Clarence Valley State of Play: as the first day of Summer draws closer memories of past summers surface

 

Right now the Clarence River flow at Newbold Crossing is registering in the >80% stream flow percentile, the Shannon Creek side dam is at 99% capacity and soil moisture is for the most part within acceptable limits across the Clarence Valley which is classified 100% non-drought.

However, the Australian Summer officially begins on 1 December 2024 and air temperatures and water evaporation rates are bound to rise.

So how is the New South Wales Combined Drought Indicator (CDI) Map likely to look come December?

Where we are going?

NSW Dept. of Primary Industries and Regional Development, Climate Branch, Drought Forecasting, 17 November 2022:

NOTE: The DPIRD drought forecast for NSW presents the ‘Most Likely’ Combined Drought Indicator (CDI) category for the forecast period. The Most Likely CDI category is determined by identifying the 'mode' of the CDI. The mode is the category that appears most frequently across all possible forecast outcomes in the ensemble run. It is the most common prediction for drought conditions in the forecast period based on the model's simulations.

Where have we been along the Clarence Valley drought history continuum, 20 November 2019 to 9 October 2024?

Click on graphs to enlarge

Fine Flower & environs

Heifer Station & environs

Grafton & environs

Maclean & environs

Yamba

*All maps & graphs were created on 17.11.24 using interactive tools created by NSW Dept. of Primary Industries and Regional Development, Climate Branch

Combined Drought Indicators

The NSW Combined Drought Indicator (CDI) includes four indicators for rainfall, soil moisture, plant growth and drought direction which, used together, can indicate the five phases of drought.

Rainfall Index (RI)

The RI is the percentile rank of rainfall aggregated over 12 months. The ranking is made using a 30 year (1980-2010) baseline which captures recent big shifts in climate variability, and factors in climate change. This provides an index between 0 and 100 where values approaching 0 are close to driest, and those approaching 100 close to the wettest, for any given region. Percentile-based indices like the RI have a uniform distribution regardless of their climatic setting, which is an attractive feature in NSW given the presence of rangeland, temperate and sub-tropical climates which have skewed, normal and log-normal rainfall distributions.

Soil Water Index (SWI)

The SI is calculated using the same procedure as the RI, but uses a soil moisture field derived from the DPI AgriModTM soil water balance. Plant available soil water from layer one (0-10cm) and layer two (11-45 cm), the assumed maximum rooting zone, are aggregated and used to calculate the SWI. Similar to the RI, the SWI is an index between 0 and 100. In most districts of NSW a value of 0 means there is no plant available water held in the profile. The SWI is a hydrological index, but its configuration means that it is more useful as an indicator of conditions for dryland than irrigated agriculture.

Plant Growth Index (PGI)

The PGI is calculated using the same general procedure as the RI, using the output from DPI’s crop and pasture models. Crop stress and pasture growth data are taken from DPI AgriModTM, and the percentile rank calculated for each day. If the predominant land use in a given area is cropping, the PGI uses the crop-derived data, otherwise it uses the pasture growth indicator. The PGI is an agronomic drought index which is not only sensitive to moisture but also temperature variation and seasonal events such as frost. It is important to note that the PGI tracks the influence of climate on production potential across broad areas only. This provides a regional indicator of conditions. In the paddock, management decisions like fertiliser application and timing, sowing times and stocking rates drive outcomes on the ground, and in-field conditions can be above or below the regional indicator reported by EDIS.

BACKGROUND

The main water supply (other than the village systems of Wooli and Minnie Water) in the Clarence Valley is sourced from the Nymboida River, flowing through a section of the wider Clarence River catchment area.

At this time of year the Clarence Valley urban water supply is drawing around 14.26ML/per day from the river weir.

The Nymboida River also gravity feeds water to Shannon Creek Dam when required and, if the Nymboida river flow is too low (less than 225 Megalitres a day) or turbid post-flood, the Clarence Valley's principal urban areas receive water sourced from the off-stream storage at Shannon Creek.

Overall, Shannon Creek Dam is used to supply the Clarence Valley’s water about 5% of the time. Right now this dam is at 99% capacity.

