Recent field investigations in crystalline rock give strong indications that water flows in largely isolated channels in fissured rock. The channels are located in fracture planes and may or may not connect to other channels in the same plane or at fracture intersections. In the present paper, hydrodynamic dispersion in such fracture networks is investigated using the concepts of residence time distribution theory. It is shown that from a set of simple relations, at least the first four statistical moments for the system response are easily obtained even for complicated networks. In particular, an equivalent dispersion coefficient may be calculated from the second central moment (variance). The effect of channeling generally decreases in systems with many mixing steps. A criterion, based on the coefficients of skewness and kurtosis, is derived for when the response of the system is in accordance with the diffusion‐dispersion model. Examples show that this limit may not be obtained under realistic repository conditions in fissured rock.
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Anders Rasmuson (1985) studied this question.