The method of characteristics is used to calculate numerical solutions for water waves generated in a reservoir by a relatively close landslide. The landslide is modelled with a vertical wall that moves a horizontal distance of at least ten reservoir depths into the reservoir and follows an assumed velocity variation with time. This allows the generated wave to be approximated with nonlinear, non-dispersive long-wave approximations. The final results are shown with dimensionless plots of maximum wave heights as functions of time and distance for both one-dimensional and axisymmetric solutions.