Cities100: Hong Kong - Landslide Protection with Low-Impact Design

Hong Kong is protecting residents from deadly, rain-induced landslides by strategically installing barriers and drainage tunnels.

The Challenge

Hong Kong is a mountainous city with dense urban development built on steep man-made and natural terrain. Many of the man-made slopes were constructed 50 years ago without proper engineering, and with the city's high rainfall, landslides are common and cause extensive socio-economic damage and fatalities.

The Solution

The topography across Hong Kong's land area is dramatic: more than 60% of the land is steeper than 15 degrees and 30% is steeper than 30 degrees. Very high rainfall on this hilly natural and man-made terrain has resulted in frequent and disastrous landslides across the densely developed city. Quantitative risk assessments had predicted up to 2,500 landslides per year and identified high-risk zones. To mitigate these risks, the city is implementing low-impact and effective landslide protection solutions. Using remote sensing tools and GIS-based landslide modeling, the city has designed and strategically placed both flexible and rigid barriers to resist the impacts of landslides. This approach was chosen in favor of slope stabilization, which is not only costly but also requires extensive earthworks and tree felling. In addition, drainage tunnels and smart monitoring technology enable better control of groundwater in the city's slopes, one of the primary drivers of landslides.

Economic Benefits – The project lowered the landslide risk to 'as low as reasonably practicable', reducing direct and indirect economic losses associated with landslides. The project also created 550 jobs during construction.

Health Benefits – Reduced landslide risk has improved public safety and created a more livable environment for Hong Kong citizens.

About Cities100

Presented by C40 Cities Climate Leadership Group (C40), Sustainia and Realdania – Cities100 2017 showcases leading solutions to urban climate challenges in five sectors: Energy, Waste, Adaptation, Mitigation and Transportation.

Available online and in print, Cities100 provides stakeholders an accessible format to explore achievable solutions for climate action in cities, and will be a useful tool for relevant groups ranging from impact investors and development organizations, to mayors and city governments. You can access the full Cities100 2017 publication online here.