![Hydrodynamic Forces on the Walls of Forebay due to Horizontal Earthquakes 1 Hydrodynamic Forces on the Walls of Forebay due to Horizontal Earthquakes](https://excel.civilmdc.com/wp-content/uploads/2021/12/Hydrodynamic-Forces-on-the-Walls-of-Forebay-due-to-Horizontal-Earthquakes.png)
Earthquakes can cause substantial hydrodynamic forces in penstocks and pressure tunnels. Depending on foundation conditions (soil type) and length of a penstock or pressure tunnel the maximum hydrodynamic pressures areĀ up to 1 MPa for a peak ground acceleration of 0.3g.