The volume of the stilling basin can be reduced, energy can be dissipated, and floods can be contained with the help of spillways. The aim of this Computational Fluid Dynamics (CFD) study is to investigate how compound slopes change water flows through spillways. To measure turbulence, the Realizable k-ε model was used, and the multiphase volume of fluid (VOF) method was utilized to determine where air and water meet. Five models of spillways with different slopes (normal slope (MS1) = 30°, compound slope(MS2 and MS3) = 20°/39°, and compound slope (MS4 and MS5) = 39°/20°) were modelled and simulated using the ANSYS Fluent software to determine their flow characteristics. Numerical simulation results were compared to experimental results, and it was found that the CFD model captured the key flow aspects accurately. The numerical model carefully observes the several flow patterns (nappe, transition, and skimming) that emerged owing to variations in slope and geometry. When it comes to dissipating energy, models with a compound slope (39°/20°) do the best. When compared to the normal slope model (30°) with a step size of 10, the increase in energy dissipation is 14%. According to the findings, the TKE (turbulent kinetic energy) was elevated by the compound slope. The results of this research show that the spillway can be operated effectively and reliably under a wide range of flow conditions, fulfilling an important goal of the project.