2DisclaimerThis presentation was prepared using draft rules which may vary slightly from those to be published in the final 2011 Coaches Manual.The rules as they appear in the 2011 NSO Coaches and Student Manuals will serve as the official rules for this event.
3Goals for this PPT Presentation Provide tips on how to coach the eventProvide a brief preview of each event topicProvide an introductory resource for participantsA number of websites recommended for both participants and event supervisors are listed at the end of this PowerPoint.
4Goals for this PPT Presentation Should you choose to have a parent or community member coach this event, you may provide a copy of this presentation to that individual so he/she may have an opportunity to preview expectations.
5Goals for this PPT Presentation Participants should resist the temptation to use this presentation as their sole source of information.Participants may develop their own Power Point presentations in a manner similar to this one as doing so provides an excellent outline.Once participants are satisfied with their own PPT presentations, they may use these to develop their resource pages.
6EARTH’S FRESH WATERSEarth’s Fresh Waters is one of four rotating, two-year events of the Dynamic Planet event.: Earth’s Fresh Waters: Glaciers: Oceanography: Earthquakes & VolcanoesShare your thoughts on replacing “Glaciers” with Earth’s Surface Features in the next segment.
7EARTH’S FRESH WATERSEarth’s Fresh Waters extends its predecessor, “Rivers and Lakes,” to include the vast groundwater resources.With the addition of groundwater most major sources of Earth’s fresh waters are addressed in the Dynamic Planet events.
8EARTH’S FRESH WATERS1. DESCRIPTION: Students will use process skills to complete tasks related to Earth’s fresh watersA TEAM OF UP TO: 2APPROXIMATE TIME: 50 Minutes
9EARTH’S FRESH WATERS TEAM SELECTION SUGGESTIONS: a. Since this is the first of a two-year event, coaches may consider selecting participants who are quite likely to be competing the following year as well.b. Road Scholar, Awesome Aquifer, and/or Remote Sensing are good “companion” events to accompany this event.c. Earth’s Fresh Waters is an excellent entry-level event.
10EARTH’S FRESH WATERS2. EVENT PARAMETERS: Each team may bring up to four 8.5” x 11” double-sided pages of notes containing information in any form from any source and bring up to two non-graphing calculators.
11EARTH’S FRESH WATERS: RESOURCE PAGES Two suggestions for participants to meet with success in this event require that they develop:1. A thorough knowledge of all topics listed within the event rules2. Thorough and well organized resource pages
12EARTH’S FRESH WATERS: Resource Pages Resource pages play a crucial role in this event.a. Encourage participants to review a vast array of published materials from credible sources – USGS, Groundwater Associationb. Serve as a tool for coaches to monitor participant preparationc. Should be continuously updated as participants become more knowledgeable through study, and experience at various levels of competition
13EARTH’S FRESH WATERS: Resource Pages Suggestions regarding resource pages:a. Choose a font large enough to permit rapid visual scanningb. Organize notes for efficient usec. Include diagrams, tables, charts, definitionsd. Remember that the contents of this PPT are simply an outline and must be expanded upon.
14EARTH’S FRESH WATERS3. THE COMPETITION: Participants will be presented with one or more tasks, many requiring the use of process skills (i.e. observing, classifying, measuring, inferring, predicting, communicating, and using number relationships) from the following topics:Note: Topics are very specific to avoid confusion as to what participants should know.
15INTERPRETATION OF FRESH WATER FEATURES a. Interpretation of fresh water features appearing on USGS topographic mapsReference: USGS Topographic Map Symbols sheet
16STREAM DRAINAGE SYSTEMS b. Stream drainage systems: drainage patterns, main channel, tributaries, V-shaped valleys, watersheds
17STREAM DRAINAGE SYSTEMS: Main Channel In rivers and hydrology, the main stem is defined as the principal channel within a given drainage basin, into which all of the tributary streams in a drainage basin flow.
18STREAM DRAINAGE SYSTEMS A drainage system is the pattern formed by the streams, rivers, and lakes in a particular drainage. They are governed bythe topography of the land,whether a particular region is dominated by hard or soft rocks,and the gradient of the land.Be aware that different sources use different names for the various drainage system patterns, in addition tosome sources including additional patterns.
19STREAM DRAINAGE SYSTEMS: Drainage Patterns: Dendritic A dendritic drainage pattern develops in regions underlain by homogeneous material. That is, the subsurface geology has a similar resistance to weathering so there is no apparent control over the direction the tributaries take.
