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Slide 1 - Groundwater/Freshwater
Slide 2 - You need to know the
- detailed version of it
- If 97% of all water on Earth is saltwater…
- where is the fresh?
- 68% Frozen: Glaciers and icebergs
- 30 % Groundwater: Water that remains in the ground, eventually flows into the ocean , some returns to the earth from springs
- 0.3 % surface water: lakes, rivers, and swamps
- The rest is in the ground & cannot be calculated…
Slide 4 - Most of the Earth’s usable fresh water is found in moving and standing water.
- Rivers, streams, and springs are moving water.
- Ponds, lakes, swamps and reservoirs are standing water.
- Fresh Water
Slide 5 - Lakes, Ponds, and Reservoirs
Slide 6 - Lakes – deep depressions in the earth’s crust filled with fresh water. common where glaciers once were.
- Ponds – shallow depressions with fresh water, plants usually throughout.
- Reservoirs – the most frequently used source of fresh water. Built by damming a stream or river and is protected from polluting by laws.
- What’s the difference??
Slide 7 - A. Prevents flooding by controlling water during heavy rains.
- B. As a source of drinking water.
- C. Provides irrigation water for farms
- D. Used to generate electricity
- Uses of Reservoirs
Slide 8 - Surface runoff – the water that enters a river or stream after a heavy rain or spring thaw.
- Pore space – the space between particles of soil. More pore space means more water the ground can hold.
- Watershed – a land area where surface runoff drains into a river or a system of rivers and streams.
Slide 9 - How much do we depend on groundwater?
- According to United States Geological Survey (USGS) figures, groundwater provides an estimated:
- •22% of all freshwater withdrawals
- •37% of agricultural use (mostly for irrigation)
- •37% of the public water supply withdrawals
- •51% of all drinking water for the total population
- •99% of drinking water for the rural population
Slide 10 - Groundwater – present because the various forms of precipitation do not stop traveling when they hit the ground. Instead it moves slowly downward through pores.
- Permeable layers– material through which water can move quickly due to pore spaces. As water travels through this layer it is naturally filtered. Ex. Sandstone, limestone, conglomerate… most sedimentary
- Impermeable layers– water cannot get through easily, allows water to accumulate Ex. Clay, granite, basalt, gneiss… most igneous & metamorphic
Slide 11 - Zone of saturation – the underground region in which all the pores are filled with water.
- Zone of aeration – a drier region in which the pores are filled mostly with air.
- Water table – the boundary between the zone of saturation and aeration, that marks the level below which the ground is saturated.
- Groundwater Zones
Slide 12 - Know it/Draw it
Slide 13 - Water Table
- This is the point when you dig down a foot or more and your hole fills up with water.
- The water table depth is different for every area, the farther away from the shore the deeper you need to dig
- In our area we have to worry about saltwater intrusion…
- Saltwater intrusion is the movement of seawater into fresh water aquifers due to natural processes or human activities. Seawater intrusion is caused by decreases in groundwater levels or by rises in seawater levels. https://www.youtube.com/watch?v=e1d5wggJ-0g
- Draw it or write it, your choice. This was a ? on the SOL last year.
- Saltwater Intrusion
Slide 16 - Solvent – a substance in which another substance dissolves. Water is the universal solvent.
- Solution – contains two or more substances mixed on the molecular level, one thing must be dissolved.
- Soluble – can be dissolved.
- Insoluble – cannot be dissolved.
- Hard water – contains large amounts of dissolved minerals, especially calcium and magnesium. Soap will not lather easily in hard water.
- Soft water – just the opposite, few minerals
- Water Words copy what you don’t know already
Slide 17 - Aquifer –a body of permeable rock that can contain or transmit groundwater. This is just below the groundwater level where a large amount of water collects. It is usually made up of sandstone, gravel, sand, or limestone (that has been weathered and is cracked).
- Aquiclude: Area of impermeable rock… small area in which little water can collect, usually found under an aquifer….
- Artesian Well/Spring: well or spring from which water flows under natural pressure without pumping.
- Cone of depression: occurs in an aquifer when groundwater is pumped from a well. In an unconfined aquifer (water table), this is an actual depression of the water level. Water is pumped up the well & the water table is pulled downward.
Slide 18 - To locate the best "spot" to find water, it becomes a guessing game. Some geologic areas are more conducive to finding water than others. The Geology in Virginia varies considerably and along with this, so does the amounts of water that may be available. Some formations are more tightly packed than others with very little fracturing within the rock and as a result, very little water will be found. Other areas may produce large sums of water due to extensive fracturing within the formation.
- Where should my well go???
Slide 19 - Point Source Pollution – oil spills, leaking toxic waste, smokestack emissions; where the source is obvious.
- Non-point pollution – where there is no single point of pollution. Examples: runoff carrying natural and human-made pollutants. (pesticides, fertilizers, petroleum products…)
Slide 20 - POLLUTIONSOLUTIONS
Slide 21 - http://www.youtube.com/watch?v=uQRvN6MUajE
Slide 22 - Groundwater Pollution
Slide 23 - Well Diagram:
- During a drought which well would dry up first? Why?
- Which well would be affected by toxic waste? Why?
- Which would be affected first by a septic tank break? Why?
- Which well would you want? Why?
Slide 24 - Karst: landscape underlain by limestone that has been eroded by dissolution, producing ridges, towers, fissures, sinkholes, and other characteristic landforms. Basically an area with limestone that has been chemically weathered and produces caves, caverns and sinkholes. Pollutants can quickly travel through Karst areas and affect the water supply miles away
Slide 25 - If too much water is withdrawn from any area the following can occur:
- drying up of wells
- reduction of water in streams and lakes
- deterioration of water quality
- increased pumping costs
- land subsidence, sinkholes form and houses, businesses, roadways can collapse.
- Water Withdrawal
Slide 26 - ****CHESAPEAKE BAY WATERSHED
- You need to know the states that make up the CBW:
Slide 27 - Virginia’s major watersheds: Chesapeake Bay, Albemarle Sound, and Gulf of MexicoVirginia’s 8 major rivers: Potomac, Rappahannock, York, James, Chowan, Roanoke, New, Big SandyThese are in order from top right to bottom left in VA… memorize them in order do you can remember their location.
Slide 28 - Name the 8 major rivers in VA:
- What are the watersheds in VA?
- What would you find in the zone of aeration?
- If you had to dig a well, what underground area would be best for a continuous water supply?
- How is a spring different from an aquiclude?
- Explain why residents of the Appalachian Plateau region do not have to worry about saltwater intrusions.
- The Valley & Ridge region is underlain with carbonate rock… what result of this can be found in farm fields? Why are these a problem to the ground water supply?
- Review the following: