Fluid flow and solute transport through three-dimensional networks of variably saturated discrete fractures

The boundary integral method is used to estimate hydraulic and solute transport properties of unsaturated, fractured rock by solving the boundary value problem within intersecting fracture planes. Flow through both impermeable and permeable rock is determined using two- and three-dimensional formulations, respectively. Synthetic fracture networks are created to perform sensitivity studies, results of which show that: (1) The global hydraulic conductivity is linearly dependent on the product of fracture transmissivity and density for fractures of infinite length: (2) The effect of correlation between fracture length and transmissivity is to increase the global hydraulic conductivity; and (3) Simulated flow through a fractured permeable matrix compare favorably with analytical results. Flow through variably saturated fractures is modeled using a constant capillary head within individual fractures. A simulated free surface compares favorably with an approximate analytic solution and with laboratory results. A simulated free surface compare favorably with an approximate analytic solution and with laboratory results. Simulations indicate zones of water under both positive and negative pressure, as well as regions of air-filled voids. Travel times and breakthrough curves are determined by integrating the inverse velocity over a streamline, and then summing overall streamlines. Faster travel times are noted as fracture saturation decreasesmore » for the fracture network examined. 212 refs., 58 figs., 19 tabs.« less