CIF Project - Rangitaiki Plains Community Irrigation Strategy

Grant No: 09/06

Last updated: August 2012

Contact details

Name of Applicant Group: Whakatane District Council/Environment Bay of Plenty
Contact person: Santha Agas
Address: Whakatane District Council, Private Bag 1002, Whakatane 3158
Telephone: (07) 306 0500 ext 7549
Facsimile: (07) 307 0718
Email: Santha.Agas@whakatane.govt.nz

Project details

Status: Finished
CIF funding: $62,500
Total project funding: $125,000
Proposed start date: 2009-07
Proposed finish date: 2011-05
Region: Bay of Plenty

Part 1 Report - Summary of the Current State
Part 2 Report - Water Demand
Part 3 Report - Evaluation of Irrigation Options
Part 4 Report - Impact Report
Part 5 Report - Final Strategy Report

Final Report
Final Financial Report

Project description

The purpose of the strategic water study (‘Rangitaiki Plains Community Irrigation Strategy’) is to:

  • Determine whether it is possible to significantly facilitate and enhance agricultural and horticultural production and associated economic growth through an efficient, integrated and sustainable local authority led Community Irrigation Scheme(s) and associated infrastructure.

The issue/opportunity

At present irrigation on the Rangitaiki Plains is largely the domain of individual landowners. There is little or no coordination of irrigation water sources and infrastructure. The Whakatane District Council (WDC) owns and operates the Plains Water Scheme but this is ‘stretched’ by increasing demand and is not available for irrigation.

A Council led water strategy with the aim of evaluating a possible Community Irrigation Scheme(s) would allow proper planning, evaluation and coordination at a district level which is considered necessary to avoid inappropriate rural irrigation related infrastructure. The proposed water strategy is to follow a logical sequence using the best available expertise and advice. The proposed approach will allow WDC, Environment Bay of Plenty (EBOP), landowners, ratepayers and stakeholders to have input and determine the best outcomes and a fairer water resource allocation for the community.

This community approach to water allocation and management has been seen to be highly effective in other regions. By coordinating all stakeholders in the decision making process often leads to far better outcomes in terms of resolving actual or perceived conflicts around water allocation and ultimately a better environmental outcome.

The context/background

The Rangitaiki Plains encompass the area between Whakatane and Matata in the north (along the coast) inland to Kawerau/ Te Teko/Awakeri in the south. The rivers run northwards to the coast – the Whakatane River discharges at the eastern margin, the Tarawera River on the western margin and the Rangitaiki River centrally. The 3 rivers are very significant watercourses by North Island standards and some adjacent landowners are making use of the surface water sources for irrigation purposes. There is a combined Plains land area of approx 30,000ha.

The proposed strategic water study also encompasses the Rangitaiki Plains groundwater system comprised of shallow unconfined aquifers up to 70m deep and deep confined aquifers with a basement of approx 400m. There is a lack of knowledge of the groundwater resource availability/sustainability although Environment Bay of Plenty is presently conducting studies on the resource.

Given the climate, irrigation of the lighter soils in particular has the potential to substantially boost agricultural and horticultural production. The mainstay of the Plains is dairying. Maize production (mainly associated with dairy supplementary feed) is also very significant on the better quality soils. Horticultural crops include kiwifruit with some berry, olive, fejoa, citrus and vegetable cropping.

Irrigation water availability during summer and autumn dry spells in particular, has the potential to substantially increase dairy production and possibility encourage expansion onto the lighter soils. There is also likely to be expansion of horticulture onto the drier alluvial plains to the south.

Increased product may well supply the local Fonterra Dairy factory, kiwifruit packhouses and fruit and vegetable markets locally and beyond the district.

Irrigation water availability may stimulate small block holders to specialise in intensive-high value crops.

The economic flow-on from development to towns such as Edgecumbe, Te Teko and Whakatane has the potential to hugely benefit areas which are recognised as lower socio economic centres.

There is opportunity for enhanced development due to a coordinated approach reducing cost and increasing availability of irrigation water.

In summary the Strategy is expected to promote irrigation and development in appropriate areas and result in the economic benefit of land realised to higher potential.

