Dolins

Dolins are depressions on the surface of karst landscapes, typically circular to oval, formed in soluble rocks such as limestone, dolomite, or gypsum. In English, dolins is the plural of dolin; they are commonly referred to as dolines or sinkholes.

Most dolins form by dissolution: slightly acidic water dissolves the rock, enlarging underground voids. Over time, the roof of a subterranean cavity may collapse, producing a collapse doline. In other cases, gradual subsidence or suffosion causes the ground to subside, creating a solution or subsidence doline. Some dolins remain as closed depressions with flat floors; others are bowl-shaped or funnel-like and may host ponds or streams.

Sizes vary from a few meters to tens of meters in diameter; depths are similar or greater. Dolins are common in limestone-dominated karst areas worldwide and often occur in fields or clusters that reflect the pattern of underground drainage. They play a key role in karst hydrology as points of groundwater recharge and surface-water infiltration; some collect rainwater or form seasonal pools.

Human activities such as land development, groundwater extraction, and mining can threaten dolins by altering drainage patterns or causing collapse; mapping and monitoring using lidar and other remote sensing aids karst management and hazard assessment.