Water Resources Exam 1

hydrologic cycle

movement of water between land, oceans, and the atmosphere

• driven by the sun

• changes form and location, never created or destroyed

• precipitation, runoff, storage, evaporation

precipitation

process of water in the atmosphere returning to the earth’s surface in liquid or solid form

• rain, snow, sleet, hail, virga

rain

type of precipitation where small moisture droplets undergo a process of coalescence/joining and fall due to gravity

snow, sleet, hail

type of precipitation where small moisture droplets undergo a process of coalescence/joining and fall due to gravity under different thermodynamic conditions

virga

rain that evaporates before reaching the ground

• type of precipitation

rain gauges

measure precipitation as simple glass tubes to elaborate weigh and tipping buckets

• info needed by growers, municipal water providers, crop scientists, forest managers, etc. to adjust water use patterns

• shouldn’t be placed near trees, buildings, etc. for accuracy

arithmetic mean method

measure precipitation as one value derived from the sum of all rainfall divided by the number of gauges

• an average precipitation for an area

Thiessen method

a weighted precipitation value calculation

• stations plotted on a map, lines connect the gauges, perpendicular bisectors drawn between lines, polygons drawn around each station, area calculated, weighted precipitation total obtained

• rainfall in volume of an area calculated based on area of individual sections

isohyetal method

a method to calculate weighted rainfall using contours of equal rainfall (isohyets)

• similar to topographic map

• use grid to determine area, multiply area by average precipitation for that isohyet

doppler radar

emits a burst of energy that strikes raindrops and scatters in all directions; a small amount is directed back toward the device

• reflected signal analyzed for strength and time of travel to the object and back, and phase shift of the pulse

• used to determine WHERE rain is falling, establish rainfall RATES, distinguish between SHOWERS vs LARGE RAIN BANDS

• more accurate method of precipitation measurement

• fast - up to 1300 times a second - how fast is a system moving?

snow pillow

a device used to measure snow depth and water equivalents

runoff

amount of water that flows along the land surface after a storm event or a melting of snow

• factors: climate, terrain (barren, urban areas have greater runoff and lower infiltration; dense vegetation slows runoff and increases infiltration), precipitation intensity and volume

• ex: Amazon River Basin (big runoff volume due to high precipitation, humidity, and massive drainage area), Los Angeles Basin (high runoff volume for short time - hard and impervious soils, extensive development areas of concrete and rooftops), and Sandhills Basin (low runoff volumes - lush ground cover and porous soil)

storage

areas holding water

• lakes - large, naturally occurring inland body of water (glacial melting and runoff)

• reservoirs - artificial or natural inland body of water used to store water for a variety of purposes

El Nino

a natural phenomenon that occurs when a warm surface ocean current forms in the eastern Pacific ocean off the coast of Ecuador and Peru; associated with southward displacement of the intertropical convergence zone (ITCZ) - southern oscillation

• warmer than average sea-surface temperatures in the equatorial Pacific

• weakened trade winds

• more eastward-moving warm water

• increased rainfall in central and eastern Pacific

La Nina

a natural phenomenon caused by cooler water in the equatorial Pacific

• cooler than average sea-surface temperatures

• stronger trade winds - push air toward Asia

• more rain to western Pacific

• cooler conditions in central Pacific

• enhanced hurricane activity in the US

storage in the Aral Sea

because of evaporation and increased concentration of pollutants, the fishing industry has been destroyed, and many fishing vessels were simply abandoned

• between former Soviet Socialist Republics

• during communist period, large scale irrigation projects were developed = dramatically reduced flows into this inland sea

• fishing villages now 60 to 90 miles from water

• Soviet Union 1918 used Amu Darya and Syr Darya rivers feeding Aral Sea to irrigate desert → by 1960, 20-50 cubic kilometers of water going each year to land instead of sea

• 1960s Aral Sea began to shrink → 1961-1970 Aral’s sea level fell at an average of 20 cm a year → 1970s average rate tripled 50-60 cm/yr → 1980s continued to drop, now 80-90 cm/yr

Great Salt Lake of Utah

changing climatic conditions caused long-term fluctuations in lake levels

evaporation

the process whereby water changes from a liquid to a gas through wind action and solar radiation

US Class A Evaporation Pan

standard instrument used to measure evaporation

• galvanized steel pan of 4ft diameter x 10ft deep

• errors caused by excess heat from wall - corrected with coefficient

• must be leveled, water level 50mm below rim

• cup anemometer placed beside the pan to measure the surface wind movement over pan

sublimation

process whereby water changes from a solid to a gas without passing through the liquid state

• evaporation rate factor

transpiration

process of a plant releasing water vapor through its living tissue (stomata)

