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Math/Science Nucleus © 2001 1

WATERTeacher Guide

including Lesson Plans, Student Readers, and More Information

Lesson 1 - Importance of Water

Lesson 2 - Water Properties (Lab) Lesson 3 - Water Chemistry (Lab)

Lesson 4 - Movement of Water

Lesson 5 - Watersheds

designed to be used as an Electronic Textbook in class or at home

materials can be obtained from the Math/Science Nucleus


Objective: Students learn why water iscritical to all life.

Teacher note

The Earth is a dynamic system, spinning on its axis as it revolves around theSun. The surface of the Earth, which includes the atmosphere, hydrosphere, andlithosphere, responds to this movement in space. The interaction of these spherescreates the life sustaining water cycle. Water has not always been on this planet.Oceans were created over eons of time as hydrogen and oxygen were united insidethe Earth to form water. Volcanic events over a long span of time have "outgassed"much of this water in the form of steam. The steam formed clouds in theatmosphere and precipitation brought the water back to Earth, to continue theendless water cycle. The miracle of water then created conditions for life to developand survive on this planet.

Water is a transparent, odorless, tasteless liquid at normal Earthtemperatures. It illustrates three states of matter including liquid (water), solid (ice),and gas (steam). Another chemical quality of water is its very large heat capacity,meaning that it can absorb a great deal of heat without, itself, becoming extremelyhot. This fact makes the oceans a large reservoir of heat, which greatly effects theoverall weather and climate patterns of the world.

Water is a peculiar substance with properties that make it an ideal fluid. Ifyou calculated the boiling and freezing temperature of water, you would find thatwater has an unusually low freezing point and a high boiling point compared to othercompounds.

In the upcoming units students will learn that water is important to our veryexistence. The fluid is so unique that without it, life as we know it would not be ableto function. With the miracle of life, also come a tragic side. Water borne diseasesand other pathogens are transferred by water and effect many areas. Thesediseases cause more death than any other cause in the world.

EARTH SCIENCES - WATER

Lesson 1 - Importance of Water MATERIALS:

reader


Ancient Roman aqueduct

Water is our lifeline that bathes us and feedsus. In ancient cultures water represented the veryessence of life. The Romans were the first to pipewater into their growing cities, especially with theiraqueducts. They also realized that sewage watercould cause damage to their people, and needed tobe removed from large areas of people. Water has played a role not only in the historyof countries, but in religion, mythology, and art.

Water in manyreligions cleansesthe soul through holywater. For example,the water at Lourdes, France is thought by many religionsto be sacred water with healing powers. In Egyptianmythology, the Nu was the beginning of everything andrepresented water. It brought life to their people, but indrought, produced chaos.

Water has always been perceived as a gift from thegods as it rained from the heavens.

The water or hydrologic cycle explains interactions between the atmosphere,hydrosphere, and lithosphere. The water or hydrologic cycle is a major driving forceon our planet. Water is in constant motion, evaporating into the atmosphere from oceans,lakes, rivers and streams. When the atmosphere can no longer support the moisturewithin the clouds, we experience rain, snow, hail, or sleet. Some water is locked in theform of ice at the polar caps and in glaciers.Water melts in the spring, producingrunoff, that percolates through the Earthas groundwater (subsurface) or makes itsway back to the sea (surface). The oceanscontain most of the water, but it is saltwater which is unuseable by mostorganisms. Only pure H2O (water) caninteract with organisms.

The movement of the oceans alsohas a direct effect on the atmosphere. Theatmosphere is that envelope of gas thatkeeps organisms living on this planet.Oceans and atmosphere interact to give usweather.


Dam in California

Entamoeba histolytica, an amoebacauses dysentery

Children with Schistosomiasis

Schistosomiasis worms, parasite inwater

Water provides the Earth with the capacity of supportinglife. An organism doesn’t have to be told how important wateris to their existence. An amphibian knows to lay their eggs inwater or else there will be no new born. Even flies know to laytheir eggs in fresh water.

The only organism that doesn’t understand theimportance of water is humans, especially in industrializedcountries. Children in those societies turn on the water in asink and never think about the trouble someone has gone forthat “miracle” to occur.

In the United States it ismandated by law that its citizensshould be given clean andabundant water. Dams,reservoirs, filtering plants, andpipes all bring clean water whenthe facet is turned on. Sewagewater is only mixed with

recycled water supplies after the water goes throughrigorous cleaning methods. Water borne diseases do noteffect the U.S. population like in other countries that do nottreat their water supply.

