The methodology of a complex engineering-geological approach to establish a Geopark: case study of the Małopolska Vistula River Gorge

Abstract

Małopolska Vistula River Gorge is located in the middle stretch of the Vistula valley between Zawichost and Puławy. Its great portion is supposed to be turned into a Geopark safely approachable by tourists along walking trails leading to planned geosites. While general criteria of geosite selection are oriented on promoting expected interesting attributes of the planned Geopark or, in a special case, on recognizing possible strong geological hazards such as volcanic, earthquake and tsunami phenomena, the inner problems of tourist safety are not commonly recognized. The Vistula Gorge and its close vicinity of Geopark is dedicated to cultural heritage, geological history, landscape and local folklore. The inner hazards of disasters are created here by steep, slippery paths, collapsible loessial canyons, rock-falls from weathered rock-walls, and high waters of the nearby river channel running alongside or flooding tourist footpaths. Recognition and preventing measures against such hazard require determination of the current engineering-geological conditions by testing rock and soil properties along the gorge, and by checking the likelihood of natural disturbance of the terrain safety. The vulnerability of exposed rocks to processes of natural erosion, steady weathering progress, turning steep clayey bluffs into slippery ground, and to an impact of long-term anthropogenic factors had to be recognized, checked, and tested for a final assessment of suitability of the selected place to serving as a Geopark. The special prognostic procedure of engineering-geological hazards was recommended, applicable prior to the Geopark planning stage. The procedure encompasses a thorough assessment of possible safe accessibility to particular geosites in the area designated to become a Geopark. The suitability of the selected area to serving as a Geopark was, thus, analyzed methodically with regard to a detailed engineering-geological and geomechanical evaluation of possible hazard factors within the whole terrain. Proven engineering geological methodologies were employed for the hazard assessment procedure. Each of the factors was subjected individually to close examination, with results recorded into a GIS integrated informative layer, and envisioned upon digital thematic maps. These maps remain to be used for the preparation of regional suitability maps of specific engineering-geological conditions.