Lecture Notes Flashcards
Hydrology
The study of water near the earth’s surface
Hydrogeology
Study of the interrelationships of geological material and processes with water. Subsurface issues
Why should we study hydrology
- Water is an important resource. It is increasingly in demand.
- There are many issues with the volume and quantity
- There are many issues with how to manage supplies of water as our climate changes
- The population is increasing which means there are more demands for water
Why is Chicago located where it is?
- Trade routes
* Small portage connecting the Great Lakes to the Mississippi
Ocean saline water
This water has zero fresh water in it
- about 97.2%
- 35 parts per thousand
- Saline does not just mean sodium and chlorine
Type of water in ice caps and glaciers
- Mostly freshwater
- 69% of the total freshwater in the world
- 2.14% of the total water
- problems-often frozen and in hard to reach places
Type of water in groundwater
- Mostly salty
- About .61% of earth’s total water
- About 30% of the world’s freshwater.
- The deeper you go into the ground the more dissolved materials that are present.
Surface water
- about .005% of earth’s total water
- Mostly freshwater
- .9% of total freshwater on earth
Atmospheric water
- .001% of earth’s total water
- Fresh water
- .1% of total freshwater on earth
How rapidly can water get exchanged between reservoirs?
It depends on the reservoir
*global ground water-1000s of years (very slow)
*global turnover atmospheric water-9 days (very quickly)
*global surface water-2-4 weeks
Varying time scales and volumes
(You don’t need to know exact numbers, just general ideas)
Residence time
total volume held is a reservoir/total flux in or out.
Units of residence time are simply in time
If a reservoir is well mixed what does the residence time give you
The average time expected for each water particle to spend there. (Every particle has the same probability of appearing anywhere in the reservoir)
Hydrologic cycle
Describes the storage and movement of water from one part of the earth to another
Ocean evaporation
Takes heat out of the ocean. As water turns from gas to liquid energy is also required.
Transpiration
plants release water during photosynthesis
Evapotranspiration
Evaporation and transpiration
What is meant by a steady state
Inputs are equal to outputs
The Aral sea
- Was a fairly large lake in the mountainous area of Asia
- A dry area without much precipitation, was fed by many rivers
- Most of the output was from evaporation
- Freshwarer coming into the lake system was diverted for agriculture
- About 90% of the surface area of the Aral sea was lost
- Sediments from under the lake caused a lot of pollution
- This lake no longer modifies climate
Mono Lake in California
- Snow from the mountains melted and ended up in mono lake
- There is a lot of volcanism in that area and the plates move relatively quickly
- This did not become and aral sea situation because there are laws in place that keep the water there
Percentage of world’s freshwater stored in the great lakes
21%
Percentage of America’s freshwater stored in the Great Lakes
84%
Drainage Basin
Also called a watershed or catchment
*Area that topographically appears to contribute water through a port of a stream.
What is the angle between hydrogens in a water molecule
105 percent
What types of bonds hold together water molecules
covalent
How does the melting and boiling point of water compare to other liquids?
It is relatively high due to hydrogen bonding.
Which is denser liquid water or water ice
Liquid water
Evaporation
break some of the hydrogen bonds and some molecules fly off into the air
What is always involved in phase changes
energy.
After evaporation remaining liquid water is cooler
What does the density of water depend on
Temperature, pressure, and chemical composition (In water this is salinity)
Pressure
The force applied perpindicular to the durface of an object. Measured in force per area.
pressure= force/area= mass*acceleration/area= N/m^2= Pa
Surface tension
why we get “nice little beads” hydrogen bonds holding molecules together. At the free surface H and O are not clinging to anything else. The net effect is an inward force at the surface that causes the water to act as if there is a membrane at the free surface of the water.
What produces capilarity?
surface tension
At what temperature is water at it’s maximum density?
About 4 degrees
Is warmer water lower or higher density than cold water.
Lower
Heat exchange
Heat added or removed as we go through different parts of the water cycle.
Specific heat
What is the amount of heat (H) that must be added to raise a unit mass (M) by a unit of temperature (T)?
Cp=H/(T*M)
How does the energy needed to increase liquid water compare to the energy needed to increase ice?
What are the implications of this?
You need 2x the energy to increase liquid that solid.
(This is why we use water to cool nuclear plants)
(This is why it is easier to get rid of glaciers)
Heat capacity
Specific heat*Objects mass measure in J/Deg C
What does it mean when we say water has a high thermal inertia?
Water tends to stay at about the same temperature unless a large amount of heat is added.
Latent heat
Energy lost or gained when an object undergoes a phase change at a constant temperature
Going from liquid to a solid
Heat is released.
Latent head of fusion
Going from a solid to a liquid
Heat is lost
Going from a liquid to a gas
Heat is lost latent heat of evaporation/vaporization
Sublimination
Ice-vapor. Solid directly to gas.
What are the different ways to measure evaporation?
- Class A evaporating pan. (National weather service standard)
- Lysimeter (Evapotranspirometer. Record precipitation and amount of water lost through soil)
- Atmometer (Measures loss of water from a wetted porous surface)
- Satellites0
What must you take into account when recording evaporation with a Class A evaporating pan
- Correction for the metal pan.
- If it is located in the sun or shade
- If it rains
- If the temperature is below freezing
- Insects (dying in the water or drinking the water)
Humidity
Amount of moisture in the air
Absolute humidity
Gram water/ M^3 air