Water borne diseases are any illnesses causedby drinking contaminated water. Diseases can includeinfection from bacteria (Salmonella), viruses, or by smallparasites (Cryptosporida, Giardia, and Toxoplasma).These organisms and viruses cause diseases likecholera, typhoid fever, malaria, botulism, polio,

dysentery, giardia,and hepatitis A. Oneof the first symptoms ofthese diseases isdiarrhea, which cause about three million deathsthroughout the world, mainly in India, Africa, and SouthAmerica.

Sewage is sometimes discharged into rivers,where children downstream might be taking a bath orusing the water to drink. The simplest treatment methodis boiling. Just bring the water to a boil for at least oneminute, then allow it to cool. But this is not alwayseffective in heavily chemical polluted water supplies.


Water creates a stable environment

Life is abundant under ice sheets

Fish use dissolved oxygen to breathe

Without water, organisms couldnot exist. Water is a resource thatshould not be taken for granted. Itneeds to be conserved, just as wesave other valuable resources.

Water is one of the weirdestcompounds known to humans. Thedifference between the boiling pointand freezing point of water is one ofthe largest ranges of any compound. Itis this span of temperature that mirrorsthe range of where life can exist, frombacteria to humans. Water also has avery high specific heat, which meansthat it can absorb or lose much heat before its temperature changes. This is important inmaintaining body heat in mammals. It also takes a lot of energy before vaporization canoccur. For this reason, water evaporates slowly from ponds and lakes, where many lifeforms are dependent on a stable, warm environment.

Water is less dense in its solidstate than in its liquid state, so that icefloats instead of sinking. This propertypermits life to develop in polar andsubpolar regions where ice floats andallows life to continue living below thesurface. If ice were heavier than water,it would sink, and more ice would formon top of it. As a result, all life in thewaters would be trapped in the ice in themany areas of the world where it getscold enough to freeze water.

Water is a remarkable solvent, where mostelements and compounds can dissolve in itspowerful molecular structure. Gases such asoxygen and carbon dioxide, can also dissolve,making it readily available for photosyntheticand nonphotosynthetic organisms to use.


Resistance of water molecules creates unevenmovement

Water also exhibits viscosity. One canobserve the effects of viscosity alongside a stream or river withuniform banks. The water along the banks is nearly still, whilethe current in the center may be swift. This resistance betweenthe layers is called viscosity. This property allows smaller fishto live near the shore, while larger fish are able to swimefficiently in strong currents. Viscosity is also responsible forthe formation of eddies, creating turbulence that leads to goodmixing of air in the water and more uniform distribution ofmicroscopic organisms.

How water provides all these properties are complex, butonly emphasizes the importance of water to every organism onEarth.


Objective: Students experiment withthe chemical properties of water.

Teacher noteThe next two labs will concentrate on water as a chemical substance. The

cohesive or attractive forces between liquid molecules are responsible for surfacetension. The molecules at the surface are attracted more to each other than thoseinternally. This forms a surface "film" which makes it more difficult to move an objectthrough the surface.

It would take a force of 72 dynes to break a surface film of water 1 cm long at25LC. The surface tension of water decreases significantly with temperature. Hot wateris a better cleaning agent because the lower surface tension makes it a better "wettingagent" to get into pores. Soaps and detergents further lower the surface tension.

Capillary action is the result of adhesion and surface tension. Adhesion of waterto the walls of the wall of a graduated cylinder will cause an upward force on the liquidat the edges. It will form a meniscus which turns upward. The surface tension acts tohold the surface intact, so instead of just the edges moving upward, the whole liquidsurface is dragged upward.

The surface tension of water provides the necessary wall tension for theformation of bubbles with water. The tendency to minimize that wall tension pulls thebubbles into spherical shapes (LaPlace's law).Answers:Experiment 1. The pepper will move away from the center, leaving a circle of clearwater. The detergent has reduced the surface tension in the center; the higher surfacetension remaining around the edge pulls the pepper particles toward the edge.Changing the surface tension has caused motion. Experiment 2. A capillary tube uses the principles of surface tension to make waterrise. Sucking will not be able to move it any faster. Experiment 3:You may want to have warm water all ready available in the classroom for Experiment3. In this way, you can have the student teams perform Experiment 3 first before thewater cools and then continue to the other experiments.


Lesson 2 - Water Properties MATERIALS:

reader pepper, water, bowls, detergent, a

capillary tube


3 forms of water: ice, water, and steam

Hydrogen bond

Water is a transparent, odorless, tastelessliquid composed of the elements hydrogen andoxygen. Water is an universal solvent, meaningthat many elements can be dissolved by water.Fresh water has relatively few elements dissolvedin the water, while the oceans contain manydissolved salts.

