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Oceans Expert Explains Why Climate Change Is A Problem To Coastal Inundation

Between June 14 and June 16, those living along Fiji’s coast experienced a phenomenon that undoubtedly many had not seen in their lifetime.
27 Jun 2022 17:00
Oceans Expert Explains Why Climate Change Is A Problem To Coastal Inundation

Between June 14 and June 16, those living along Fiji’s coast experienced a phenomenon that undoubtedly many had not seen in their lifetime.

The King Tide, coupled with the low pressure system felt to the far south of Fiji, resulted in what can only be described as unprecedented high tides.

It was reported that those taking their morning walk along the Nasese seawall were met with extraordinary waves crashing onto the seawalls and onto the pathway and the roads.

 

In Kadavu, villagers told the same how the waves seeped right into their homes forcing some to move immediately to higher grounds.

On June 14 at 6:15pm the high tide was at 1.99 metres (low to moderate chance of sea flooding).

At 6.18am the next day the tide was at it highest recorded at 2.28 metres (high chance of sea flooding), the evening high tide recorded two metres (moderate chance of sea flooding).

A village in Kadavu is being protected from heavy waves and sea level rise as a result of climate change.

A village in Kadavu is being protected from heavy waves and sea level rise as a result of climate change.

The following day, at 7.13am the high tide was recorded at 2.26 metres with 1.99 metres in the evening.

The above data came from the Fiji Meteorological Service.

But what did it mean? Why now? Why was this not felt before or if it was, how did it came to be?

That is the ongoing question that Herve Damlamian has been trying to answer and understand for the past 15 years in his career.

 

Mr Damlamian works for the Pacific Community (SPC) as its team leader Ocean Prediction and Monitoring.

He spent more than 15 years studying the ocean.

And his answers and understanding seem to be the same as every other expert on climate change – that is, climate change exacerbates the risk and frequency of coastal inundation.

Surprisingly, he said, waves could inundate coastal communities during fine weather when it was least expected.

 

Explaining The Science Of  Forecasting

Mr Damlamian highlighted that inundation events could be triggered by a combination of factors such as the wave, the water level in the ocean which depends on the tide and other phenomena such as ElNino/LaNina.

ElNino/LaNina refers to climate patterns in the Pacific Ocean that can affect the weather across the globe.

“Waves are the major trigger to coastal inundation, especially for communities located along reef fronted shorelines,” he said.

A river in Kadavu bursts its bank when sea water inundated its outlet.

A river in Kadavu bursts its bank when sea water inundated its outlet.

“To forecast coastal inundation, we first need to localise global wave forecasts.”

These global wave forecasts provide wave predictions seven days into the future, but are too coarse to see all the islands.

For the forecasts to be precise, they localise the wave forecast.

It is called downscaling.

 

“Once we can accurately forecast  waves off a coastal community, we combine it with prediction of tide and other components of the sea level to estimate the coastal flooding/ coastal inundation that could occur,” he added.

“To transform offshore ocean conditions into coastal inundation we first need accurate bathymetry (shape of the sea floor) and topography.”

“These datasets entered into computer models capable of simulating the nearshore processes relevant to coastal inundation events.”

Walkway along the Suva seawall covered with seawater and debris.

Walkway along the Suva seawall covered with seawater and debris.

The system is operational in Fiji through the national weather centre.

However, the model is used more on the south-west of Fiji rather than the others.

It is looking into opportunities to expand the system to the whole of Fiji.

 

But it is significantly held back due to lack of funding.

Funding is required to expand the system to have accurate baseline data (bathymetry/ topography).

It is needed to ensure the quality of the forecast system.

 

Recent Event

Coastal inundation can occur anytime as a result of inclement weather; however, it could result in both a local storm and even one outside of Fiji waters.

The recent inundation was on June 15, 2022, heavy rain and damaging hail hit some parts of South Australia.

Despite being miles away, heavy swells ran across in the Pacific Ocean and landed on coastlines in Fiji.

 

The Fiji Meteorological Services issued a warning for coastal areas of southern Viti Levu, southern coastal areas of Mamanuca Group, Beqa, Kadavu, Vatulele, Southern Lomaiviti Group, Moala Group, Southern and Central Lau Group.

The office warned of waves more than two metres high.

Other warnings had included waves as high as five metres.

Waves are most damaging during high tides.

water

As a result, most parts of these areas were inundated.

Waves can unexpectedly crash into homes.

The Fiji Sun reported that boats washed ashore, seawater crashing onto high seawalls and disruption of the Suva bowling games are but some of the results of the coastal inundation and damaging swells.

 

What You Need To Do

The National Disaster Management Office coordinates the disaster operations when there is one.

It always warns of vigilance during disasters.

 

People Must:

1. Watch for rapidly rising water

2. Store drinking water in sealed plastic containers as water supply may be interrupted

3. In an event where there is flooding, pedestrians and motorists are advised to refrain from crossing flooded roads, footpaths and rivers

4. In an event of a landslide, avoid going to places affected by debris flow

 

The World Meteorological Organisation said early warning signs include heavy rain, increasing onshore winds, and increasing heavy swells.

It further said people must know their evacuation routes and locations of evacuation centres.

People must also tune into local radio stations for weather updates and warnings.

 

People must evacuate when told to do so.

Move to higher grounds, however, people must move to the highest level of a building if inside but must not enter the attic otherwise they would be trapped.

Fast moving waters can wash away bridges.

The organisation further stated that people must not walk, drive or swim in flooded waters.

 

Health Risk

Mr Damlamian said the inundation could leave people sick if they were unprotected.

“In some respect, the coastal inundation event can really impact a range of sectors,” he said.

“It can lead to diseases like leptospirosis, typhoid, dengue and diarrhoea – commonly known in short as LTDD.

 

“Food security can be impacted through saltwater going into crops and then obviously, impacting the crops and livelihood of some communities,” he added.

“We also have communities, especially in rural areas that might depend on boreholes for freshwater etc.

Well, if we have some inundation event that saltwater can penetrate the groundwater and then pull it through.”

He said Fijians must remain vigilant and remain cautious when such a warning was issued.

 

Feedback: josefa.babitu@fijisun.com.fj

  • The Fiji Sun would like to thank SPC, ABC International Development and the Australia Pacific Climate Partnership for their support for this story.


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