Agenda of Maori Committee - 15 February 2016

HAWKE’S BAY REGIONAL COUNCIL

Maori Committee

Monday 15 February 2016

Subject: Current Forestry Management Practices

Reason for Report

1. The purpose of this paper is to provide background information to inform a discussion relating to actual and perceived issues and effects of forestry on the environment and communities within Hawke’s Bay.

Background

2. Council understands and acknowledges that there are a variety of agencies and companies who have a role to play in managing the forestry industry and that there are gaps in approaches and potentially unresolved conflicts. Council is proposing to lead a process that begins to understand the “gaps” and solutions to resolve these issues.

3. Council is considering how we will manage the current risks and plan strategically for a further forestry cycle.

4. Since the 1960s significant areas of plantation forest have been planted by the Crown and other entities on highly erodible land classes in Hawkes Bay. Land price and regulation have tended to push forestry toward land types which are steeper and more susceptible to erosion.

5. The Crown has subsequently sold many of its forests into private ownership and in some instances Maori have reclaimed land ownership through the Deed of Treaty Settlement process and now lease this land to other forestry entities. Today various Hawke’s Bay forests are in Maori ownership or are on land owned by Maori.

6. Forests established during the 1980s and 1990s are currently being harvested and we are facing some effects on our environment and communities. These effects are due to the legacy of very steep, highly erodible land which was planted. This land is also prone to risks from extreme weather events.

Kopuawhara Catchment

7. On the 23 May 2015 a rain fall event in the Wharerata Ranges in the Gisborne District, recorded rainfall of 105 mm in 24 hours and 52 mm across two hours – a 1:20 year event. Windblown pines, forestry slash, other woody debris and sediment were mobilised, ending up in the Kopuawhara River adjacent to Kaiwaitu Road Other storm events has resulted in woody debris ending up on beaches and resulting in impacts on infrastructure and social structures within the Hawke’s Bay region.

8. The northern end of the Kopuawhara Catchment falls within the Gisborne District Council and is where forestry harvesting was being carried out at that time.

9. The Gisborne District Council requires forestry companies to apply for resource consent for harvesting of plantation forests. Depending of the type of land to be harvested (based on a land overlay rating) the activity status ranges from controlled to discretionary for non-compliance with conditions.

10. As part of the post event monitoring, Gisborne District Council staff looked at compliance with resource consents issued for forestry activities in the Kopuawhara Catchment and found that in the affected areas, compliance in relation to the resource consents had been good and industry best practice followed.

11. Juken NZ limited (the forest owner) has since agreed to fund the cleanup in the Hawke’s Bay region from the rain event that caused the log jam in the Kopuawhara River.

12. Issues of concern include:

12.1. Clear fell harvesting on steep and erosion prone sites.

12.2. Wood waste (slash) management.

12.3. Mid-slope failure

13. Forestry typically operates in an approximately 27 year cycle from planting to harvest. During this time many operational activities are undertaken that have no significant impacts on the environment or our communities. The positive ecosystem services of biodiversity, water quality and soil erosion mitigation are significant, but not generally overtly apparent and so are easily dismissed.

14. The key forestry activities of concern are during the harvest cycle when clear felling of trees takes place. Harvesting can generate ongoing issues regarding the management of wood waste.

15. In some cases wood waste is uneconomical to remove as smaller diameter and shorter material is generally un-merchantable and this may be retained in the forest or distributed across the harvested site.

16. There are a broad range of approaches to the management of wood waste in the region, with some companies choosing to remove more waste from harvested sites than others. This variability in approach depends on options for sale or disposal of this material, and on individual company policy.

17. Mid slope failure is common in steeper Hawke’s Bay hill country. Mid slope failure occurs when existing conditions of geology and slope combine with rain events and woody debris is carried into waterways. Such failures have the ability to transport wood waste as woody debris from harvest sites downslope with considerable force. It is important to recognise that the mobilisation of woody debris is triggered by inevitable natural phenomena.

18. The forestry industry has made ongoing improvements to practices around harvest wood waste over the past 30 years and promotes continual development of best practice. Landing and roading failures are now relatively uncommon as a source of woody debris due to improved forest engineering, stormwater management and harvest practices.

19. As forest harvest operations on steep lands have proceeded, the issue of sediment and mobilised woody debris deposition into waterways, onto floodplains and ultimately the coastal environment have become of increasing concern, particularly in heavy rain events. These impacts are well recognised by the forestry industry.

20. Such events have occurred several times in the Kopuawhara Catchment, the most recent in May 2015. As other steep lands (especially Classes 7 & 8) are harvested these concerns are expected to continue.