This scenario is complicated by the fact that historically the Clarence Valley also supplies water out of the catchment to Coffs Harbour City local government area and this draw on catchment water is constant and always exceeding an optimal sustainability level for average daily drawn down.

New South Wales might still be in the grip of drought, however December rains did some good

 

Those rolling thunderstorms, wind, rain and flash flooding that plagued the state in December were not just uncomfortable - at times they were dangerous. 

Even now in the first two days of 2024 the NSW State Emergency Service (SES) has responded to more than 115 incidents in the past 24 hours, in response to the impacts of storms and flooding in the north east of the state.

However, all that weather has produced one set of images to bring smiles to the faces of some people in a number of coastal districts.

It's not enough to come out of drought but areas of intense drought have shrunk somewhat.

The Northern Rivers region has seen the Intense Drought category sink back down to 14.5 per cent from a Spring high of an est. 42.8 per cent of all land. While the Drought category fell from 41.6 per cent to 29.1 per cent, with those decreases moving over to being Drought Affected land sitting at 56.3 per cent of the region. 

This of course is 2024, the year of accelerated global warming and erratic weather patterns, so it feels like a coin toss as to whether the Australian east coast and the Northern Rivers in particular have three months of destructive storms ahead or a return to below average rainfall until Winter arrives.

NEW SOUTH WALES DROUGHT PERCENTAGES 29.12.23

NSWDPI Combined Drought Indicator

From Port Macquarie-Hastings to Tweed on the NSW-Qld border drought conditions on the North Coast & Far North Coast are intensifying

 

Combined Drought Indicator
NSW Dept. of Primary Industries
Click on image to enlarge

As of 14 October 2023 est. 40 per cent of the NSW North Coast from Port Macquarie-Hastings to the NSW-Qld border is "Drought Affected".

Another 44.2 per cent is in "Drought" and, a further 15.6 per cent is experiencing "Intense Drought". 

The Northern Rivers regions local government areas with the most land classified as in "Intense Drought" are Clarence Valley and Richmond Valley. 

Typically intense drought field conditions are; Ground cover is very low, soil moisture stores are exhausted and rainfall been minimal over the past 6-12 months.

The Rainfall Index across these valleys has been dropping since the beginning of May 2023 and generally a lessening of soil moisture has been occurring since April.   

The Soil Water Index (SWI) with a range of 0 to 100 is now falling alarmingly in sections of these valleys.

As an example, Taloumbi & Harwood parishes in the Clarence Valley and Coraki & Richmond parishes in the Richmond Valley - all designated as in intense drought - had SWIs of 0 on 14 October 2033. 

While Bureau of Meteorology (BOM) forecasting indicates that heat may be an issue going forward.

BOM, screenshot,10 Oct 2023

Tweed Shire expects to start rolling out water restrictions within next few weeks and rest of the Northern Rivers region likely to be following its lead sooner rather than later

NSWDPI Combined Drought Indicator (CDI) mapping, 23 September 2023. CDI = Combined Drought Indicator. RI = Rainfall Index. SWI = Soil Water Index. PGI = Pasture Growth Index. DDI = Drought Direction Index

Click on map to enlarge

There are 19 large dams on NSW regional regulated rivers and hundreds of smaller dams, reservoirs & weirs associated with a mix of environmental use, off-farm agricultural and urban water storage on other rivers.

Across the seven local government areas in the Northern Rivers region water storage locations include:

Toonumbar Dam

Rocky Creek Dam

Clarrie Hall Dam

Emmigrant Creek Dam

Korrumbyn Creek Dam

Shannon Creek Dam

Bray Park weir

Tyalgum weir

Mullumbimby Power Station weir

Jambour weir

Kyogle weir

Nymboida weir

Rushforth Road 100ML Reservoir.

Tweed Shire Council is strongly alerting its residents and ratepayers as to the current situation and what may lie ahead.

The Echo, 27 September 2023:

Following the devastating floods of 2022 we are back to dry weather. The Bureau of Meteorology (BOM) has declared an El Nino weather pattern and it has predicted that there will be less-than-average rainfall in the Northern Rivers this year. Tweed Council is reminding residents and visitors that it is important to save water as we head into dry weather.

