Presentation on theme: "Groundwater 97% of all of the Earth’s water is found in our oceans (salt water) Of the 3% of freshwater that remains 2/3 of it is frozen in the ice caps."— Presentation transcript:
Groundwater 97% of all of the Earth’s water is found in our oceans (salt water) Of the 3% of freshwater that remains 2/3 of it is frozen in the ice caps Only less than a percent of all of the Earth’s water is usable freshwater Most of the usable freshwater is stored as groundwater. It is not found in lakes and streams.
The Water Cycle The movement of water from one part of the hydrosphere to another Hydrosphere is the water of Earth’s surface (includes groundwater, running water, lakes, and oceans)
The Water Budget The income and spending of water for a region Recharge - When it rains and the plants need little moisture the extra water is stored between the grains of soil. A surplus of water exists when the rainfall is greater than the need for moisture and the soil water storage is filled. Usage occurs when the need for moisture is greater than the rainfall and plants draw water up from the water supply A deficit can occur when the need for moisture is greater than the rainfall and the water storage is gone.
Water in the Ground Porosity is the percentage of a materials volume that is pore space. Round particles have more pore space then angular ones Well sorted particles (particles of the same size) have more pore space they unsorted particles (mixture of different sized particles) Well-sorted particles of any size can have almost the same porosity and it may be more than 40%
Permeability is the rate at which rocks transmit water through pore space The larger the grain size the more easily water passes through Impermeable is a material that water cannot pass through (clay/shale) Capillary water is the water that sticks to particles as water passes through the sediment.
The Water Table When water enters the ground from presipitation the water that is not absorbed by plants will infiltrate until it reaches an impermeable layer. Then the water will begin to fill up the pore spaces above the impermeable layer. The zone of saturation is the part of the ground where all of the pore spaces are filled with water The water table is the surface of the zone of saturation
The zone of aeration exists from the water table to the surface where the ground can still hold more water The capillary fringe is located just above the water table where water is drawn upwards by capillary action The depth of the water table can vary throughout the course of a year based on rainfall, the season, slope of the land, etc. In areas such as swamps, lakes, and rivers the water table is at the surface When below the surface the water table generally has a pattern like that of the surface (hills and valleys
A well is a way of reaching the water table by digging or drilling into the ground A spring is a location on a hillside where the water table meets the surface and water flows out Artesian Wells are wells in which water comes from an aquifer that lies between two impermeable layers and is under pressure Aquifer – Permeable materials that contain and carry groundwater. Aquitard is a layer of impermeable rock A cap rock is the upper impermeable layer of an artesian formation (usually shale) A cone of depression can be formed by overpumping a well and causing the water table to drop considerably.