It is a snow avalanche or simply an avalanche. (Also known as a snowslide or snowslip.)
Runoff is the water flowing downhill across the surface of the Earth.
This is the water cycle.
Naturally formed mass of ice and snow that moves downhill on land under the influence of gravity
Valley glaciers form when ice and snow accumulate in a mountain valley due to the accumulation of snow exceeding the rate of melting. Over time, the ice flows downhill, shaping the valley and creating a distinct U-shaped profile.
The process by which lava flows is called volcanic eruption. Lava is molten rock that erupts onto the Earth's surface from a volcano, typically flowing downhill due to its high temperature and low viscosity.
An avalanche
Water which flows after heavy rain, sleet, or as snow is melting is referred to as runoff. Runoff occurs as soil becomes too saturated to absorb more water. It is often a contributing factor in water erosion.
The source of a river is usually a spring. Rain sinks into soil or rock layers, then flows downhill until a point where it emerges, which is called a spring. The water then flows downhill on the surface as a river. Some rivers, however, source from the melting ice and snow at the tops of very tall mountains.
Grills
Mudflow
Runoff is the water flowing downhill across the surface of the Earth.
river
water
When water flows downward what will it posses
runoff
The direction that a river flows is called the flow or the drainages. Water generally flows downhill or from a higher elevation to a lower one.
It is a snow avalanche or simply an avalanche. (Also known as a snowslide or snowslip.)