 The Earth is a "closed system,“ That means that the Earth neither gains nor loses much matter, including water.  Water is continually moving around, through, and above the Earth as water vapor, liquid water, and ice  Although some matter, such as meteors from outer space, are captured by Earth, very little of Earth's substances escape into outer space.

 The same water that was on the Earth millions of years ago is still here.  the same water is continually being recycled all around the globe.  It is entirely possible that the water you drank for lunch was once used by Mama Allosaurus to give her baby a bath.

 97.2% of the Earth’s water supply is salt water  Only about 2.8% is freshwater

 Freshwater ◦ 0.6% is groundwater (we can use some of this water) ◦ 0.01% is in lakes and streams (we can use some of this water) ◦ 2.2% is in glaciers and icecaps ◦ 0.001% is water vapor

 Groundwater storage is water existing for long periods below the Earth's surface.  Most of the water in the ground comes from precipitation that infiltrates downward from the land surface

 The upper layer of the soil is the unsaturated zone, where there is air and water that is present in varying amounts that change over time, but does not saturate the soil.  In between is the water table where spaces are filled with water  Below this layer is the saturated zone, where all of the pores, cracks, and spaces between rock particles are saturated with water. This is groundwater.

 Another term for ground water is "aquifer,"  This term is usually used to describe water- bearing formations capable of yielding enough water to supply peoples' uses.  Aquifers are a huge storehouse of Earth's water and people all over the world depend on ground water in their daily lives  Aquifers are replenished by the seepage of precipitation that falls on the land

 The top of the pool of water in this hole is the water table.  the water level in the hole is the same as the level of the ocean.

1. Three main stages in the water cycle are: _____________, _______________, and ______________. 2. Most of the earth’s supply of freshwater is stored in _______ and _______. 3. ______________ storage is water existing for long periods below the Earth's surface 4. Two sources of water available for our use are: __________water and _________ water Look back in your notes for help! precipitationevaporation surface water runoff Ice-capsglaciers Groundwater groundsurface

Problems and Solutions

In coastal areas when fresh water is withdrawn at a faster rate than it can be replenished, salt water from the ocean intrudes into the fresh water aquifer as shown in the diagram. The result is that fresh water supplies become contaminated with salt water as is happening to communities along the Atlantic and Gulf coasts.

Negative Impacts of Over-pumping  Plants that grew because of the close proximity of the water table to the land surface may not survive as the depth to water increases  Drying up of wells  Reduction of water in streams and lakes  Deterioration of water quality  Increased pumping costs  Land subsidence

 Land subsidence is a gradual settling or sudden sinking of the Earth's surface due to movement of earth materials.  The photograph to the left illustrates subsidence in the San Joaquin Valley, California. In the photo, USGS scientist, Joe Poland shows subsidence between 1925 and 1977 due to fluid withdrawel and soil consolidation.

 Land subsidence occurs when large amounts of ground water have been withdrawn from certain types of rocks, such as fine-grained sediments.  The rock compacts because the water is partly responsible for holding the ground up. When the water is withdrawn, the rocks falls in on itself.

 Use sources of water other than local ground water  Change rates or spatial patterns of ground- water pumpaging  Increase recharge to the ground-water system. (injection)

 A spring is a water resource formed when the side of a hill, a valley bottom or other excavation intersects a flowing body of ground water at or below the local water table  A spring is the result of an aquifer being filled to the point that the water overflows onto the land surface

 The quality of the water in the local ground-water system will generally determine the quality of spring water.  The quality of water discharged by springs can vary greatly because of factors such as the quality of the water that recharges the aquifer and the type of rocks with which the ground water is in contact.  The quality of the water also can be affected by the mixing of freshwater with pockets of ancient seawater in the aquifer or with modern seawater along an ocean coast. (FYI)

 A river is nothing more than surface water finding its way over land from a higher altitude to a lower altitude, all due to gravity.

 Rivers are invaluable to not only people, but to life everywhere!  People use river water for drinking-water supplies and irrigation water, to produce electricity, to flush away wastes (hopefully, treated wastes), to transport merchandise, and to obtain food.  Rivers even help keep the aquifers underground full of water by discharging water downward through their streambeds.

 A watershed is the area of land where all of the water that falls in it and drains off of it goes to the same place.  It’s not just the rivers…

Austin-Oyster Watershed

 The main influence on streamflow is precipitation runoff in the watershed  The size of a river is highly dependent on the size of its watershed. Large rivers have watersheds with lots of surface area; small rivers have smaller watersheds.

 A lake is where surface-water runoff (and maybe some ground-water seepage) have accumulated in a low spot, relative to the surrounding countryside.  It's not that the water that forms lakes gets trapped, but that the water entering a lake comes in faster than it can escape, either via outflow in a river, seepage into the ground, or by evaporation.

 A reservoir is a manmade lake that is created when a dam is built on a river. River water backs up behind the dam creating a reservoir.  Lakes formed by the erosive force of ancient glaciers, such as the Great Lakes, can be thousands of feet deep. Some very large lakes may be only a few dozen feet deep