Water is important to our lives, and withoutit we could not live. In fact, there are no livingcreatures that can live without water. Water mostprobably originated on this planet as gases wereemitted from volcanoes. The Earth's atmospherecaptured this water and has continuously recycledit throughout time, in what is called the water cycle.

Water evaporates and forms clouds – the clouds provide rain and snow – which iscollected in rivers, lakes, underground reservoirs, and oceans – that are the source forfurther evaporation. Water is the perfect substance for the water cycle, because it has ahigh boiling point and a low freezing point.

The molecular structure of water resemblesthat of a teddy bear’s head. The hydrogen and theoxygen atoms have a very tight covalent bondformed where the hydrogen and the oxygen shareelectrons. Bonding between molecules of water iscalled a hydrogen bond, which has a weakerattraction. The hydrogen atoms of one watermolecule stick to theoxygen atoms ofn e a r b y w a t e rmolecules. Theseweak bonds are veryimportant for thechemistry of life.Molecules whichstick to water, such

as alcohol and sugar, are called hydrophilic, meaning"water loving.”

Not all molecules are sticky. The scientific name ishydrophobic which means "water fearing.” Examples ofslippery molecules are fats and oils.


Droplets are caused by surfacetension

Caddisflies

Capillary action

Water exhibits surface tension. Surface tensionof water or the ability of a substance to stick to itselfmakes water an excellent substance to float heavyobjects on its surface. The molecules of water on thesurface of a calm and quiet pond tend to be drawn intothe liquid, so that the liquid surface is taut, like a sheetof rubber drawn over the open mouth of a jar. Thistautness is caused by surface tension.

Surface tension is responsible for the shape ofliquid droplets. Although easily deformed, droplets ofwater tend to be pulled into a spherical shape by thecohesive forces ofthe surface layer.

The surface of water can support small objects like asewing needle until the surface tension is broken. This"skin" on the water aids the growth of mayflies andcaddisflies that are attached to the water’s surface.However, surface tension can also trap flying insectsthat accidently fall into the water and are unable to flyout.

Soaps and detergents help the cleaningof clothes by lowering the surface tension of thewater. This allows the water to soak intopores and dirty areas more effectively. Smallinsects such as the water strider can walk onwater because their weight is not enough topenetrate the power of surface tension.

Common tent materials are somewhatrainproof because surface tension of water willbridge the pores in the finely woven material.

But if you touch the tent material with your finger, you will break the surface tension andthe rain will drip through.

Water can defy gravity as it can “walk” up the sides of a thin tube. The moleculeis actually attracted to the side and pulls itself up. It might take a long time to get up a thincapillary tube, but it is working against gravity.



PROBLEM: How can you explain different properties of water?

HYPOTHESIS:

MATERIALS: water, beaker, pepper, detergent, alcohol, capillary tube, washing soda,rice, sugar

PROCEDURE: Experiment 1. Partially fill a glass with water. Sprinkle pepper all overthe surface. Now drip a drop of liquid detergent onto the surface, in the center of thepeppered area. Record what happens and why?

Drop a little alcohol on a peppered surface. What happens?

Experiment 2. Try and suck water through a capillary tube (like you would through adrinking straw). What happens and why?

Experiment 3. Using 250 ml of water, try to dissolve 1 ml of salt, fine sand, tea leaves,washing soda, rice, and sugar. Record what happens. Warm the water with a Bunsenburner or heating surface. Try and dissolve the same amount of substance in warm water.Record what happens.

SUBSTANCE COLD WARM

SALT

FINE SAND

TEA LEAVES

WASHING SODA

RICE

SUGAR

CONCLUSION: Identify the scientific principle in each experiment?


Objective: Students learn theprocedure for pH, dissolved oxygen,and nitrates.

Teacher note

There are many tests that can determine the components that are dissolvedin water. Water quality uses chemical analysis of water to collect and comparedata. Water testing is usually done over a long period of time and the scientists arelooking for unusual levels of different components.

You can even use this lab as a trial, and then students can conduct thesesame tests on a nearby creek, river, or pond. Make sure that your students alsorecord any unusual conditions that might help to interpret the data. For example,you have found a high level of copper in your water samples. In your notes youwrote down that the sample site is near a heavily used roadway and that this wasthe first rain. This would provide you with the information you need to determinethat the braking of the cars probably was the cause of the high copper content.When you put your brake on, you scape off copper. The first rain concentrated thecopper levels from the roadway that were accumulating during the dry spell.

Problem solving is very important in water testing, and not just the individualtest. Emphasize with students about replication of sample, to make sure the datais accurate.