Methods

It is intended to:

  • Determine what is known about the groundwater and surface water resources including wastewaters suitable for irrigation – their status, availability, allocation, nature/condition. Prepare a technical literature review in conjunction with EBOP.
  • Carry out a gap analysis of essential information needs and determine if and how these gaps can be filled and if so in what time frame.
  • Obtain an up to date water allocation report based on water permits and general takes (from EBOP).
  • Obtain an up to date environmental flow report from EBOP for the management of rivers (including minimum flow requirements).
  • Compile a water demand report and determine landowner and community needs for irrigation, taking account of present and predicted future requirements, possible effects of climate change and economic, social, cultural and environmental outcomes. Identify the areas of greatest demand and the degree of interest in supporting a local government led water strategy with a view to promoting a Community Irrigation Scheme(s) for the Plains.
  • Define and compare the economic, social and environmental benefits of a Community Irrigation Scheme approach versus the adhoc individual landowner approach. Determine whether a Community Irrigation Scheme approach would facilitate growth and economic development.
  • Consider opportunities for using waste water from industrial and municipal sources for irrigation.
  • Ascertain water quality requirements and match these with potential sources.
  • Identify opportunities to smooth water demand (for example early spring kiwifruit frost protection water use followed by maize establishment irrigation followed by horticultural crop and pasture and forage crop irrigation) and how best to manage water reticulation infrastructure to ensure existing pipe/canal networks are not doubled up.
  • Identify opportunities that may exist with linking irrigation supplies and improving the existing Plains Water Scheme (non irrigation supply).
  • Evaluate the Matahina Dam pipeline option (previously considered excessive capital cost) versus the development of a network of deep bores or river abstraction points as the source of the Plains Community Irrigation supply.
  • Increase the knowledge of the performance and use of drainage of canal systems on the Plains for possible irrigation network.

The findings, first order concept plans and recommendations will be made available for consultation with the Rangitaiki Plains Community. The resulting report will be presented to Council for assessment and approval.

It is proposed this strategic study be carried out over the period November 2009 to 30 June 2011.

Project Update:  February 2013

Parts 1 to 4 Reports were completed earlier and are described in earlier updates.

Report 5 – Final Strategy Report. . Part 5 report has been completed. A meeting was held with the WDC Plains Water Committee on 10 August 2012 and the findings of Reports 3 and 4 were presented to the members. Feedback was received from the Committee including the request to further involve Federated Farmers. The Plains Water Committee also resolved to invite the Bay of Plenty Regional Council to present their latest findings on allowable takes from surface and groundwater sources. As part of the process of developing the final report (Part 5 Report) a workshop was held on the 27 September 2012. Stakeholders that had been previously involved were invited to participate and to discuss a way forward and included agricultural and horticultural advisors, key landowner (dairy and horticulture) reps, regional council technical water experts and local iwi. Federated Farmers representatives were also invited and were represented. Loretta Dobbs IAF Project Advisor from MPI attended and participated in the Workshop and provided an overview of the Irrigation Acceleration Fund and answered a range of questions.

The Draft Part 5 Report summarizes findings of the previous four reports and canvases matters of interest for further discussion and consideration including availability of irrigation water at peak demand, soil productive capability and general scheme affordability/landowners ability to pay. The report also provides feedback from the WDC Water Committee meeting and the stakeholders workshop and provides some conclusions and recommendations.

The report will be discussed with the Plains Water Supply Special Committee on 25 March 2013. In this meeting a decision will be made on the next steps of irrigation strategy study.


Project Update:  October 2012

Parts 1 to 3 Reports were completed earlier and are described in earlier updates.

The Part 4 Report – "Impact Report"

This report has been completed. The impact report (economic, environmental, social/cultural) compares the benefits of a community irrigation scheme approach for the Rangitaiki Plains  with the adhoc individual landowner approach to determine if a community approach would facilitate growth and economic development. Most emphasis has been on analysis of economic impacts which have been assessed quantitatively.  The social and environmental impacts have been assessed, to a lesser extent, qualitatively. The analysis is largely centered upon irrigated pasture for dairy production and to a lesser extent irrigation for kiwifruit production where land is suitable for horticulture. The analysis focuses on the area of approximately 11,700ha of higher priority for irrigation land to the south/central and south western reaches of the Rangitaiki Plain.

Overall a community irrigation scheme appears to be financially viable for dairy farmers to support. In other words there is a positive net present value. That said, dairy farmers that have viable private water supplies for irrigation and are currently irrigating are unlikely to be financially better off joining the scheme.  However, dairy farms/farmers that do not have private water supplies for irrigation or who have not yet developed their own potential irrigation water sources are likely to be better off joining a community scheme.

