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1GEOG landscapes and water
Water Resources
24
Geography
Undergraduate 1
03/29/2010

Additional Geography Flashcards

 


 

Cards

Term
how do we use water in the U.S?
Definition

48% thermoelectric power generation

34% irrigation

11% public supply

5% industrial

less than 1%: domestic wells, livestock, mining, aquaculture

Term
how is water used for electric power generation?
Definition

water is used for once-through cooling in power generation plants

 

1/3 water used for this purpose is saline

1kWh electricity requires 37 gallons H2O for fossil fuel plant

1KWh electricity requries 54 gallons H2O for nuclear power plants

1kWh is the amount of electricity used to power 140 W bulb all day long, a pc for 2.5 hours, or a clothes dryer for 15 min

Term
How much of the water on earth is freshwater?
Definition
about 2.5%
Term
where is freshwater found (list from greatest reservoir to smallest) on earth?
Definition

Glaciers and snow 24,064 x 10^3 km^3

Groundwater 23,400 x 10^3km^3

Permafrost 300 x 10^3km^3

Lakes 175 x 10^3km^3

Soil moisture 17 x 10^3km^3

Wetlands 17 x 10^3km^3

Water vapor over sea 10 x 10^3km^3

Water vapor over land 3 x 10^3km^3

Rivers 2 x 10^3km^3

Biological water 1 x 10^3km^3

 

1km^3 = 1kmx1kmx1km or .6mi x .6 mi x .6 mi

the average daily water use accross the USA is 1.5km^3 as of 2000

Term
what is the largest useful water reservoir?
Definition
groundwater
Term
The Hydrologic Cycle
Definition

evapotransporation, transpiration, transport (of water vapor or water), and condensation

 

[image]

Term
what is flux?
Definition

the amount of flow per unit of time

 

can be expressed as volume per time, like gallons per minute or liters per second or thousands of cubic kilometers per year

 

can be expressed as the volume passing through a cross-sectional area per time, which has units of length per time, like millimeters per hour

 

the ___ of water during rainstorms is usually expressed in units of length per time

Term
How much water evaporates over the ocean each ear?
Definition
436.5 thousand km3
Term
How much precipitation occurs over the ocean each year?
Definition
391 thousand km3
Term
How much precipitaion occurs over land each year?
Definition
111 thousand km3
Term
How much water evapotranspires from land each year?
Definition
65.5 thousand km3
Term
What is the net runnof from land (in rivers and groundwater) each year?
Definition
45.5 thousand km3
Term
What is evapotranspiration?
Definition

it includes two parts: evaporation from surfaces and transpiration from plants (respiration and passive transfer of water up from roots and through stomata)

 

an important source of water to the landsurface: over half of the rain and snowfall on land has been recycled at least once on land

Term
How do we calculate how much time water spends within a particular reservoir?
Definition

to find this, you need to know the size of the reservoir and the rate of flow in or out of the reservoir

 

residence time = (volume of reservoir) / (flow rate in or out)

 

 

Term
what is the residence time?
Definition
something with units of time that can be though tof as the time to fill an empty reservoir, or the average time a parcel of water will spend in the reservoir
Term
What are the respective sizes, fluxes, and residence times of: water in the atmosphere, water in rivers, and groundwater?
Definition

Water in the atmosphere: 13 x103km3 = size, 502x103km3/yr = flow, 0.025yr or 9.5 days = residence time

 

Water in rivers: 2 x103km3 = size, 45.5x103km3/yr = flow, 0.044 yr or 16 days = residence time

 

Groundwater: 23,400x103km3 = size, 30.2x103km3/yr = flow, 775 yr = residence time

Term
How do we calculate how much water is available for use?
Definition

Q = P - ET

 

Q = runoff (Q is commonly used to designate a flux, a rate of flow, in many systems: river discharge, flux of heat etc)

P = precipitation

ET = evapotranspiration

Term
What is the global value for Q (runoff)?
Definition
45.5 thousand km3/year
Term
What are the current water withdrawls by humans?
Definition
3.8 thousand km3/year
Term
How much water, of the available potable water on earth, do humans use and why do people talk about water crises/shortages?
Definition
we use only 10% but water resources and human demands for water are not distributed evenly across the globe
Term
Water Scarcity Index (Rws) - definition and equation
Definition

the ratio of water withdrawn for human use divided by the renewable water available for human use

 

Rws = W - S

          Q

 

Rws = water scarcity index

W = total water withdrawn for human use

S = amount of fresh water produced by desalination for human use

Q = available freshwater (runoff)

Term
when is a region considered highly water stressed and why?
Definition

when Rws is greater than 0.4

 

even though this is less than half it's water stressed b/c

1. H2O used for more than just drinking by humans. H2O in rivers needs for riparian communities, fish habitat etc.

2. numbers used in evaluating Rws are annual averages, water delivery in rain and removals for domestic, power, agricluture, and industry all vary in time. a cusion is needed in this annual average to survive drought years or dry seasons

Term
Generally, where is Rws greatest on the globe?
Definition
in highly populated areas
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