CE%20394K.2%20Hydrology%20

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CE 394K.2 Hydrology Lecture 1

• Syllabus, term paper, sequence of topics
• Hydrologic cycle and world water balance
• Water quantities in Texas
• Readings
• For today Applied Hydrology, Chapter 1
• For Tuesday AH, Sections 2.1 and 2.2

Some slides in this presentation were prepared by
Venkatesh Merwade
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Hydrologic Cycle
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Global water balance (volumetric)
Precipitation 100
Precipitation 385
Evaporation 424
Atmospheric moisture flow 39
Evaporation 61
Surface Outflow 38
Land (148.7 km2) (29 of earth area)
Ocean (361.3 km2) (71 of earth area)
Subsurface Outflow 1
Units are in volume per year relative to
precipitation on land (119,000 km3/yr) which is
100 units
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Digital Atlas of the World Water
Balance(Precipitation)
http//www.crwr.utexas.edu/gis/gishyd98/atlas/Atla
s.htm
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Global water balance (mm/yr)
Precipitation 800
Precipitation 1270
Evaporation 1400
Atmospheric moisture flow 316
Evaporation 484
Outflow 316
Land (148.7 km2) (29 of earth area)
Ocean (361.3 km2) (71 of earth area)
What conclusions can we draw from these data?
Applied Hydrology, Table 1.1.2, p.5
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Global Water Resources
105,000 km3 or 0.0076 of total water
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(No Transcript)
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Residence Time
Residence time Average travel time for water to
pass through a subsystem of the hydrologic
cycle Tr S/Q Storage/flow rate
Residence time of global atmospheric moisture
(Ex. 1.1.1) Volume (storage) of atmospheric
water 12,900 km3 Flow rate of moisture from the
atmosphere as precipitation 577,000 km3/yr Tr
12,900/577,000 0.022 yr 8.2 days
One reason why weather cannot be forecast
accurately more than a few days ahead!
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Population and Water Use
global freshwater use is 4000 km3/year 10 of
the renewable supply (44,800km3/year)
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Global Water Availability
500
1350
3850
10000
37500
325000
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Watershed system
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Hydrologic System
Take a watershed and extrude it vertically into
the atmosphere and subsurface, Applied Hydrology,
p.7- 8 A hydrologic system is a structure or
volume in space surrounded by a boundary, that
accepts water and other inputs, operates on them
internally, and produces them as outputs
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Texas Surface Water
Colorado River
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Aquifers in Texas
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Homework 1 How much water is there in Texas?
Category Area (km2) Volume, V (km3) Standard Error Estimate of V
Atmospheric water
Biological water
Rivers
Reservoirs
Small lakes and farm ponds
Marshes
Estuaries
Soil water
Groundwater - fresh
Groundwater - saline
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Standard Error of Estimate
Statistical average, estimates mean m
Standard deviation, estimates s
Standard error of estimate (SEE) of the mean m is
Provided all samples xi are statistically
independent of each other (see Applied Hydrology
Section 11.1 for definition of independence)