20STREAM DRAINAGE SYSTEMS: Drainage Patterns: Parallel Parallel drainage patterns form where there is a pronounced slope to the surface.Tributary streams tend to stretch out in a parallel-like fashion following the slope of the surface.
21STREAM DRAINAGE SYSTEMS: Drainage Patterns: Trellis Trellis drainage develops in folded topography like that found in the Appalachian Mountains of North America.Down-turned folds called synclines form valleys in which the main channel of the stream resides.
22STREAM DRAINAGE SYSTEMS: Drainage Patterns: Rectangular The rectangular drainage pattern is found in regions that have undergone faulting.Streams follow the path of least resistance and thus are concentrated in places where exposed rock is weakest.
23STREAM DRAINAGE SYSTEMS: Drainage Patterns: Radial The radial drainage pattern develops around a central elevated point.This pattern is common to such conically shaped features as volcanoes.
24STREAM DRAINAGE SYSTEMS: Drainage Patterns: Centripetal The centripetal drainage pattern is just the opposite of the radial as streams flow toward a central depression.This pattern is typical in the western and southwestern portions of the United States where basins exhibit interior drainage.
25STREAM DRAINAGE SYSTEMS: Drainage Patterns: Contorted Deranged or contorted patterns develop from the disruption of a pre-existing drainage pattern.
26STREAM DRAINAGE SYSTEMS: Tributaries A tributary is a stream or river which flows into a main stem river.A tributary does not flow directly into a sea, ocean, or lake.Tributaries and their main stem river serve to drain the surrounding drainage basin of its surface water and groundwater by leading the water out into an ocean or some other large body of water.
27STREAM DRAINAGE SYSTEMS: V-Shaped Valleys A V-shaped valley is a narrow valley with steeply sloped sides that appear similar to the letter "V" from a cross-section.They are formed by strong streams, which over time have cut down into the rock through a process called downcutting.These valleys form in mountainous and/or highland areas with streams in their "youthful" stage.
28STREAM DRAINAGE SYSTEMS: Watersheds A drainage basin is the topographic region from which a stream receives runoff, throughflow, and groundwater flow.Drainage basins are separated from each other by topographic barriers called watersheds.A watershed represents all of the stream tributaries that flow to some location along the stream channel.
30CHANNEL TYPES: Defined A stream is a body of water that transports rock particles and dissolved ions and flows downslope along a clearly defined path, called a channel.The deepest part of a channel occurs where the stream velocity is greatest.
34SEDIMENTd. Sediment: weathering, erosion, forms and sizes, transportation, deposition
35SEDIMENT : Erosion by Streams Stream flow can be either laminar, in which all water molecules travel along similar parallel paths, or turbulent, in which individual particles take irregular paths.
36SEDIMENT: Erosion by Streams Streams erode because they have the ability to pick up rock fragments and transport them to a new location.The size of the fragments that can be transported is dependent upon the velocity of the stream and whether the flow is laminar or turbulent.
37SEDIMENT: Erosion by streams Turbulent flow can keep fragments in suspension longer than laminar flow.Streams may erode by undercutting their banks resulting in mass-wasting processes like slumps or slides.When the undercut material falls into the stream, the fragments can be transported away by the stream.
38RIVER VALLEY FORMS AND PROCESSES e. River valley forms and processes: geology, gradient, base level, floodplain features, dynamic equilibrium, nick points, waterfalls, stream capture, deltas and fans
39RIVER VALLEY FORMS AND PROCESSES: Gradient Long Profile - a plot of elevation versus distance.Usually shows a steep gradient near the source of the stream and a gentle gradient as the stream approaches its mouth.
40RIVER VALLEY FORMS AND PROCESSES: Gradient When a natural or artificial dam impedes stream flow, the stream adjusts to the new base level by adjusting its long profile.
41RIVER VALLEY FORMS AND PROCESSES: Gradient Erosion takes place downstream from the dam.Just upstream from the dam the velocity of the stream is lowered so that deposition of sediment occurs causing the gradient to become lower.
42RIVER VALLEY FORMS AND PROCESSES: Base Level Base Level - base level is defined as the limiting level below which a stream cannot erode its channel.For streams that empty into the oceans, base level is sea level.Local base levels can occur where the stream meets a resistant body of rock, where a natural or artificial dam impedes further channel erosion, or where the stream empties into a lake.
