Design Abraham Miller-Rushing, Ph. Biology Anica Miller-Rushing, M. Curriculum and Instruction. Chelsea Zillmer. Covitt, University of Montana Jenny D. Ingber Meghan E. For information on user permissions, please read our Terms of Service. If you have questions about how to cite anything on our website in your project or classroom presentation, please contact your teacher.
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You cannot download interactives. Of that, only about 1. Most of our drinking water comes from rivers and streams. This water is the lifeline of ecosystems around the world. Clean fresh water is a limited and valuable resource. In this module, students consider the question: will there be enough fresh water?
Students explore the distribution and uses of fresh water on Earth. They explore models of porosity and permeability, run experiments with computational models, and hear from a hydrologist working on the same question.
Students explore maps to discover the distribution of fresh water resources on Earth, and they examine graphs to discover how fresh water supplies are used by humans. Salt water is used in the mining process, in industry, and in power generation.
The oceans also play a vital role in the hydrologic cycle, in regulating the global climate, and in providing habitats for thousands of marine species.
Rivers and streams constitute the flowing surface waters. The force of gravity naturally draws water from a higher altitude to a lower altitude. Rivers obtain their water from two sources: groundwater, and runoff. Rivers can obtain their water from the ground if they cut into the water table, the area in which the ground is saturated with water. This is known as base flow to the stream. Runoff flows downhill, first as small creeks, then gradually merging with other creeks and streams, increasing in size until a river has formed.
These small creeks, or tributaries, where the river begins are known as the headwaters. Springs from confined aquifers also can contribute to rivers. A river will eventually flow into an ocean. A river's length can be difficult to determine, especially if it has numerous tributaries.
The USGS Web site defines a river's length as "the distance to the outflow point from the original headwaters where the name defines the complete length. The land that is upgradient of any point on the river is known as the drainage basin or watershed. Ridges of higher land, such as the Continental Divide, separate two drainage basins. Flowing water is extremely powerful and plays an important role in creating the landscape and in humans' lives. Flowing water is used for numerous reasons including irrigation and hydroelectric power production.
Rivers erode the landscape and change the topography of the Earth by carving canyons and transporting soil and sediment to create fertile plains. Rivers carry soil and sediment that have been washed into the river when it rains or snow melts. The faster the water moves, the larger the particle size the river is capable of carrying. The USGS measures how much sediment a river carries by measuring the streamflow, or the amount of water flowing past a given site; and the sediment concentration.
Sediment in the river can be helpful and harmful. Sediment, when deposited on the banks and in the flood plain, makes excellent farmlands. However, sediment can harm and even destroy dams, reservoirs and the life in the stream. Also, during floods, these sediments can be left behind as sticky, smelly mud in unwanted places.
Measuring the streamflow is accomplished by determining the stream stage and the stream discharge. The stream stage, or datum, is the height of the water surface, in feet, above an arbitrary reference point. The stream discharge is a measurement of the amount of water that is flowing at a particular point in time. It is measured in cubic feet per second. A discharge measurement determines the amount of water that is flowing in the river at any given stream stage.
In order to make this measurement, the width of the river, and the water's depth and velocity at various points must be measured at several different stream stages.
A cross-section of the river is divided into intervals and the area of each interval is calculated. If the velocity was measured at different depths on the same vertical interval, then the velocity is averaged. To determine the discharge for the interval, the area is multiplied by the velocity. To find the entire stream's discharge, an average of all the intervals' discharges is calculated.
It is important to take discharge measurements of the stream at various stream stages, even flood stage. A river reaches flood stage when the river overflows its banks. The flood stage can be determined by measuring the gage height, or simply the height of the water in the stream measured from the river's bottom.
The streamflow can increase exponentially as the gage height increases. Thus, a small increase in gage height may indicate that a river has reached its flood stage. Floods are a fairly common, yet dangerous, natural disaster. They normally occur because a storm or rapid snow melt has produced more runoff than a stream can carry. Dams failing, landslides blocking stream channels, and high tides are some other causes of flooding. Weather patterns can greatly influence when and where flooding will occur.