• evaporation rate factor

evapotranspiration (ET)

includes all evaporation from water and land and transpiration from plants

• evaporation rate factor

potential evapotranspiration

maximum amount of ET that would occur if soil moisture was unlimited

Penman equation

mathematical equation used to determine evaporation rate from an open water surface

modified penman equation

improved Penman equation

Blaney-Criddle method

mathematical method used to determine evapotranspiration rates

lysimeter

field device containing soil and vegetation used to measure ET

• ET = Si - Sf - P + I - D

• evapotranspiration = initial volume of soil moisture - final volume of soil moisture - precipitation entering + irrigation entering - moisture drained from soil

consumptive use (CU)

total amount of water used by the plant in transpiration and evaporation in any specific time

• may be different for different crops and may be different for the same crop at different times and places

• CU = ET + Sc (amount of water stored in plant tissue)

climate

sum of all statistical weather information that helps describe a region and can generally be predicted for centuries into the future

• long term weather pattern in a particular area

• factors: air currents, ocean currents, tilt of Earth; persistent winds caused by uneven distribution of sun heat on Earth

weather

the state of the atmosphere at any given time and place

• only predictable in short time

• moisture, temperature, pressure, wind

Hadley cell

direct, thermally driven circulation near the equator where warm air rises, flows poleward, and sinks around 30 degrees latitude, creating deserts

Ferrel cell

indirect, tilted circulation in mid-latitudes (30-60 degrees) driven by Hadley and Polar cells

• surface air flows poleward (westerlies)

• higher-altitude air flows equatorward = temperate zone weather

Polar cell

large-scale atmospheric circulation pattern in each hemisphere, centered on the polar regions, where cold, dense air sinks at the poles, creating high-pressure zones and polar easterlies

• sinking air spreads toward equator at surface, rises around 60 degrees latitude, then flows back toward poles at higher altitudes

• smallest of the 3

troposphere

lower levels of the atmosphere extending from the Earth’s surface up to the tropopause (small layer beneath stratosphere)

• convection air movements and large vertical temp change

• warm light air at surface rises, cold dense air from upper troposphere sinks (convection)

• warmer temp in tropical/equatorial areas causes high moisture content to be carried in warm air - moisture from low to high latitudes

radiation incoming from the sun

• 25% reflected back by atmosphere

• 5% reflected back by surface of the earth

• 25% absorbed by atmosphere and radiated back to space

• 45% absorbed by surface of land and water

wind

air moves from high to low pressure and differential pressures are caused by differential heating (sun)

• small scale = lake effect

• larger scale = sea breeze

• global scale = wind belts

intertropical convergence zone (ITCZ)

low-pressure zone at the equator where northeast and southeast trade winds flow together; characterized by strong upward air motion and heavy rainfall

Coriolis effect

deflective force of the earth’s rotation on all free-moving objects, including the atmosphere and the ocean; the apparent deflection of objects from a straight path if the objects are viewed from a rotating frame of reference

• manifested in counterclockwise rotation (right) north of the equator and clockwise (left) south of the equator

• true for baseball, air-masse, space-ship, tornado, bullet, etc.

• strongest at poles, weakest at equator

radiation

only form of energy that can be propagated without a transfer medium

• greatest input of energy to Earth-atmosphere system

• can be represented as a stream of particles or as an electric and magnetic wave system

• shorter wavelengths = higher energy photons

electromagnetic radiation (EMR)

energy of a wave in motion at the speed of light

barometer

instrument that measures atmospheric air pressure

humidity

amount of water vapor in the air in a given location

• 4% (hot, humid day in the tropics) to 0.3% (cold winter day) in terms of volume

• dew point (state of total saturation of atmosphere)

• condensation (process of precipitation that occurs when the dew point is reached)

adiabatic process

when an air mass rises and expands without exchanging heat with its surroundings

adiabatic lapse

unsaturated rising and expanding air will drop in temperature at a constant rate of 1 degree C per 100m

• same parcel gain temperature as it falls at the same rate

clouds

dense concentration of suspended water droplets or tiny ice crystals in the atmosphere

• classified on shape, appearance, and height

cumulus clouds

puffy, round, individual cloud masses, often have flat base, formed when hot humid air rises due to convection heating

• stratocumulus - cumulonimbus - altocumulus - cirrocumulus

stratus clouds

low sheet (blanket appearance) or layers of clouds covering much or all the sky

• nimbostratus - altostratus - cirrostratus

cirrus clouds

highest clouds in the sky, composed of thin delicate ice crystals, looks like filaments or feathers, composed entirely of ice crystals

density lifting

clouds move up, due to warm, low-density air due to convection heating

warm weather front

frontal lifting of clouds caused by warm, moist air moving over cooling air → clouds build up and precipitation

cold weather front

frontal lifting of clouds caused by cool air moving under warmer air → clouds formation and precipitation

stationary weather front

Weather fronts with little or no movement

• boundary between 2 fronts, neither of which is strong enough to replace the other