43RIVER VALLEY FORMS AND PROCESSES: Floodplain features As a stream overtops its banks during a flood, the velocity of the flood will first be high, but will suddenly decrease as the water flows out over the gentle gradient of the floodplain.Because of the sudden decrease in velocity, the coarser grained suspended sediment will be deposited along the riverbank, eventually building up a natural levee.
44RIVER VALLEY FORMS AND PROCESSES: Floodplain Features Terraces are exposed former floodplain deposits that result when the stream begins down cutting into its flood plain.This is usually caused by regional uplift or by lowering the regional base level, such as a drop in sea level.
45RIVER VALLEY FORMS AND PROCESSES: Floodplain Features When a steep mountain stream enters a flat valley, there is a sudden decrease in gradient and velocity.Sediment transported in the stream will suddenly become deposited along the valley walls in an alluvial fan.
46RIVER VALLEY FORMS AND PROCESSES: Floodplain Features When a stream enters a standing body of water such as a lake or ocean, again there is a sudden decrease in velocity and the stream deposits its sediment in a deposit called a delta.
47STREAM FLOWf. Perennial and intermittent stream flow, stream gauging and monitoring, stream flow calculations, discharge, load, floods, recurrence intervals, and for C-Division only – Chezy and Manning equations
48STREAM FLOW: Manning Equation (C-Division only) One the most commonly used equations governing Open Channel Flow is known as the Manning’s Equation.It was introduced by the Irish Engineer Robert Manning in 1889 as an alternative to the Chezy Equation.Manning’s equation is an empirical equation that applies to uniform flow in open channels and is a function of the channel velocity, flow area and channel slope.
49STREAM FLOW: Open Channel Flow Defined The analysis of flow patterns of water surface shape, velocity, shear stress and discharge through a stream reach falls under the heading Open Channel Flow.Open Channel Flow is defined as fluid flow with a free surface open to the atmosphere. Examples include streams, rivers and culverts not flowing full. Open channel flow assumes that the pressure at the surface is constant and the hydraulic grade line is at the surface of the fluidSteady and unsteady flow depend on whether flow depth and velocity change with time at a point. In general, if the quantity of water entering and leaving the reach does not change, then the flow is considered steady.
50STREAM FLOW: Chézy Formula In fluid dynamics, the Chézy formula describes the mean flow velocity of steady, turbulent open channel flow.
51STREAM FLOW: Discharge Discharge - The discharge of a stream is the amount of water passing any point in a given time.Q = A x VDischarge (m3/sec) = Cross-sectional Area [width x average depth] (m2) x Average Velocity (m/sec).
52STREAM FLOW: Discharge As the amount of water in a stream increases, the stream must adjust its velocity and cross sectional area in order to form a balance.Discharge increases as more water is added through rainfall, tributary streams, or from groundwater seeping into the stream.As discharge increases, generally width, depth, and velocity of the stream also increase.
53STREAM FLOW: LoadThe rock particles and dissolved ions carried by the stream are called the stream's load. Stream load is divided into three parts:Suspended loadBed loadDissolved load
54STREAM FLOW: Suspended Load Suspended Load - particles that are carried along with the water in the main part of the streams.The size of these particles depends on their density and the velocity of the stream.Higher velocity currents in the stream can carry larger and denser particles.
55STREAM FLOW: Bed LoadBed Load - coarser and denser particles that remain on the bed of the stream most of the time but move by a process of saltation (jumping) as a result of collisions between particles, and turbulent eddies.
56STREAM FLOW: Dissolved load Dissolved Load - ions that have been introduced into the water by chemical weathering of rocks.This load is invisible because the ions are dissolved in the water.The dissolved load consists mainly of HCO3- (bicarbonate ions), Ca+2, SO4-2, Cl-, Na+2, Mg+2, and K+. These ions are eventually carried to the oceans and give the oceans their salty character.
57STREAM FLOW: FloodsFloods occur when the discharge of the stream becomes too high to be accommodated in the normal stream channel.When the discharge becomes too high, the stream widens its channel by overtopping its banks and flooding the low-lying areas surrounding the stream.The areas that become flooded are called floodplains.
58STREAM FLOW: Recurrence Intervals Statistical techniques, through a process called frequency analysis, are used to estimate the probability of the occurrence of a given event.The recurrence interval is based on the probability that the given event will be equaled or exceeded in any given year.
