Water Resources Exam 1

Two distinct forms of water resources

Surface water and groundwater

Cultural hearth

A source area from which new ideas radiate

Qanat

Underwater channel tapping groundwater supplies which wells could be drilled into; common in middle east and still used today

Aquaduct

Gravity fed delivery system to bring water to urban centers; invented in Rome

Cistern

Underground reservoirs lined with clay or dug into limestone

Hydrologic cycle

Movement of water between the land, oceans, and atmosphere; most found in oceans, very little accessible as fresh drinking water

Precipitation

The process of water in the atmosphere returning to the earth’s surface in liquid or solid form (rain, sleet, snow, virga)

Rain gauge

Instrument used to measure rainfall amounts; not to be placed near buildings or trees

Arithmetic mean

Measures average rainfall for an area (total rainfall/number of gauges)

Thiessen Method

Alternative method to measure average rainfall in area; weighted to be more accurate; plot gauges on map and connect with lines. Using perpendicular bisectors, gauge area is determined

Isohyetal method

Method for weighting rainfall using contours of equal precipitation

Doppler Radar

More accurate method of precipitation measurement in terms of coverage; uses energy bursts to determine strength and distance from storm, and how fast storms are moving

Snow tube

Used to observe snow cores to determine snow depth and characteristics, as well as water equivalent

Snow Pillow

Device that measures snow depth and water equivalents using a pressure plate

Runoff

The amount of water that flows of the land’s surface after a storm event or melting snow; climate, terrain, and precipitation volume/intensity effect runoff values

Lake vs reservoir

Reservoir manmade, lake natural

Wetland

remnant of meandering river

Aral sea

Big lake in arid region (needs river runoff to maintain water levels); severe shrinkage after river water was diverted to farming and irrigation

Evaporation

The process whereby water changes state from a liquid to a gas due to solar radiation and wind action

US class A evaporation pan

Standard instrument used to measure evaporation; pan coefficient used to correct error caused by excess heat from the walls of the pan; must be leveled for accurate calculations and water must be held 50 mm below rim; cup anemometer is often placed next to pan to measure wind

Sublimation

The process in which water changes from a solid to gas state without entering the liquid phase

Transpiration

The process of a plant releasing water vapor through its living tissue

Evapotranspiration

Includes all evaporation from water and land and all transpiration

Potential evapotranspiration

Maximum amount of evapotranspiration that would occur if soil moisture was unlimited

Penman equation

Equation used to determine evaporation rate from an open water surface

Blaney-Criddle method

Equation used to determine evapotranspiration rates

Lysimeters

Field device containing soil and vegetation used to measure evapotranspiration

Consumptive use

The total amount of water used by the plant in transpiration and evaporation in any specific time; may vary among crop species, as well as within species over time or location

Climate

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

Weather

The state of the atmosphere at any given time or place; only predictable in the short term

Conevection

When warm, light air at the earth’s surface rises and cold, dense air from the troposphere sinks

Troposphere

The lower levels of the atmosphere extending from the earth’s surface up to the tropopause

Wind

Occurs when air moves from high to low pressure areas (caused by unequal heating of earth’s surface), small scale: lake effect, larger scale, sea breeze, global scale, wind belts

Intertropical convergence zone

Low-pressure zone at the equator where northwest and southwest trade winds flow together; strong upward air movement and heavy rainfall

Coriolis effect

Deflection force of the earth’s rotation on all free-moving objects, including the earth’s atmosphere and oceans; deflects to the right in the northern hemisphere and to the left in the southern; strongest at poles, weakest at equator

Dendrochronology

The study of tree rings to study the historic climate data

Ice cores

Oxygen isotopes can reveal changes in climates over thousands of years

Ocean corals

Another way to observe historic climate data

Sediment cores 

Climate, environmental, and geological information as far back as 5 million years

Five factors of weather

Air pressure, humidity, temperature, heating, and wind speed/direction

Radiation

The only form of weather that can be propagated without a transfer medium; greatest input to atmosphere; shorter wavelengths=higher energy

Dew point/frost point

Rate of total saturation in the atmosphere; when dew point is reached condensation occurs

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 C/100 m; the same parcel will gain temperature as it rises at the same rate

Clouds

Dense concentration of suspended water droplets or tiny crystals in the atmosphere; classified based on shape, appearance, and height

Cumulus clouds

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

Stratus clouds 

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

Cirrus clouds

Highest clouds in the sky; composed of thin and delicate ice crystals; looks like filaments or feathers

Warm fronts

Frontal lifting caused by warm, moist air moving over cool air; leads to cloud buildup and precipitation

Cold front

Frontal lifting caused by cool air moving under warmer air ; leads to cloud building and precipitation

Stationary front

Weather fronts with little to know movement

Orographic lifting 

Occur when moisture-laden air meets a mountain and the air is forced to ascend; leads to high amounts of precipitation

Convergence lifting

Occurs when two air masses collide and both are forced upwards

Convergence

The process where two air streams come together into a smaller central area, pushing the air molecule in the center to form an upward current (high pressure); divergence is when are moves away from a central area (low pressure)

High pressure vs low pressure northern hemisphere 

Low pressure counterclockwise, high pressure clockwise (opposite in southern hemisphere)

Occluded front

Occurs when a cold front takes over the warm front, forcing it aloft

El nino

A natural phenomena that occurs when a warm surface ocean current forms in the eastern pacific ocean off of the coast of Ecuador and Peru; associated with the southern oscillation

La nina

A natural phenomena caused by cooler water in the equatorial Pacific 

Southern oscillation

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

Isobars

Lines on a map that connect locations of equal air pressure (barometers)

Jet stream

Very strong winds at high latitudes created by differences in air Pr gradient

Air Pr gradient 

Determined by the distance between isobars

Cloud seeding

Introduction of dry ice or silver iodide into clouds to enhance precipitation or retard hail development

Causes of floods

Summer thunderstorms

melting snow

Ice jams in swollen

seasonal monsoons

Drought

Period of extended dry weather that is abnormal for a region 

Aridity

Permanent, dry climatic conditions in a region where annual precipitation is less than 10 inches

Meteorological drought

Departure from normal precipitation

Hydrological drought 

Below surface and groundwater supplies

Agricultural drought

Inadequate water supplies to grow a particular crop

Socioeconomic drought

Inadequate water supplies to serve local community

Drought indices 

Numerical method to assess the severity of below average precipitation in a  region

Palmer index

Index used to determine when to provide emergency drought assistance