In this exercise students learn about temperature, nitrate, dissolved oxygen,and pH. Have them read the information and then have them all test the samewater. If you are using other test kits, change the worksheets accordingly. Discusswith students any differences among the different data collected. Depending ontime, you can have the student replicate the same sample 3 times. Practice makesperfect!


Lesson 3 - Water Chemistry (Lab) MATERIALS:

readerthermometerLa Motte Nitrate kitLa Motte Dissolved Oxygen kitLa Motte pH kit


Polluted water

Sampling water

Industrial plants can causethermal pollution

Gills beat faster in warm water

Testing of water is important to humansbecause we need clean, fresh water. Keepingthe water healthy for plants and other organismsalso provides recreational sports for humans.Polluting our water supplies causes a rippleeffect that eventually harms the originalpolluters.

Many people feel that just put a little oil inthe storm drain or riding gas driven boats ondrinking water reservoirs won’t hurt anything. Ifonly one person

polluted, maybe nothing would happen. But that is never thecase.

Humans were originally nomads because their waterand land would become polluted from their use. If youdefecated into your water supply, mysterious diseases wouldoccur. It took humans a long time before they figured out,they were the ones causing the health problems.

This lab looks at testing temperature, dissolvedoxygen, nitrates, and pH of water. These are only four tests,out of many, you can determine for water. Directions are onyour lab sheet. First, read the information on why these testsare important and then perform the test.

Water temperature is an important factor for survival ofaquatic life. Very high and very low water temperature can kill manyaquatic plants and animals. The temperature can affect how anorganism’s internal mechanisms (metabolism) work. For examplesalmon and trout prefer temperatures between (4.5° C) 40° and 20°C (65° F). Different stages of the growth of fish are susceptibleranges of fish. In the summer when temperatures are high, juvenilefish actively look for the cooler pools of water. A fish must pumpwater across its gills to meet its need for oxygen. If the dissolvedoxygen in water is low, the gills mustmove faster to get enough oxygen forthe fish to survive.

Thermal pollution can occurwhen heated water is discharged intocooler streams or rivers. This heatedwater generally is from power plants

or industrial processes. If the water is not cooled downbefore entering into a stream or pond, it can causeorganisms to die of increased temperature.


A simple test to determine chemicalsdissolved in water that might be harmful toorganisms is pH. The percentage of free hydrogen(H� ) and a hydroxy ion (OH�) determines the pHof the liquid. Pure water (HOH) is made up onepart hydrogen and one part hydroxy and given aneutral standing or a “7.” If you have morehydrogen than hydroxy it is an acidic solution. Ifthe hydroxy ions, are greater than the hydrogenions you have a basic or alkaline solution. Theconcentration of the hydrogen ions [H+] in asolution determines the pH.

A pH of 6.0 to 9.0 is the range that fishesand invertebrates can successfully survive. Eachspecies has its own tolerance level. The tablebelow gives some special effects of pH on fish andaquatic life.

Minimum Maximum Effects

3.8 10.0 Fish eggs could be hatched, but deformed young are often produced

4.0 10.1 Limits for the most resistant fish species

4.1 9.5 Range tolerated by trout

4.3 Carp die in five days

4.5 9.0 Trout eggs and larvae develop normally

4.6 9.5 Limits for perch

5.0 Limits for stickleback fish

5.0 9.0 Tolerable range for most fish

8.7 Upper limit for good fishing waters

5.4 11.4 Fish avoid waters beyond these limits

6.0 7.2 Optimum (best) range for fish eggs

1.0 Mosquito larvae are destroyed at this pH value

3.3 4.7 Mosquito larvae live within this range


Oxygen rich water

Wastewater adds nitrogen in water

Although water is made of H2O, the oxygen is notavailable for organisms. Dissolved oxygen in water isrequired for most organisms. Dissolved oxygen (DO)refers to the volume of oxygen that is contained in water.Oxygen enters the water by photosynthesis of aquaticplants and by the transfer of oxygen across the air-waterinterface. The amount of oxygen that can be held by thewater depends on the water temperature, salinity, andpressure. Gas solubility increases with decreasingtemperature (colder water holds more oxygen)

Flowing water is more likely to have higherdissolved oxygen levels than is stagnant water becauseof the water movement at the air-water interface. Inflowing water, oxygen-rich water at the surface isconstantly being replaced by water containing lessoxygen as a result of turbulence. Because stagnant waterundergoes less internal mixing, the upper layer ofoxygen-rich water tends to stay at the surface, resulting inlower dissolved oxygen levels throughout the watercolumn.

