Ground Report | New Delhi: Flood risk may increase up to 50 times; Climate change and anthropogenic pressures are expected to increase flooding in coastal areas. A recent study has estimated coastal overtopping to be occurring on a global scale. This study not only explained the rise in sea level but attributed it to an increase in storms.
The study is published in Nature Communications noted that worldwide overtopping hours have increased by almost 50 percent every year over the past two decades. Overtopping: This rise is mainly due to sea-level rise and ocean tides, combined with storm waves. Rising water levels combined with sea-level rise, tidal, storm waves have increased the need for natural and artificial coastal protection by almost 50 percent in the past two decades.
The researchers combined satellite data and digital models to see that the rise in sea level, the waves, led to the rise in the water level (overtopping) on the coasts. As a result, the risk of flooding in tropical regions could increase up to 50 times under high emissions global warming scenarios.
About 10 percent of the world’s population lives in low-lying coastal areas or seaside areas. In addition to erosion and rising sea levels in these areas, their unique ecosystems are facing devastating threats. In which due to the wild rise in the water level, the natural, artificial defenses are broken from time to time by floods. As in 2005, due to the arrival of Hurricane Katrina in America. In 2013, Typhoon Haiyan was the largest tropical cyclone ever to hit Asia.
Events like these are expected to become more severe and more frequent due to global warming. All this is partly due to anthropogenic pressures, such as coastal and infrastructure development, rapid urbanization, etc. Although the magnitude and frequency of these events remain uncertain, scientists believe that tropical countries will be particularly affected by such events.
Despite the important role of ocean waves in determining sea level, their contribution to coastal flooding has previously been largely overlooked. The main reason for this is said to be a lack of accurate information on coastal topography.
In the study, together with collaborators from several countries including France’s Institute of Research for Development (IRD), the National Center for Space Studies (CNES), an unprecedented global digital for surface height came with new estimates of sea level. The model has been added. Rising water levels include analysis of tides, wind-driven waves, and existing measurements of natural and artificial coastal defenses.
The study has been done by quantifying the increased incidence of flooding or submersion worldwide between 1993 and 2015 . To take this further, satellite data were used to meet two key parameters for coastal topography, which include the slope of the local coastline and the maximum height of the coasts. Coastal water peak levels were calculated hourly to identify the number of possible annual hours.
Rafael Alamar, a researcher in coastal dynamics at the IRD, says that large waves, tides and the timing of their arrival play a major role in coastal water level rise. “We identified hot-spots where the increased risk of overtopping is high, such as in the Gulf of Mexico, the southern Mediterranean, West Africa, Madagascar, and the Baltic Sea,” he said (Flood risk may increase up to 50 times).
The scientists also conducted a preliminary global assessment of coastal overtopping in the 21st century, taking into account various sea-level rise scenarios. The results suggest that the rate of overtopping may increase every hour faster than the average rate of sea level rise.
The frequency of overtopping is increasing rapidly and will clearly be much higher in the early 2050s, regardless of the climate scenario. Its intensity by the end of the century will be based on greenhouse gas emissions, so sea level rise will depend on all these factors.
Rafael Almar warned that in the case of a higher emissions scenario, the number of overtopping hours globally could increase fifty times compared to current levels. As we move forward with the 21st century, coastal flooding, especially in tropical countries, will increase due to the overtopping of more and more areas.