21. Key effects associated with forest harvest activities are:

21.1. Sedimentation

21.2. Mobilisation of Woody debris

21.3. Erosion

21.4. Increased evapotranspiration rates.

22. For the majority of the forestry cycle, well planned and executed plantation forest provides significant environmental services. Forestry provides habitat for our flora and fauna, mitigates erosion, reduces sediment entering our waterways (improving water quality) and moderates water quantity.

23. There is a public perception that any wood in waterways is a significant negative impact of forestry. It is important to recognise that wood alone generally has minor actual environmental issues associated with it. While the physical nuisance of woody debris can have significant impacts on downstream infrastructure and communities, its importance as a pollutant is low, relative to sediment.

24. The adverse effects on communities arising from woody debris in waterways relate largely to impacts on settlement patterns and the development of infrastructure on flood plains. Historical development decisions have placed communities and infrastructure in sites that are prone to flooding which in turn has exacerbated the adverse effects resulting from woody debris in waterways.

25. Some wood in waterways and beaches offers ecological benefits for aquatic biodiversity and improved habitat. In the past when Hawke’s Bay was fully forested there would have been heavy loading of woody debris in streams and on beaches.

26. Plantation forests can reduce the amount and degree of erosion by intercepting rainfall, increasing evapotranspiration rates and reinforcing soils through the root network. About 25% of a trees mass is underground. Good forestry practice can reduce the risk of soil erosion that may follow harvesting, particularly when followed by storm events.

27. The level and extent of erosion that results from the removal of trees is dependent on a number of factors including the tree species, the area felled, the method of felling, the implementation of other forestry management techniques used to minimise runoff and erosion and the underlying geology.

The Pakuratahi-Tamingimingi Landuse Study

28. The Pakuratahi – Tamingimingi Landuse Study Report (ISBN 1-877405-05-01) compared the sediment yields from two catchments, the first in pasture and the second with forestry cover. The Study found that forestry had the lowest overall yield of sediment even when the sediment discharge during harvest was taken into account. The environmental benefits of forestry lead to improved water quality relative to farmland over a 27 year rotation, but with a period of increased sedimentation at harvest. The study showed a net water quality benefit relative to farming over the life of the forest. These catchments represent difficult and erodible Hawkes Bay hill country.

29. Sixty four percent (approximately 900,000ha) of the region’s rural land is classed as erodible to highly erodible hill country. Of this, approximately 300,000ha is under a land use that is likely to exceed the sustainable capacity of the soil. The Pakuratahi Project recognised that commercial forestry is a sustainable land use.

National Environmental Standard for Plantation Forestry (NES-PF)

30. On 17th June 2015, the Ministry for Primary Industries released a discussion document containing a draft NES-PF. Submissions on the draft NES-PF closed on 11th August 2015. The discussion document proposed an NES-PF to cover the whole plantation forest cycle and included draft activity-specific rules that are intended to provide certainty for local authorities, forest owners and communities.

31. The NES-PF would prescribe technical standards, methods or requirements for plantation forestry. An NES takes immediate effect and may be absolute, effectively overriding rules of a district or regional Plan. Local authorities cannot have plan rules that are more lenient than the NES and may only include more stringent controls through rules if the NES provides for this. Any rules that duplicate or conflict with the provisions of a NES must be removed from a plan. This must be done as soon as practicable after the NES comes into effect without using the Schedule 1 process.

32. Council broadly supported the intent of the draft NES-PF but made specific comments on how the draft NES-PF relies heavily on the preparation and monitoring of various plans for different activities without providing councils with an ability to assess whether such plans adequately address the risks and to not approve them where they do not.

Regional Plans and Strategies

33. Forestry is seen as a key resource management tool to mitigate soil loss in landscapes that are highly susceptible to erosion. Relative to some other land uses forestry also provides further key environmental services such as carbon sequestration, improved water quality and enhanced biodiversity.

34. The Hawke’s Bay Land and Water Management Strategy (LAWMS) provides direction and a common focus for the management of land and water for improved economic and environmental outcomes. It recognises that development potential and pressures vary across the region, as do the values associated with the land, rivers, lakes and wetlands. This implies that different responses are required according to local conditions.

35. The loss and degradation of soils in Hawke’s Bay’s hill country, particularly in northern and coastal areas, is considered to be a regionally significant issue in the Regional Resource Management Plan (RRMP). While there is a natural rate of erosion under natural vegetation, accelerated erosion due to the removal of natural forest and pasture establishment, and aggravated erosion due to inappropriate land management practices are of most concern.

