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Hydrology is the study of water properties amounts distribution movement hydrologic cycle.

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Presentation on theme: "Hydrology is the study of water properties amounts distribution movement hydrologic cycle."— Presentation transcript:

1 Hydrology is the study of water properties amounts distribution movement hydrologic cycle

2 Why do we care about water? Necessary for life on earth Supply of water available for use is limited Human activities may affect water supplies and water quality

3 What do we use water for? Drinking Washing Cooking Playing Irrigation Livestock Mining Industry Fishing Others?

4 How much water do we use in the U.S.?

5 Most of the water that humans use comes from streams. Water in streams comes from precipitation runoff from the land surface around the stream. Some precipitation evaporates, is diverted by people, used by plants and animals, or soaks into the ground. The area of land that drains into a stream is called a watershed. Where does the water we use come from?

6 The area of land that drains all the streams and precipitation to a common channel such as a larger stream, lake, reservoir, or ocean.

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8 What kinds of things can we learn about the water in our streams? How much is there? Does this change over time? What lives in the water in our streams? What substances are in the water? What is the temperature of the water? What affects water in our streams? Others?

9 What can we use this information for? How much water is available in an area for various uses and when is it available? Will there be enough for the future if the community grows or changes? Is the water of good quality for use? Are there changes in flows due to changes in Land use? Water use? Climate? Is there good habitat available for wildlife species that use our streams and lakes?

10 A network of schools monitoring streams in the Southwest Crown of the Continent

11 Stream monitoring data we’ll collect in our study: Streamflow (also called discharge) Turbidity Temperature Other topics of interest? (fish, macro- invertebrates…)

12 Streamflow What is it? The amount of water going through a stream at one spot during a unit of time How do we measure it? Area (Depth x Width) x Velocity

13 Measuring Water Velocity 1. You can record how long it takes a floating object to travel a certain distance: 50 ft = 0.5 ft/sec 100 sec

14 Measuring Water Velocity 2. You can use a flow meter attached to a top-setting rod that measures speed by recording how fast the water makes a propeller turn:

15 can be measured by a stream gage that you read and record Pressure Transducer or by a device that measures and records water pressure electronically Stream depth

16 Calculating Area If streams were perfect rectangles, it would be easy: But streams are irregular and tend to be flat (but not smooth) at the bottom, rise steeply, and then have flatter banks as they near the top. When a stream's gage height doubles from 10 feet to 20 feet, the flow can more than just double.

17 Water Velocity is also different in different parts of the stream! Where do you think water would flow faster in a stream? Why? Water tends to flow faster in the middle of the channel than along the edges and faster near the surface than at the bottom: Rocks and other irregularities also affect flow

18 So how do we calculate flow, if a stream can be different widths and depths and velocities at the same location?!

19 Hydrologists have come up with a method: measure depth, width, and velocity at a bunch of different spots all across the stream, and sum their products for the total flow (discharge).

20 Stream depth and stream flow Measuring flow this way takes a lot of time and effort. If we record the water depth and flow at the same time, we can use water depth as a substitute for measuring flow! But remember how changes in depth don’t always cause equal changes in flow, due to the shape of the stream? So, we have to measure flow when the stream is at several different depths before we can predict what the flow is at a particular depth.

21 How to predict flow from depth 1. Each time we take a flow measurement, we take a gage reading. Gage (ft)Flow-Q (cfs) We keep a record of each flow measurement and the corresponding gage reading. 3. Once we have enough data, we simply plot these two variables on a graph and draw or compute the resulting curve.

22 How to predict flow from depth 1. Each time we take a flow measurement, we take a gage reading. Gage (ft)Flow-Q (cfs) We keep a record of each flow measurement and the corresponding gage reading. 3. Once we have enough data, we simply plot these two variables on a graph and draw or compute the resulting curve.

23 For any gage reading we have, we can figure out the corresponding flow. A computer program can do this for thousands of gage readings in an instant!

24 We can create a hydrograph like this one: Data collected by Seeley Swan High School Students

25 Steps to monitor streamflow

26 Stream monitoring data we’ll collect in our study: Streamflow (also called discharge) Turbidity Temperature Others?

27 Turbidity is a measurement of how cloudy or murky water is, due to sediment suspended in it. What is turbidity?

28 Why do we want to measure it? High turbidity can degrade lakes and streams, harming recreation and tourism. Turbidity can provide food and shelter for disease-causing microbes, increasing the cost of treating water for drinking and other uses. It can bring other pollutants with it. It can harm fish and other aquatic life by reducing food supplies, degrading spawning beds, and affecting gill function.

29 What causes turbidity? Heavy precipitation and runoff causes sediment particles to be washed into streams. High water flows can cause sediment already in streams to be stirred up and carried along. Turbidity can increase due to erosion from wildfires, animal activity, and other sources in the watershed. Human activities that remove vegetation near streams or disturb soil in the watershed can increase turbidity.

30 Sometimes it’s easy to see the difference between clear and turbid water : Smaller changes are harder to see, and often we should measure turbidity, to compare between sites or over time.

31 A Secchi Disk is a black and white disk that is lowered into the water until it vanishes from sight. The depth at which it disappears is the Secchi depth. The clearer the water, the greater the depth. A turbidity meter has a light source that shines through a water sample and a photoelectric cell that measures the amount of the light. The clearer the water, the more light shining through it. Measuring turbidity

32 We can use our turbidity data to graph changes over time Data collected by Seeley Swan High School students

33 Stream monitoring data we’ll collect in our study: Streamflow (also called discharge) Turbidity Temperature Others?

34 Water Temperature Temperature determines what can live in rivers and lakes. Fish, insects, microorganisms, plants, and other aquatic species all have an acceptable temperature range. As temperatures get too far above or below this range, growth declines and individuals may move or die.

35 Water temperature and Oxygen Warm water holds less dissolved oxygen than cool water, and may not have enough dissolved oxygen for some species, such as trout, to survive. Could water temperature affect the amount of oxygen in the water?

36 Measuring Water Temperature Water temperature can be measured more or less continuously with a thermograph. A thermograph electronically records temperature as often as we program it to. The temperature data can be downloaded onto our computers and graphed.


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