Chapter 11 Preview Section 1 The Active River

Chapter 11 Preview Section 1 The Active River
Rivers and Groundwater Preview Section 1 The Active River Section 2 Stream and River Deposits Section 3 Using Water Wisely Concept Map

Chapter 11 Section 1 The Active River Bellringer Do you think a river can have a source? Describe where you would expect to find a river’s source. Write your answers in your science journal.

Chapter 11 What You Will Learn
Section 1 The Active River What You Will Learn Moving water shapes the surface of Earth by the process of erosion. The sun is the major source of energy that drives the water cycle. Three factors that affect the rate of stream erosion are gradient, discharge, and load.

Rivers: Agents of Erosion
Chapter 11 Section 1 The Active River Rivers: Agents of Erosion Six million years ago, the area now known as the Grand Canyon was as flat as a pancake. Tectonic uplift raised the land, and water running downhill became the Colorado River. The Colorado River cut down into the rock.

Rivers: Agents of Erosion, continued
Chapter 11 Section 1 The Active River Rivers: Agents of Erosion, continued The river formed the Grand Canyon over millions of years through the process of erosion. Erosion is the process by which wind, water, ice, and gravity move soil and sediment from one place to another. Rivers are agents of erosion that shape Earth’s landscape.

Chapter 11 The Water Cycle
Section 1 The Active River The Water Cycle The water in rivers is part of the water cycle. The water cycle is the continuous movement of water between the atmosphere, the land, and the oceans. The major source of energy that drives the water cycle is the sun.

The Water Cycle, continued
Chapter 11 Section 1 The Active River The Water Cycle, continued

Chapter 11 Section 1 The Active River River Systems A river system is a network of streams and rivers that drain an area of its runoff. A stream that flows into a lake or into a larger stream is called a tributary. (the small stream is contributing to a larger one) A tributary is part of a river system.

River Systems, continued
Chapter 11 Section 1 The Active River River Systems, continued River systems are divided into regions called watersheds. A watershed is the area of land that is drained by a river system. Watersheds vary in size.

Chapter 11 Section 1 The Active River River Systems, continued The largest watershed in the United States is the Mississippi River watershed.

Chapter 11 Section 1 The Active River River Systems, continued The Mississippi River watershed has hundreds of tributaries. These tributaries extend from the Rocky Mountains in the West to the Appalachian Mountains in the East. A main stream that drains a large watershed and has many tributaries is called a river.

Chapter 11 Section 1 The Active River River Systems, continued The Mississippi River watershed covers more than one-third of the United States. Other major river systems are the Columbia River, the Rio Grande, and the Colorado River watersheds. Watersheds are separated from each other by an area of higher ground called a divide.

Chapter 11 Stream Erosion
Section 1 The Active River Stream Erosion A stream forms as water erodes soil and rock to make a channel. A channel is a path that a stream follows. As the stream continues to erode rock and soil, the channel gets wider and deeper.

Stream Erosion, continued
Chapter 11 Section 1 The Active River Stream Erosion, continued Over time, tributaries join the main channel. The increased flow from the tributaries causes the stream to become longer and wider. Increased flow can be caused by heavy rains and snow melting.

Chapter 11 Section 1 The Active River Stream Erosion, continued Gradient is the measure of the change in elevation over a certain distance. (slope) The water in a stream that has a high gradient moves very rapidly. (the steeper the slope the faster the water moves) This rapid water gives the stream or river a lot of energy to erode rock and soil.

Chapter 11 Section 1 The Active River Stream Erosion, continued A river or stream that has a low gradient has less energy for erosion. The amount of water that a stream or river carries in a given amount of time is called discharge. The discharge of a stream increases when a major storm occurs or when snow melts rapidly.

Chapter 11 Section 1 The Active River Stream Erosion, continued As the stream’s discharge increases, the water’s speed and erosive energy increase. The amount of solid material that the stream can carry also increases. The faster the water is moving the more particles it can carry down stream.

Chapter 11 Section 1 The Active River Stream Erosion, continued The materials carried by a stream are called the stream’s load. The size of particles in a stream’s load is affected by the stream’s speed. Fast-moving streams can carry large particles.

Chapter 11 Section 1 The Active River Stream Erosion, continued Rocks and pebbles scrape along the bottom and sides of the stream bed. A stream that has a load of large particles has a high rate of erosion. Streams that move more slowly carry smaller particles and have less erosive energy.

Chapter 11 Rivers and Groundwater Types of Load

Chapter 11 Describing Rivers
Section 1 The Active River Describing Rivers William Morris Davis was a geomorphologist who studied how rivers shape the landscape. He developed a model to describe the stages of river development. Davis described rivers as evolving from a youthful stage to an old-age stage.

