Uvala, Karst Depression Landscape

This is a common karst landform with enclosed negative topography. It is sometimes difficult to distinguish it clearly from a karst funnel or doline. In general, karst depressions have larger areas with bottom diameters greater than one hundred metres. The surfaces are relatively flat and covered with loose sediments. Dolines and avens are common. These depressions are generally appropriate for agricultural use, whereas karst dolines are generally smaller and hence are not suitable for agricultural use. Karst depressions have obvious zonal characteristics. They have star shapes or polygonal shapes in humid regions, such as the cone karst area of southern China. There are at least 2,851 enclosed depressions in an area of 1,000 km²in the subterranean river district in Du’an, Guangxi Province. However, in the semi-arid north, the depressions are small, sparse and nearly circular. In tectonic areas, they can develop into bead-like depressions. Some countries use a broad definition of...