Nitrogen is found in the cells of all living things and is a major component ofproteins. Nitrogen may exist in the free state as a gas N2, or as nitrate (NO3-), nitrite(NO2-), or ammonia (NH3+). Organic nitrogen is found in proteins and is continuallyrecycled by plants and animals. Nitrogen is important to organisms, but too much cancause damage.

Nitrogen containing compounds act as nutrients in streams and rivers. Nitratereactions in fresh water can cause oxygen depletion. Organisms depending on the supplyof oxygen in the stream will die. The sources ofnitrogen into bodies of water are municipal andindustrial wastewater, septic tanks, feed lotdischarges, animal wastes (including birds andfish), and discharges from car exhausts.

Nitrites can produce a serious condition infish called "brown blood disease." Nitrites alsoreact directly with hemoglobin in human blood andother warm-blooded animals to producemethemoglobin. Methemoglobin destroys theability of red blood cells to transport oxygen. Thiscondition is especially serious in babies less thanthree months of age. It causes a condition knownas "blue baby" disease.



PROBLEM: Why should you test for pH, nitrates, and dissolved oxygen?

HYPOTHESIS:

MATERIALS: thermometer, La Motte test kits for pH, nitrate, and dissolved oxygen,water samples

PROCEDURE: Use only with LaMotte kits and materials

pH Testing Procedure1. Rinse each test tube with the water sample. Gloves should be worn to avoid skincontact with the water. 2. Fill the tube to the 5mL line with sample water.3. While holding a dropper bottle vertically, add 10 drops of Wide Range IndicatorSolution.4. Cap and invert several times to mix.5. Insert the tube into the Wide Range pH Comparator. Hold the comparator up to a lightsource. Match the sample color to a color standard.6. Record the pH value.7. Wash your hands

Nitrate Testing Procedure1. Fill the sample bottle with sample water. Use gloves if drawing the sample by hand.2. Rinse and fill one test tube to the 2.5 mL line with water from the sample bottle.3. Dilute to the 5 mL line with the Mixed Acid Reagent. Cap and mix. Wait 2 minutes.4. Use the 0.1 g spoon to add one level measure (avoid any 50-60 times in one minute).Wait 10 minutes.5. Insert the test tube into the Nitrate Nitrogen Comparator. Match the sample color to acolor standard. Record the result as mg/L(ppm) Nitrate Nitrogen (NO3-N). To convert tomg/Nitrate (NO3) multiply by 4.4.6. Place the reacted sample in a clearly marked container. Arrangements should be madewith toxic material handlers for safe disposal. Please wash your hands after this water testis completed.

Dissolved Oxygen Testing Procedure1. If you have a barometer, record the atmospheric pressure. Remove the cap andimmerse the DO bottle beneath the river’s surface. Use gloves to avoid contact with theriver.2. Allow the water to overflow for two to three minutes (This will ensure the elimination ofbubbles).3. Make sure no air bubbles are present when you take the bottle from the river.


4. Add 8 drops of Manganous Sulfate Solution and 8 drops of Alkaline Potassium IodideAzide.5. Cap the bottle, making sure no air is trapped inside, and invert repeatedly to fully mix.Be very careful not to splash the chemical-laden water. Wash your hands if you contactthis water. If oxygen is present in the sample, a brownish-orange precipitate will form(floc). The first two reagents “fix” the available oxygen.6. Allow the sample to stand until the precipitate settles halfway. When the top half of thesample turn clear, shake again, and wait for the same changes.7. Add 8 drops of Sulfuric Acid 1:1 Reagent. Cap and invert repeatedly until the reagentand the precipitate have dissolved. A clear yellow to brown-orange color will developdepending on the oxygen content of the sample. 8. Fill the titration tube to the 20 mL line with the “fixed”: sample and cap.9. Fill the Direct Reading Titrator with Sodium Thiosulfate 0.025 N Reagent. Insert theTitrator into the center hole of the titration tube cap. While gently swirling the tube, slowlypress the plunger to titrate until the yellow-brown color is reduced to a very faint yellow.If the color of the fixed sample is already a faint yellow, skip to step 10.10. Remove the cap and Tritrator. Be careful not to disturb the Titrator plunger, as thetiration begun in step 8 will continue in step 11. Add 8 drops of Starch Indicator Solution.The sample should turn blue.11. Replace the cap and Titrator. Continue titrating until the sample changes from blueto a colorless solution. Read the test result where the plunger top meets the scale.Record as mg/L (ppm) dissolved oxygen.