59GROUNDWATERg. Groundwater: zone of aeration, zone of saturation, water table, porosity, permeability, aquifers, confining beds, hydraulic gradient, water table contour lines, flow lines, capillarity, recharge and discharge
60GROUNDWATER: Fascinating Facts Groundwater makes up about 1% of the water on Earth (most water is in oceans).But, groundwater makes up about 35 times the amount of water in lakes and streams.Groundwater occurs everywhere beneath the Earth's surface, but is usually restricted to depths less that about 750 meters.The volume of groundwater is equivalent to a 55 meter thick layer spread out over the entire surface of the Earth.The surface below which all rocks are saturated with groundwater is the water table.
61GROUNDWATER: Zone of Aeration Rain falling on the surface seeps down through the soil and into a zone called the zone of aeration or unsaturated zone where most of the pore spaces are filled with air.
62GROUNDWATER: Zone of Saturation As water penetrates deeper it eventually enters a zone where all pore spaces and fractures are filled with water.This zone is called the saturated zone.
63GROUNDWATER: Water Table The surface beneath the saturated zone in which all openings in the rock are filled with water is called the water table.
64GROUNDWATER: Porosity vs. Permeability The rate of groundwater flow is controlled by two properties of the rock: porosity and permeability.
65GROUNDWATER: Porosity Porosity is the percentage of the volume of the rock that is open space (pore space). This determines the amount of water that a rock can contain.
66GROUNDWATER: Porosity Well-rounded, coarse- grained sediments usually have higher porosity than fine- grained sediments, because the grains do not fit together well.
67GROUNDWATER: Porosity Poorly sorted sediments usually have lower porosity because the fine-grained fragments tend to fill in the open space.
68GROUNDWATER: Porosity Since cements tend to fill in the pore space, highly cemented sedimentary rocks have lower porosity.
69GROUNDWATER: Porosity In igneous and metamorphic rocks porosity is usually low because the minerals tend to be intergrown, leaving little free space.Highly fractured igneous and metamorphic rocks, however, may have high porosity.
70GROUNDWATER: Permeability Permeability is a measure of the degree to which the pore spaces are interconnected, and the size of the interconnections.Low porosity usually results in low permeability, but high porosity does not necessarily imply high permeability.
71GROUNDWATER: Permeability It is possible to have a highly porous rock with little or no interconnections between pores.A good example of a rock with high porosity and low permeability is a vesicular volcanic rock, where the bubbles that once contained gas give the rock a high porosity, but since these holes are not connected to one another the rock has low permeability.
72GROUNDWATER: Permeability A thin layer of water will always be attracted to mineral grains due to the unsatisfied ionic charge on the surface. This is called the force of molecular attraction.
73GROUNDWATER: Permeability If the size of interconnections is not as large as the zone of molecular attraction, the water can't move.Thus, coarse-grained rocks are usually more permeable than fine-grained rocks, and sands are more permeable than clays.
74Porosity vs. Permeability: Possible Activity Gather a sampling of slate, vesicular basalt, clay, sand, small pebbles, etc.Ask participants to classify the materials as having high or low porosity, high or low permeability, and explain why they classified the materials as they did.
75Groundwater: Aquifers An aquifer is a large body of permeable material where groundwater is present in the saturated zone.Good aquifers are those with high permeability such as poorly cemented sands, gravels, and sandstones or highly fractured rock.
76Groundwater: Confining Beds A layer of geologic material which hampers the movement of water into and out of an aquifer. Examples are unfractured igneous rock, metamorphic rock, and shale, or unconsolidated sediments such as clays. This is also known as a confining bed.
77GROUNDWATER: Hydraulic Gradient The rate at which groundwater moves through the saturated zone depends on the permeability of the rock and the hydraulic gradient.The hydraulic gradient is defined as the difference in elevation divided by the distance between two points on the water table.
78GROUNDWATER: Water Level Contour Maps Contours are lines on 2-dimensional maps representing equal values of a parameterYou are probably used to looking at topographic maps which show contour lines of ground surface elevationWhen a map is made with equal interval contour lines (every 1 ft, or every 2 ft, or every 5 ft, etc.), the spacing of contour lines provides visual clues to the change in slopeClosely spaced contour lines would represent steep slopesWidely spaced contour lines would represent gentle slopesWater level contour maps provide the same information on water level slopes (hydraulic gradients)
79GROUNDWATER: Water Table Contour Lines Besides surface water, topography of the land surface also determines the general direction of groundwater flow.Topography influences groundwater recharge and discharge.