By studying these patterns, geologists can determine the susceptibility of a region to having a flood at certain times of the year. The recurrence interval, measured in years, describes the magnitude of a flood.
Changes in the drainage basin, such as harvesting timber or housing developments, can change the magnitude of a flood. The normally dry land that becomes covered with water during a flood is known as the flood plain. Restrictions on land use in flood plains is regulated by flood-plain zoning. Dams and levees have been built to help reduce damage caused by floods. When flowing water travels to an area of land that is completely surrounded by higher land, a lake is formed.
The water is not trapped in this low area, the water just escapes at a slower rate than the rate of incoming water. Lakes can vary greatly in area, depth, and water type. Most lakes are fresh water, however some, such as the Great Salt Lake and the Dead Sea, are salt water. Contrary to common belief, a reservoir is not the same as a lake. A reservoir is a manmade lake caused by a river being dammed.
The water in a reservoir is very slow moving compared to the river. Therefore, the majority of the sediments that the river was carrying settle to the bottom of the reservoir.
A reservoir will eventually fill up with sediment and mud and become unusable. The hydrologic cycle or water cycle is a graphic representation of how water is recycled through the environment.
Water molecules remain constant, though they may change between solid, liquid, and gas forms. Drops of water in the ocean evaporate, which is the process of liquid water becoming water vapor. Evaporation can occur from water surfaces, land surfaces, and snow fields into the air as water vapor. Moisture in the air can condensate, which is the process of water vapor in the air turning into liquid water. Emergency Management. Survey Manual. Earth's water is almost everywhere: above the Earth in the air and clouds and on the surface of the Earth in rivers, oceans, ice, plants, and in living organisms.
But did you know that water is also inside the Earth? Read on to learn more. Earth's water is almost everywhere: above the Earth in the air and clouds , on the surface of the Earth in rivers , oceans , ice , plants , in living organisms, and inside the Earth in the top few miles of the ground.
For an estimated explanation of where Earth's water exists, look at this bar chart. You may know that the water cycle describes the movement of Earth's water, so realize that the chart and table below represent the presence of Earth's water at a single point in time.
If you check back in a million years, no doubt these numbers will be different! Here is a bar chart showing where all water on, in, and above the Earth exists. The left-side bar chart shows how almost all of Earth's water is saline and is found in the oceans. Of the small amount that is actually freshwater, only a relatively small portion is available to sustain human, plant, and animal life.
Notice how of the world's total water supply of about And, of the total freshwater, over 68 percent is locked up in ice and glaciers. Another 30 percent of freshwater is in the ground. Yet, rivers and lakes are the sources of most of the water people use everyday. One estimate of global water distribution Percents are rounded, so will not add to The Earth is a watery place.
But just how much water exists on, in, and above our planet? Read on to find out. Earth's water is always in movement, and the natural water cycle, also known as the hydrologic cycle, describes the continuous movement of water on, above, and below the surface of the Earth.
Water is always changing states between liquid, vapor, and ice, with these processes happening in the blink of an eye and over millions of years.
A huge amount of water exists in the ground below your feet, and people all over the world make great use of it. But it is only found in usable quantities in certain places underground — aquifers. Read on to understand the concepts of aquifers and how water exists in the ground. The atmosphere is the superhighway in the sky that moves water everywhere over the Earth. Water at the Earth's surface evaporates into water vapor which rises up into the sky to become part of a cloud which will float off with the winds, eventually releasing water back to Earth as precipitation.
Ice and glaciers are part of the water cycle, even though the water in them moves very slowly. Ice caps influence the weather, too. The color white reflects sunlight heat more than darker colors, and as ice is so white, sunlight is reflected back out to the sky, which helps to create weather patterns. Read on to learn how glaciers and ice caps are part of the water cycle. Our interactive diagrams allow you to "mouse around" the parts of the water cycle and view explanations, pictures, and more.
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