The integrated monitoring of karst systems (MIKS) model, applied in karst studies in Bulgaria

Karst is a widespread natural phenomenon that is highly sensitive and very vulnerable to both natural and various anthropogenic impacts. This is due to the complex structure of karst territories, which comprise both surface forms and complex systems of underground cavities. Therefore, the study of karst requires a geosystem approach and integrated monitoring, which gives a real idea of the state of karst geosystems and the impacts of global changes on karstogenesis. The article presents a model of this approach, which is applied in karst studies in Bulgaria. The methodological basis is the original ProKARSTerra paradigm, based on the geosystem approach. Its main part is the Integrated Monitoring of Karst Systems (MIKS). It combines six types of monitoring, and it is carried out in three forms: expeditionary, remote and stationary with continuous instrumental measurements. They are concentrated in cave systems representative of karst in Bulgaria, in two of which networks of underground monitoring stations (Speleo-MIKS) have been built. The most important problems in the organization and maintenance of MIKS are summarized based on many years of experience. Examples of interpretation of results from the conducted long-term monitoring using the geosystem approach are presented in Supplementary information to the article.