80GROUNDWATER: Water Table Contour Lines In an unconfined aquifer like the one covering most of Portage County, recharge areas usually occur in high topographic areas. In Portage County, a groundwater divide is formed by glacial moraines that run from north to south through the center of the County.
81GROUNDWATER: Water Table Contour Lines As shown on this map, groundwater flowing west of this divide discharges into the Wisconsin River system.Groundwater flowing east of the divide discharges into the Tomorrow River system.
82GROUNDWATER: Flow Lines Water table contour lines (or flow lines) are similar to topographic lines on a map. They essentially represent "elevations" in the subsurface. Water table contour lines can be used to tell which way groundwater will flow in a given region.
84GROUNDWATER: Capillarity Plants pull water upward from the water table into open spaces through capillary action.Capillarity refers to the rate at which this water is pulled upward.Soils containing large open spaces have high permeability and low capillarity.
85GROUNDWATER: Recharge Areas Areas where water enters the saturated zone are called recharge areas, because the saturated zone is recharged with groundwater beneath these areas.
86GROUNDWATER: Discharge Areas Areas where groundwater reaches the surface (lakes, streams, swamps, & springs) are called discharge areas because the water is discharged from the saturated zone.
87KARST FEATURESh. Karst features: sinkholes, solution valleys, springs, disappearing streams, caves developed as a consequence of subsurface solution.Karst topography: a distinctive landform assemblage developed as a consequence of the dissolving action of water on carbonate bedrock (usually limestone, dolomite, or marble).
88KARST TOPOGRAPHY: Sinkholes Sinkholes are commonly funnel-shaped and broadly open upward.Sinkholes may be a few feet to more than 100 feet in depth, though usually ranging from 10 to 30 feet.Sinkhole diameter sizes range from a few square yards to several acres in area.
90KARST TOPOGRAPHY: Solution Valleys Solution valleys (or Karst valleys) are the remains of former surface stream valleys whose streams have been diverted underground as karst developed.They may develop a series of sinkholes in the valley floor.
91KARST TOPOGRAPHY: Springs Karst springs occur where the groundwater flow discharges from a conduit or cave.Karst springs or "cave springs" can have large openings and discharge very large volumes of water.Sinkholes and sinking streams that drain to a large karst spring can be many miles away from the spring.
92KARST TOPOGRAPHY: Disappearing Streams Streams flowing along the surface may enter a sinkhole as a "disappearing stream" and flow underground for some distance to reappear at the surface.
94KARST TOPOGRAPHY: Caves Caves (or caverns) are large, open underground areas occurring in massive limestone depositions at or near the surface.Two stages of cavern formation:1. Initial excavation, when water dissolves the limy bedrock and leaves voids.2. Decoration stage, when water leaves behind the compounds it had been carrying in solution (stalactites and stalagmites).
95LAKE FORMATION AND TYPES i. Lake formation and types: faulting, rifting, volcanic action, glaciation, damming of rivers, changes over time
96LAKE FORMATION AND TYPES: Faulting A significant lake-forming force is movement of the tectonic plates that form the Earth’s crust.These lakes typically form at fault lines where plates meet and earthquakes are more common.When adjacent plates separate at fault lines, the steep, narrow gap between them can result in the formation of a graben.Some of the largest, deepest, and oldest lakes on Earth are graben lakes.
97LAKE FORMATION AND TYPES: Rifting A rift lake is a lake formed as a result of subsidence related to movement on faults within a rift zone, an area of extensional tectonics in the continental crust.They are often found within rift valleys and may be very deep.Rift lakes may be bounded by large steep cliffs along the fault margins.
98LAKE FORMATION AND TYPES: Volcanic Action Lakes formed by volcanic activity tend to be relatively small.These lakes may form within the crater of an active but quiet volcano, in a caldera produced by explosion and collapse of an underground magma chamber, on collapsed lava flows, and in valleys dammed by volcanic deposits.
99LAKE FORMATION AND TYPES: Glaciation Lakes tend to be largest and most abundant in high latitude areas in the Northern Hemisphere that were once occupied by glaciers.
