ARC60211) for Auckland Regional Council. Technical Report 2009/060
  • Swales, A. (2007). Contribution of coastal erosion to sedimentation in the Mahurangi Harbour. Prepared by NIWA (Client Report: HAM2007-040) for Auckland Regional Council. Auckland Regional Council  Working Report No. 124
  • Swales, A.; Hume, T.M.; Oldman, J.W.; Green, M.O. (1997). Mahurangi estuary: sedimentation history and recent human impacts. Prepared by NIWA (ARC60210) for Auckland Regional Council. Auckland Regional Council Technical Report 2009/061
  • Auckland Regional Council. (1993). Review of Mahurangi catchment, estuary and harbour: water quality. Technical Publication Number 27
  • Cummings, V. (2007). Mahurangi Estuary ecological monitoring programme – report on data collected from July 1994 to January 2007. Prepared by NIWA (ACR07207) for Auckland Regional Council. Technical Publication Number 335
  • Cummings, V.J.; Funnell, G.A.; Schultz, D.; Thrush, S.F.; Berkenbusch, K.; Nicholls, E. (2001). Mahurangi estuary ecological monitoring programme - report on data collected from July 1994 to January 2001. Prepared by NIWA for Auckland Regional Council Technical Publication Number 175
  • Cummings, V.J.; Funnell, G.A.; Thrush, S.F. (1999). Mahurangi Estuary Ecological Monitoring Programme: report on data collected up to January 1999. Prepared by NIWA for Auckland Regional Council. Auckland Regional Council. Technical Publication Number 111
  • Cummings, V.J.; Halliday, J.; Thrush, S.F.; Hancock, N.; Funnell, G. (2005). Mahurangi estuary ecological monitoring programme - report on data collected from July 1994 to January 2005. Prepared by NIWA for Auckland Regional Council. Technical Publication Number 227
  • Cummings, V.J.; Hewitt, J.E.; Wilkinson, M.R.; Thrush, S.F.; Turner, S.J. (1995). Mahurangi Harbour biological monitoring programme - report on data collected during the first year of monitoring. Prepared by NIWA for Auckland Regional Council Technical Report 2009/039
  • Cummings, V.J.; Nicholls, P.; Thrush, S.F. (2003). Mahurangi estuary ecological monitoring programme - report on data collected from July 1994 to January 2003. Prepared by NIWA for Auckland Regional Council. Technical Publication Number 209
  • Cummings, V.J.; Thrush, S.F.; Pridmore, R.D.; Hewitt, J.E. (1994). Mahurangi Harbour soft-sediment communities: predicting and assessing the effects of harbour and catchment development Prepared by NIWA for Auckland Regional Council. Technical Report 2009/040
  • Cummings, V.J.; Turner, S.J.; Funnell, G.A.; Milburn, C.J.; Thrush, S.F. (1997).
  • Mahurangi estuary ecological monitoring programme: report on data collected up to January 1997 Prepared by NIWA for Auckland Regional Council. Technical Publication Number 86
  • Feeney, C.M.; Challis, D. (1984). Water and soil management issues in the Mahurangi catchment, estuary and harbour. Technical Publication 29.
  • Gibbs, M. (2004). Relating terrigenous sediment deposition in Mahurangi Harbour to specific land use in the catchment: a pilot study. Prepared by NIWA for Auckland Regional Council. Technical Publication Number 299
  • Gibbs, M. (2005). Sediment tracking method refinement. Prepared by NIWA for Auckland Regional Council. Technical Publication Number 294
  • Gibbs, M. (2006). Sediment source mapping in Mahurangi Harbour. Prepared by NIWA for Auckland Regional Council. Technical Publication Number 321
  • Hicks, D.L.; Hawcridge, E.A.R.C. (2004). A survey of sediment sources on streams in the Mahurangi Catchment. Technical Publication Number 270
  • Oldman, J.W.; Black, K. (1997). Mahurangi Estuary numerical modelling. Prepared by NIWA for Auckland Regional Council. Technical Report 2009/041
  • Oldman, J.W.; Stroud, M.J.; Cummings, V.J., Cooper, A. B. (1998). Mahurangi land-use scenario modelling. Prepared by NIWA for Auckland Regional Council. Technical Report 2009/042
  • Stroud, M.J. (2003). Modelling long-term daily sediment loads to the Mahurangi Estuary. Prepared by NIWA for Auckland Regional Council. Technical Report 2008/018
  • Stroud, M.J.; Cooper, A.B. (1997). Modelling sediment loads to the Mahurangi estuary. Prepared by NIWA for Auckland Regional Council. Technical Report 2009/060
  • Swales, A. (2007). Contribution of coastal erosion to sedimentation in the Mahurangi Harbour. repared by NIWA for Auckland Regional Council. Working Report 124
  • Swales, A.; Hume, T.M.; McGlone, M.S.; Pilvio, R.; Ovenden, R.; Zviguina, N.; Hatton, S.; Nicholls, P.; Budd, R.; Hewitt, J.E.; Pickmere, S.E.; Costley, K.J. (2002). Evidence for the physical effects of catchment sediment runoff preserved in estuarine sediments: Phase II (field study). Prepared by NIWA for Auckland Regional Council. Technical Publication 221
  • Swales, A.; Hume, T.M.; Oldman, J.W.; Green, M.O. (1997). Mahurangi estuary: sedimentation history and recent human impacts. Prepared by NIWA for Auckland Regional Council. Technical Report 2009/061 Wilcock, R.J. (1994). Pesticide use in the Mahurangi catchments: assessment of impact on the aquatic environment. Prepared by NIWA for Auckland Regional Council. Technical Report 2009/056
  • Wilcock, R.J.; Kemp, C.L.S. (2003). Water quality surveys of Mahurangi Harbour, Upper Waitemata Harbour & Tamaki Estuary, 1992-2001. Prepared by NIWA for Auckland Regional Council. Technical Publication 191
  • Wilcock, R.J.; Martin, M.L. (2003). Water quality surveys of Mahurangi harbour, Upper Waitemata Harbour and Tamaki Estuary. Annual report January – December 2002. Prepared by NIWA for Auckland Regional Council. Technical Publication 208.
  • Wilcock, R.J.; Stroud, M.J. (2000). Review of the long-term baseline water quality programme for freshwater streams 1992 - 2000. Prepared by NIWA for Auckland Regional Council. Technical Publication 132

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