Bioremediation of oil spills on beaches commonly involves the addition of nutrients to stimulate the growth of indigenous oil-degrading bacteria. The selection of the best application strategy of nutrients requires an understanding of the physical factors affecting beach hydraulics and hydrodynamics. The authors investigated these factors here using a laboratory beach and a numerical model that is able to simulate density-dependent flows in two-dimensional variably-saturated media. The authors found that beach geometry plays a major role in beach hydraulics and hydrodynamics because the flow lines are perpendicular to the beach surface. Under tidal action, the authors found that seawater enters the beach from the top and causes the entrapment of less saline water in the beach. Guidelines for the selection of the best application strategy of nutrients are provided.