Quick review of remote sensing, Introduction to remote sensing in hydrology, hydrological cycle and

energy balance

Lecture 1

Hydrology focuses on the global hydrologic Hydrology focuses on the global hydrologic cycle and the processes involved in the land cycle and the processes involved in the land phase of that cycle. Hydrology describes and phase of that cycle. Hydrology describes and predicts:predicts:

1.1. The spatial and temporal variations of water The spatial and temporal variations of water substance in the terrestrial, oceanic, and substance in the terrestrial, oceanic, and atmospheric compartments of the global atmospheric compartments of the global water system.water system.

2.2. The movement of water on and under the The movement of water on and under the earth’s surface, the physical, chemical, and earth’s surface, the physical, chemical, and biological processes accompanying that biological processes accompanying that movement.movement.

Historical Benchmarks

• Monitoring of river flows started by Egyptians Monitoring of river flows started by Egyptians 3800 3800 B. P.B. P.

• Concept of hydrologic cycle, 3000 Concept of hydrologic cycle, 3000 B. P.B. P., King , King Solomon in Ecclesiastes:Solomon in Ecclesiastes:

All the rivers run into the sea; ….. unto the place from whence All the rivers run into the sea; ….. unto the place from whence the rivers come, thither they return again.the rivers come, thither they return again.

• Rainfall measuring, 2400 Rainfall measuring, 2400 B. P.B. P. in India. in India.

........

• Formal recognition of the scientific status of Formal recognition of the scientific status of hydrology, 1920’s and 1930’s, UGG, AGU…hydrology, 1920’s and 1930’s, UGG, AGU…etc.etc.

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.

1.Hydrologic

cycle

Reservoirs

http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hyd/bdgt.rxml

Volume (km3) Percent of

totalPercent of freshwater

Residence time (yr)

Water in Land Areas: 47,971,710 3.5

(All surface water:) 4.0

Lakes:

Fresh 91,000 0.007 0.26

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

Groundwater: (All subsurface water:) 20,000 Fresh 10,530,000 0.76 30.1

Saline 12,870,000 0.93

Biological Water 1,120 0.0001 0.003

Icecaps and glaciers 24,364,100 1.76 69.6

Atmosphere 12,900 0.001 0.04 0.02

Oceans 1,338,000,000 96.5 2,650

Total 1,385,984,610 100 100

Hornberger et al., 1998

Water Storage in the Atmosphere

• 0.001%0.001%• Water vapor Water vapor • CloudsClouds

(water vapor (water vapor condensed on condensed on particulate)particulate)

where: M = mass within the control volume [M]; t = time [T]; I' = mass inflow rate [M T1]; and O' = mass outflow rate [M T1].

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].

Water Balance Equation

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 T1].

What drives the hydrologic cycle?

http://geography.otago.ac.nz/Courses/283_389/Resources/palaeo/GlobalEnergyBalance.html

2. Energy Balance

•Write the energy balance equations for the earth

http://www.physicalgeography.net/fundamentals/7i.html

Short-wave radiation

Campbell and Norman, 1998

http://www.physicalgeography.net/fundamentals/7i.html

Long-wave radiation

•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?

http://www.agu.org/eos_elec/95206e.html

Describe the patterns, and Explain…

Find the difference between the two

How is the Hydrological Cycle driven?

http://ess.geology.ufl.edu/ess/Notes/AtmosphericCirculation/atmosphere.html

3. Atmospheric circulations

If no earth rotation With earth rotation

http://www.blueplanetbiomes.org/climate.htm

http://www.uwsp.edu/geo/faculty/ritter/images/maps/ocean_currents.jpg

4. Oceanic circulations

Hydrologic Information System to the Statein (Near) Real Time Via Internet

Products: - Rainfall- Snow cover- Runoff- River flow- Recharge- ET-Soil Moisture-LULC-VI