36. Currently there are no rules specifically managing ‘plantation forestry’ in the RRMP or the Regional Coastal Environment Plan (RCEP). Instead generic rules apply to forestry activities, for example; vegetation clearance, and generic rules on discharges of contaminants – to land/water.

37. HBRC currently understands that there is no arrangements between forest owners and land owners that encourages forest companies to retire highly erodible land or riparian areas following harvest.

East Coast Hill Strategy

38. HBRC is currently undertaking work towards an East Coast Hill Country Strategy which will consider in part the environmental and economic sustainability of further development or retirement of the East Coast’s hill country, and forestry is likely to be a significant element of that strategy.

39. Research has not yet been done on the overall impact of forestry on steep land with very thin soils, and a key question is whether the benefits still outweigh the costs – and whether forestry on a 20-30 year rotation is sustainable in class 7 and 8 land.

Hawke’s Bay Forestry Group

40. Forestry is a leading primary sector in Hawke’s Bay and will continue to grow. Forestry is the largest primary sector exporting out of the Port of Napier.

41. Established in 2002, the Group represents significant forest ownership in Hawke’s Bay. The Hawke’s Bay Forestry Group - the local sector organisation - accounts for over 100,000 of the 134,000 hectares of plantation forest. The membership is around 10 companies and includes the Hawke's Bay Regional Council.

42. The Group appointed CEO Keith Dolman in 2015 to lead its commitment to community, environment, best practice and career aspects of forestry.

Looking forward

43. There is no quick fix solution to the adverse effects of forestry (sedimentation and the downstream impacts of woody debris on infrastructure) due to the current land types and weather risks that apply where forestry is conducted. However HBRC is undertaking a series of interventions to mitigate adverse impacts going forward. These interventions include:

43.1. Working with industry and in particular the Hawke’s Bay Forestry Group to identify and promote best practice;

43.2. A strategic policy response which will be driven out of the East Coast Hill Country Strategy;

43.3. Working with forestry companies and landowners to identify and promote the retirement of steep hill country;

43.4. Developing forestry as part of the toolbox for sustainable land use and resilient communities in erodible Hawkes Bay hill country;

43.5. Proactively interfacing with industry by employing a forestry professional;

43.6. Pursuing appropriate outcomes through participation in forestry environmental activity at a local and national level.

43.7. Engaging in the submission process relating to implementation of the NES for plantation forestry.

Decision Making Process

44. Council is required to make every decision in accordance with the Local Government Act 2002 (the Act). Staff have assessed the requirements in relation to this item and have concluded that, as this report is for information only and no decision is to be made, the decision making provisions of the Local Government Act 2002 do not apply.

Recommendation

1. That the Maori Committee receives the “Current Forestry Management Practices” report.

Esther-Amy Powell

Planner

James Powrie

Land Services Advisor

Mike Adye

Group Manager
Asset Management

Iain Maxwell

Group Manager
Resource Management

James Palmer

Group Manager
Strategic Development

Attachment/s

There are no attachments for this report.

Wairoa Flood Mitigation Regional Council paper - 19 December 2000

Attachment 1

AGENDA ITEM 10

HAWKE'S BAY REGIONAL COUNCIL

Tuesday 19 December 2000

SUBJECT: WAIROA FLOOD MITIGATION

INTRODUCTION:

Under the Soil Conservation and Rivers Control Act 1941, Council has a legal obligation to mitigate the effects of flooding within its region. Over the past several years Council has investigated a number of options to mitigate the effects of flooding on the urban area of Wairoa, with some mitigation initiatives being implemented. The initiatives already implemented focus on the early warning of an impending flood rather than any physical mitigation of the potential effects of a flood on people or property in Wairoa.

Council has been advised of much of the work undertaken to date. This paper summarises all of that work, proposes a course of action to manage the risk of flooding to the Wairoa urban area, and seeks Council decisions on the proposed course of action.

COMMENT:

1) Background

Wairoa has a present population of 4,884 and was built adjacent to the local river as early Wairoa relied entirely on the sea for access to the outside world and markets. The town subsequently grew with much of the development being on the flat land adjacent to the original town. That flat land was formed from deposits from successive river floods and remains at risk from flooding. The infrequent flooding of that developed flat land and the lack of significant development in recent years in the area meant that even in the days of significant government subsidy for the construction of flood control schemes, Wairoa did not receive flood mitigation works.

Wairoa therefore remains at risk from flooding with no mitigation works ever being built. To compound Wairoa’s risk, water levels in the lower reaches of the river, can be artificially heightened when the river mouth bar has a reduced flood capacity. The river mouth drifts up or down the coast over a distance of approximately 2km depending on sea and river conditions. Under certain sea and river conditions, or when the river mouth is in certain locations the mouth can become blocked. Lower areas of Wairoa town can be flooded unless the river mouth is mechanically opened.