It also appears to be financially viable to convert dairy runoff land to irrigated horticultural orchards (where soils are suitable) by joining the scheme.

The Report sets out expected cash flow for a range of scenarios over 30 years. The net present value (NPV) results are based on a discount rate of 8% (and a comparative 5%) and are presented in terms of a sensitivity test based on pessimistic, most likely and optimistic estimates of product price and productivity. 

Report 5 – Final Strategy Report

A draft for comment has been completed.  A meeting was held with the WDC Plains Water Committee on 10 August 2012 and the findings of Reports 3 and 4 were presented to the members. Feedback was received from the Committee including the request to further involve Federated Farmers. The Plains Water Committee also resolved to invite the Bay of Plenty Regional Council to present their latest findings on allowable takes from surface and groundwater sources.    As part of the process of developing the final report (Part 5 Report) a workshop was held on the 27 September 2012.  Stakeholders that had been previously involved were invited to participate and to discuss a way forward and included agricultural and horticultural advisors, key landowner (dairy and horticulture) reps, regional council technical water experts and local iwi. Federated Farmers representatives were also invited and were represented. Loretta Dobbs IAF Project Advisor from MPI attended and participated in the Workshop and provided an overview of the Irrigation Acceleration Fund and answered a range of questions.

The Draft Part 5 Report summarises findings of the previous four reports and canvases matters of interest for further discussion and consideration including availability of irrigation water at peak demand, soil productive capability and general scheme affordability/landowners ability to pay. The report also provides feedback from the WDC Water Committee meeting and the stakeholders workshop and provides some conclusions and recommendations.


Project Update:  June 2012

Part 1 Report: "Summary of Current State" has been completed.

This report summarises what is known about the groundwater and surface water resources of the Rangitaiki Plains, outlines gaps in essential information needs and provides available water allocation and environmental river flow data.

The Part 2 Report: "Water Demand" has been completed. This report focuses on understanding the Rangitaiki Plains soil and land units where irrigation would be of greatest benefit and outlines in general terms how much water is needed, when it is needed and where. The Report presents an analysis of the soils, the climate and natural moisture availability based on soil hydraulic properties.

Following the analysis of a range of soil and soil moisture characteristics, an Irrigation Priority scoring and ranking for the Plains has been developed. This is based on elevation, soil drainage class and the topsoil/growing zone susceptibility to drought. A map reflecting land areas that have a Low, Intermediate and High need for irrigation has been developed. Paradoxically a number of soils are seasonally imperfectly drained but have topsoils that dry out and are drought prone in summer and autumn and would respond well to irrigation.

The Report looks closely at the Plains climate – particularly "growing season" rainfall, evapotranspiration and effective precipitation. A soil moisture balance has been used to estimate the availability of water within the soils for each month of the year. The soils water balance/budget accounts for water added (precipitation), water stored in the soil (Profile Readily Available Water Content) and water removed from the system (evapotranspiration). When soil moisture is insufficient to meet evapotranspiration, the resulting deficit places plants under stress and the soil and crop needs irrigation to prevent lost production or even plant mortality. Water balances for various soil storage capacities have been calculated and the volume of water that would need to be applied each month to offset the soil moisture deficit determined.

A Water Demand Workshop held in August 2010 with key landowners, irrigators, agricultural and horticultural advisors and Council representatives noted there is a wide and positive interest in a possible Community Irrigation Scheme. The participants conveyed that landowner and industry sector commitment to such a Scheme would be tentative until landowners could see more detail of a reliable and cost effective opportunity. Such aspects are to be addressed in the next two reports.

Dairy pasture and kiwifruit (on suitable soil units) dominate the current landuse. Water demand for these 2 crops on a per hectare basis is very similar (crop factor of 1) and is at the upper end of water required for a wide range of crops on a per hectare basis.

Part 3 Report: "Evaluation of Irrigation Options" has been completed. Several broad abstraction and reticulation options were evaluated to first order concept plan and rough order cost stage for a possible Rangitaiki Plains Community Irrigation Scheme. Preliminary modelling of four different options to supply water primarily from surface water sources to approx 11,700ha was considered. These include utilising a number of river abstraction points and an option involving a Matahina Dam pipeline. Utilising water from deep bores to increase the scheme's reliability was also considered.

