Chapter 10 Section 1 Movement and Storage of Groundwater

Chapter 10 Section 1 & 2 How do groundwater storage and underground movement relate to the water cycle? 1  How are the components of aquifers related to the presence of springs? The Hydrosphere The water on and...

Chapter 10 Section 1 & 2 How do groundwater storage and underground movement relate to the water cycle? 1  How are the components of aquifers related to the presence of springs? The Hydrosphere The water on and in Earth’s crust makes up the hydrosphere, named after hydros, the Greek word for water. Copyright © McGraw-Hill Education Movement and Storage of Groundwater 2 The Hydrosphere Freshwater is one of Earth’s most abundant and important renewable resources. However, of all the freshwater, about 70 percent is held in polar ice caps and glaciers. Copyright © McGraw-Hill Education Movement and Storage of Groundwater Groundwater and Precipitation Evaporation of seawater cycles water into the atmosphere in the form of invisible water vapor. Water vapor can condense to form visible clouds. Precipitation brings atmospheric moisture back to Earth’s surface. Infiltration is the process by which precipitation that has fallen on land trickles into the ground and becomes groundwater. Copyright © McGraw-Hill Education Movement and Storage of Groundwater 3 Groundwater Storage Although Earth’s crust appears solid, much of it is composed of soil, sediment, and rock that contain countless small openings called pore spaces. Because of the enormous volume of sediment and rock beneath Earth’s surface, enormous quantities of groundwater are stored in the pore spaces. Copyright © McGraw-Hill Education Movement and Storage of Groundwater Groundwater Storage Porosity, the amount of pore space in a material, depends on the size and variety of particles in a material. Well-sorted, large sand grains Unsorted sand grains Well-sorted, small sand grains Copyright © McGraw-Hill Education Movement and Storage of Groundwater 4 The Zone of Saturation The region below Earth’s surface in which groundwater completely fills all the pores of a material is called the zone of saturation. Copyright © McGraw-Hill Education Movement and Storage of Groundwater The Zone of Saturation The upper boundary of the zone of saturation is the water table. Copyright © McGraw-Hill Education Movement and Storage of Groundwater 5 The Zone of Saturation In the zone of aeration, which is above the water table, materials are moist, but because they are not saturated with water, air occupies much of the pores. Copyright © McGraw-Hill Education Movement and Storage of Groundwater The Zone of Saturation Water movement Water in the zone of saturation and zone of aeration can be classified as either gravitational water or capillary water. Copyright © McGraw-Hill Education Movement and Storage of Groundwater 6 The Zone of Saturation Water movement Gravitational water trickles downward as a result of gravity. Capillary water is drawn upward through capillary action above the water table and is held in the pore spaces of rocks and sediment because of surface tension. Copyright © McGraw-Hill Education Movement and Storage of Groundwater The Zone of Saturation The water table The depth of the water table often varies depending on local conditions. Copyright © McGraw-Hill Education Movement and Storage of Groundwater 7 The Zone of Saturation The water table Because of its dependence on precipitation, the water table fluctuates with seasonal and other weather conditions. Copyright © McGraw-Hill Education Movement and Storage of Groundwater Groundwater Movement The ability of a material to let water pass through it is its permeability. Copyright © McGraw-Hill Education Movement and Storage of Groundwater 8 Groundwater Movement Permeability An aquifer is a layer of permeable subsurface material that is saturated with water. Copyright © McGraw-Hill Education Movement and Storage of Groundwater Groundwater Movement Permeability Impermeable layers, called aquicludes, are barriers to groundwater flow. Copyright © McGraw-Hill Education Movement and Storage of Groundwater 9 Groundwater Movement Flow velocity The flow velocity of groundwater is proportional to both the slope of the water table and the permeability of the material through which the water flows. Copyright © McGraw-Hill Education Movement and Storage of Groundwater Springs Groundwater tends to discharge at Earth’s surface where an aquifer and an aquiclude are in contact. These natural discharges of groundwater are called springs. Copyright © McGraw-Hill Education Movement and Storage of Groundwater 10 Springs Emergence of springs Springs can emerge from sides of valleys, at the edges of perched water tables, along faults, and from underground pathways. Copyright © McGraw-Hill Education Movement and Storage of Groundwater Visualizing Springs A spring is the result of groundwater that emerges at Earth’s surface. Springs can be caused by a variety of situations. Copyright © McGraw-Hill Education Movement and Storage of Groundwater 11 Springs Temperature of springs The temperature of groundwater that is discharged through a spring is generally the average annual temperature of the region in which it is located. Copyright © McGraw-Hill Education Movement and Storage of Groundwater Springs Temperature of springs In some regions around the world, springs discharge water that is much warmer than the average annual temperature. These springs are called warm springs or hot springs. Copyright © McGraw-Hill Education Movement and Storage of Groundwater 12 Springs Temperature of springs Geysers are explosive hot springs in which water is heated past its boiling point, causing it to vaporize. The resulting water vapor builds up tremendous pressure, which fuels eruptions at the surface. Copyright © McGraw-Hill Education Movement and Storage of Groundwater Wells Wells are holes dug or drilled into the ground to reach an aquifer. Copyright © McGraw-Hill Education Groundwater Supply 13 Wells Ordinary wells The simplest wells are those that are dug or drilled below the water table, into what is called a water-table aquifer. Overpumping from one well or multiple wells can result in a cone of depression and a general lowering of the water table. Copyright © McGraw-Hill Education Groundwater Supply Wells Artesian wells An artesian aquifer contains water under pressure. Copyright © McGraw-Hill Education Groundwater Supply 14  Wells Artesian wells The pressurized water in a well drilled into an artesian aquifer can spurt above the land surface in the form of a fountain known as an artesian well. Copyright © McGraw-Hill Education Groundwater Supply Artesian wells Each person turns In their own paper 1.Part 1 Experiment 1. Half fill a plastic container with sand. Add enough water to saturate the sand. Cover the sand completely with a 1- or 2-cm layer of clay or a similar impermeable material. 2. Tilt the container at an angle of about 10. Use a book for a prop. 3. Using a straw punch three holes through the clay, one near the low end, one near the middle, and one near the high end of the container. Insert a clear straw through each hole into the sand below. Seal the holes around the straws. 2. Part 2 Questions 1. Where is the water level the highest? The lowest? 2. The water table in the container 3. Where is the water under greatest pressure? Explain. 4. What will happen to the water table and the surface if the water flows from one of the straws. 15