Two notable events this century resulted in floodwaters escaping from the Wairoa River channel and discharging overland through the town. These were:

a. May 1948. A quote from the publication “Floods in New Zealand 1920-53” (with metric conversions included) aptly describes this flood “The Wairoa River rose to a record height to submerge the decking of the town’s traffic bridge and enter buildings to a depth of 0.9m. The bridge itself took a battering from the large amount of debris and timber which came down in the flood waters. The peak discharge was 11,440 cumecs, this being one of the highest recorded discharges of any river in New Zealand.”

Telephone lines 4.3m above road level were carrying grass and twigs, showing the phenomenal rise of the floodwaters. Several bridges were swept away and others severely damaged.”

b. March 1988. (Cyclone Bola). Floodwaters left the channel and crossed overland through part of the town to rejoin the river further downstream. Considerable damage resulted including loss of the State Highway 2 bridge in the centre of Wairoa.

Events resulting in flooding of low lying areas of Wairoa township as a direct result of the river mouth being inefficient include:

a. June 1971

b. August 1980

It is not simply a remote (or low probability) storm event which can cause serious flooding of the Wairoa township and river flats. The May 1948 event was a 100 year flood in the river, yet it was in response to a 10 to 15 year rainfall event. Likewise the August 1980 event arose from only moderate rainfall yet produced a flood of magnitude sufficient to inundate parts of the Wairoa urban area. The event would not have been significant if it had not been for the combination of the flood peak arriving with a high spring tide and poor river mouth conditions which resulted in lower areas of the Wairoa township being flooded.

These two flood events act as reminders that flooding can happen and it will happen again in the future.

2 Investigations/initiatives undertaken

Council will be aware that the following investigations and initiatives have been undertaken.

2.1 Rainfall Index.

According to Wairoa District Council civil defence staff the results of a survey of Wairoa urban area residents indicated that approximately 90% of householders recognise that their properties are at risk of flooding. Given this knowledge, civil defence staff were keen to ensure that they had as much time as possible to warn residents of an impending major flood.

To meet this requirement Regional Council staff developed the Rainfall Index. This has involved the installation of 3 additional telemetered river level and rainfall gauging sites and the establishment of a computer model. The rainfall index system is an early warning system for Wairoa that models the antecedent (ie conditions leading up to the present) and forecast rainfall in the entire catchment. On receipt of a heavy rain warning the computer model is used to predict the likely flood discharges. This discharge information can then be converted to flood levels and inundation maps used to determine flooding extents. The model has been developed and used a number of times to assist Wairoa civil defence staff to determine possible river levels during rainfall events. However although predictions to date have proved reasonably accurate, more events will need to be monitored and predicted before staff have confidence in the model for very large events. Accurate predictions are important if Wairoa or parts of the floodplain need to be evacuated before the flooding actually occurs.

2.2 Catchment Works and Stopbanking

A report outlining stopbank requirements as a mitigation option was prepared in 1994. Channel improvements and catchment planting for interception of some flood water, are not considered to be practical options because due to the size of the catchment they will have little overall affect on the runoff from the catchment. Stopbanking of the entire floodplain is not feasible because of the cost and the difficulty of controlling silt banked rivers, and inundation of the floodplain in larger events will remain a relatively high risk. Stopbanking of some areas to isolate them from direct effects of a flood is feasible and a staged construction sequence was outlined in the report.

Indicative estimates for the cost of the work necessary for stopbank construction are given below.

	Indicative estimate of cost
Stopbank construction stage 1	$1,450,000
Stopbank construction stage 2	$2,000,000
Stopbank construction stage 3	$1,750,000
TOTAL	$5,200,000

This total equates to approximately $2,600 per rateable property. Each stage of the proposed stopbanking would result in a reduced flood risk to only a portion of the urban area and therefore the actual area of benefit is limited, and the cost per rateable property would be much higher than that stated previously were the direct beneficiaries to pay each time. To be effective stopbanking in some areas would need to be set back from the top of the riverbank as ongoing slumping of the banks (which is a natural process of the river channel) could result in sections of the bank being lost. The potential loss of an attractive view of the river that would result from constructing a stopbank is one reason why stopbanking is not an option favoured by parts of the Wairoa community. The cost is the other reason. Wairoa is a low income township which cannot afford flood protection measures at this cost. In the public consultation that occurred during 2000 residents confirmed this view. Statistics related to Wairoa township are attached in Appendix 1.

