Lesson 3: Water and Its Distribution
Getting Started
In this unit, you have started to explore and understand features associated with the hydrosphere's primary component, water. So far you have studied density, polarity, cohesion, and surface tension. Now that you have developed a better understanding of water, it is important to understand more about the abundance of waters that make up the hydrosphere, where these waters are located, and how these reservoirs can be impacted by living things, including you.
Stuff You Need
- Painless Earth Science by Edward J. Denecke, Jr. (green edition)
- large clear cups (kit)
- masking tape* (Activity 1 - optional)
- pebbles (kit)
- permanent marker
- sand (kit)
- scissors
- sponge (kit)
* - denotes an optional material that may or may not be needed
Ideas to Think About
- Where are Earth's waters located?
- What causes some areas to have a lot of groundwater?
- How might the presence of an aquifer influence life in an area?
Things to Know
- Groundwater is water contained in the open spaces (pores) found in soil and/or rock.
- An aquifer is a layer of permeable rock through which water flows freely. It act as a reservoir for groundwater.
- An impermeable layer is a layer through which water does not flow or pass (for example, granite).
- A permeable layer is a layer through which water flows or passes easily (for example, limestone).
- A reservoir is a "storehouse" or a natural location where something is kept or stored (for example, a lake).
- The zone of saturation is the zone found in an aquifer that has all the pores filled with water.
- The water table is the top surface of the zone of saturation. It may be above or under ground.
- The zone of aeration is an area of an aquifer where the pores are partially filled with water and partially filled with air.
Skills
- Analyze evidence to explain observations, make inferences and predictions, and develop the relationship between evidence and explanation. (S)
- Analyze and evaluate information from a scientifically literate viewpoint by reading, hearing, and/or viewing scientific texts, articles, and events in the popular press. (S)
- Explain the structure of the hydrosphere including water distribution on Earth, local river basin, and local water availability. (S)
Introducing the Lesson
In this lesson, your child will begin to move beyond the small-scale picture of a water molecule and its qualities and begin thinking about water on a much larger scale. This lesson will focus on the idea of water being found in reservoirs around the world. The goal is for your child to build connections between the importance of water and life. The objective is for your child to understand more about the hydrosphere while continuing to develop the ability to make inferences based on information gained from collected data.
Materials: Painless Earth Science by Edward J. Denecke, Jr. (green edition)
Read pages 113-117 in Painless Earth Science. While evidence is plentiful that living organisms can survive in salt water, fresh water is needed to survive on a very basic level. Think about how fresh water is gathered on the Earth's surface.
Questions
- What percentage of the Earth's water reservoirs are made up of fresh water? Can all of that be readily utilized?Three percent of the Earth's waters are fresh water. It cannot all be utilized because 1/5 of the fresh water is frozen.
- What renews the Earth's fresh water supply?Water evaporation, condensation, and precipitation, which clean the water for reuse.
- How does water become part of the Earth's underground water supply?Water infiltrates, or seeps between, the particles of loose rock and soil.
- What does permeable and impermeable mean for soils? How does it relate to groundwater?Groundwater is located in pores (spaces in rock or soil). Some layers of soil and some layers of rock are porous and good for holding water, while others are not very porous and do not hold water. Porous rock is permeable rock and non-porous rock is impermeable.
- Why is it possible to dig in the soil and not find water, yet when you go to an ocean or lake and dig, you often reach water very quickly?The water table on the coast is very close to the surface on a beach. When digging a well, the water table is often much further down in the ground, so it will not be shallow. Where the water table is shallow is generally where one finds a lake or pond.
- How deep does a well need to be? Why?It has to be deep enough to be below the water table in the zone of saturation. This is between the zone of saturation and the zone of aeration. The zone of aeration has pores that are partially filled with air and partially filled with water. Beneath this zone is the zone of saturation. This zone is full of water.