Ground Water Summit registrants may enroll in these short courses held in conjunction with the event for an additional fee. Coupled surface-subsurface modeling is becoming an increasingly useful tool for describing many hydrologic systems. Increasing recognition that groundwater, surface water and land-surface processes are linked has lead to exciting new tools for simulating these systems. This short course will provide some background on the theory of coupled surface-subsurface modeling techniques and parallel applications. It will then provide hands-on experience using ParFlow, an open-source, object-oriented, parallel watershed flow model. ParFlow includes fully-integrated overland flow, the ability to simulate complex topography, geology and heterogeneity and coupled land-surface processes including the land-energy budget, biogeochemistry and snow. It is multi-platform and runs with a common I/O structure from laptop to supercomputer. ParFlow is the result of a long, multi-institutional development history and is now a collaborative effort between CSM, LLNL, UniBonn and UCB. Many different configurations, related to common hydrologic problems, will be discussed. This course is intended for hydrologists, hydrogeologists, scientists and engineers.