• remain essentially in the same area for an extended period of time

• variety of weather - usually clouds and prolonged precipitation

• dissipate after several days or devolve into shear lines, can change into cold/ warm front if conditions aloft change

• frequent in summer

• marked with alternating red half-circles and blue spikes pointing in opposite directions

orographic lifting

when moisture laden air meets a mountain and the air is forced to ascend → high amounts of precipitates

• ex: Oregon and Washington

convergence lighting

when 2 air masses collide and are both forced upward

occluded front

formed when a cold front overtakes a warm front, forcing the warm air aloft

• 2 fronts curve up naturally to the triple point of occlusion

• variety of weather - thunderstorms; drying of air mass

• indicated by purple line with alternating half circles and triangles pointing in direction of travel

• form around mature low pressure areas

southern oscillation

changing pattern of atmospheric pressure along the equator in the Pacific ocean

• ex: el Nino

wind

horizontal movement of air caused by differences in air pressure

isobars

lines on a map that connect locations of equal air pressure (barometer)

air pressure gradient

determined by the distance between isobars

low barometric pressure

area where air near the ground flows into a region of low pressure

high barometric pressure

area where air near the ground flows away from a region of high pressure

jet stream

very strong winds at high altitudes created by differences in air pressure gradient

weather modification

any change in local weather events caused by humans

cloud seeding

introduction of dry ice or silver iodide into clouds to enhance precipitation or to reduce hail development

• creating nucleus by converting gaseous water to solid state = rain

drought

period of extended dry weather that is abnormal for a region

• meteorological (not normal precipitation)

• hydrological (below surface and groundwater supplies)

• agricultural (inadequate water supplies to grow a particular crop)

• socioeconomic (inadequate water supplies to serve local)

aridity

permanent, dry climatic condition in a region where average annual precipitation is less than 10 inches

palmer index

index used to determine when to provide emergency drought assistance

water resources

all aspects relating to the development of water as vital natural resource

• forms: surface and groundwater

qanat

a gently sloping underground channel or tunnel constructed to lead water from the interior of a hill to a village below

• middle east - originated in Persia (Iran)

• planning: examine landscape, survey assessment

• circular strips used to hold tunnel from collapsing

• Khettara, Surangam, Foggara, Falaj

aqueduct

gravity fed delivery system to provide water to urban centers

• invented by Romans in 312 BC

• excess water used for fountains and to flush sewers

cistern

underground reservoirs lined with clay or dug into limestone

China 2280 to 500 BC

precipitation ranges from 5-32 inches annually → flood control and irrigation (levees, dams, reservoirs)

• 1360-1644 (canalization of floodwater areas, tambour auger-type device, increase in velocity → increase scouring of riverbed to greater depth → decrease in flooding)

Sumerian 3000-2000 BC

first time extensive laws were adopted to properly operate water resources

• middle east

Assyrians 2400 BC

extension of law to precipitation, groundwater, and water stored in cisterns

• middle east

Spain and Portugal Moorish 711 to 1499

new irrigation techniques

• acequias - irrigation and water supply channels

• acenas - water mills

• charcas - water reservoirs

Europe

• 1236 pipeline systems constructed in London

• 1619 first private company (New River Company) started to deliver water throughout London (first time every home in a city received water through pipes)

• end 1800s - most towns/cities in Great Britain had municipal water systems

NA Brigham Young + Mormon followers 1801-1877

canals along Jordan river - Utah (2ft/mile)

• 1862 Congress passed Homestead Act = ownership of 160 acres of land if lived on it for 5yrs

• Horace Greeley 1870 - irrigation canal ditch

irrigation

supplying water to crops to ensure they can survive drought

water screw

• physical remains found in places, such as Beaune, France, Pasadas, Cordoba, and Sotiel, Coronada (Spain)

• origins to Archimedes 230 BC

• invented to help Egypt with irrigation

force pump

constructed for scientific demonstrations, not practical applications

• used as: fire extinguishers; wash high vaulted ceilings; small-scale extraction of water from wells for irrigation; bilge pump for grain boats and supplying household needs

• composition: mainly bronze - sometimes wood (cheaper)

• Ctesibius of Alexandria 270 BC

compartmented wheel

a narrow body with hollow interior compartments, providing relatively low but quick lift

• open body composed of spokes with compartments in hollow rim of wheel for larger diameter of wheel and higher lift