An additional option of realigning the river channel to remove the ongoing risk of flooding as a result of the river overtopping its banks at what is locally known as the show grounds bend has been considered. The estimated cost of such a realignment is in excess of $6 million. This option has not been pursued because of the cost.

2.3 River Mouth Control

The Wairoa River mouth migrates over approximately 2km of coastline depending on river levels and sea conditions. The state of the Wairoa River mouth affects the level of flood water in the lower section of the river in small to medium events. If the Wairoa River mouth could be trained or encouraged to stay open and remain in a location such that flood waters are efficiently discharged, the risk of flooding the low lying areas would be reduced. A major flood is expected to force its own mouth, although the location and timing of a forced opening are unknown, and increased flooding levels may result before an efficient opening is achieved.

There are several options available for maintaining an opening through the barrier beach including groynes. If the construction of groynes is the favoured option then a number of alternative groyne designs and layouts are possible. A pre-feasibility design study has been carried out by a coastal engineering consultant to determine the most cost effective option including the use of new technology to keep the mouth open and efficient.

The study examined a short groyne field (low cost, high risk) and a dual groyne system (high cost, low risk) as part of the conventional methods of maintaining an opening through the beach barrier.

Two innovative solutions using largely unproven technology were also examined. These were

· fluidisation of the beach barrier, and

· constructing an impermeable barrier within the beach crest.

Both have the potential to achieve the desired objective with less risk from marine forces and less environmental disruption, however as the technology is unproven, the risk of either option not operating as designed is high.

In addition a river training groyne which would provide the additional benefit of improving access to the beach, and combating erosion of Pilot Hill, has also been investigated.

It is estimated that ensuring an efficient river mouth would reduce the risk of flooding to 152 urban properties in Wairoa. (ie 7.5% of the rateable Wairoa urban properties.)

Although these options appear to have some promise, the cost per benefiting property and the risk of them failing to function as designed, mean that it would be difficult to obtain community agreement to them.

The estimated costs of options originally considered were as follows:

Description	Estimated capital cost	Annual operating, depreciation and maintenance cost	Annual cost²	Annual cost adjusted¹	Annual cost /property³	Annual cost /property adjusted^1&3
Status Quo		$10,000	$10,000		$0	$0
Short groyne field	$1,126,000	$52,200	$179,760	$123,900	$796	$548
Dual groynes	$8,240,000	$60,200	$993,680	$937,040	$4,397	$4,146
Fluidisation	$765,000	$42,400	$129,060	$72,420	$571	$320
Impermeable barrier	$1,800,000	$66,000	$269,920	$213,270	$1,194	$943
Stopbanks	$740,000	$15,000	$98,830	$42,190	$642	$274
Pilot Hill Groyne	$700,000	$15,000	$94,300	$40,194	$613	$261

Note 1 The adjusted annual costs have been calculated assuming the Regional Council subsidises the capital cost of the project with a contribution of $500,000 as was provided for in the 10-year Plan.

Note 2 The annual costs include the cost of loan servicing based on an interest rate of 7.5% and repayment of the principal over 15 years, plus maintenance, operating, and depreciation costs. Depreciation of the groyne and stopbank options has been assessed as nil as has been used for other similar Regional Council assets. Depreciation of the impermeable barrier and the fluidisation system has been assessed assuming a 30 year life.

Note 3 The annual costs per property assume the distribution of costs across the benefiting properties only. As a portion of the benefits can be attributable to the wider community the actual charge if these properties were rated is likely to be less by the proportion of costs considered to be attributable to the wider benefit area.

Note 4 These costs include design, construction and resource consents.

Following Council consideration of the Wairoa River mouth issue on 7 June 2000, staff appointed a consultant to further consider the most cost effective options for controlling the Wairoa River mouth. The consultant has now further assessed the following two options;

· Pilot Hill Groyne

· Fluidisation

a) Pilot Hill Groyne

The proposed groyne will span between Pilot Hill and the beach crest, with the specific objective of preventing the river mouth from migrating into the Whakamahi Lagoon area to the west of the neutral river mouth position. The consultant has considered a number of options for the location of the groyne. All options will achieve the objective but the cost of the options vary considerably.

The proposed design would be a relatively low level, permeable, rock and concrete block structure. Water would be able to pass through the groyne structure thus allowing for tidal movement in the Whakamahi Lagoon area. The low level of the groyne would allow for overtopping of the structure in a major flood.

The potential benefits of the groyne are;

1. To train river flow - This is not expected to significantly reduce the number of mechanical openings that will be required, however it is expected to make the process easier as the length over which the river mouth can migrate will be reduced to approximately 60% of the existing distance.

