Question

Falling of water vertically down a steep slope​

Answer 1

Water can seep into the soil or rock and replace the air in the pore space or fractures. Since water is heavier than air, this increases the weight of the soil. ... Water has the ability to change the angle of repose (the slope angle which is the stable angle for the slope).

Of course if the material forming the flat surface becomes weak or fails, then the unsupported mass will move downward.

On a slope, the force of gravity can be resolved into two components: a component acting perpendicular to the slope and a component acting tangential to the slope.

$\huge\blue{answer\ddot \smile}$