Describing Rivers, continued
Chapter 11 Section 1 The Active River Describing Rivers, continued Today, scientists support a different model of river development. Scientists now take into account climate, local geology, gradient, and load to model the development of a river. However, scientists still use some of Davis’s terms to describe a river.

Chapter 11 Section 1 The Active River Describing Rivers, continued A youthful river erodes its channel deeper rather than wider. Its channel is narrow and straight. The river tumbles over rocks in rapids and waterfalls.

Chapter 11 Section 1 The Active River Describing Rivers, continued Youthful rivers have very few tributaries. These rivers flow quickly because they have steep gradients. Many youthful rivers have steep gradients because the areas that these rivers drain have been tectonically lifted.

Chapter 11 Section 1 The Active River Describing Rivers, continued A mature river erodes its channel wider rather than deeper. The gradient of a mature river is not as steep as that of a youthful river. Therefore, a mature river has fewer falls and rapids.

Chapter 11 Section 1 The Active River Describing Rivers, continued A mature river is fed by many tributaries. Because of its large watershed, a mature river has more discharge than a youthful river does. A mature river also tends to curve back and forth. These curves or bends in the river channel are called meanders.

Chapter 11 Section 1 The Active River Describing Rivers, continued A rejuvenated river forms when land has been raised by tectonic activity. When land rises, the river gradient becomes steeper and the river flows more quickly. Rapid flow allows the river to cut more deeply into the valley floor, causing step-like formations called terraces.

Chapter 11 Section 1 The Active River Describing Rivers, continued An old river has a low gradient, so it has little erosive energy. Instead of widening or deepening its banks, the river deposits rock and soil in and along its channel. An old river has wide, flat floodplains, or river valleys, and many bends.

Chapter 11 Section 1 The Active River Describing Rivers, continued An old river has fewer tributaries than a mature river does. The old river has fewer tributaries because its smaller tributaries have joined together. An old river commonly forms an oxbow lake.

Chapter 11 Section 1 The Active River Describing Rivers, continued An oxbow lake forms when the strip of land that separates parts of a meander is eroded. An oxbow lake looks like a horseshoe. The process of forming an oxbow lake shortens the river’s length.

Old and Rejuvenated Rivers
Chapter 11 Rivers and Groundwater Old and Rejuvenated Rivers

Chapter 11 Section 2 Stream and River Deposits Bellringer Even though flooding along rivers is potentially harmful, many farms are located near rivers. Why do people grow food along rivers? Write your answers in your science journal.

Section 2 Stream and River Deposits What You Will Learn Three types of stream deposits are deltas, alluvial fans, and floodplains. Rivers and streams flood their banks in natural and recurring patterns, and these floods affect humans and wildlife habitats.

Chapter 11 Stream Deposits
Section 2 Stream and River Deposits Stream Deposits Rivers and streams carry large amounts of material, such as soil and rock. Rivers may carry fertile soil to farmland and wetlands. Although erosion is a big problem, rivers also renew soils and help form new land.

Stream Deposits, continued
Chapter 11 Section 2 Stream and River Deposits Stream Deposits, continued After rivers erode rock and soil, they drop, or deposit, their load downstream. Deposition is the process in which material is laid down or dropped. Rock and soil that are deposited by streams are called sediment.

Chapter 11 Section 2 Stream and River Deposits Stream Deposits, continued Rivers deposit sediment where the speed of the water decreases– often along the inside bank of a bend. A river’s current slows when a river empties into a large body of water, such as a lake or the ocean. As the current slows, a river may deposit its load in a fan-shaped pattern called a delta.

Chapter 11 Section 2 Stream and River Deposits Stream Deposits, continued A delta forms on a flat surface and is made mostly of mud. These mud deposits form new land and cause the coastline to grow. The world’s deltas are home to a rich diversity of plant and animal life.

Chapter 11 Section 2 Stream and River Deposits Stream Deposits, continued In the United States, the Mississippi Delta has formed where the Mississippi River flows into the Gulf of Mexico. Each of the fine mud particles in the delta began its journey far upstream. Parts of Louisiana are made of particles from as far away as Montana and Minnesota.

Chapter 11 Section 2 Stream and River Deposits Stream Deposits, continued When a fast-moving mountain stream flows onto a flat plain, the stream slows down quickly. As the stream slows down, it deposits sediment. The sediment forms an alluvial fan.

Chapter 11 Section 2 Stream and River Deposits Stream Deposits, continued Alluvial fans are fan-shaped deposits of material that, unlike deltas, form on dry land. Alluvial fans can be found in some desert regions of California.

