Meeting of the Drought Committee
Date: Tuesday 10 March 2020
Time: 10.00am
Venue: |
Council Chamber Hawke's Bay Regional Council 159 Dalton Street NAPIER |
Agenda
Item Subject Page
1. Welcome/Notices/Apologies
2. Conflict of Interest Declarations
Information or Performance Monitoring
3. Welcome from Rex Graham, Chair, Hawke's Bay Regional Council
4. Indroduction from Cr Will Foley
5. Situation update from the Hawke's Bay Rural Advisory Group (HBRAG) 3
6. Situation update: Hawke's Bay Regional Council Science Team 15
7. Catchment Management Update - Dean Evans, Hawke's Bay Regional Council 23
8. Situation update: Hawke's Bay Regional Council Regulation Team (verbal)
9. Situation update: East Coast Rural Support Trust (verbal)
10. Roles and Responsibilities of the Drought Committee
11. Aim for the Drought Committee and mandate to act - Cr Will Foley (Background) 27
12. Are the right people in the room?
13. Agreed Actions points
14. Next meeting date
Drought Committee
Tuesday 10 March 2020
Subject: Situation update from the Hawke's Bay Rural Advisory Group (HBRAG)
Discussion
1. Minutes from the 4 March 2020 HB Rural Advisory Committee meeting has been attached for ease of reference.
2. The minutes includes next steps for getting a classification of the drought as a medium-scale event under the Government’s Primary Sector Recovery Policy.
3. The following link provides more information and resources on dealing with droughts and how MPI assesses the severity of dry conditions:
4. Information on what is required if a medium-scale classification is sought as proposed by the HBRAG is attached hereto.
5. A press release dated 6 March 2020 is attached.
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Authored by:
Annelie Roets Governance Administration Assistant |
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Approved by:
Joanne Lawrence Group Manager Office of the Chief Executive and Chair |
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⇩1 |
Minutes from the 4 March 2020 HBRAG meeting |
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⇩2 |
Assessment of Drought - matters to address |
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⇩3 |
Press release - 6 March 2020 |
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Drought Committee
Tuesday 10 March 2020
Subject: Situation update: Hawke's Bay Regional Council Science Team
Reason for Report
1. The Hawke’s Bay Drought Committee is meeting 9 March 2020 to discuss the current extended dry period and to consider actions that may be required to prepare for the possibility that the dry period may be prolonged further.
2. This report is to inform the Committee on the current climatic and hydrological status, along with a summary of the outlook and seasonal forecasts from various models.
Discussion
3. The NIWA New Zealand Drought Index (NZDI) is updated every two days and as at 6 March, when it was last updated, the NZDI showed dry conditions of varying severity across the region. The driest areas were the Ruahine Range and surrounds (Figure 1).
Figure 1: NIWA’s NZDI as at 6th March 2020 (source https://niwa.co.nz/climate/information-and-resources/drought-monitor).
4. Alongside the NZDI, NIWA’s soil moisture deficit map indicated that the driest areas in Hawke’s Bay are on the Heretaunga Plains, Central Hawke’s Bay and the region’s south coast (Figure 2 – map on right).
Figure 2: NIWA’s daily soil moisture deficit map as at 8 March 2020 (source https://niwa.co.nz/static/climate/smd_map.png?1234)
5. Hawke’s Bay Regional Council monitoring up until the end of February showed –
5.1 The Ruahine Range, Heretaunga Plains, Ruataniwha Plains and southern coastal area experienced four months of below normal rainfall (i.e. November to February inclusive). February totals in those areas were approximately 10% of monthly averages, with only 2-18 mm recorded at rainfall sites.
5.2 The Nov-Feb rainfall totals in the Ruahine Range and Ongaonga area were the lowest recorded in the last 50-60 years.
5.3 Daytime temperatures in both Nov 2019 and February 2020 were 3 °C warmer than the respective monthly average. Average potential evapotranspiration (PET) rates in those months were the highest recorded since monitoring began 10-15 years ago. December and January were also both 0.8 °C warmer than average. Sea surface temperatures through February and the summer season were warmer than usual around Hawke Bay.
5.4 Cumulative rainfall minus PET at sites in the Heretaunga and Ruataniwha Plains indicated that conditions were drier than average at this point in the hydrological year (July to June) and also compared to 2012-13.
5.5 Soil moisture was below average and in the lowest 10th percentile in most of the region apart from northern areas.
5.6 Many rivers and streams in the southern part of the region were under water take bans.
6. Since the end of February, the region experienced three days of rain and showers. The individual site rainfall totals for seven days from 2 February are displayed in Figure 3. The highest totals were recorded in the north and in the western ranges, though less so in the southern part of the Ruahine Range. Much of Central Hawke’s Bay and the south coast received less than 10 mm.
