Karst Geo-hazards: Causal Factors and Management Issues

Abstract

Karst terranes exhibit spectacular landforms that are often exploited as natural parks and show caves, and hosts very important natural resources. Further, karst terranes cover 20% of the Earth’s surface and provides 20−25% of high-quality groundwater for drinking water. The fragility of karst environments makes it highly vulnerable to a variety of different geological hazards (or geo-hazards). This is due to its peculiar geological and hydrological features such as sinkholes and caves. In particular, the strict connection between surface and subsurface features emphasizes the fragile nature of karst. The occurrence of geo-hazards in karst terranes greatly differs from other natural settings. Natural and man-induced subsidence and sinkholes, slope movements favored by karst conduits and caves, flash floods related to inability of the system to manage water from heavy rainstorms, and pollution caused directly or indirectly by human actions are the main types of geo-hazards typical of karst terranes. Although mostly related to natural processes, their occurrence and consequent damage to both the natural and anthropogenic environment are often caused or exacerbated by man. As a consequence, management of karst terranes cannot be enacted without taking into account the peculiar features and behavior of karst terranes and aquifers, and the delicate balance with the different types of geo-hazards that may occur. Specific management actions should, therefore, be pursued in this fragile environment, with the intention of safeguarding the natural resources, biota, and population. Naravne nesrece na Krasu: Vzrocni dejavniki in vprasanja upravljanja Kraska obmocja odlikujejo spektakularne reliefne oblike, ki so pogosto povod za ustanovitev naravnih parkov ali turisticnih jam, ter pomembne naravne vire. Kras pokriva okoli 20% kopnega in zagotavlja okoli 20−25 % potreb po pitni vodi. Krhkost kraskih okolij so razlog za njihovo visoko dovzetnost za razlicne geoloske in druge naravne nesrece. Razlogi so v posebnih geoloskih in hidroloskih znacilnostih, kot so vrtace in jame. Krhko naravo krasa zlasti poudarja tesna povezava med povrsinskimi in podzemnimi oblikami. Pojavljanje naravnih nesrec v krasu se mocno razlikuje od tistih v drugih naravnih okoljih. Naravno in s strani cloveka povzroceno pogrezanje, udori in plazenje so pod mocnim vplivom kraskih kanalov in jam. Poplave so povezane z nezmožnostjo sistema prevajati nalivne vode. Onesnaženje, ki ga clovek povzroci posredno ali neposredno s svojimi aktivnostmi, so poglavitne nesrece v krasu. Ceprav so naravne nesrece vecinoma povezane z naravnimi procesi, njihovo pojavljanje in posledicno skodo tako za naravno kot antropogeno okolje pogosto povzroca ali pospesi clovek. Upravljanje kraskih obmocij zato ne more biti nacrtovano brez upostevanja specificnih lastnosti in obnasanja kraskih pokrajin, vodonosnikov in krhkega ravnotežja med razlicnimi vrstami nesrec, ki se lahko pojavijo. Zato bi bilo z namenom varovanja naravnih virov, živih bitij in prebivalstva treba uvesti posebne ukrepe upravljanja v tem obcutljivem okolju.