Based on the four preliminary models, the rough order initial capital cost of the proposed scheme (to farm gate only) has been estimated in the range from $40M to $81M or $3400 - $6900 per hectare. The wide variance in capital cost can be attributed in part to one of the models providing a higher level of service in terms of delivery pressure compared to the others.

The ongoing operating and maintenance costs (excluding annual fixed distribution and transmission line charges) has been estimated to range between $2M and $3.2M per annum or $170- $270 per hectare per annum. The expected annual water charge based on the annualised capital and ongoing costs for models 1 to 3 is approximately $543/ha/year.

The in-stream minimum flow requirement in the Rangitaiki River is a critical parameter affecting Scheme viability and needs to be confirmed for Scheme investigations to proceed past the Part 4: Impact Report (economic analysis).

Subject to confirmation of the reliability of the surface water sources, deep groundwater sources may be used to supplement supply. The allowable abstraction from deep groundwater for irrigation purposes needs to be established for this purpose.

Off– river surface storage is unlikely to be required for increased reliability. This is because the Rangitaiki Plains normally receives good annual rainfall and the proposed community irrigation scheme would already act as a means of increasing reliability to support dairy pasture and horticulture production.

The figures in the report provide sufficient cost information to advance the investigations to the Part 4 Report: "Impact Report" (economic analysis). This will then enable stakeholders to gauge the feasibility of the proposed community irrigation scheme.

The Part 4 Report: "Impact Report" was completed as a draft for circulation on 16 December 2011. The impact report (economic, environmental, social/cultural) compares the benefits of a community irrigation scheme approach for the Rangitaiki Plains with the adhoc individual landowner approach to determine if a community approach would facilitate growth and economic development. Most emphasis has been on analysis of economic impacts which have been assessed quantitatively. The social advisors and environmental impacts have been assessed, to a lesser extent, qualitatively. The analysis is largely centered upon irrigated pasture for dairy production and to a lesser extent irrigation for kiwifruit production where land is suitable for horticulture. The analysis focuses on the area of 11,700ha of higher priority for irrigation land to the south/central and south western reaches of the Rangitaiki Plain.

Overall a community irrigation scheme appears to be financially viable for dairy farmers to support. In other words there is a positive net present value. That said, dairy farmers that have viable private water supplies for irrigation and are currently irrigating are unlikely to be financially better off joining the scheme. However dairy farms/farmers that do not have private water supplies for irrigation or who have not yet developed their own potential irrigation water sources are likely to be better off joining a community scheme.

It also appears to be financially viable to convert dairy runoff land to irrigated horticultural orchards (where soils are suitable) by joining the scheme.

The Report sets out expected cash flow for a range of scenarios over 30 years. The net present value (NPV) results are based on a discount rate of 8% (and a comparative 5%) and are presented in terms of a sensitivity test based on pessimistic, most likely and optimistic estimates of product price and productivity.

Report 5: "Final Strategy Report" is well advanced. As part of the process of developing the final report a further meeting is planned with the WDC Water Committee in early August 2012 and following that meeting there is the intention to hold a workshop with the group of stakeholders that have been previously invited to comment including agricultural and horticultural, key landowner (dairy and horticulture) reps, regional council technical water experts and local iwi to discuss the way forward. The Part 5 Report summarises findings of the previous four reports and canvases matters of interest for further discussion including availability of irrigation water at peak demand, soil productive capability and general scheme affordability/ability to pay. It is intended that Report 5 will also provide feedback from the WDC Water Committee meeting and the stakeholders' workshop and provide recommendations for a way forward.


Project Update:  February 2012

Part 1 Report –"Summary of Current State" has been completed. This report summarises what is known about the groundwater and surface water resources of the Rangitaiki Plains, outlines gaps in essential information needs and provides available water allocation and environmental river flow data.

The Part 2 Report – "Water Demand" has been completed. This report focuses on understanding the Rangitaiki Plains soil and land units where irrigation would be of greatest benefit and outlines in general terms how much water is needed, when it is needed and where. The Report presents an analysis of the soils, the climate and natural moisture availability based on soil hydraulic properties.

Following the analysis of a range of soil and soil moisture characteristics, an Irrigation Priority scoring and ranking for the Plains has been developed. This is based on elevation, soil drainage class and the topsoil/growing zone susceptibility to drought. A map reflecting land areas that have a Low, Intermediate and High need for irrigation has been developed.  Paradoxically a number of soils are seasonally imperfectly drained but have topsoils that dry out and are drought prone in summer and autumn and would respond well to irrigation.

