Exam 1 Flashcards
Modern Hydrology
the dist of water on Earth’s surface and the movement of water (under/over surface and throughout atmosphere)
Hydrologist
primary focus is fresh water
Water Distribution %s
Oceans: 96.8%
Freshwater: 3.2% (ice=75%; GW=25%) lakes: 0.3; Biosphere: 0.24; soil: 0.06; clouds: 0.03; rivers: 0.003
Amount of freshwater available for use:
0.3%
Water demand growth per year
60 billion cubic m/year
water stressed defiition
any country with less than 1700 cubic m/person
% people water stressed by 2030
47%
% population at risk of water shortages
80%
Global use of water
world avg (ag: 70%; industry: 22%; Domestic: 8%)
Low/middle income countries (ag: 82%; Industrial: 10%; domestic: 8%)
High income countries (industrial: 59%; ag: 30%; domestic 11%)
Water Budget Equation
in flow - outflow = chg storage
P + E + Q + chg S = 0
Precipitation
the release of water from the atmosphere to the surface of the Earth
(expressed as vertical depth)
happens when atmosphere is saturated, small particles present (dust)
water/ice particles large enough to reach earth against updrafts
Boyle’s Law:
P = 1/V
If temp cools:
there is less ability of air to hold moisture (condensation: dew/frost)
Convective precipitation definition
uplift caused by heating of the Earth’s surface
Orographic precipitation definition
air mass is forced to rise over an obstruction (ex: mountain range)
Frontal/ cyclonic precipitation definition
a low pressure weather system where air is constantly being forced upwards
Cloud seeding definition
purposefully putting particles of some sort in the air to entice precipitation to occur
Collision coalescence definition
droplets grow as they collide with other smaller droplets as they fall -pressure will often lift them again until they have enough mass (usually in warm clouds abt 5F)
Bergeron Process definition
a process of ice crystal growths in clouds containing a mixture of supercooled water (abt -40F) and ice when ambient vapor pressure falls between the saturation vapor pressure over water and the lower saturation vapor pressure of ice.
Since ice has less vapor pressure than the supercooled water and water vapor, the water will connect to the ice particles, increasing their size. This often results in precipitation.
(large particles grow at expense of small)
-most common at mid - high latitudes
Dewfall definition
dew forms as temps drop and objects cool down - if cool enough, will also cool air, making it less able to hold the vapor, so the water vapor condenses into dew
Static influences on precipitation distribution
geography, altitude, aspect, and slope
rain shadow definition
when the geographical differences in rainfall in two adjacent regions are very visible (ex: forested mountains vs desert valley)
Rainfall measurement errors
instrumentation and sampling errors
Wetting loss definition
water that stays on the surface of the tunnel and is lost to evaporation
deciding how many rain gauges are needed
the number of gauges will increase with the size of the watershed
Arithmetic mean
taking average of all gauge estimates