Q1.
How does water seep through the surface of the Earth?
Answer
Rainwater that falls on the ground does not all flow away. Part of it sinks into the tiny spaces between the particles of soil and the cracks in rocks and moves slowly downwards. This process of surface water seeping through soil and rocks is called infiltration.
Rain falls on the ground
↓ enters the spaces between soil and rock particles (infiltration)
↓ moves deeper through the pore spaces
↓ collects in the pore spaces of sediments and openings in rocks
= groundwater, stored in layers called aquifers
↓ enters the spaces between soil and rock particles (infiltration)
↓ moves deeper through the pore spaces
↓ collects in the pore spaces of sediments and openings in rocks
= groundwater, stored in layers called aquifers
What decides how fast: water infiltrates more readily if the spaces between the soil and rock particles are wider, open and interconnected (Fig. 7.11). Activity 7.5 tests exactly this with clay, sand and gravel.
Tip: the water people draw from wells and handpumps is this same seeped water, brought back up to the surface.