The Report looks closely at the Plains climate – particularly 'growing season' rainfall, evapotranspiration and effective precipitation. A soil moisture balance has been used to estimate the availability of water within the soils for each month of the year. The soils water balance/budget accounts for water added (precipitation), water stored in the soil (Profile Readily Available Water Content) and water removed from the system (evapotranspiration). When soil moisture is insufficient to meet evapotranspiration, the resulting deficit places plants under stress and the soil and crop needs irrigation to prevent lost production or even plant mortality. Water balances for various soil storage capacities have been calculated and the volume of water that would need to be applied each month to offset the soil moisture deficit determined.

A Water Demand Workshop held in August 2010 with key landowners, irrigators, agricultural and horticultural advisors and Council representatives noted there is a wide and positive interest in a possible Community Irrigation Scheme. The participants conveyed that landowner and industry sector commitment to such a Scheme would be tentative until landowners could see more detail of a reliable and cost effective opportunity. Such aspects are to be addressed in the next two reports.

Dairy pasture and kiwifruit (on suitable soil units) dominate the current landuse. Water demand for these 2 crops on a per hectare basis is very similar (crop factor of 1) and is at the upper end of water required for a wide range of crops on a per hectare basis.

Part 3 Report – "Evaluation of Irrigation Options" – has been completed.  Several broad abstraction and reticulation options were evaluated to first order concept plan and rough order cost stage for a possible Rangitaiki Plains Community Irrigation Scheme. Preliminary modeling of four different options to supply water primarily from surface water sources to approx 11,700ha was considered.  These include utilising a number of river abstraction points and an option involving a Matahina Dam pipeline. Utilising water from deep bores to increase the scheme's reliability was also considered.

Based on the four preliminary models, the rough order initial capital cost of the proposed scheme (to farm gate only) has been estimated in the range from $40M to $81M or $3400 - $6900 per hectare. The wide variance in capital cost can be attributed in part to one of the models providing a higher level of service in terms of delivery pressure compared to the others.

The ongoing operating and maintenance costs (excluding annual fixed distribution and transmission line charges) has been estimated to range between $2M and $3.2M per annum or $170- $270 per hectare per annum.

The in-stream minimum flow requirement in the Rangitaiki River is a critical parameter affecting Scheme viability and needs to be confirmed for Scheme investigations to proceed past the Part 4 – Impact Report (economic analysis).

Subject to confirmation of the reliability of the surface water sources, deep groundwater sources may be used to supplement supply. The allowable abstraction from deep groundwater for irrigation purposes needs to be established for this purpose.

Off– river surface storage is unlikely to be required for increased reliability. This is because the Rangitaiki Plains normally receives good annual rainfall and the proposed community irrigation scheme would already act as a means of increasing reliability to support dairy pasture and horticulture production.

The figures in the report provide sufficient cost information to advance the investigations to the Part 4 Report – "Impact Report" (economic analysis). This will then enable stakeholders to gauge the feasibility of the proposed community irrigation scheme.

The Part 4 Report – "Impact Report" was completed as a draft for circulation on 16 December 2011. The impact report (economic, environmental, social/cultural) compares the benefits of a community irrigation scheme approach for the Rangitaiki Plains  with the adhoc individual landowner approach to determine if a community approach would facilitate growth and economic development. Most emphasis has been on analysis of economic impacts which have been assessed quantitatively.  The social and environmental impacts have been assessed, to a lesser extent, qualitatively. The analysis is largely centered upon irrigated pasture for dairy production and to a lesser extent irrigation for kiwifruit production where land is suitable for horticulture. The analysis focuses on the area of 11,700ha of higher priority for irrigation land to the south/central and south western reaches of the Rangitaiki Plain.

Overall a community irrigation scheme appears to be financially viable for dairy farmers to support. In other words there is a positive net present value. That said, dairy farmers that have viable private water supplies for irrigation and are currently irrigating are unlikely to be financially better off joining the scheme.  However dairy farms/farmers that do not have private water supplies for irrigation or who have not yet developed their own potential irrigation water sources are likely to be better off joining a community scheme.

It also appears to be financially viable to convert dairy runoff land to irrigated horticultural orchards (where soils are suitable) by joining the scheme. 