100LAKE FORMATION AND TYPES: Damming of Rivers Deposits of eroded glacial debris may disrupt drainage patterns.New York state's Finger Lakes formed by glacial sediment damming rivers and streams.Kettle lakes, common in the Midwest, formed as ice blocks melted in-place within glacial sediment.
101LAKE FORMATION AND TYPES: Changes over Time Lake size and depth can change over time, owing to various reasons.Through natural processes, lakes will ultimately fill with sediment, thereby "evolving" into a terrestrial ecosystem.Human influences can accelerate the process through diversion of water for irrigation.The salinity of a lake can change over time.
102LAKE FEATURESj. Lake features: inflow and outflow, physical and chemical properties, stratification, shorelines, waves
103LAKE FEATURES: Inflow and Outflow Changes in the level of a lake are controlled by the difference between the input and output compared to the total volume of the lake.Significant input sources include precipitation onto the lake, runoff carried by streams and channels from the lake's catchment area, groundwater channels and aquifers, and artificial sources from outside the catchment area.
104LAKE FEATURES: Inflow and Outflow Output sources include evaporation from the lake, surface and groundwater flows, and any extraction of lake water by humans.As climate conditions and human water requirements vary, these will create fluctuations in the lake level.
105LAKE FEATURES: Physical and Chemical Properties Lakes vary physically in terms of light levels, temperature, and water currents.Lakes vary chemically in terms of nutrients, major ions, and contaminants.
106LAKE FEATURES: Stratification Due to the unusual relationship between water temperature and its density, lakes form layers called thermoclines, layers of drastically varying temperature relative to depth.
107LAKE FEATURES: Shorelines Shorelines are forever changing in response to tides, nearshore currents, sea level changes and the supply of sediment from rivers.The end result is that existing shorelines will be modified overtime.
108LAKE FEATURES: WavesWave size is dependent upon wind speeds, duration and the distance the wind blows over a continuous water surface or fetch.Lakes and rivers have less surface area so they have less fetch and smaller waves than the oceans.
109WETLANDSk. Wetlands: bogs and marshes, interactions between surface and groundwater
110WETLANDS: Bogs and Marshes Marshes form near ponds and lakes. Reeds, grasses and other soft-stemmed plants grow there.Bogs begin as shallow ponds that slowly fill with rotting leaves and plants. Then mosses and other plants grow spreading out from the shore across the surface of the bog, forming a thick mat. There is little air under the mat and the acids from plants build up. This slows decay, so things, which fall into bogs, take a long time to rot.
111WETLANDS: Interactions between Surface and Groundwater
112EFFECTS OF LAND USE CHANGES l. Effects of land use changes, dams and levees: sedimentation, diversion of water, flooding, ecological changes
113EFFECTS OF LAND USE CHANGES: Dams and Levees Dams alter the flow, temperature, and sediment regime of lotic systems. Additionally, many rivers are dammed at multiple locations, amplifying the impact.Dams can cause enhanced clarity and reduced variability in stream flow, which is due to an increase in periphyton abundance.Invertebrates immediately below a dam can show reductions in species richness due to an overall reduction in habitat heterogeneity.
114EFFECTS OF LAND USE CHANGES: Dams and Levees Thermal changes can affect insect development, with abnormally warm winter temperatures obscuring cues to break egg diapause and overly cool summer temperatures leaving too few acceptable days to complete growth.Dams fragment river systems, isolating previously continuous populations, and preventing the migrations of anadromous and catadromous species.
115EFFECTS OF LAND USE CHANGES: Sedimentation Direct participants to the “Background” link on this website - Rolling Down the River: Sediment in Streams
116EFFECTS OF LAND USE CHANGES: Diversion of Water What happened in the mid 1930’s to slow the flow of water from the Colorado River? Construction of the Hoover Dam
117EFFECTS OF LAND USE CHANGES: Flooding Hundreds of years ago, the Delaware River Basin was covered by forests. This maximized the infiltration of rainfall and slowed the movement of runoff.As the land was cleared for agriculture, infiltration rates were reduced and runoff rates increased. The increase in runoff rates widened flood plains and stream channels in many of the basin's watersheds.With gradual urbanization and the increasing use of asphalt and concrete paving, in addition to densely spaced buildings, infiltration rates were further reduced with corresponding increases in runoff rates.
