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 Definitions:
 Precipitation: Rain, Sleet, Hail, or Snow
 Evaporation: Transformation of water from liquid state to vapor state.
 Transpiration: Water vapor released by plant leaves, similar to
breathing by animals and humans by breaking down nutrients to generate
energy. You transpire when you run away from a mountain lion, or when
you take the final exam.

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 Surface Runoff:
 The water that runs off over the ground into streams and rivers.
 Base Flow:
 The water that seeps up into a stream from groundwater or water
springs.
 Watershed or Basin:
 Is an area where the precipitation will shed into a stream.

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 Precipitation:
 mm/h (millimeter/hour), approximately 1 mm of water is equivalent to 10
mm of snow. How about wet snow in April?
 Stream Flow:
 m^{3}/s (cubic meter/second). One m^{3}= 1000 liters.

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 Speed:
 m/s (meter/second).
 You can also use the English System (Ft, Gallon, etc.). I will do my
best not to use it because it is dumb, but if you have any questions I
will help.

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 Sources:
 1. Direct Runoff
 2. Groundwater exfiltration, or
also called Base flow (opposite of infiltration)

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 Some of it will evaporate on the way down, air temperature is a factor.
 What is left will hit the ground, some will infiltrate, some will be
trapped in puddles, and some will runoff to streams and rivers. Is a lake a large puddle?

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 Evaporation: Rain, Snow, Surface water, Lakes, Oceans, etc.
 Transpiration: Plants, animals, and wild humans.

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 Can you believe it is Solar Energy?
 Solar Energy causes also wind. Wind increases the rate of evaporation,
why? If you do not know the answer, ask Mr. Science in class, but be
nice.
 Next we will see the processes.

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 The sun heat evaporates water, also creates differences in temperatures
in air masses vertically and horizontally creating wind which will
evaporate water. Animals exhale water vapor, plants exhale water vapor
after sunset.
 The warm vapor cloud rises and moves with the wind. It hits a cool
front, condensates into small droplets, the droplets get bigger and
heavier and fall as rain, snow, or hail, some will evaporate while
falling.

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 Some of the precipitation will be trapped in puddles, some will
evaporate, some will infiltrate the ground, and some will run off into
steams.
 GoTo the beginning of last slide. Now you learned a new word; GoTo, it
is a statement in every programming language, you guessed it, it means
go to.

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 This is not the Monster at the End of this Book! I am scared; Equation!
 Ok, let’s make it simple.
 You have a piggy bank, and you put in $10 each day, take out $16 each
week, how much money did you store in the bank after 28 days?
 If you replace the dollars with m^{3} of water, and the bank
with a stream what will that be?
 Answer: The Hydrologic Equation.

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 To design a water system, we need to know the future water demand, water
supply, and per capita daily use.
 First, we need to forecast the population, using historical growth data.
 Population Growth versus Time can fit:
 Arithmetic (Linear) Growth
 Geometric Growth
 Growth at a declining rate of increase

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 Psat Is the saturation population, the maximum population when the
growth rate reaches zero in a declining growth rate population. An example of a country with a
declining growth rate is China, the population is still growing, but due
to the policy of one child per couple, the annual rate of growth is
declining.
 Ka, Kg, Kd, a, b are assumed constants

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 Remember, when you calculate Psat, the time intervals between P0P1, and
P1P2 have to be equal.
 In the Mathematical Logistic Curve Method, Equation 1.8 in the Text, t
is the time from P0 to Pt.
 Equation 1.19 does not hold if the population is > 10,000
(multiplication by 0)

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 Hydrology Text, Problem 1.1

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