‘Without significant rain, the Tweed will head into water restrictions, with restrictions for Tyalgum looking likely in the next few weeks,’ said Tweed Shire Council’s (TSC) water and wastewater business and assets manager Michael Wraight.

‘We source our water from the Tweed River at Bray Park and Uki, plus the Oxley River at Tyalgum. The river flows are down and the weir pools at Bray Park and Tyalgum are drying up.

‘While Clarrie Hall Dam is currently sitting at 98 per cent capacity, it will now drop about 1 to 1.5 per cent, per week, as we start releasing water to supply the Bray Park Weir – the source of water for most of the Shire.

‘We will trigger level 1 water restrictions when the Clarrie Hall Dam level drops to 85 per cent.

‘Restrictions at Tyalgum will be introduced sooner. The flow of the Oxley River at Tyalgum is down to a trickle and the weir pool there is dropping fast.’

Loss of soil moisture and drought conditions continue to grow across New South Wales in September 2023

 

NSW DPI COMBINED DROUGHT INDICATOR MAPPING

Click on image to enlarge

Data current to 10/9/2023 (AEST)

CDI = Combined Drought Indicator. RI = Rainfall Index. SWI = Soil Water Index. PGI = Pasture Growth Index. DDI = Drought Direction Index

NOTE: The CDI and its individual rainfall, soil moisture and crop/pasture growth metrics are leading biophysical indices of seasonal conditions and drought status. Other factors affecting production and economic responses usually lag the CDI.

From Hastings/Port Macquarie up to the NSW-Qld border 78.7% of the North Coast is Drought Affected and 9.2% In Drought. Only 12.1% is currently considered unaffected by drought.

Water NSW: regional water storage levels as of 14 September 2023

Updates can be found at https://www.waternsw.com.au/nsw-dams/nsw-storage-levels/regional-nsw-dam-levels

According to the NSW Department of Primary Industries, end August 2023:

Drought conditions are continuing to expand and intensify on the North Coast, Northern Tablelands, Hunter and the South East Local Land Services (LLS) Regions of NSW. These conditions are consistent with the onset of a major drought in these regions, and the drought indicators show that the area of this event is growing across the Northern Tablelands and North-West. Producers are continuing to monitor on-ground conditions and climate forecasts closely, while implementing actions in line with their individual drought strategies.

Seasonal Climate Outlook

Seasonal climate forecasts indicate increased likelihood of warmer than average daytime and overnight temperatures for most of NSW for the September to November period.

Rainfall has an increased likelihood of being below average to well below average for most of NSW for the next three months.

The ENSO Outlook status remains at El Niño ALERT. When El Niño ALERT criteria have been met in the past, an El Niño event has developed around 70% of the time.

The Indian Ocean Dipole (IOD) is currently positive

The NSW coastal drought continued to grow in July 2023

 

As of 23 July 2023 – Day 53 of the 92 day official Australian Winter – an est. of 97.7 % of the land area of the NSW wider North Coast is identified Non Drought, 2% Drought Affected and 0.3% in Drought , according to the NSW Department of Primary Industries (DPI).

SEE: https://edis.dpi.nsw.gov.au/

The DPI Combined Drought Indicator mapping currently indicates that in the seven Northern Rivers local government areas of north-east NSW at rough estimates:

Est. 7% of the Clarence Valley is In Drought, est. 57% is Drought Affected and 36% Non Drought;

Est. 8% of the Richmond Valley is In Drought, est. 72% is Drought Affected and 20% is Non Drought;

Est. 7% of Lismore is Drought Affected and 93% Non Drought;

Est. 21% of Kyogle is Drought Affected and 79% Non Drought;

Est. 56% of Tweed is Drought Affected and 44% Non Drought;

Est. 100% of Ballina is Non Drought; and

Est. 100% of Byron is Non Drought.

Rainfall deficiencies, Australia, December 2022 to June 2023:

Click on image to enlarge

In north-east New South Wales, an area of serious deficiency extends inland from the west of the ranges, with pockets of serious and severe deficiency east of the Divide and in the Hunter District. [Australian Bureau of Meteorology, 6 July 2023]

DROUGHT: and so it begins.....

