Landslides are becoming more frequent and deadly in recent years, with 2022 recording one of the highest numbers of fatalities. This phenomenon is caused by the two major factors of climate change and urban sprawl.
Landslide occurrences have increased tenfold in the past five decades, and the combined impact of climate change and urbanization will further heighten the risk. Scientists must now evaluate the extent and location of such hazards.
Rising occurrence of Landslides
Over the past 50 years, landslides have become ten times more frequent, and the trend is likely to continue. The combination of climate change and urbanization is further exacerbating the situation.
The increasing risk is a cause for concern, and scientists are currently evaluating the extent and location of such hazards.
Landslides occur when the forces of gravity surpass the strength of soil or rock on a slope, leading to a mass of material sliding, falling, or flowing downhill.
Heavy rainfall is the main trigger, as it infiltrates the soil, increasing the pressure in pores, making the ground weaker. Steep hillslopes with weak materials are more prone to instability, while plant roots provide some reinforcement.
Human modifications to slopes, such as cutting into them, flattening them for construction, or removing plant cover, make them steeper and more vulnerable to landslides. Activities like mining and infrastructure development also increase the risk of landslides.
Human Modifications to Slopes
Human modifications to slopes, such as cutting, terracing, or flattening them for construction, make them steeper and more vulnerable to landslides.
Removing vegetation cover and adding water through poor drainage or leaking pipes also increases the risk of landslides. Infrastructure development and mining activities, such as road construction, increase the risk of landslides.
Informal settlements, home to more than a billion people, are particularly vulnerable to landslides, and the annual number of deaths from landslides linked to human activities has increased fivefold since 2004.
Risks of landslides and climate change
Climate change is one of the main factors contributing to the increasing occurrence of landslides.
Rising global temperatures and resulting changes in weather patterns have led to an increase in the frequency and intensity of extreme weather events, such as heavy rainfall, flooding, and landslides. With rising sea levels and increased coastal erosion, landslides can also occur in coastal regions.
Melting glaciers and ice caps can lead to the formation of glacial lakes, which can cause catastrophic flooding and landslides if the lakes break.
Retreating glaciers and snow cover also reduce the ability of slopes to hold their position, increasing the likelihood of landslides.
Impact of urbanization on landslide risks
Urbanization, especially unplanned urban sprawl, has been identified as another important factor contributing to the increasing incidence of landslides.
As more people move to cities, the demand for land increases, leading to the construction of buildings and infrastructure on steep slopes.
The use of heavy machinery to cut slopes and flatten soil for construction can weaken the soil, making it more susceptible to landslides.
Slope steepness is a crucial factor in landslide hazards, with slopes greater than 10° more prone to instability. Cities like Caracas in Venezuela and Taiz in Yemen each have more than 1.6 million people living on land with slopes greater than 15°.
With more people living on slopes with angles greater than 10°, the risk of landslides is increasing. The plains below the slopes are also at risk from debris flows.
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