The Report sets out expected cash flow for a range of scenarios over 30 years. The net present value (NPV) results are based on a discount rate of 8% (and a comparative 5%) and are presented in terms of a sensitivity test based on pessimistic, most likely and optimistic estimates of product price and productivity. 

Report 5 – "Final Strategy Report"is in train. As part of the process of developing the final report a further meeting is planned with the WDC Water Committee, agricultural advisors, key landowner (dairy and horticulture) reps, regional council technical water experts and local iwi to discuss the way forward. Meetings with senior Ngati Awa representatives have already been held and there is significant interest by the local iwi in the opportunities that a community irrigation scheme could provide to Maori landowners.


Project update:  October 2011

Part 1 Report: 'Summary of Current State' has been completed. This report summarises what is known about the groundwater and surface water resources of the Rangitaiki Plains, outlines gaps in essential information needs and provides available water allocation and environmental river flow data.

The Part 2 Report – 'Water Demand' has been completed. This report focuses on understanding the Rangitaiki Plains soil and land units where irrigation would be of greatest benefit and outlines in general terms how much water is needed, when it is needed and where. The Report presents an analysis of the soils, the climate and natural moisture availability based on soil hydraulic properties.

Following the analysis of a range of soil and soil moisture characteristics, an Irrigation Priority scoring and ranking for the Plains has been developed. This is based on elevation, soil drainage class and the topsoil/growing zone susceptibility to drought. A map reflecting land areas that have a Low, Intermediate and High need for irrigation has been developed.  Paradoxically a number of soils are seasonally imperfectly drained but have topsoils that dry out and are drought prone in summer and autumn and would respond well to irrigation.

The report looks closely at the Plains climate – particularly ‘growing season’ rainfall, evapotranspiration and effective precipitation. A soil moisture balance has been used to estimate the availability of water within the soils for each month of the year. The soils water balance/budget accounts for water added (precipitation), water stored in the soil (Profile Readily Available Water Content) and water removed from the system (evapotranspiration). When soil moisture is insufficient to meet evapotranspiration, the resulting deficit places plants under stress and the soil and crop needs irrigation to prevent lost production or even plant mortality. Water balances for various soil storage capacities have been calculated and the volume of water that would need to be applied each month to offset the soil moisture deficit determined.

A Water Demand Workshop held in August 2010 with key landowners, irrigators, agricultural and horticultural advisors and Council representatives noted there is a wide and positive interest in a possible Community Irrigation Scheme. The participants conveyed that landowner and industry sector commitment to such a Scheme would be tentative until landowners could see more detail of a reliable and cost effective opportunity. Such aspects are to be addressed in the next two reports.
Dairy pasture and kiwifruit (on suitable soil units) dominate the current landuse. Water demand for these 2 crops on a per hectare basis is very similar (crop factor of 1) and is at the upper end of water required for a wide range of crops on a per hectare basis.

Part 3 Report – 'Evaluation of Irrigation Options' – has been completed. Several broad abstraction and reticulation options were evaluated to first order concept plan and rough order cost stage for a possible Rangitaiki Plains Community Irrigation Scheme. Preliminary modeling of four different options to supply water primarily from surface water sources to approx 11,700ha was considered.  These include utilising a number of river abstraction points and an option involving a Matahina Dam pipeline. Utilising water from deep bores to increase the scheme’s reliability was also considered.

Based on the four preliminary models, the rough order initial capital cost of the proposed scheme (to farm gate only) has been estimated in the range from $40M to $81M or $3400 - $6900 per hectare. The wide variance in capital cost can be attributed in part to one of the models providing a higher level of service in terms of delivery pressure compared to the others.

The ongoing operating and maintenance costs (excluding annual fixed distribution and transmission line charges) has been estimated to range between $2M and $3.2M per annum or $170- $270 per hectare per annum.

The in-stream minimum flow requirement in the Rangitaiki River is a critical parameter affecting Scheme viability and needs to be confirmed for Scheme investigations to proceed past the Part 4 – Impact Report (economic analysis).

Subject to confirmation of the reliability of the surface water sources, deep groundwater sources may be used to supplement supply. The allowable abstraction from deep groundwater for irrigation purposes needs to be established for this purpose.

