Hydrology

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Author:
ichiban2008
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107678
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Hydrology
Updated:
2011-10-11 01:16:10
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water
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Test 1
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  1. Decimals
    WHEN WRITING DECIMALS, ALWAYS PUT A 0 IN FRONT IF THERE ARE NO OTHER DIGITS; 0.5 NOT .
  2. Precision
    the degree or fineness of a measurement
  3. Discharge Equation
    Q = V*A
  4. hydrology
    the geoscience that describes and predicts the occurrence, circulation, and distribution of the water of the earth and its atmosphere

    • concerned with the land phase of the hydro cycle
    • the distribution (and storage) of water on the surface and beneath the surface, and the physical, chemical and biological interactions with the materials of the earth and the living things on it.

    fresh water is the main concern but salt is not forgotten

    concerned with enginering to find solutions to problems posed by water
  5. Hydro Cycle

    Model

    Conservative quantity
    the distribution and spatial and temporal variations of water substance in the terrestrial, oceanic, and atmospheric compartments of the global water system.

    A conceptual model of how water moves around between the Earth and the atmosphere in different states (gas, liquid, solid).

    A conservative quantity is one that cannot be created or destroyed within the system. (don't gain or lose in total, its just moves from one thing to the next)
  6. Why the Hydro Cycle is important
    life, manufacturing, cooling systems (nuclear), solvent, agriculture, transportation, electricity (turbines), politically/weapon (cut off water supply), cooking, disinfect (boiling), modifies climate via heat transfer
  7. Hydrogen Bonding
    the attraction of H to O between the positively charges end of one molecule (H) and the negatively charged end of another (O)

    • +H
    • -O

    the attractive interaction of a hydrogen atom with an electronegative atom, such as nitrogen, oxygen or fluorine, that comes from another molecule or chemical group. The hydrogen must be covalently bonded to another electronegative atom to create the bond. These bonds can occur between molecules (intermolecularly), or within different parts of a single molecule
  8. Heating Water

    Cooling Water
    high additions of energy cause the eventually breaking down of all hydrogen bonds till evaporation occurs

    the energy is so low that the hydro bonds lock together the molecules into 3D crystals of ice
  9. Less dense to more dense from...
    gas to solid to liquid
  10. Heat Capacity
    the amound of energy needed to raise 1 gram of water 1 degree C

    water has a high heat capacity meaning it changes temperatures slowly

    important due to lakes heat/cool slower than land

    resistant to sudden changes in tempo

    moderate the earth temp

    acts as a coolant/heater during sudden temp changes
  11. Latent Heat
    the energy absorbed or released during a change of state

    when a solid turns into a liquid (v.v) energy must be supplied to stop it from being a solid.

    this energy, supplied externally does not bring about a change in temp
  12. latent heat of vaporization
    when water is heated above 100, more heat is needed to cause the water to evaporate
  13. latent heat of fusion
    when water is cooled to 0, more heat must be removed to form ice
  14. Viscosity
    the resistance of a liquid to motion

    • low - warm - fast flow
    • high - cold - slow flow

    important to marine life

    causes small animals/plants to not sink

    allows for liquid to flow through pipes easily (oil ex)
  15. Cohesion
    the action or property of like molecules sticking together, being mutually attractive. This is an intrinsic property of asubstance that is caused by the shape and structure of its molecules which makes the distribution of orbitingelectrons irregular when molecules get close to one another, creating electrical attraction that can maintain a macroscopic structure such as a water drop.
  16. Surface Tension
    because of cohesion, water has a high surface tension, or high resistance to penetration or stretching of the surface
  17. Cohesion/Surface Tension importance
    formation of waves

    suporting surface for organisms

    water fills pore space; gives soil its look
  18. Capillarity
    the ability of a narrow tube to draw a liquid upwards against the force of gravity

    importants cause it is responsible for moving goundwater from wet areas to dry areas
  19. Universal Solevant of Water ???
    due to the marked polarity of the water molecule and its tendency to form hydrogen bonds with other molecules.
  20. What is water solevency good for
    • Vital reactions in living organisms occur in water
    • Living organisms receive nourishment through food dissolved in water
    • Water dissolves chemicals from rocks and adds them to the soil and lakes, rivers, and the ocean
    • Water also dissolves and makes available substances essential to marine organisms, like fertilizers and carbon dioxide (for plants) and oxygen (for animals)
    • Coke, Pepsi, sweet drinks
    • Dissolves statues, buildings, other things we make and expose to water
  21. What powers the Hydro cycle
    main power source is the sun

    gravity adds some energy along with humans

    plants add energy when burned as wood
  22. Water Balence Equation
    A mathematical description of the processes operating within a given timeframe that incorporates principles of mass and energy continuity.

