Characteristic of Lang Son Karst Poljes in Vietnam and Geohazards

Abstract

In the karst regions of Vietnam, there are many different terrains. The most important one is karst polje. Because there are a lot of residential areas and important economic regions. Based on the study of Geomorphology, geological structure analysis, Geophysics document analysis, and karstification process research at Lang Son karst polje. The author gives conclusions: Lang Son karst polje was formed from the limestone of Bac Son Formation, 700 – 800 m thick. Lang Son karst polje was formed from anticline structure, the limestone of Bac Son Formation that has high karstification level. Lang Son karst polje has only one karst aquifer which is a water supply source for residential areas in Lang Son city. This karst aquifer distributes in limestone blocks of the Bac Son Formation. Geohazards on Lang Son karst polje include collapse, sinkhole, flood, and pollution of water. Among them, the most dangerous one is the collapse of the underground karst caves.