DYNAMIC PLANET:EARTH’S FRESH WATERS Presented by: Linder Winter Earth Science Rules Committee Member
Disclaimer • This 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.
Goals for this PPT Presentation • Provide tips on how to coach the event • Provide a brief preview of each event topic • Provide an introductory resource for participants • A number of websites recommended for both participants and event supervisors are listed at the end of this PowerPoint.
Goals 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.
Goals 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.
EARTH’S FRESH WATERS • Earth’s Fresh Waters is one of four rotating, two-year events of the Dynamic Planet event. 2011-1012: Earth’s Fresh Waters 2013-2014: Glaciers 2015-2016: Oceanography 2017-2018: Earthquakes & Volcanoes Share your thoughts on replacing “Glaciers” with Earth’s Surface Features in the next segment.
EARTH’S FRESH WATERS • Earth’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.
EARTH’S FRESH WATERS • 1. DESCRIPTION: Students will use process skills to complete tasks related to Earth’s fresh waters • A TEAM OF UP TO: 2 • APPROXIMATE TIME: 50 Minutes
EARTH’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.
EARTH’S FRESH WATERS • 2. 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.
EARTH’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 rules 2. Thorough and well organized resource pages
EARTH’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 Association b. Serve as a tool for coaches to monitor participant preparation c. Should be continuously updated as participants become more knowledgeable through study, and experience at various levels of competition
EARTH’S FRESH WATERS: Resource Pages • Suggestions regarding resource pages: a. Choose a font large enough to permit rapid visual scanning b. Organize notes for efficient use c. Include diagrams, tables, charts, definitions d. Remember that the contents of this PPT are simply an outline and must be expanded upon.
EARTH’S FRESH WATERS • 3. 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.
INTERPRETATION OF FRESH WATER FEATURES • a. Interpretation of fresh water features appearing on USGS topographic maps Reference: USGS Topographic Map Symbols sheet
STREAM DRAINAGE SYSTEMS • b. Stream drainage systems: drainage patterns, main channel, tributaries, V-shaped valleys, watersheds
STREAM 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.
STREAM DRAINAGE SYSTEMS • A drainage system is the pattern formed by the streams, rivers, and lakes in a particular drainage. They are governed by • the 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.
STREAM 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.
STREAM 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.
STREAM DRAINAGE SYSTEMS: Drainage Patterns: Trellis • Trellis drainagedevelops 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.
STREAM 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.
STREAM 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.
STREAM 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.
STREAM DRAINAGE SYSTEMS: Drainage Patterns: Contorted • Deranged or contorted patterns develop from the disruption of a pre-existing drainage pattern.
STREAM 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.
STREAM 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.
STREAM 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.
CHANNEL TYPES • c. Channel types: braided, meandering, straight
CHANNEL 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. • Thedeepest part of a channel occurs where the stream velocity is greatest.
SEDIMENT • d. Sediment: weathering, erosion, forms and sizes, transportation, deposition
SEDIMENT : 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.
SEDIMENT: 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.
SEDIMENT: 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.
RIVER 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
RIVER 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.
RIVER 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.
RIVER 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.
RIVER 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.
RIVER 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.
RIVER 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.
RIVER 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.
RIVER 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.
STREAM FLOW • f. 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
STREAM 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.
STREAM 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 fluid • Steady 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.
STREAM FLOW: Chézy Formula • In fluid dynamics, the Chézy formula describes the mean flow velocity of steady, turbulent open channel flow.