In karst environments, heavy rainfall is known to cause multiple geohydrological hazards, including inundations, flash floods, landslides and sinkholes. We studied a period of intense rainfall from 1 to 6 September 2014 in the Gargano Promontory, a karst area in Puglia, southern Italy. In the period, a sequence of torrential rainfall events caused severe damage and claimed two fatalities. The amount and accuracy of the geographical and temporal information varied for the different hazards. The temporal information was most accurate for the inundation caused by a major river, less accurate for flash floods caused by minor torrents and even less accurate for landslides. For sinkholes, only generic information on the period of occurrence of the failures was available. Our analysis revealed that in the promontory, rainfall-driven hazards occurred in response to extreme meteorological conditions and that the karst landscape responded to the torrential rainfall with a threshold behaviour. We exploited the rainfall and the landslide information to design the new ensemble–non-exceedance probability (E-NEP) algorithm for the quantitative evaluation of the possible occurrence of rainfall-induced landslides and of related geohydrological hazards. The ensemble of the metrics produced by the E-NEP algorithm provided better diagnostics than the single metrics often used for landslide forecasting, including rainfall duration, cumulated rainfall and rainfall intensity. We expect that the E-NEP algorithm will be useful for landslide early warning in karst areas and in other similar environments. We acknowledge that further tests are needed to evaluate the algorithm in different meteorological, geological and physiographical settings.

A high dynamic environment is typically interested by changes affecting the natural processes and their related consequences. Landslides do not only alter the landscape, but substantially affect human activities. When it comes to natural hazards, landslides have been acknowledged as one of the main causes of human casualties or damage to assets. Furthermore, economic losses to rural lands are also significant, despite often being underrated, especially in rural areas. In not densely populated territories, the main productive activities are in fact often based on the agricultural and pastoral resources. We intend to propose a methodology that helps to investigate the potential loss of value (expressed in €) of lands usually exploited for economical profit in rural areas. We test the method on two case studies, belonging to different European Countries with very different economical assets and geological, geomorphological, and environmental conditions. The first study area is located in the Southern Italian Apennines, in the Molise region, while the second area is located in Buzau County, a region belonging to the Romanian Curvature Carpathians and Subcarpathians. Our analysis is focused not only on the actual situation, represented by the past and present landslides, but also on potential future scenarios for 2050. The scenarios foresee future similar socio-economical and technological activities, with no major changes expected. The loss estimation is based on the presence of landslides affecting the rural lands, but it also considers both a present and future landslide susceptibility scenario. This procedure allowed the estimation of the economic losses in the two case-study areas, highlighting how the same natural processes might result in different economical consequences. Following our approach, the results highlight that for the Italian case study there is a loss of 10.4% for 2007 and 9.9% for 2050 of the total land value as concerns landslides susceptibility. In the Romanian case study, on the other hand, the loss corresponds to 29.6 and 29.8% for 2010 and 2050, respectively. In addition, the proposed procedure could be considered a valuable methodological approach to assess landslide-induced economic losses, and be effectively used during spatial planning activities, aimed at supporting decision makers for a more sustainable land management.