Chapter 11 Section 2 Stream and River Deposits Floods The amount of water in a stream usually varies seasonally. During periods of high rain or rapid snowmelt, the amount of water in a stream increases. As a result, the stream may overflow its banks in a flood.

Chapter 11 Floods, continued
Section 2 Stream and River Deposits Floods, continued Flooding can cause a stream to change its path. During a flood, a stream’s banks may collapse and may change the water’s course. This process commonly forms oxbow lakes.

Section 2 Stream and River Deposits Floods, continued When a stream floods, a layer of sediment is deposited on land. The area along a river that forms from sediment deposited when a river overflows its banks is called a floodplain. Floodplains are rich farming areas because periodic flooding brings new soil to the land.

Section 2 Stream and River Deposits Floods, continued Floods are natural events that happen in recurring patterns. These natural events can cause a great deal of damage. Wildlife habitats can be buried or washed away.

Chapter 11 Floods, continued Human property may be damaged.
Section 2 Stream and River Deposits Floods, continued Human property may be damaged. The flooding of the Mississippi River in 1993 caused damage in nine states. Farms were destroyed, and whole towns were evacuated.

Section 2 Stream and River Deposits Floods, continued Many people have lost their lives in floods. Barriers can help to control floods. One type of barrier is called a dam.

Section 2 Stream and River Deposits Floods, continued A dam is a barrier that can redirect and hold a portion of the floodwater in a reservoir. Another type of barrier is a levee. A levee is the buildup of sediment deposited along the channel of a river.

Section 2 Stream and River Deposits Floods, continued This buildup helps keep the river inside its banks. Sandbags can be used to build artificial levees to control water during flooding.

Chapter 11 Section 3 Using Water Wisely Bellringer Identify each of the following resources as either renewable or nonrenewable: air soil rocks minerals petroleum fresh water wildlife forests What makes a resource renewable? Write your answers in your science journal.

Section 3 Using Water Wisely What You Will Learn California’s water needs are supplied by using groundwater and surface water, by transporting water from one region of California to another, and by importing water from other areas. Conserving water and protecting water sources are important in California because the water supply is limited.

Chapter 11 Using Water Wisely
Section 3 Using Water Wisely Using Water Wisely The amount of fresh water available on Earth is limited. Only 3% of Earth’s water is drinkable. Of that 3%, 75% is frozen in the polar icecaps. Therefore, protecting our water resources is important.

Chapter 11 Groundwater A large amount of water flows underground.
Section 3 Using Water Wisely Groundwater A large amount of water flows underground. Rainwater and water from streams seeps through the soil and into underground rock and soil. Then, water collects between spaces in rock particles.

Groundwater, continued
Chapter 11 Section 3 Using Water Wisely Groundwater, continued The water found in rocks below Earth’s surface is called groundwater. The rock layer that stores groundwater and allows the flow of groundwater is called an aquifer. The upper surface of underground water is called the water table.

Chapter 11 Section 3 Using Water Wisely Groundwater, continued

Chapter 11 Section 3 Using Water Wisely Groundwater, continued The water table can rise or fall depending on the amount of water in the aquifer. In wet regions, the water table can be at or just beneath the soil’s surface.

Chapter 11 Water in California
Section 3 Using Water Wisely Water in California California’s aquifers cover much of the state. Unfortunately, many of these aquifers are contaminated by pollutants.

Water in California, continued
Chapter 11 Section 3 Using Water Wisely Water in California, continued In some of California’s aquifers, more water is being pumped out than is being replaced by rain. This process is called overdraft. Californians get their water not only from the ground, but also from surface water, such as rain.

Chapter 11 Section 3 Using Water Wisely Water in California, continued Surface water is captured and stored in reservoirs. The water you drink and use to shower in may come from one of those reservoirs.

Chapter 11 Section 3 Using Water Wisely Water in California, continued The area in California that is north of Sacramento receives about 75% of the annual precipitation in California. But about 75% of the demand for water comes from areas south of Sacramento. Most Californians live in Southern California.

Chapter 11 Section 3 Using Water Wisely Water in California, continued Most irrigated farmland is in Central California. Thus, much of the state depends on a system that moves water between places. The California aqueduct carries water from Northern California to Southern California.

Chapter 11 Section 3 Using Water Wisely Water in California, continued California also receives water from nearby areas, such as Oregon, Colorado, and Mexico. The agricultural industry in California is the leading producer of crops in the United States. This industry can use up to 50% of the state’s water supply.

Chapter 11 Section 3 Using Water Wisely Water in California, continued The state’s water supply is also used for environmental management. Businesses and households also use the state’s water. This use of water is called urban use.