2. To reduce the flow volumes entering the lagoon during flood events - The groyne will have the effect of establishing a much larger area of lagoon with relatively still water. Although flood flows will enter this area, the volume of water will be significantly less than if the river had direct access to it.

3. To protect Pilot Hill from ongoing erosion - Pilot Hill has eroded significantly over the past years and erosion will continue if no physical works are put in place to prevent it. It is not envisaged that the proposed groyne would prevent further erosion, however it could slow the present rate of erosion. The level of protection against erosion provided to Pilot Hill will vary depending on the exact location of the proposed groyne.

4. To provide more direct access to the beach - This is seen as a benefit for recreation and possibly as a future platform for an ocean discharge pipe from Wairoa’s sewage treatment facility. It will also provide improved access for plant moving to mechanically open the river mouth.

5. To improve water quality in the lower Wairoa River - This is a possible benefit if the river mouth is more easily opened, or if the river mouth tends to remain open for longer periods than it does at present. Whether the groyne will actually provide this benefit is not known, as the actual effect of the groyne has not been fully established.

6. To have insignificant impact on coastal processes - As the groyne does not extend out to sea there will be insignificant impact on the coastal processes.

On the surface it appears that the Pilot Hill Groyne may provide some benefits to the Wairoa community and possibly may provide for some enhancement of the Whakamahi Lagoon. However although it will reduce the length of beach over which the river mouth can migrate, it will not alter the conditions required for a successful river mouth opening and therefore is unlikely to make the management of the Wairoa River mouth much simpler or openings much easier to achieve.

b) Fluidisation

Fluidisation is the process of developing a flow path through the intertidal beach barrier to initiate a breaching failure of that barrier. Through this process it is believed that the river mouth can be maintained in a specific location even at relatively low river flows.

The technology is relatively new and as far as staff and the consultant are aware has not been tried in coarse sand/fine gravel similar to the material on the Wairoa beach. There would need to be a considerable trial period to establish a system to operate at the river mouth without any guarantee that any system would be successful. Staff are also concerned about the practicalities of maintaining the system, and particularly its reinstatement after flood damage.

If successful there are however benefits that the system would provide. These include;

· The potential to provide more regular controlled breaching of the beach barrier, improving water quality and possibly flood levels within the estuary.

· The system would have no significant adverse impact on coastal marine area, natural character of the area, or coastal processes.

Assessment of Pilot Hill Groyne and Fluidisation Options

Neither of the two options would significantly reduce the risk of flooding to the Wairoa urban area. Both of the options considered above have the potential to provide more certainty in the beach barrier opening process and thus reduce the risk of flooding within the Wairoa urban area. The reduced risk of flooding will arise from the greater certainty that the river mouth will be open rather than providing any direct flood protection.

Staff believe that fluidisation will require considerable on site trial work before they could be confident that this would provide the envisaged benefit. In addition staff are concerned about the ability to maintain the system and to reinstate it after any flood damage would be extremely difficult. Staff are unable to give any realistic estimate of cost for the trial work necessary before they would have confidence in such a system. Staff therefore recommend that this option be taken no further.

The Pilot Hill Groyne option would appear to potentially provide the most benefit. Much of the benefit is however not associated with flood mitigation. Although this option is feasible in that it would involve conventional construction methods, the actual effect of the groyne needs further investigation before a final decision should be made whether or not to proceed. Computer modelling work would provide more confidence of the benefits that could be provided by the groyne, but could not be expected to accurately predict the effect that the groyne would have on the frequency of mechanical openings of the river mouth that would still be required. The investigation work would involve modelling of the river mouth and a more detailed assessment of the likely effect of the groyne on the Whakamahi Lagoon area.

Engineering investigation work is estimated to cost approximately $30,000 and a further amount of $15,000 should be considered for some investigation of the possible benefits to the lagoon area. Should the project proceed beyond this stage then it is expected that this investigation work will be valuable in the resource consent process.

Indicative costs have been developed for the groyne in two possible locations. The two options are shown on the attached sketch.

Option	Indicative cost
Option 1	$960,000
Option 2	$610,000

Although there may be benefits to the community from the groyne, there will be little direct benefit to property from the construction of such a groyne, and therefore the costs cannot be justified.

Both options are located in a Department of Conservation Reserve and the Coastal Marine Area and would therefore require an assessment of environmental effects and a resource consent before any physical work could proceed.

2.4 The existing approach

At present Council undertake the necessary work to open the Wairoa River bar. This is achieved by mechanically excavating the beach barrier in the ideal location to form a new outlet. However the success of this work is highly dependent on having the right conditions. It is not possible to re-establish a new opening using these techniques while there is a small flow from an existing inefficient opening, as no head of water forms behind the beach barrier. Mechanically closing the existing inefficient mouth is not an option because of the type of material available on the beach barrier. This material is highly mobile and therefore washes away extremely rapidly making it impossible for conventional plant to achieve an effective closure.