 

The green map of New South Wales is changing colour as soil moisture begins to fall.

Thus far drought affected land is confined to the north-east and north-west of the state, with 10.9% of land on the North Coast affected.

 An est. 35 parishes are drought affected in the Clarence Valley, 13 parishes in the Richmond Valley and 3 border parishes in Tweed Shire.

The Dept. of Primary Industry seasonal update considers that "Drought Affected Land" status is intensifying in the Clarence Valley. Currently that status appears to cover an area roughly from just south of Lawrence following the river to land up past Dumbudgery and, from the Yulgilbar district in the north to the Elland district in the south.

NSW Dept. of Primary Industries, Combined Drought Indicator, mapping as of 3 June 2023

So this Australian Winter was expected to be drier and warmer than the median mark, but now it seems twice as likely a rainfall suppressing El Niño event will also start this year

During the multi-year Millennium Drought from 1997 to 2010, south east Australia experienced its lowest 13-year rainfall record since 1865 over the years 2006 to 2010.

Temperatures were also much hotter than in previous droughts and temperature extremes peaked during the heatwave and bushfires in early 2009. This culminated in the loss of 374 lives in Victoria and many more over the larger southeast in the heatwave leading up to Black Saturday. There were 173 lives lost in the fires.

The years 2015 to 2016 saw El Niño combined with a positive Indian Ocean Dipole in the second half of 2015 further suppressing rainfall, so that rainfall was the equal fourth-lowest on record for Australia during September, Tasmania had its driest Spring on record and mean temperatures were also highest on record for October to December 2015. This El Niño also contributed to an early start to the 2015-16 southern fire season.

By 2017 Australia was again in the grips of a multi-year drought. Very dry conditions in the cool season were followed by only a limited recovery in the October–December period in 2017 and 2018. This meant record-low rainfalls over various multi-year periods.

By June 2018 more than 99% of NSW was declared as affected by drought. The most extreme rainfall deficiencies over multi-year periods occurring in the northern half of New South Wales.

In June-July 2019 New South Wales began a trial by mega bushfires, as did other east coast states, that lasted through to January 2020.

Widespread drought was not an issue for the remainder of 2020 through to the present day, given La Niña visited three times in three years bringing high rainfall events and record floods in the eastern states.

However, the Australian Dept. of Agriculture, Forestry and Fisheries (ABARE) is now drawing attention to this:

All but one international climate model surveyed by the Australian Bureau of Meteorology suggest sea-surface temperatures in the tropical Pacific will exceed El Niño thresholds in June. [ABARES Weekly Australian Climate, Water and Agricultural Update, 25 May 2023] 

[ABARES, 25 May 2023] Click on image to enlarge

Suggesting in its climate update that there is now twice the risk of an El Niño event this year, with a likelihood of it making itself felt sometime between August and October.

The overall outlook for this Australian Winter continues to be below median rainfall and warmer median temperatures. 

The main urban centres in the Clarence Valley have a chance of unusually warm temperatures over the winter months of between est. 55-60% (Maclean-Yamba-Iluka) and 59-65% (Grafton). While elsewhere in the Northern Rivers region unusually warm temperatures are expected in Lismore with est. 58-59% chance, Tweed Heads est. 59-62% chance, with Byron Bay & Ballina at est. 60-61% chance. [BOM, Climate outlooks—weeks, months and seasons, June-September 2023]

How this developing scenario affects agricultural growing seasons over the next twelve months is anyone's guess.

In New South Wales only the parishes of Newbold and Braylesford in the Clarence Valley are showing Combined Drought Indicator (CDI) at “Drought Affected”. 

Nevertheless, root-zone soil moisture has been falling across north-east NSW so that by end of April 2023 it was very much below average in from the coast. 

Remembering that drought 'safety net' Shannon Creek Dam, which supplies urban town water to both Coffs Harbour City and Clarence Valley resident populations (total 134,538 persons, June 2022) is currently at 92.6% capacity or 27,677 megalitres, perhaps we may see increased water restrictions by the next Christmas-New Year period. Given the tourist-driven seasonal population rise increases water consumption and that 80% dam capacity is the increased restrictions trigger.

