A new report has revealed that between 1985 and 2015, urban development around the world has expanded “continuously and rapidly” into high-hazard flood zones like floodplains and riverbeds.
A report in the respected journal Nature shows that growth in these risky areas has more than doubled (122%) in the period, compared to growth in less flood prone settlements (60%).
“In many regions, growth in the most hazardous flood zones is outpacing growth in non-exposed zones by a large margin,” says the paper.
“Year-on-year growth estimates confirm that… settlement growth in the highest-hazard flood category has increased by almost 3% a year.”
The urban development in highest-hazard zones is most prevalent in the East Asia and Pacific region. “‘No hazard’ settlements expanded by just over 100%, whereas ‘very high hazard’ settlements expanded by over 160%.”
There are some surprises – what we sometimes call “the driest state in the driest continent” – South Australia – experienced greater than 50% growth in people living in flood prone areas, while Queensland, which was inundated in the 2010-2011 floods, and suffers cyclones every year, is experiencing a reduction in population in risky regions.
The study, when analysing historical floods, noticed that not all types of floods were recorded (fluvial, pluvial, and coastal flooding).
Fluvial floods are river floods; pluvial floods are flash floods and surface water; and coastal floods are storm surges on the sea shore.
The report also shows economic status influences an individuals’ risk to live on flood prone areas.
“Of the 36,500 square kilometres of settlements built in highest-hazard zones since 1985, 1.1% are in low-income countries (LICs), 20.5% are in lower-middle-income countries (LMICs), 60.8% are in upper-middle-income countries (UMICs) and 17.6% are in high-income countries (HICs).”
Low-income countries include North Korea, and a large portion of Africa, etc. Lower-middle-income countries include India, Vietnam, Ukraine. Upper-middle-income countries included Russia, China, South America. High-income countries include Australia, USA, majority of Europe.
Why are we building on floodplains?
The paper suggests: “urbanization, land scarcity, socioeconomic trends and institutional and regulatory factors,” are responsible for the trends.
The Ultramarine project – focussing on research and innovation in our marine environments – is supported by Minderoo Foundation's Flourishing Oceans initiative.