Chapter 11 Water Pollution
Section 3 Using Water Wisely Water Pollution Water pollution is waste matter or other material that is introduced into water and that is harmful to organisms. Water pollution is harmful to organisms that live in, drink, or are exposed to the water. Surface water can be polluted by waste from cities, factories, and farms.

Water Pollution, continued
Chapter 11 Section 3 Using Water Wisely Water Pollution, continued In some cases, polluted water can be deadly. To prevent water pollution, people must understand where pollutants come from. Pollutants can come from a single source, such as a factory or a leaking gas station tank.

Chapter 11 Section 3 Using Water Wisely Water Pollution, continued Pollution from a single source can often be identified and traced to the source. When pollution comes from various sources, identifying those sources can be difficult. Runoff from a rainstorm can carry pollution from multiple sources into a river or lake.

Chapter 11 Section 3 Using Water Wisely Water Pollution, continued

Chapter 11 Section 3 Using Water Wisely Water Pollution, continued In 1969, the Cuyahoga River in Cleveland, Ohio, was so polluted that the river caught fire. This shocking event helped pass the Clean Water Act of 1972. The purpose of the act was to “restore and maintain the chemical, physical, and biological integrity of the nation’s waters.”

Chapter 11 Section 3 Using Water Wisely Water Pollution, continued The goal of the act was to make all surface water clean enough for fishing and swimming by 1983. This goal was not achieved. However, much progress has been made since the act was passed.

Chapter 11 Section 3 Using Water Wisely Water Pollution, continued The number of lakes and rivers that are fit for swimming or fishing has increased. Many states, including California, have passed stricter water-quality guidelines of their own. The Clean Water Act of 1972 opened the door for other water-quality laws.

Chapter 11 Section 3 Using Water Wisely Water Pollution, continued The Marine Protection, Research, and Sanctuaries Act of 1972 has strengthened the laws against ocean dumping. The Oil Pollution Act of 1990 requires all tankers traveling in U.S. waters to have double hulls by 2015 to protect against oil spills.

Chapter 11 Section 3 Using Water Wisely Water Pollution, continued The Safe Drinking Water Act of 1975 introduced programs to protect groundwater and surface water from pollution. Legislation has improved water quality. However, the cooperation of individuals, businesses, and the government will be necessary to maintain a clean water supply in the future.

Chapter 11 Water Conservation
Section 3 Using Water Wisely Water Conservation Fresh water is a limited natural resource. To make sure we have enough to meet our needs in the future, we have to conserve it. Conservation is the preservation and wise use of natural resources.

Water Conservation, continued
Chapter 11 Section 3 Using Water Wisely Water Conservation, continued Farmers have learned that most water loss in agriculture comes from evaporation and runoff. The amount of water loss can be reduced by using drip irrigation. Drip irrigation systems deliver small amounts of water directly to plant roots.

Chapter 11 Section 3 Using Water Wisely Water Conservation, continued The plants take up the water before it can evaporate or run off. Many industries conserve water by recycling cooling water and wastewater. Instead of discharging water into a nearby river, businesses often recycle water and use it again.

Chapter 11 Section 3 Using Water Wisely Water Conservation, continued Conserving water at home is important. Low-flow toilets and shower heads can be installed to lower the amount of water used in the bathroom. To reduce the amount of water lost to evaporation, lawns can be watered at night.

Chapter 11 Section 3 Using Water Wisely Water Conservation, continued Water can also be conserved by landscaping with a technique called xeriscaping. Xeriscaping involves designing a landscape with native plants. Native plants don’t need to be watered because they receive enough water from the natural environment.

Chapter 11 Section 3 Using Water Wisely Water Conservation, continued When you join the millions of people who are trying to save water, you can make a big difference. Your behavior alone can help conserve water. For example, you can avoid running the water while brushing your teeth or washing dishes.

Chapter 11 Section 3 Using Water Wisely Water Conservation, continued You can take shorter showers. You can wash the car by using only a bucket and a hose that has a shutoff nozzle. You can run the dishwasher or washing machine only when they are full.

Chapter 11 Rivers and Groundwater Concept Map Use the terms below to complete the concept map on the next slide. deltas dams levees floods alluvial fans

Chapter 11 Rivers and Groundwater Concept Map

Chapter 11 Preview Section 1 The Active River

Similar presentations

Presentation on theme: "Chapter 11 Preview Section 1 The Active River"— Presentation transcript:

Similar presentations

About project

Feedback

Log in

Auth with social network:

Chapter 11 Preview Section 1 The Active River

Similar presentations

Presentation on theme: "Chapter 11 Preview Section 1 The Active River"— Presentation transcript:

Similar presentations

About project

Feedback