Unit 1 Lesson 3 Surface Water and Groundwater Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 3 Surface Water and Groundwater Getting Your Feet Wet Where on Earth is fresh water found? • Only 3% of Earth’s water is fresh water, and most of that is frozen as ice and snow. So only about 1% of Earth’s water is fresh liquid water. • This fresh liquid water is found both on and below Earth’s surface. • This tiny percentage of Earth’s water must meet the large demand that all living things have for fresh, clean water. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 3 Surface Water and Groundwater Where on Earth is fresh water found? • Water that collects on Earth’s surface is called surface water. It is found in streams, rivers, and lakes. • It may begin as precipitation in the form of rain, snow, sleet, or hail. On Earth’s surface, it flows from higher ground to lower ground. • The water that flows across Earth’s surface is called runoff. Eventually, runoff can enter bodies of water. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 3 Surface Water and Groundwater Where on Earth is fresh water found? • Some rainwater and water from streams seeps down into the ground, collecting in spaces between rock particles. • Water found in the spaces between rock particles below Earth’s surface is called groundwater. • The water table is the upper boundary of the rock or sediment that is saturated with water. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 3 Surface Water and Groundwater Where on Earth is fresh water found? • How does fresh water move through this environment? Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 3 Surface Water and Groundwater Cry Me a River How does water move on Earth’s surface? • Water trickling down a hillside may flow together to form a stream, eroding soil and rock to make a channel. • A channel is the path that a stream follows. Over time, the channel gets wider and deeper, as the stream erodes rock and soil. • Streams typically flow along weaknesses in bedrock. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 3 Surface Water and Groundwater How does water move on Earth’s surface? • A tributary is a smaller stream that feeds into a river and eventually into a river system. • A river system is a network of streams and rivers that drains an area of its runoff. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 3 Surface Water and Groundwater How does water move on Earth’s surface? • A watershed is the area of land drained by a river system. • Streams, rivers, flood plains, lakes, ponds, wetlands, and groundwater all contribute water to a watershed. • Watersheds are separated from one another by a ridge or an area of higher ground called a divide. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 3 Surface Water and Groundwater How does water move on Earth’s surface? • Gradient is a measure of the change in elevation over a certain distance. In other words, it is a measure of the slope of the land. • A river’s flow is the amount of water that moves through the river channel in a given amount of time. • Materials carried by a stream are called stream load. Rivers eventually deposit their stream loads downstream. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 3 Surface Water and Groundwater How does water move on Earth’s surface? • Identify the tributary, river, divide, load, and watershed in the environment below. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 3 Surface Water and Groundwater In Deep Water How does groundwater flow? • When water trickles down from the surface and reaches a rock layer with no pores or cracks, the water pools to form an aquifer. • An aquifer is a rock layer that stores groundwater and allows the flow of groundwater. • The water table can rise or fall depending on the amount of water in the aquifer. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 3 Surface Water and Groundwater How does groundwater flow? • An aquifer stores water in open spaces, or pores, between particles of rock or soil. • The storage space in an aquifer is measured by porosity, which is the percentage of the rock that is composed of pore space. • The greater the pore space is, the higher the porosity is. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 3 Surface Water and Groundwater How does groundwater flow? • Permeability is a measure of how easily water can flow through an aquifer. • High permeability means that the pores in the aquifer are connected to one another, so that water can flow easily. • A useful aquifer has both high porosity and high permeability. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 3 Surface Water and Groundwater How does groundwater flow? • Gauge the extent of porosity and permeability (high or low) in each image. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 3 Surface Water and Groundwater How does groundwater flow? • The process by which surface water trickles down and enters an aquifer is called recharge. It occurs in an area called the recharge zone. • The process by which groundwater becomes surface water is called discharge and happens in discharge zones. • Through discharge and recharge, the same water circulates between surface water and groundwater. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 3 Surface Water and Groundwater How does groundwater flow? • Label the discharge and recharge zones of the aquifer. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 3 Surface Water and Groundwater Making a Splash How do people use surface water and groundwater? • In a typical home, about 50% of all water used is for washing clothes, bathing, washing dishes, and flushing toilets. • About 33% is used to water lawns and gardens. The rest is used for drinking, cooking, and washing hands. • In the United States, about 40% of fresh water is used for agricultural activities like growing crops and raising livestock. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 3 Surface Water and Groundwater How do people use surface water and groundwater? • About 45% of the fresh water used in the United States is used for industry. • Surface water in rivers, streams, and lakes is used to transport products and people, and for various recreational activities. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 3 Surface Water and Groundwater Troubled Waters • The limited supply of fresh water must be managed to meet the demands of a growing population. • Scientists estimate that about 1 billion people around the world do not have an adequate supply of clean, fresh water. • Scientists are developing technologies to obtain clean, fresh water to meet global needs. Copyright © Houghton Mifflin Harcourt Publishing Company
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