In the hardrock environment of the Bohemian Massif (Czech Republic) inhomogeneity elements of at least three orders of magnitude were defined. Local fissure systems of different dip and strike (local inhomogeneities) might be seen at outcrops of hard rocks and are tapped by particular water wells or determined by well-logging techniques. Inhomogeneities of a medium scale (sub-regional inhomogeneities) usually follow river valleys and/or are represented by fractured zones characteristic by higher prevailing transmissivity. Regional scale inhomogeneities are evidently caused by different neotectonic activities. This hierarchic system of fracture inhomogeneities of different orders of magnitude is decisive for spatial distribution of transmissivity in hard rocks. Practical consequences for regional groundwater flow modelling, safe yield assessment, well siting and groundwater vulenrability studies are evident. Small differences in transmissivity caused by distinct lithologic composition of hard rocks are usually masked by rock fracturation, causing larger differences.
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