Off-river surface storage is unlikely to be required for increased reliability. This is because the Rangitaiki Plains normally receives good annual rainfall and the proposed community irrigation scheme would already act as a means of increasing reliability to support dairy pasture and horticulture production.
The figures in the report provide sufficient cost information to advance the investigations to the Part 4 Report – “Impact Report” (economic analysis). This will then enable stakeholders to gauge the feasibility of the proposed community irrigation scheme.

The Part 4 Report – 'Impact Report' is well advanced. The objective is to compile an impact report (economic, environmental, social/cultural) to compare the benefits of a community irrigation scheme approach versus the ad hoc individual landowner approach and determine if a community approach would facilitate growth and economic development. The economic impacts are being assessed quantitatively and the social/environmental impacts are being assessed qualitatively. The analysis is largely centered upon irrigated pasture for dairy production and to a lesser extent irrigation for kiwifruit production where land is suitable for horticulture


Project update June 2011

Part 3 Report – "Evaluation of Irrigation Options" – has been completed to final draft stage. Copies were delivered to WDC and BOPRC representatives in June 2011.

Several broad abstraction and reticulation options were evaluated to first order concept plan and rough order cost stage for a possible Rangitaiki Plains Community Irrigation Scheme. Preliminary modelling of four different options to supply water primarily from surface water sources to approx 11,700ha was considered. These include utilising a number of river abstraction points and an option involving a Matahina Dam pipeline. Utilising water from deep bores to increase the scheme's reliability was also considered.

Based on the four preliminary models, the rough order initial capital cost of the proposed scheme (to farm gate only) has been estimated in the range from $40M to $81M or $3400-$6900 per hectare. The wide variance in capital cost can be attributed in part to one of the models providing a higher level of service in terms of delivery pressure compared to the others.

The ongoing operating and maintenance costs (excluding annual fixed distribution and transmission line charges) has been estimated to range between $2M and $3.2M per annum or $170-$270 per hectare per annum.

The in-stream minimum flow requirement in the Rangitaiki River is a critical parameter affecting Scheme viability and needs to be confirmed for Scheme investigations to proceed past the Part 4 – "Impact Report" (economic analysis).

Subject to confirmation of the reliability of the surface water sources, deep groundwater sources may be used to supplement supply. The allowable abstraction from deep groundwater for irrigation purposes needs to be established for this purpose.

Off–river surface storage is unlikely to be required for increased reliability. This is because the Rangitaiki Plains normally receives good annual rainfall and the proposed community irrigation scheme would already act as a means of increasing reliability to support dairy pasture and horticulture production.

The figures in the report provide sufficient cost information to advance the investigations to the Part 4 Report – "Impact Report" (economic analysis). This will then enable stakeholders to gauge the feasibility of the proposed community irrigation scheme.

Update: February 2011

Part 1 Report: Summary of Current State (as at mid 2010) has been completed.

A draft of the substantial Part 2 Report – Water Demand was completed in December 2010. Client review comments have since been received and incorporated (February 2011).

The Part 2 Report – Water Demand, focuses on understanding the Rangitaiki Plains soil and land units where irrigation would be of greatest benefit and outlines in general terms how much water is needed, when it is needed and where. The Report presents an analysis of the soils, the climate and natural moisture availability based on soil hydraulic properties.

Following the analysis of a range of soil and soil moisture characteristics, an Irrigation Priority scoring and ranking for the Plains has been developed. This is based on elevation, soil drainage class and the topsoil/growing zone susceptibility to drought. A map reflecting land areas that have a Low, Intermediate and High need for irrigation has been developed. Paradoxically a number of soils are seasonally imperfectly drained but have topsoils that dry out and are drought prone in summer and autumn and would respond well to irrigation.

The Report looks closely at the Plains climate – particularly 'growing season' rainfall, evapotranspiration and effective precipitation. A soil moisture balance has been used to estimate the availability of water within the soils for each month of the year. The soils water balance/budget accounts for water added (precipitation), water stored in the soil (Profile Readily Available Water Content) and water removed from the system (evapotranspiration). When soil moisture is insufficient to meet evapotranspiration, the resulting deficit places plants under stress and the soil and crop needs irrigation to prevent lost production or even plant mortality. Water balances for various soil storage capacities have been calculated and the volume of water that would need to be applied each month to offset the soil moisture deficit determined.

A Water Demand Workshop held in August 2010 with key landowners, irrigators, agricultural and horticultural advisors and Council representatives noted there is a wide and positive interest in a possible Community Irrigation Scheme. The participants conveyed that landowner and industry sector commitment to such a Scheme would be tentative until landowners could see more detail of a reliable and cost effective opportunity. Such aspects are to be addressed in the next two reports.