Over the past several years Regional Council staff resident in Wairoa and local contractors have become more experienced in the river mouth opening process and have developed a good understanding of the conditions required for a successful opening, and the risks involved in not achieving a successful opening. Staff cannot however guarantee that this present level of expertise will be retained in Wairoa in the long term. It would therefore be prudent for Council to consider what can be done to reduce the present reliance on local experience and knowledge to undertake successful openings thus minimising the risk of flooding.

At times of low flow in the river and when the mouth is inefficient staff arrange for work to be undertaken in preparation for an opening. This involves excavating a partial opening so that less work is required when the right conditions are likely to arise. Although this can assist in reducing the time necessary to achieve a new opening when the right conditions occur, it does mean that piles of excavated material need to be removed before machinery can get into position to effectively work. In addition access to the eastern side of the river mouth is dependent on the good will of landowners in the area and can never be guaranteed.

There is therefore room for some improvement in the present approach, however the risk of not achieving a successful opening at a critical time remains high. Staff are presently working to resolve some of the difficulties and risks associated with this approach that have recently come to light.

2.5 Non Physical Options

Options such as insurance and the establishment of a flood relief fund have also been considered but ruled out. To be equitable, property owners who had insured their properties should be treated equally to those who had inadequate or no insurance cover. The administration of such a scheme would be a major undertaking and it was decided on this basis that these options were impractical.

2.6 The future

Hawke’s Bay Regional Council is well aware of its responsibilities under the Soil Conservation and Rivers Control Act 1941, to mitigate the effects of flooding. It has taken what it believes to be a practical and realistic approach to establishing the risk and assessing options for the mitigation of that risk. It has implemented an early warning system which will help minimise the risk of loss of life or personal injury in a major flood event, however it has established that all physical options for the mitigation of the flood risk are technically difficult and too expensive for the community to reasonably afford.

The information has been presented to the community, and feedback was that the physical mitigation options such as stopbanks and river mouth training groynes would be unlikely to receive the support of the community on the grounds of both cost, overall effectiveness in reducing the risk, and visual impact. Staff believe that Council has therefore fully met its statutory obligations.

Council is however aware that when properties suffer damage from a flood event in the future they will receive criticism from parts of the community and possibly central government for failing to adequately fulfill their statutory obligations. Present legislation does not however provide Council with sufficient powers to impose mitigation options on the community.

Staff believe that there would be benefit from the establishment of clear national guidelines with regard to what will constitute the fulfillment of statutory obligations for the mitigation of the effects of flooding on communities, and are presently promoting this at a national level with Ministry for Emergency Management and through the River Managers Group

2.7 Conclusion

Council has now undertaken considerable investigations into the feasibility of a wide range of options for the mitigation of the flood risk to the Wairoa township. Options investigated include;

· Systems for providing early warning of any impending flood

· stopbanking and realignment of the river channel

· control of the Wairoa River mouth

· non physical options such as bulk insurance

Council has already implemented an improved early warning system and will continue to enhance this system in the future. Staff have concluded that all other physical and non-physical options would be technically difficult and/or expensive to achieve, and that the areas of direct benefit would be relatively small unless extensive works were undertaken.

The most practical options that can be achieved at a reasonable cost are to continue with the status quo. This includes an early warning system and mechanical opening of the river mouth. Staff have however identified a number of areas where improvements to these two approaches can be achieved that would result in a lower risk of damage as a result of flooding, and will implement the required improvement work over the coming months.

However there will be an ongoing risk of flooding in the Wairoa township area and this risk will be dependent on individuals being in the right place at the right time. Protocols to ensure that this risk is minimised are being put in place.

3 Funds

Council have recently remitted surplus funds to the majority of ratepayers in the region. However only a portion of those funds were remitted to rural ratepayers in the Wairoa District, and the remittance was withheld from Wairoa urban ratepayers pending an outcome on the Wairoa River Mouth flood mitigation works. $100,000 of surplus funds were withheld from rural ratepayers and $44,000 from urban ratepayers.

In addition Council has indicated that it is willing to contribute $500,000 to any work which would mitigate the risk of flooding from the Wairoa River.

Staff propose that Council consider establishing a reserve fund for these funds as set out in the recommendation below. This would ensure the funds would be available in the future should any physical mitigation work be undertaken on the Wairoa River and that the funds are in the meantime available to help repair any damage caused by a major flood with the interest used for a proposed new scheme in the Wairoa District.