It doesn't take a genius to suspect that should a drought develop, the 2024 and 2025 bush fire seasons might also be highly problematic for rural and regional areas across Australia.

Unsurprisingly New South Wales is yet to officially enter drought. However, soils do appear to be drying out in some regions.

 

Unsurprisingly New South Wales is yet to officially enter drought. However, soils do appear to be drying out in some regions.

The Australian Water Outlook for 11 January 2023 shows the Clarence River catchment rootzone soil moisture is 21% in absolute terms (below average) and in the 11^th percentile in relative terms – representing the percentage of available water content in the top 1m of the soil profile.

While the upper layer soil moisture is 2% in absolute terms (below average) and the 8^th percentile ranking in relative terms – representing the percentage of available water content in the top 10 cm of the soil profile.

Across the entire Northern Rivers region it appears that only the Brunswick and Richmond river catchments are coming in with an average soil moisture content for the month of January 2023 to date.

Overall the average first 10cm of the state's top soils holds only 0.83% moisture in absolute terms and the root zone 10% moisture.

The Australian Bureau of Meteorology gives north-east NSW a 50–55 chance of exceeding median rainfall between February and May 2023.

On Thursday 12 January 2023 the NSW Rural Fire Service recorded an ongoing bushfire fire at Townsend in the Lower Clarence on 6ha of grass & close tree cover and a fire at Malabugilmah on a 19 ha mix of grass and open woodland. Both fires are under control

Clarence Valley Independent, 11 January 2023:

Smoke rises into the sky as a massive fire takes hold of the Australian Community Care Network (ACCN) and the adjoining property Broomy’s Towing and Recovery on December 28. Image: Ross Pritchard

Heavy black smoke billowed over Grafton’s CBD shortly after 4pm on December 28, as close to 70 firefighters and emergency services personnel fought to contain a large-scale fire which seriously damaged two properties in Fitzroy and Victoria Streets and impacted several nearby businesses.

A spokesperson for NSW Police said the blaze began in a storage area at the rear of the Australian Community Care Network (ACCN) in Fitzroy Street and quickly spread to the adjoining business in Victoria Street, Broomy’s Towing and Recovery.

As Grafton Fire and Rescue 306 Station Captain Garry Reardon and several of his crew members battled the flames from Victoria Street, Grafton Fire and Rescue 306 Station Deputy Captain Chris Rumpf undertook fire attack from Fitzroy Street.

Describing the blaze as extremely fierce, Captain Reardon said local crews were aided by firefighters from Ballina, Lismore, Goonellabah, Casino, Maclean, Yamba, Woolgoolga, and Coffs Harbour, along with Rural Fire Service (RFS) crews from Southampton, Ulmarra, Grafton, and Casino.

NSW Ambulance paramedics also attended the scene and treated several firefighters who suffered minor burns and dehydration as they fought to bring the fire under control and save neighbouring properties.

No other injuries were reported.

“It was a massive blaze,” Captain Reardon said.

“It certainly took hold of the buildings very quickly.

“From Victoria Street, we had fire control within half an hour, but it was still roaring in Fitzroy Street.”

Deputy Captain Rumpf recalled being faced with a wall of flames upon his arrival at the scene, and said conditions were very hot and very intense……

Manager of the ACCN Alison Tomlinson described the situation as a nightmare, and revealed the business lost more than 50 percent of its stock including numerous food and household items, a cool room, and a large freezer, and is currently unable to trade.

Dean Broomhall from Broomy’s Towing and Recovery confirmed they are still operating after their tow truck was saved from the flames which caused significant internal damage to their building…...

Firefighters battle to control the fire after it spread into Broomy’s Towing and Recovering in Victoria Street. Image: contributed

Read the full article here.

Australian Prime Minister Scott Morrison is back trying to pretend the politically inconvenient fact of climate change is not occurring in the leadup to the 2022 federal election

Australian Bureau of Meteorology

On 5 November 2021 Australian Prime Minister & Liberal MP for Cook (NSW) Scott Morrison issued a lengthy media statement which ended with these three lines:

“High Risk Weather Events

National Cabinet received a briefing from Emergency Management Australia on the 2021-22 High Risk Weather Season, and noted that a La Niña watch has been issued in 2021.”