Dairy pasture and kiwifruit (on suitable soil units) dominate the current Plains landuse. Water demand for these 2 crops on a per hectare basis is very similar (crop factor of 1) and is at the upper end of water required for a wide range of crops on a per hectare basis.

Part 4 Report – Evaluation of Irrigation Options – is in train. Several broad abstraction and reticulation options are being evaluated to first order concept plan and rough order cost stage. There are a range of possibilities being considered including utilizing a number of river abstraction points, a network of bores, and a Matahina Dam pipeline.

Update:  October 2010

Part 1 Report - Summary of Current State is largely complete within the bounds of available information and data. The Part 1 Report is available and is being used as a working draft. The GNS groundwater work that BOPRC separately commissioned was not available as at 31 October but was close to being finalized and expected to be available at the end of November 2010. This information will be important in helping fill remaining information gaps.

Part 2 Report - Water Demand - is well advanced. As was mentioned in the last progress report, background research and key contacts have been made with Plains landowners, irrigators and agric/hort business consultants.

On 5 August an Irrigation Demand Workshop was held at Whakatane District Council Offices involving 15 invited participants holding key experience and knowledge. This was a very successful meeting and participants were supportive of the Rangitaiki Plains Community Irrigation Strategy approach. Key Workshop messages and direction have been recorded and will become an appendix to the Part 2 Report.

Of particular importance to determining water demand are the characteristics of the Plains soils and the climate.

The best available soils data (pre digital 1985 at scale of 1:31,680) has been digitized into GIS.  Soil parameters of key importance have been interpreted and analysed including soil type, depth, texture, drainage class, permeability and soil moisture storage.

Lidar elevation information has also been made available by BOPRC which has been helpful in the analysis.

Climate data has also been assessed for all Plains weather stations including mean annual and monthly medians, special distribution, evapotranspiration and effective precipitation.

This data is now available and has been recorded for several zones (4) across the Plains.

The next steps (early December 2010) involve determining soil moisture deficit/water balance data and information for the Plains by zone. This requires amongst other parameters, Soil Profile Ready Available Water content (soils available moisture content). This particular information is of limited availability and reliability and so some interpretation is being carried out.

Finally the volume of irrigation water needed to offset the soil moisture deficit will be calculated for the Plains by zone and by month. 

Update:  June 2010

Part 1 Report - Summary of Current State is largely complete within the bounds of available information and data.  The Part 1Report is available and is being utilized as a working draft. Some in-stream low flow information is not available from BOPRC (Regional Council does not have the information) and the GNS work that BOPRC has separately commissioned was not yet available as at 30 June 2010 - but is expected shortly.

Part 2 Report - Water Demand - is in train with background research and key contacts made with Rangitaiki Plains landowners, irrigators and agri/hort businesses/consultants.

There is significant interest in the Project by plains landowners. The summer/autumn of 2010 was very droughty and dairy production was down by approx 15 percent on average even on land that traditionally holds up well in drier years. There have been 3 dry summers in a row on the Rangitaiki Plains.

A Water Demand Workshop with key players has been set up for early August.

Update:  February 2010

On Whakatane District Council and Environment Bay of Plenty’s behalf, Opus commenced the Rangitaiki Plains Community Irrigation Strategy project in late January 2010.

A literature review is well advanced and all appropriate publications and data from Environment Bay of Plenty (EBOP) and Whakatane District Council (WDC) has been sought.

Sub reports showing minimum flows for the Whakatane, Rangitaiki and Tarawera Rivers and minimum in stream flow requirements for the Whakatane and Tarawera Rivers have been supplied by Environment Bay of Plenty.

EBOP have supplied data relating to all Rangitaiki Plains bores and related water permits to abstract groundwater. Most of this information was received in February 2010.

Awaiting information (from EBOP) on Rangitaiki River minimum in stream flow requirements and data on surface water takes and associated water permits on the Rangitaiki Plains.

EBOP has separately commissioned GNS (PA White) to provide geological/aquifer/groundwater mapping in the Eastern Bay of Plenty which will include the Rangitaiki Plains area. This work is expected to be completed in the next few months and although not directly tied to this CIF project, the information will be invaluable.

 

Last Updated: 17 June 2013

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