Quick review of remote sensing,
Introduction to remote sensing in
hydrology, hydrological cycle and
energy balance
Lecture 1
Hydrology focuses on the global hydrologic
cycle and the processes involved in the land
phase of that cycle. Hydrology describes and
predicts:
1. The spatial and temporal variations of water
substance in the terrestrial, oceanic, and
atmospheric compartments of the global
water system.
2. The movement of water on and under the
earth’s surface, the physical, chemical, and
biological processes accompanying that
movement.
Historical Benchmarks
• Monitoring of river flows started by Egyptians
3800 B. P.
• Concept of hydrologic cycle, 3000 B. P., King
Solomon in Ecclesiastes:
All the rivers run into the sea; ….. unto the place from whence
the rivers come, thither they return again.
•. Rainfall measuring, 2400 B. P. in India.
..
.
• Formal recognition of the scientific status of
hydrology, 1920’s and 1930’s, UGG,
AGU…etc.
1.
Hydrologic
cycle
All units in the picture above are 1012 m3.
http://www.globalchange.umich.edu/globalchange1/current/labs/water_cycle/water_cycle.html
• Identify the reservoirs of the hydrological cycle
• Hydrological processes (flux) connecting the reservoirs
• Write the water balance equations for ocean, atmosphere, and land.
Reservoirs
http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hyd/bdgt.rxml
Volume (km3)
Percent of
total
Percent of
freshwater
47,971,710
3.5
Fresh
91,000
0.007
Saline
85,400
0.006
Rivers
2,120
0.0002
0.006
Marshes
11,470
0.0008
0.03
Soil moisture
16,500
0.0012
0.05
Water in Land Areas:
Residence
time (yr)
Lakes:
0.26
Groundwater:
Fresh
10,530,000
0.76
Saline
12,870,000
0.93
1,120
0.0001
0.003
1.76
69.6
0.001
0.04
Biological Water
Icecaps and glaciers 24,364,100
Atmosphere
12,900
Oceans
1,338,000,000 96.5
Total
1,385,984,610 100
30.1
(All surface
water:)
4.0
(All subsurface
water:)
20,000
0.02
2,650
100
Hornberger et al., 1998
Water Storage in the
Atmosphere
• 0.001%
• Water vapor
• Clouds
(water vapor
condensed on
particulate)
Water Balance Equation
where: M = mass within the control volume [M]; t = time [T]; I' =
mass inflow rate [M T-1]; and O' = mass outflow rate [M T-1].
where: V = volume of water within the control volume [L3]; I =
volume inflow rate [L3 T-1]; and O = volume outflow rate [L3 T-1].
where: V = average volume of water stored, and assumed to be
constant; P = average precipitation rate; rsi = average surface
water inflow rate; rgi= average groundwater inflow rate; rso=
average surface water outflow rate; rgo= average groundwater
outflow rate; and et = average evapotranspiration rate. All terms
in the equation have dimensions of volume per time [L3 T-1].
What drives the hydrologic cycle?
2. Energy Balance
http://geography.otago.ac.nz/Courses/283_389/Resources/palaeo/GlobalEnergyBalance.html
•Write the energy balance equations for the earth
Short-wave radiation
http://www.physicalgeography.net/fundamentals/7i.html
Campbell and Norman, 1998
Long-wave radiation
http://www.physicalgeography.net/fundamentals/7i.html
•Write the energy balance equations for the earth surface
Campbell and Norman, 1998
Discussion
• What determine incident short-wave radiation
on the earth surface?
– Solar constant: Describes the Solar Radiation that falls on an
area above the atmosphere at a vertical angle: s = 1.37 kW / m².
– others
• What control out-going long-wave radiation
from the earth surface?
Describe the patterns, and
Explain…
Find the difference
between the two
http://www.agu.org/eos_elec/95206e.html
How is the Hydrological Cycle driven?
3. Atmospheric circulations
If no earth rotation
With earth rotation
http://ess.geology.ufl.edu/ess/Notes/AtmosphericCirculation/atmosphere.html
http://www.blueplanetbiomes.org/climate.htm
4. Oceanic circulations
http://www.uwsp.edu/geo/faculty/ritter/images/maps/ocean_currents.jpg
Hydrologic Information System to the State
in (Near) Real Time Via Internet
Products:
- Rainfall
- Snow cover
- Runoff
- River flow
- Recharge
- ET
-Soil Moisture
-LULC
-VI