Description

A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. Most sinkholes are caused by karst processes - the chemical dissolution of carbonate rocks, collapse or suffosion processes. This article is focused on sinkholes/collapses that impact aviation operations and are primarily caused by human activities.

Sinkhole beneath an airport runway

Causal Factors

High and rising water tables, altered underground water courses as a result of human activity, increased runoff from impervious surfaces such as runways due to heavy rainfall can all accelerate human-induced sinkhole collapses. Soft materials such as chalk, limestone, sand and soil are more vulnerable to being washed away and undermining the structures above.

Warning signs

The potential for sinkhole collapse must be part of land-use planning. The presence of subsurface cave systems and unstable voids, or existing natural sinkholes in the vicinity of the aerodrome should be mapped and avoided when constructing runways and taxiways.

Airport authorities should monitor water level changes. Sinkholes can develop with little warning but may be preceded by cracks in the pavement or sagging areas of asphalt.

Operational consequences

Clearly, the repair of sinkhole damage to aircraft operating surfaces can render the runway or taxiway concerned unusable for a lengthy period of time. Changed taxi routes and temporary runway crossing procedures need to be managed to avoid any increase in runway incursion risk.