    P + Gin - (Q+ ET + Gout) = change in S

    • Precipitation
    • Ground Water In Out
    • Discharge
    • Evapotranspiration
    • Storage

    -----------------------------

    Input - Output = Change in Storage
  23. Evapotranspiration Equation
    P - Q = ET
  24. You have an uncovered swimming pool (20 ft * 20 ft * 6 ft) with a leak at the bottom. You want to know how much water you are losing in ft3 /day and in gallons per day . (Water costs money).

    After 10 days, the water is 60 in deep.
    Over the 10 days, the evaporation adds up to 3 in. Rainfall going in is 1 in.
    What is your water loss in in? In ft?
    • 12 inches - 3 inches + 1 inch =
    • loss of 10 incheschange
    • 0.83 ft in
    • 1 inch a day/.08 ft a day depth

    Change in Volume

    • [(10 in) * (1 ft/12in) * (20 ft) * (20ft)
    • = 33.3 ft^3 per day
  25. Watershed
    the area of land that drains water, sediment, and disolved materials to a common outlet at some point along a stream channel

    An area surrounded by a continuous topographic divide within which all runoff joins and single stream and extends downstream to the point that the stream crosses the divide.

    The area that appears on the basis of topography to contribute all the water that passes through a given cross section of a stream

    The surface trace of the boundary that delimits a watershed is called the divide.

    A watershed is a natural landscape unit
  26. Errors with WBE
    • Model Error
    • Change in Storage might be 0
    • Gin/out might be negligble
    • Measurement Error
    • P/Q/ET/etc might not be accurate
  27. Spatial Variability
    precip gauges are unevenlly distributed over any given region, therefore sample is technically unrepresentative

    cant put buckets everywhere
  28. Temporal Variability

    Y
    inputs, storage, and outputs are all time distributed variables; they vary over time

    stream flow is highly variable, causing estimates to be off, causing problems with management

    Y

    • It depends on season
    • It depends on daily P (even within one day)
    • It depends on groundwater flow
  29. Time Series

    EX
    discrete sequence of values with each value assigned to a particular time in the sequence

    EX) the number of days with moer than 1 mm rain in each year at a particular place
  30. Flow Duration Curve

    Y
    The flow duration curve is a plot that shows the percentage of time that flow in a stream is likely to equal or exceed some specified value of interest.

    • FDC concerned with the amount of time a certain flow is exceeded
    • Use daily mean flow (average for each day) NOT
    • Mean daily flow (average of a series of daily flows)
    • More than 5 years usually needed

    Y

    Range of flows and their frequency (how often)
  31. how is the earth heated
    70% comes from the earths surface

    30% comes from solar radiation

    earth is warmed from BELOW

    suns incoming shortwave radiation is transformed to longwave radiation after hitting the earth and bouncing back into the atmosphere (GREENHOUSE)
  32. Radiation
    process by which electromagnetic energy emits from an object

    hotter the body, more intens radiation, the shorter the wavelength
  33. Conduction
    the movement of energy from one molecule to another WITHOUT CHANGES in the relative positions of the molecules

    EX) movement of heat from metal to hand to brain to cussing
  34. Convection
    the transfer of heat by a MOVING SUBSTANCE

    molecules actually move from one place to another
  35. what causes season
    tilt of the earth

    the seasons are caused by the contrasts in the solar radiation receipts as the north and southern hemisphere are alternately tilted toward (summer) and away from (winter) the sun
  36. What causes wind to blow?
    • heating of the earth…causing a difference in pressure
    • cold air is more weight creating more pressure
    • vice versa
    • high pressure goes clockwise and outward and spreading out
    • vice versa
  37. what factors affect global distribution of precipitation
    latitude

    altitude

    slope

    topography
  38. teleconnection
    a climatic anomaly that is a distant consequence of another climatic anomaly

    EX) ENSO

    El Nino Southern Oscillation

    warm phase - abnormally high sea surface temp occur along with low pressure in eastern pacific and high pressure in western pacific

    this shift can ause droughts, unusually cold/warm winters, torrential (heavy,violent) rains
  39. 3 types of sediment load carried by rivers
    • disolved
    • product of chemical weathering
    • suspended
    • fine particles carried long distances
    • small
    • largest fraction of the sediment being carried
    • bed
    • particles moved along by rolling, sliding, or saltation
    • BIG
  40. Types of Precip
    • Drizzle
    • fine mist
    • low intensity
    • Rain
    • all liquid heaver than drizzle
    • low to moderate to high intensity
    • Sleet
    • rain that freezes as it falls
    • Freezing Rain
    • supercooled rain falling on surfaces that are below freezing
    • Snow
    • ice crystals that reach the ground as single or joined together crystals as snow flakes
    • Hail
    • round lumps of ice
  41. Adiabatic cooling
    Adiabatic cooling is due to change in density/pressure without an addition or loss of heat
  42. Convectional Lifting
    as earth is heated by the sun, bubbles of hot air (thermals) rise upward from the warm surface

    a thermal cools as it rises and becomes diluted as it mixes with the surrounding air

    the moisture condenses and is visible as a cloud
  43. Convergent Lifting
    resulting from air being forced upward in a low pressure system

