Reducing the risk of landslides and erosion

Signs to look out for

• If trees and poles on a slope start to lean in the same direction.
• If chunks of earth begin to slide. Small landslides (initial landslides) can be a sign that a larger landslide may occur.
• Erosion damage to watercourses.
• Newly developed and growing cracks in soil.
• Foundation settlements in buildings, such as doors and windows that cannot be opened.
• Breakage of pipes and cables in the ground.
• Sudden interruption of flow, increased flow or turbidity of water in a watercourse may indicate landslides or avalanches upstream.
• In the case of rockfall, loose boulders on a rock slope.

Activities that can trigger landslides and avalanches

These activities can trigger landslides and avalanches.

Increased load on slope crests

• Heavy objects, such as parked cars, scrap metal, excavated material and piles of firewood weighing down the slope.
• Garden waste dumped on the slope increases the load on the slope and can smother vegetation.
• Snow piles dumped on the slope put pressure on it, and meltwater from the snow can erode the soil.
• Water can accumulate in the soil due to heavy rainfall or leaking water and sewer pipes.

Reduced counterweight in slope base

• Excavation at the bottom of a slope increases the risk of landslides.
• Rain and meltwater from roofs and streets, and drainage water that is channelled into a slope, can excavate and wash away the soil on the slope. The soil around the outlet of the pipeline should therefore be protected from erosion using gravel.
• Fills, jetties, piers and erosion protection can change flow conditions in a watercourse. This means that a new part of the slope may be exposed to water erosion, resulting in landslides. Anyone who has built something that causes damage downstream will be liable to pay compensation to repair the damage. To carry out work in water, you may need a permit under the Environmental Code.
• Severe disturbance, such as an explosion or vibration in the ground.

Repairing the ground

A slope or hillside damaged by erosion can be repaired by planting cuttings or tree seedlings where the soil is damaged. Use tree species that are naturally found in the area. The roots of the trees hold the soil together, thus preventing erosion, and should be left on the slope.

However, you may cut down large, individual trees that begin to lean. Like trees, plants are important because they absorb water and bind the soil together.

Contacting municipalities

You can always contact the local planning office in your municipality, or the municipal rescue services, if you have questions about landslides.