Flood risk debates in the Hawkesbury-Nepean Valley following the flooding in March this year have prominently featured climate change. They highlight the immediate need for action to mitigate these risks. Yet, Dr. Stephen Yeo, an expert in flood risk, called attention to an extreme flood event that impacted the region. It delivered punishing precipitation over a seven-day period. This situation underscores the urgency of addressing the flood plain’s challenges, especially with over 114,000 residents living in vulnerable areas.
The New South Wales (NSW) Reconstruction Authority showed it was serious about protecting residents from future flooding. They are actively pursuing a range of mitigation measures such as constructing new levees and improving evacuation routes. Yet with climate change making these risks worse, each degree of atmospheric warming adds about eight percent to rainfall. Leaders are confronted with urgent choices.
The Role of Indigenous Knowledge
Dr. Daryl Lam assured the attendees that Aboriginal oral history should not be overlooked when it came to identifying past flood events. He stressed that these narratives go back hundreds of years. They would provide essential information on how climate change will increase future flood risks. According to historical archives, the flood in 1780 was possibly two to three meters above the known record flood of 1867. That means the prior event was much, much worse.
What is needed, as Dr. Stephen Yeo pointed out, is to integrate Indigenous storytelling fully. He noted that such an effort might increase our understanding of floods in history down to 200 or even 500 years.
“So that’s actually really valuable information from that Aboriginal storytelling,” – Stephen Yeo
These narratives serve as a reminder of the region’s long history with flooding, which is documented through early colonial accounts. Windsor Records from Windsor are among the earliest in the province, dating back to the first years of European settlement. What’s more, they indicate that a much larger flood took place eight years before the First Fleet landed.
Current Research and Future Planning
Researchers are now working on a disaster adaptation plan for the Hawkesbury-Nepean Valley. This effort seeks to combat the growing severity and regularity of flooding crises brought on by climate change. In addition, Dr. Lam stressed that the severity of floods will continue to worsen. These floods are now projected to occur much more frequently.
“What we do know about climate change is there is going to be an increase in the intensity of events, so the magnitude will definitely increase, and it’s likely we are going to see an increase in the frequency of events,” – Daryl Lam
To that, Dr. Yeo can only strongly agree. He notes that the historical data from this river system offers the longest documentation of floods in Australia, reaching back to the early 1790s.
“On this river system, we have the longest record of floods in Australia from the early 1790s right up to the present,” – Stephen Yeo
Experts believe that scientific data paired with Indigenous knowledge creates the most effective protection against future disasters. Building this integration is crucial for making sound flood management investments and strategies in the future.
A Call for Action
As climate change exacerbates the effects of severe weather, local governments and researchers are under an increasingly pressing threat. Together, the effects of soaring temperatures and more precipitation is a grave danger to communities that reside on flood plains. As Dr. Yeo highlighted, history provides evidence that past events can recur:
“History is telling us what has happened before really can happen again, so if we can find evidence of big floods from the past, it gives us some understanding of what we can potentially see in climate change,” – Daryl Lam
Now more than ever, authorities need to take bold action and put the most efficient and effective mitigation strategies to work to protect this vulnerable area’s lives and property.
