Subsurface flow

Subsurface flow

Subsurface flow is the way water moves underground as part of the water cycle. When rain or snow falls on land, some of it stays on top and makes streams and rivers. But some water goes down into the soil. This is called infiltration.

The water then travels under the ground. It keeps the soil wet and fills special places called aquifers. These are stores of water deep in the Earth. The water that flows underground is called subsurface runoff. Scientists study this to learn how groundwater moves.

Runoff

Water moves from places where the water table is higher to places where it is lower. This water can flow on the surface in rivers and streams, or it can travel underground through rocks and soil. How much water reaches the surface or underground depends on many things like rain, how wet the soil is, and how easily water can pass through the ground. The way underground water moves is mostly decided by how much the water level slopes and what kind of ground it is moving through. The time it takes for this underground water to move can be many years.

Surface return

Subsurface water can come back up to the surface in different ways, like from a spring, seep, or water well. It can also flow back into streams, rivers, and oceans. This water returns to the land lower than where it first soaked into the ground, moving because of gravity. Groundwater moves very slowly and can stay underground in places called aquifers for many thousands of years. Much of this water eventually reaches the ocean, where the water cycle begins again.

Subsurface flow

When rain falls on the land, some water stays on top and forms streams and rivers. But some water goes into the ground. This water moves through the soil below us. This movement of water under the surface is called subsurface flow.

Subsurface flow can happen even when the soil is not very wet, but it moves faster when parts of the soil are soaked with water.