NOTE: Emergency Management Australia falls within the Dept. of Home Affairs. It organises the National Catastrophic Natural Disaster Plan (NATCATDISPLAN) last updated in 2017, republished in 2020.

To be honest I did not think why those three lines had been tacked on at the end of a statement which covered Vaccination and Booster Plans, Ensuring COVID-19 Outbreak Readiness for Indigenous Communities, National Plan to Transition Australia’s COVID-19 Response, Living with COVID-19 - Revised Test, Trace, Isolate and Quarantine (TTIQ) and Public Health and Social Measures (PHSMs), Living with COVID-19 - Health System Capacity, Borders and International Travel, along with this live link Doherty Institute COVID-19 modelling: 2nd tranche [PDF 651 KB].

At most all I thought was ‘Oh yes, the La Niña ALERT. North Coast Voices covered that in October and November posts'.

What I didn’t know and the Prime Minister did, was that the Australian Bureau of Meteorology had put together a rather more pointed weather outlook and forecast in power point form, which brought together the dry technical language on its website & its YouTube videos in a way that clearly showed where climate change had landed us all in 2021-22.

It must have been as obvious to the Prime Minister, as it was to me once I sighted segments of that presentation, that this was not information that a notorious climate change trivialising federal government would want to highlight going into an election year. However, as a slippery, slithering game player who is always looking for plausible deniability, those three brief lines would allow Morrison to say 'but I told Australia about it!' if a journalist thought to ask.

Here are a selection of slides from that presentation courtesy of Senator Rex Patrick’s Twitter account:

Click on images to enlarge.

The Guardian, 4 December 2021:

Tropical cyclones and flooding are set to pummel Australia over summer, national cabinet documents reveal.

The Bureau of Meteorology briefed the meeting of premiers, chief ministers and the prime minister on 5 November about the high-risk weather facing the nation until April.

National cabinet documents are usually kept secret, but South Australian senator Rex Patrick obtained these under freedom-of-information laws.

Last week Patrick, the Labor leader, Anthony Albanese, and One Nation’s Malcolm Roberts all launched attacks on the prime minister’s department for its secrecy. There is a broader legal question about whether national cabinet is entitled to the cabinet-in-confidence protection, with critics saying that merely calling it a cabinet does not actually make it one.

The bureau director general, Joe Buffone, presented Emergency Management Australia’s 2021-22 High Risk Weather Season briefing.

The PowerPoint presentation shows there are increased chances of widespread flooding, coastal flooding and erosion, tropical cyclones and marine heatwaves, compared with average summers and early autumns.

There is a lower chance of drought and dust.

The overall risk of severe storms is on par with other years, while parts of Queensland and NSW have an increased risk of bushfire, and there is a higher chance of heatwaves than usual.

Warm waters mean slightly above average tropical cyclone numbers – the average is 11 per season.

La Niña means the weather is likely to be cooler, wetter and stormier. Areas that had above-average rainfall during spring, and therefore more grass, could lead to a heightened grassfire risk, while parts of the east coast will have a lower risk – because the 2019-20 fires reduced fuel loads.

The bureau’s presentation was prepared with publicly available information.

Patrick said the prime minister, Scott Morrison, should have released the documents when he released a media statement about the national cabinet meeting. That statement focused almost entirely on Covid, with a single line about the briefing.

That line prompted Patrick to make the FOI request to the Department of Home Affairs…….

And so it starts.

NSW and Victoria floods: rivers break banks as rain and wind lash Australia’s eastern states, The Guardian, 13 November 2021.

NSW flood damage bill expected to exceed $1b as November rain submerges crops, ABC News, 1 December 2021.

Man dies in Queensland floodwaters as heavy rainfall causes Inglewood to be evacuated, cars swept off road in state's south, ABC News, 1 December 2021.

BOM issues flood warning for Chinchilla on the Western Downs, as parts of southern Queensland begin clean-up, ABC News, 3 December 2021.