118EFFECTS OF LAND USE CHANGES: Ecological Changes The following human activities, performed on land, bring about major ecological changes in river and stream environments:DamsChannelizingDevelopmentLoggingUrban RunoffDisappearing StreamsMining and MineralsInvasive SpeciesFor more information on each of these topics, visit
119HYDROLOGIC CYCLE & WATER BUDGETS m. Hydrologic cycle and water budgets: precipitation, runoff, evaporation
120HYDROLOGIC CYCLE & WATER BUDGETS: Hydrologic Cycle
121HYDROLOGIC CYCLE & WATER BUDGETS: Water Budget Every drainage basin has inputs and outputs of water. It is possible to measure these and, by using a simple equation, work out the water budget for the basin Runoff = precipitation - evaporation + changes in storage The river flow out of a drainage basin depends upon three main factors:1. The amount of precipitation2. The losses by evaporation or evapotranspiration3. The gains or losses from the storage areas: surface storage, soil moisture and groundwater stores.
122POLLUTIONn. Pollution: types, sources and transport
123POLLUTION: types, sources, transport A lotic ecosystem is the ecosystem of a river, stream or spring. Included in the environment are the biotic interactions (amongst plants, animals and micro-organisms) as well as the abiotic interactions (physical and chemical).Note: the definition of a lotic ecosystem has been included to assure that the reader can better understand the contents of the next slide.
124POLLUTION: types, sources, transport Pollutant sources of lotic systems are hard to control because they derive, often in small amounts, over a very wide area and enter the system at many locations along its length.Agricultural fields often deliver large quantities of sediments, nutrients, and chemicals to nearby streams and rivers.
125POLLUTION: types, sources, transport Urban and residential areas can also add to this pollution when contaminants are accumulated on impervious surfaces such as roads and parking lots that then drain into the system.Elevated nutrient concentrations, especially nitrogen and phosphorus which are key components of fertilizers, can increase periphyton growth, which can be particularly dangerous in slow moving streams.
126POLLUTION: types, sources, transport Another pollutant, acid rain, forms from sulfur dioxide and nitrous oxide emitted from factories and power stations.These substances readily dissolve in atmospheric moisture and enter lotic systems through precipitation.This can lower the pH of these sites, affecting all trophic levels from algae to vertebrates (Brown 1987).Mean species richness and total species numbers within a system decrease with decreasing pH.
127EARTH’S FRESH WATERS 4. REPRESENTATIVE TASKS: a. Analyze and interpret features and actions of a stream or river appearing on a topographic map including contour intervals, elevation, gradient, direction of flow, drainage pattern, valley shapes, erosional landscapes, and depositional features
128EARTH’S FRESH WATERS 4. REPRESENTATIVE TASKS: b. Construct a water table contour map and indicate the direction of groundwater movement.
129EARTH’S FRESH WATERS 4. REPRESENTATIVE TASKS: Analyze data on the thermal structure of a lake and determine how the stratification changes seasonally.
130EARTH’S FRESH WATERS5. SCORING: Points will be awarded for the quality and accuracy of responses. Ties will be broken by the accuracy and/or quality of answers to pre-selected questions.
131EARTH’S FRESH WATERSRECOMMENDED RESOURCES: Websites:Books: Tarbuck, Edward J. and Frederick K. Lutgens, Earth Science. Prentice Hall, 2006.ISBN-10: ; Leopold, Luna B., Water, Rivers and Creeks. University Science Books, ISBN
132EARTH’S FRESH WATERSNATIONAL SCIENCE EDUCATION STANDARDS: Middle School/Junior High: Content Standard D: Structure of the Earth System; Earth’s historySenior High School: Content Standard D: Energy in the earth system; Geochemical cycles; Origin and evolution of the earth system
134EARTH’S FRESH WATERS: Helpful Websites by Topic Basics of Stream Ecology:Earth's Water – Groundwater topics:Lake Formation:Manning’s Equation
135EARTH’S FRESH WATERS: Helpful Websites by Topic Lake formationWater budgetDrainage patterns
136EARTH’S FRESH WATERS: Helpful Websites by Topic Lake originsBogs and MarshesInteractions between surface and groundwater
137EARTH’S FRESH WATERS: Helpful Websites by Topic Meandering rivers: lots of diagrams and activities (Outstanding/PDF)
138Workshop Activity # 1The next five slides show five different kinds of drainage patterns.The drainage patterns illustrated, in mixed order, are: annular, radial, dendritic, trellis and deranged.Write these names onto a piece of scratch paper for use in identifying the five drainage patterns that follow.