For a diverging-converging surface, the kinematic wave equations are solved using an implicit finite difference method. This diverging-converging representation is applicable to a natural watershed that has a leaf-shaped geometry. The results are compared with other idealistic representations. These are: plane surface, diverging surface, and converging surface. The diverging-converging model gives hydrograph values between those of converging and diverging models, depending on the geometric parameters. In general, the geometry of a watershed has important effects on the runoff hydrograph for both equilibrium and partial equilibrium conditions.