Study of Drawdown Characteristics of Fracture Rock Aquifers Using Discrete Fracture Network Modeling Tools

Understanding the dynamics of groundwater movement in fractured rocks, especially when fractured aquifers are subjected to extraction of large quantities of water and perturbations in climatic variables are vital to improving our ability of ensuring sustainability of groundwater resources. Drawdown contour maps provide us with a tool to evaluate anisotropy and help predict the spatial variation in expected level of water so that better strategies for utilizing groundwater resources can be developed. The magnitude of drawdown depths are also important for understanding many other site-specific issues such as, probability of capturing undesirable elements in extracted water. A two-dimensional discrete fracture network (DFN) simulation provides the basis for investigating how complex patterns of connectivity and variations in fracture attributes produces irregular patterns of drawdown when fractured rock aquifers are subjected to pumping and climatic perturbations. The pattern and expanse of drawdown maps are found to be highly sensitive to multi-scale heterogeneity in the network arising from the geometric configuration of interconnected, discontinuous fractures of varying length scales, orientation, transmissivity and local density.