Groundwater

When it precipitates, water will either run off the land, evaporate, transpirate, or infiltrate the soil where it may become part of the groundwater system.  Groundwater is the water that seeps into cracks or crevices in the earth, becomes part of the water table, or water that is stored in aquifers – the layers of soil, sand and rocks where water moves.  

http://water.tamu.edu/aquifers.html, diagram from this link.  get permission

Aquifers usually consists of permeable materials such as gravel, sand, sandstone, or fractured rock such as limestone.  It is easy for water to flow through these materials because of the pore space, and size of the materials.  Clays and shales have small pore spaces, thus they are “impermeable”, and water cannot pass through them easily. 

http://capp.water.usgs.gov/gwa/ (USGS Groundwater Atlas of the United States)

Click here for a report on the groundwater of Ackerly Creek. 

What is a Watershed, Water Cycle, Habitats, Human Impacts on Water Quality, Global Water Issues, Macroinvertebrates, Geology, Groundwater