RECOMMENDATION:

That Council:

1. Note that there is an ongoing risk of flooding to Wairoa township.

2. After having carried out extensive investigation and feasibility assessments since 1994, agree to discontinue any further investigation initiatives for the foreseeable future into the physical mitigation of the flood risk to the Wairoa township, as the technical difficulty and cost of the options (including stopbanking and control of the river mouth), the limited extent of benefit of the options to households and the Wairoa township, and consequently affordability by the direct beneficiaries; has rendered impractical and unachievable any physical flood mitigation measures.

3. Instruct staff to report back on any further non-physical mitigation measures that could be undertaken or developed to reduce the impact of a flood on the Wairoa township including enhancements to the early warning system, the rainfall runoff modelling, and opening of the Wairoa River mouth.

4. Agree to the $500,000 committed by Council at its meeting on 7 June 2000 to Wairoa flood mitigation works, as well as the $144,000 retained as part of the surplus funds share due to Wairoa area ratepayers, be transferred to a district wide flood reserve with the following purpose, operating criteria, and limitations.

Purpose

The reserve will be established to fund flood mitigation and recovery work within the Wairoa District.

How it operates and how it was created

The reserve will be managed such that until any capital is authorised to be withdrawn from the reserve by Council, the capital purchasing power of the reserve sum shall be maintained by increasing the reserve each year in proportion to any increase in the Construction cost index (CCI)..

Council may authorise capital sums to be drawn from the reserve to undertake specific major flood mitigation projects or flood recovery works within the Wairoa District.

This reserve was created from the following sources:

· $500,000 as a public good contribution from general funding sources of Council in recognition of the need to address flood risk particularly to the Wairoa township and as recognition of this community’s ability to pay for the costs of any mitigation initiatives.

· $100,000 retained in the distribution of Council’s surplus funds in 2000 to Wairoa rural ratepayers as the indirect benefit share of any flood mitigation measures for the Wairoa township.

· $44,000 retained as the share due to Wairoa township as their share of Council’s surplus funds distribution in 2000 to be used for flood mitigation measures for Wairoa township.

Limitations

Any use of the reserve’s capital sum (as adjusted annually by CCI)will only be made upon agreement of Council.

How it is invested

The reserve funds will be invested in short term (ie less than 12 months) or long term investments as specified in Council’s investment policy (refer to Section 2.1.3.1)

Use of Income

Income earned on investment of the reserve shall first be used to maintain the capital purchasing power of the reserve. After deduction of the amount necessary to achieve this, the balance shall be transferred as a credit to the proposed Wairoa District Rivers and Streams Flood Scheme.

5. Agree that the Wairoa urban community be advised of the Council’s decisions and the reasons for them.

Mike Adye Andrew Caseley

GROUP MANAGER ASSET MANAGEMENT GENERAL MANAGER

WAIROA TOWNSHIP STATISTICS

(all $ are pre-tax)

· Total Population 4884

· 32% (ie 733) of the population are under 15 years of age.

· Households: There are

· 1470 houses

· 132 flats

· 21 non private dwellings and 15 “other”

· 34% of all households have no telephone.

· Incomes

· 24% of households are 1 person with an average income of $13,500/ annum.

· 46% of households are 2 person with an average income of $33,000/ annum.

· 30% are couples with no dependants with an average income of $27,500.

· 51% of households rely on benefits.

· The district wide average income is $28,625.

RESOLUTION FROM HBRC MTG MINS – WEDNESDAY 19 DECEMBER 2000

Resolution

That Council:

6. Note that there is an ongoing risk of flooding to Wairoa township.

7. After having carried out extensive investigation and feasibility assessments since 1994, agree to discontinue any further investigation initiatives for the foreseeable future into the physical mitigation of the flood risk to the Wairoa township, as the technical difficulty and cost of the options (including stopbanking and control of the river mouth), the limited extent of benefit of the options to households and the Wairoa township, and consequently affordability by the direct beneficiaries; has rendered impractical and unachievable any physical flood mitigation measures.

8.
Instruct staff to report back by 30 June 2001 on any further non-physical mitigation measures that could be undertaken or developed to reduce the impact of a flood on the Wairoa township including enhancements to the early warning system, the rainfall runoff modelling, and opening of the Wairoa River mouth.

Von Dadelszen / McIntyre

9. Agree to the $500,000 committed by Council at its meeting on 7 June 2000 to Wairoa flood mitigation works, as well as the $144,000 retained as part of the surplus funds share due to Wairoa area ratepayers, be transferred on 30 June 2001 to a district wide flood reserve with the following purpose, operating criteria, and limitations.