Presentation on theme: "Chapter 2 Fresh Water Section 5 Water Underground"— Presentation transcript:
1 Chapter 2 Fresh Water Section 5 Water Underground
2 Underground LayersJust like rivers and lakes, groundwater comes from precipitation.Water underground trickles down between particles of soil and through cracks and spaces in layers of rock.
3 Underground LayersDifferent types of rock and soil have different-sized spaces, or pores, between their particles.Materials that allow water to easily pass through their pores are called permeable.EXAMPLE: sand and gravel.
4 Underground LayersEventually the water will soak down to layers it cannot go through.Materials that water cannot pass through easily are called impermeable.EXAMPLE: clay and granite.
5 Underground LayersOnce water reaches an impermeable layer, it’s trapped and begins to fill up the spaces above the impermeable layer.The area of permeable rock or soil that is totally filled with water above the impermeable layer is called the saturated zone.
6 Underground LayersThe top of the saturated zone is called the water table. Knowing the depth of the water table will help communities know how far down they have to go to find groundwater.Soil and rock above the water table have some water in between their pores, but they still have some air as well, making this the unsaturated zone.
8 AquifersAny underground layer of rock or sediment that holds water is called an aquifer.They range in size.Aquifers keep the groundwater moving. The speed depends on:The aquifer’s slopeThe rock/soil’s permeability
12 Bringing Groundwater to the Surface If the well pumps out too much water in a short amount of time, the well could run dry.If a well runs dry, you will have to dig deeper or wait for rain to refill it.New water that enters the aquifer from the surface is called recharge.
13 Bringing Groundwater to the Surface If an aquifer is trapped between two layers of impermeable materials, the water is under a great amount of pressure.If the top layer is punctured, water flows without having to pump it out of the ground.
14 Bringing Groundwater to the Surface A well in which water rises because of pressure within the aquifer is called an artesian well.
15 Springs and GeysersPlaces where groundwater bubbles or flows out of cracks in the rock are called springs.Can be very hot if the water is heated by hot rocks below the surface, like in Hot Springs, AR.
16 Springs and GeysersA geyser is a type of hot spring from which water bursts periodically into the air.
17 Springs and GeysersA geyser forms when very hot water from deep underground begins to rise through narrow passages in the rock. The pressure builds and builds as it is trying to squeeze through the rock until it finally all erupts high into the air as steam, other gases, and water.
18 Springs and Geysers“Old Faithful” at Yellowstone National Park in Wyoming is an example of a geyser.