    air pushed together can only go up


    ---------->>>>> ^ <<<<<<------------
  44. Oragraphic Lifting
    resulting from the lifting of air masses due to topography
  45. Cyclonic Lifting
    low pressure system

    air rushes into the low and rises, expecially if air is warm and moist

    Non-frontal convergence

    ITCZ – converging trade winds lead to lifting and condensation
  46. Factors causing precip distributions of time
    • seasonal variations
    • huricane seasons
    • mid lat regions
    • longterm variations
    • periods of drought
    • movement of fronts
    • on/off shore winds
    • mountain/valley winds
    • wind/storm speed
  47. uses of precip data
    • weather
    • flood prediction
    • event planning
    • agriculture
    • water supplies
    • buildig structures
    • recreation
  48. why is it hard measuring snow/rain
    wind

    gauge may be functionally incorrectly

    plain and simple human error

    trees/buildings

    splash

    evaporation

    water on sides and top of gauges
  49. what times scales are we interested in
    • per day
    • per hour
    • per month
    • per year
  50. Theissen Polygons
    plot gauges

    draw lines conecting stations

    draw lines perpindicular through the midpoint of each line

    measure each area and express it a a percent of the basin

    add to get average

    ------

    allows for uneven distributions of stations

    allows for inclusion of stations not in basisn

    words well for high topographic regions
  51. Isohytel
    most accurate

    plot gauges

    draw lines of equal rainfall

    find averages between lines

    find area; express as a %

    multiply by rainfall

    add both to get average
  52. Magnitude
    amount of rain
  53. Intensity
    rainfall per unit of time

    How much rain we can expect during a 30-minute, 1 hour, 6 hour, 24 hour storm

    rate/time ex) 1 inch per hour
  54. Duration
    how long the rainfall even lasts or period of rainfall you are interested in

    how long does it last for
  55. Frequency
    how often an event occurs

    • How often a certain amount of rainfall is likely to occur
    • Based on the probable occurrence of such a rainfall in a given year
    • e.g. a 2-yr rainfall has a 50% chance of occurring in a given year or once every 2 years
    • e.g. a 100-yr rainfall has a 1% chance of occurring in a given year or once every 100 years
  56. Accuracy

    factors causing inaccuracy
    the degree of conformity of a measured/calculated quantity to its actual (true) value

    inaccuracy:

    • What size should the orifice (opening) be?
    • How should the orifice be oriented?
    • How much should the gage protrude above the ground surface?
    • Should the gage have a wind shield?
    • How far should the gage be from trees, buildings, etc.?
    • How can we prevent water from splashing in or out?
    • How about evaporation?
  57. Precision
    the degree that further measurements or calculations will show the same or similar results
  58. Rain Gauges Common Errors
    • Losses due to evaporation
    • Losses due to wetting of the gage
    • Over-measurement due to splash from surrounding area
    • Under-measurement due to turbulence around the gage
    • Instrument error
    • Human error


    • There are about 13,000 gages sites in the US
    • 10,000 non-recording and 3000 recording
    • They are maintained by professionals at weather stations and by unpaid observers at many other sites
    • On average, each station represents about 235 sq mi
  59. Anual seasonal averages are good for what
    planning for urban areas

    agriculture

    flood mitigation

    structure; design

    water supply
  60. PMP/F
    Probable Max Precip/Flood

    the greatest depth of P for a given period that is physically possible over a given storm
  61. PMP/F estimation
    examine rainfall data for largest flood in and near the region of interest

    estimate the combo of conditions that could have produced the rainfall

    uses PMP maps based on meterological analysis

    storm size based on basin size/duration/intensity
  62. Cumulative Frequecny Distribution
    Fi = (m(n+1) *100

    Fi - % of years with a rainfall less than or equal than the particular rainfall

    M - smallest rainfall; then up...

    N - number of values you have

    -------

    *gives the N anual precip values according to size
  63. IDF
    Intensity Duration Frequency Analysis

    T = 1/p = (n+1)/M

    T - recurrence interval (return period) - average interval between events greater than or equal to a given magniuted; expressed in years

    P - probability that the anual max will be equal to or greater
  64. IDF EX
    10 year range

    24 hour max is 8 inches

    on average, 1/10 years, you will have 8 inches of rain

    Recurrance Interval is the "1/10 years"
  65. What problems can we encounter when we use IDF? What factors do we have to consider?
    problems; but no other method to use with current technology

    1) extrapolating to periods longer than we have data for can lead to large errors

    estimating only events with a return period no longer than the length of the record is best but often estimates for long periods are needed despite lack of data

    using a small sample size is not a good thing

    2) This approach does not take climatic change into consideration

    the probabilities we calculate using the sample may not represent the actual population

    climate changes; next 30 years could be different, so using the previous 30 years data is useless

    3) due to persistence in the climate, data points might not be independent

    assumptions is its independent

    4) use of different data samples (periods) gives different results. Which is true?

    changing the period changes the data

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