Figure 3: Site rainfall totals from 3rd March 2020 to midday 6th March 2020
Soil moisture
7. As at 9 March, soil moisture on both the Heretaunga and Ruataniwha Plains (Figure 4) showed limited response to the rainfall and remains at similar levels to those seen at the same time in 2012-13.
Figure 4: Daily soil moisture levels at Bridge Pa on the Heretaunga Plains (top) and Ongaonga on the Ruataniwha Plains (bottom).
River flows
8. Flows measured in the Ngaruroro River at Fernhill and in the Tukituki River at Red Bridge also remain within the lowest 5th percentile of historical records (Figure 5).
Figure 5: Daily mean river flows in the Ngaruroro River (upper plot) and Tukituki River (lower plot).
Groundwater
9. While some groundwater levels during February 2020 remained normal for that time of year, most levels were below normal or the lowest recorded observation (Figure 6). Although some rain has fallen since groundwater levels were measured in February, telemetered data indicate that groundwater levels have merely stablised or experienced a small recovery. The continuous groundwater level plot for Bridge Pa (Figure 7) is an example of this. Hence, groundwater levels are currently expected to be similar to the data shown in Figure 6.
Figure 6: Regional groundwater levels during February 2020, compared with historic groundwater levels for February. Wells with less than 5 years of record were excluded from analysis.
Figure 7: Telemetered groundwater level data from Well 1003 (Bridge Pa, depth 9m below ground level), 1 November 2019 to 8 March 2020
Risk of saltwater intrusion to aquifer systems
10. While aquifer systems in Northland have been reported at risk of saltwater intrusion, due to loss of aquifer pressure during the extended dry period, this is very unlikely to be a risk for major aquifer systems in Hawke’s Bay. The Ruataniwha aquifer system is inland and has no direct connection with the coast. The Heretaunga aquifer system has considerable hydraulic head at the coast (up to 10m above ground) and the groundwater is understood to discharge to the ocean approximately 20km offshore. This means that reduction of aquifer pressure during this extended dry period is highly unlikely to cause saline intrusion to the major Heretaunga groundwater resource.
Restrictions on surface water abstraction
11. The recent rain enabled some bans on the Ngaruroro River to be lifted on 6 March but on 9 March flow at the Fernhill site has again dropped below the trigger flow for full ban (2,400 L/s). Extensive bans remain on rivers and streams in Central Hawke’s Bay (Figure 8), with a full ban on the Tukituki River at Red Bridge.
Figure 8: The status of bans on rivers and streams in Hawke’s Bay. Red symbols indicate a ban is in force. (Sourced 9 March 2020 https://www.hbrc.govt.nz/environment/low-flows/)
Outlook
12. The weather outlook in the short term, is for scattered rain or showers to start the week. More significant rain is possible at the end of the week as a low approaches the country from the northwest and an ex-tropical cyclone may influence the country’s weather next week.
13. The three month seasonal forecasts (from NIWA, Metservice and various forecast models) are for near normal rainfall and normal or warmer than usual temperatures. ENSO is in neutral mode and is not a driver in our weather currently. Tropical cyclone activity is currently subdued but invigorates later in the week. Tropical systems have the potential to disrupt the pattern of weather that has otherwise been dominant, whereby low pressure systems move onto the southwest of NZ and weaken as they encounter a ridge of high pressure over central and northern NZ. Any continuation of that pattern is a concern and to date has contributed to the dry conditions.
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Authored by:
Dr Kathleen Kozyniak Principal Scientist (Air) |
Dr Jeff Smith Manager Scientist |
Approved by:
Iain Maxwell Group Manager Integrated Catchment Management |
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Drought Committee
Tuesday 10 March 2020
Subject: Catchment Management Update - Dean Evans, Hawke's Bay Regional Council
Discussion
1. Report attached.
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Authored by:
Dean Evans Manager Catchments Delivery |
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Approved by:
Joanne Lawrence Group Manager Office of the Chief Executive and Chair |
Iain Maxwell Group Manager Integrated Catchment Management |
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HBRC Catchment Management update |
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Drought Committee
Tuesday 10 March 2020
Subject: Aim for the Drought Committee and mandate to act - Cr Will Foley (Background)
Discussion
Hawke’s Bay Drought Committee
1. The Drought Committee is activated at times of severe drought in HB to enable a coordinated response to the situation. Participants include District Councils, East Coast Rural Support Trust, Ministry of Primary Industries, and many stakeholders involved in the primary productive sector.
2. This Committee is facilitated by HBRC as part of its overview of natural hazards for Hawke’s Bay and the Civil Defence Emergency Management Joint Group.
3. During the 2012-13 summer drought the Committee was chaired by the Regional Council Chairman.
4. Two representatives from Hawke’s Bay Regional Council were appointed on 6 November 2019 to the Drought Committee, being Councillors Will Foley and Jerf van Beek.
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Authored by:
Annelie Roets Governance Administration Assistant |
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Approved by:
Joanne Lawrence Group Manager Office of the Chief Executive and Chair |
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