A method of hydrodynamics-based gridding (Hydro-Grids) for creating geologic models of subsurface volumes, such as reservoirs, is disclosed. Geologic data is obtained. Vertical grid surfaces are created. Lateral grid surfaces are created to correspond to surfaces of constant geologic time during the deposition of sediments in the subsurface volume. Geologic properties within each cell are represented as values within each cell created by the vertical and lateral surfaces. Reservoir performance is simulated using the represented geologic properties of the subsurface volume. A hydrocarbon reservoir is developed based on the simulated reservoir performance.