DATA SHEET

Sample # temperature dissolved O2 nitrate pH

Average

Describe conditions:

Describe water:

Conclusions:


Objective: Students learn aboutsurface and ground water.

Teacher note

Water is a renewable, basic natural resource which is essential to allorganisms. Humans have trapped water for use in agriculture and industrialactivities. Our society can create large cities like New York and Chicago and createreservoirs to service the people of those areas. More importantly, we havedeveloped ways to clean and reuse our wastewater. We have also learned thatdeserts can become large metropolitan areas, like Los Angeles, if only we providewater.

There are two sources of water that this reader summarizes, ground andsurface water. These two sources move in their own unique ways. Humans useboth surface and ground, but surface is much easier to control.

Runoff from surface water includes all surface flow through streams aschannel flow. Runoff is mainly derived from excess precipitation which does notinfiltrate into the soil to become groundwater. Groundwater recharges itself throughprecipitation or pools of water (lakes, ponds) that percolate through the soil andpores of rocks.

Water looks for different routes as it heads for sea level. The movement ofwater and how it meandering through the land will define drainage systems or whatis referred to as watersheds.

Make sure students understand all the components of the water cycle. Theymay have learned the easy processes of evaporation and precipitation, but in thislesson they should begin interpreting the components in different places. The watercycle is complex but so very important to our lives.


Lesson 4 - Movement of Water MATERIALS:

reader


Surface movement includes rivers, streams,creeks, lakes, ponds, and human-made “flood”control. All surface water is trying to reach sealevel due to gravity. As water flows in channels,the streambed and banks of the channel willresist the flow of water. The velocity of the wateris dependant on steepness of the slope, type ofrock or soil, amount of vegetation, shape of streambed, and obstructions. Surface water provides theliquid where most evaporation takes place.

Groundwater refers to water that haspenetrated the soil or bedrock and moves through rocks that have a high pore space. The

water comes from infiltration of surface watersincluding lakes, rivers, recharge ponds, and evenwaste-water treatment systems. Groundwater isalso affected by the force of gravity. However,because of some of the properties of water, it canpool in higher area and actually defy gravity insome cases. The water stable is the upper levelof the saturated zone of groundwater.

Rivers, streams and creeksare a surface water system with anetwork of channels that collect andmove runoff. Runoff is excesswater that is not adsorbed by thesurrounding area. Runoff can becreated by rainfall, melting snow, orgroundwater discharge. The shapeof the river system will depend onthe topography, the type of rock orsoil it is traveling through, and thestyle of its biological diversity. Forinstance, pine trees require a lot ofwater to grow. Runoff in a pine treeforest would be less than if the areawas populated by oak trees. Oaktrees require less water than pine, so more water would be available as runoff.


Perennial streamDry or ephermeral creek

Braided streams

Rivers and streams change depending on the amount ofwater that flows throughout the year. This relies on a continuoussource of water is from the surface or subsurface. A perennialflow is a channel that has water all yearround. An example would be the greatrivers of the world including the GangesRiver (India), Amazon River (SouthAmerica), or the Nile River (Africa). Anintermittent stream would be a flow thatis more than 50% during the year. Anephemeral flow generally refers to astream or creek that only has water part ofthe year. This is usually in areas, likedeserts, that are dry most of the year, butdo have maybe 2 months of rain.

Surface flows will wiggle and wind through thesurface landforms. There are many flow types dependingon the velocity of the river. If the velocity is high, it tends tocut into bedrock in a “straight” line. Velocities will be highif there is sufficient relief. When the velocity is low, thestream will tend to meander if the rock type and topographypermit it.

Water velocity helps to create three basic types ofchannel patterns, including braided, meandering, andstraight. There are many patterns that grade into eachother. Rivers in a straight pattern do not stay ruler straightfor long! The physical properties of water and the area theriver is eroding tend to have the deepest part of the river (called the thalweg) alternating

from side to side on the channel. Erosion of theland starts a physical separation of the pieces.Larger pieces don’t move very far and drop out ofthe system. However, finer grained sedimentsettles out in quieter area. So water will beattacking one side of the river and the other side willbe depositing sediment. Over the years this willcreate meandering.

In many areas where you find braidedchannels, surface water is just “dumped” into alower topographic area. The sediment load is largeand the river gets confused and breaks up intosmaller channels with a branching, but braided look.


Riffles

The flow will also dictate how the sediment is deposited,which in turn contributes to the type of habitat available todifferent types of organisms. Three types of bedforms provideexcellent “living” space, including mud, riffles, and pools. Theaccumulation of fine-grained sediments (mud) in quiet rivers caninfluence growth for small invertebrates and fish eggs. The mudrepresents a “cushion”, and if disturbed because of increasedmovement of water, can cause damage to the organisms thatlive there.

