Groundwater is all the water that has penetrated the earth'ssurface and is found in one of two soil layers. The one nearest the surface is the "zone of aeration", where gaps between soil are filled with both air and water. Below this layer is the "zone of saturation", where the gaps are filled with water. The water table is the boundary between these two layers. As the amount of groundwater water increases or decreases, the water table rises or falls accordingly. When the entire area below the ground is saturated, flooding occurs because all subsequent precipitation is forced to remain on the surface.
The amount of water that can be held in the soil is called "porosity". The rate at which water flows through the soilis its "permeability". Different surfaces hold different amounts of water and absorb water at different rates. Surface permeability is extremely important for hydrologists to monitor because as a surface becomes less permeable, an increasing amount of water remains on the surface, creating a greater potential for flooding. Flooding is very common during winter and early spring because thefrozen ground has no permeability, causing most rainwater and meltwater to become runoff.
Water that infiltrates the soil flows downward until it encounters impermeable rock (shown in gray), and then travels laterally. The locations where water moves laterally are called "aquifers". Groundwater returns to the surface through these aquifers (arrows), which empty into lakes, rivers, and the oceans. Under special circ*mstances, groundwater can even flow upward in artesian wells. The flow of groundwater is much slower than runoff,with speeds usually measured in centimeters per day, meters per year, or even centimeters per year.
Groundwater is all the water that has penetrated the earth's surface and is found in one of two soil layers. The one nearest the surface is the "zone of aeration", where gaps between soil are filled with both air and water. Below this layer is the "zone of saturation", where the gaps are filled with water.
Groundwater is water that has infiltrated the ground to fill the spaces between sediments and cracks in rock. Groundwater is fed by precipitation and can resurface to replenish streams, rivers, and lakes.
It runs over the surface into rivers, lakes or the ocean, and becomes surface water, or it soaks into the earth and becomes groundwater. When water enters soil-infiltration-gravity pulls it down through the unsaturated zone where spaces between soil particles are empty and water can readily pass through.
Water infiltrates the soil by moving through the surface. Percolation is the movement of water through the soil itself. Finally, as the water percolates into the deeper layers of the soil, it reaches ground water, which is water below the surface.
The top of the saturated zone (called the water table) may be only a foot below the ground's surface, or it may be hundreds of feet down. The water table may be shallow or deep; and may rise or fall depending on many factors.
Introduction: My name is Dan Stracke, I am a homely, gleaming, glamorous, inquisitive, homely, gorgeous, light person who loves writing and wants to share my knowledge and understanding with you.
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