Planning for gypsum geohazards in Lithuania and England

摘要

The rapid underground dissolution of gypsum, andthe evolution of the gypsum karst in Lithuania and England,results in subsidence problems which can make constructiondifficult. The natural dissolution yields sulphate-richgroundwater of poor quality and the karst is susceptible to therapid transmission of pollutants.In the north of Lithuania gypsum karst is developed inDevonian gypsum. Here the towns of Birai, Pasvalys and thesurrounding countryside suffer subsidence and some buildingshave been damaged. The majority of the potable water in theseareas is derived from groundwater extracted from sandstonesequences that underlie the gypsum. In Lithuania conservationmeasures have been introduced to control agriculture and preventpollution of the gypsum karst. These measures includeenvironmentally-friendly farming, restrictions on land use andexclusion zones around subsidence hollows.In England subsidence caused by the dissolution of Permiangypsum has caused severe problems in the vicinity of the town ofRipon. Numerous buildings have been damaged and new sites aredifficult to develop. Here formal planning regulations haverecently been introduced to help to protect against the worsteffects of subsidence resulting from gypsum dissolution.