Riffles are relatively shallow portions of a river with achange in elevation where water cascades over cobbles orboulders along its path. The fast-moving water allows gas inthe atmosphere to mix with the water, therefore increasing thedissolved oxygen that enters the water system. Behind therocks are areas that debris can build up and act as a habitat forfly larvae and other small invertebrates.

Pools of water are areas that are deeper. When water reaches a pool the velocityof the water slows down, making it an excellent resting place for fish.

Ground water as it movesthrough soil and rock is actually beingnaturally filtered. Some substanceslike sand can help filter pollutants andparticles easily. Clays in soil androck also act as a way to “capture”and exchange some elements andcompounds when they are dissolvedin water. This helps to eliminate otherpollutants that filtration cannothandle.

Water is stored in aquifers,which have similar characteristics ofreservoir rocks that store soil and

gas. Well-sorted sediments with high porosity (A) and highly fractured (C) rocks areexcellent candidates for aquifers. If poorly sorted rocks are partially cemented (B), theyare not good reservoir rocks. The fluid must have room to move around. An aquifer is notan underground river, it just retains the water until it is pumped out through a well ornaturally emerges as a spring.


Objective: Students use the internet tofind their watershed.

Teacher note

Watersheds refer to how water moves through a defined topographic area.A more detailed definition would include a geographic area in which all sources ofwater, including lakes, rivers, estuaries, wetlands, and streams, as well as groundwater, drain to a common surface water body. Watersheds are diverse. You canhave a desert watershed, flatland watersheds, mountainous watersheds, as well ascoastal watersheds.

In the United States watersheds are delineated by U.S. Geological Surveyusing a nationwide system based on surface hydrologic features. This systemdivides the country into 21 regions, 222 subregions, 352 accounting units, and 2,262cataloguing units.

In this activity students will use the “Surf Your Watershed” website from theEnvironmental Protection Agency to locate their watershed. You can extend thislesson by having them locate other watersheds. This will help students learn howto use this valuable resource to locate information.

Below are a few websites that might help you get more information onwatersheds.

Know your Watershed (Purdue University)http://www.ctic.purdue.edu/KYW/glossary/whatisaws.html

Surf Your Watershed (Environmental Protection Agency)http://www.epa.gov/surf/

Locate your Local Watershed (Environmental Protection Agency)http://cfpub1.epa.gov/surf/locate/index.cfm


Lesson 5 - Watersheds

MATERIALS:

readerInternet


Continental Divide

Stream order formationDendritic pattern of river formation.

A watershed or drainage basin refers to asystem controlled by topography which defines howwater will flow. You refer to a watershed by the largestbody of water that the creeks, rivers or streams feedinto. For example, all creeks that flow in the SanFrancisco Bay are part of the San FranciscoWatershed. However, there are many smallerwatersheds within this area depending on flowpatterns. Alameda Creek Watershed would be anarea that drains into Alameda Creek.

When it rains, water will flow into its appropriatewatershed. A ridge ortopographical higherareas that connectstwo waters are called adivide. In the UnitedStates there is an areain the Rocky Mountaincalled the “continental divide.” This refers to water on theeast of the divide flows into the Atlantic. The water on thewest side flows into the Pacific.

A watershed has an orderly flow pattern. The pattern is dendritic or branching, asit flows from the headwaters to a larger body of water. When one stream flows into alarger stream or river they are called tributaries. The smallest channels in a watershedwith no tributaries are called first order streams. A second order stream is when two firstorder streams join. If you look at the stream order diagram, you can see the creation ofa fifth order stream channel. Fifth to sixth order streams are usually larger rivers, whilefirst and second order are often small, steep, or intermittent.


Steep banks, rapid erosion

Watersheds are affected by differentphysical and climatic differences. Climatesrefer to the weather in a region over a longperiod of time. Your location will determine thetype of the seasonal input of water.Temperature of the atmosphere caused bysolar radiation will also control the rate andnature of the precipitation.

Physical make-up of the area wherewater flows will also make a difference. If therocks and soil are “soft,” water can erode iteasily. The steeper the topography the greaterthe runoff and erosion. An earthquake cancause an uplift in an area that can change the

shape and extend of how the water flows. Humans can create a dam or build a largestructure which change the course of a river, which effect an entire area.

The vegetation in watershedseffects the quality of the water.Grasses, shrubs, and trees make upthe majority of plant cover. As theyfall and decompose, they add theorganic components to the soil. Treesare the protectors of the watershed.The tree litter protects the soil’ssurface as the roots of the tree protectthe soil from erosion. Trees alsoprovide a canopy that keeps the watercool so organisms don’t die of thermalpollution. The canopy can alsoreduce the force of the rain and thevelocity of wind in a watershed.

Plant cover is important to a watershed to prevent the erosion of valuable soil aswater rushes downstream. Plant cover also provides food and protection for many smallorganisms.


The green zone along a stream ecosystem iscalled a riparian area and has several uniqueproperties. Riparian zones have the capacity to bufferrivers and other waters from runoff from agricultural,urban, or other areas. Healthy riparian zones canabsorb sediments, chemical nutrients, and othersubstances contained in runoff.

Riparian areas provide all the componentsneeded for a wildlife habitat including food, water, andcover. Diversity of organisms living in these wetlandareas is very high. A riparian habitat includes threeareas depending on the influence of water. The aquaticarea refers to the area that is the stream channel orpond. The organisms that live in this area must beadapted to a wet lifestyle. Not far from the banks of thewater is an area referred to as the riparian area whichare organisms that require a moist habitat. Many plantsrequire their roots to be moist. A transition areabetween a riparian area and upland cover is called anarea of influence. Moisture decreases as you moveaway from the water.

Riparian vegetation adds to theshade of an area which helps toc o n t r o l t e m p e r a t u r e a n dphotosynthesis of plants living in thestream. It also is a source of largerand fine plant detritus which is usedby many insects and invertebrates fortheir food source. If you have avigorous riparian zone, you will havea diverse flora and fauna living in thisarea.

Watersheds naturally cleanthemselves as water can be filteredas it flows in the system. However, wesometimes pollute these watersheds through industrial or municipal waste discharging intothe watershed (point source pollution). This overloads the systems and pollutionincreases. Even non point source pollution (many contributors to pollution) canaccumulate and cause as much damage. Our watersheds reflect the health of ourenvironment. Water that migrates through the different levels of the watershed nourishesbiological life. In this activity you are to search the internet and find out more about thewatershed that you live in. Use the worksheet to help find this information.



PROBLEM: How can you locate more information about your local watershed?

HYPOTHESIS:

MATERIALS: Internet

PROCEDURE: Use the Environmental Protection Agency (EPA) website to findinformation about your local watershed (http: //www.epa.gov/surf/). Answer the questionsbelow and then print out a map of the completed assignment.

1. Name of watershed

2. USGS cataloging unit number

3. State and Counties covered by map:

4. Look at the Environmapper for watersheds. Click on the different mapping features thatyou want to locate. Then click on the map and these symbols will appear on the map.

List the symbols you have chosen.

5. Print out a map as instructed by your teacher.


Earth Science- Water - Unit Test

Part 1. Definitions Match the number of the term or concept in Column 1 with the letterof the correct definition in Column 2.

Column 1 Column 21. riparian a. resistance between layers

2. watershed b. excess water that flows after a rainstorm

3. aquifer c. larger, quieter area in a stream

4. viscosity d. a river channel that has a “s” shape

5. runoff e. requirement of many organisms in water

6. pool f. green zone

7. ephermeral g. channel that has water all year

8. perennial h. dry part of the year

9. dissolved oxygen i. drainage basin

10. meandering j. underground storage of water

Part 2. Multiple Choice Choose the best answer to complete each statement.

1. Water can be founda. only on th Earth’s surfaceb. inside the Earth onlyc. on the surface and subsurface of the Earthd. none of these

2. Which of the following is not a classification of a stream channel?a. meanderb. flowc. braided d. straight

3. Dissolved oxygen enters water througha. waterfalls b. soilc. rocksd. humans


4. Ice floats becausea. it is denser than waterb. water is denser than icec. it is cold d. the molecules are far apart

5. Abundant water in the U.S. is not caused bya. reservoirsb. sewage treatment c. damsd. beavers

6. Water is a. a semiliquidb. a universal solventc. a normal componentd. non-renewable resource

7. Which of the following chemical parameters does not affect organisms?a. hardness of waterb. pHc. dissolved oxygend. viscosity

8. Which of the following is not considered a division of a riparian area?a. braidedb. area of influencec. ripariand. aquatic

9. Riparian canopy vegetation helps to controla. pHb. amount of waterc. temperatured. salinity

10. What is it called when one stream flows into another?a. steepb. intermittentc. divided. tributary


ANSWERS:Part 1.

1. F2. I3. J4. A5. B6. C7. H8. G9. E10.D

Part 2.1. C2. B3. A4. B5. D6. B7. A8. A9. C10. D

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