Section 3

PRECIPTATON 1/31/12 tuesday
key fea
WATER CYCLE includes precipitation lakes ect, various mechanisms of global circulation.

high PRCIPIATION close to the ocean, HOT air can hold MORE water, higher temps higher humidity close to ocean, air RISING,

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loW precip, dry
Air decending, getting “cooler?” and it now maks watervapor, don’tget as much precipititin?? check it out…

o What tools can be used to monitor quantity and patterns of precipitation?
1. Tipping bucket, (aka raingage?)can continuously measure QUATITY of rain, measuring pecipitation ky one of mst important measurements
2. “Belfort” gage (weighing gage)
Can also continously monitor ACCUMULTION of precip, QUANTITY!!
*more common in sowy enviornmets, weighshow much snow comes in
*alta shield, wind deflector breaks it up a little befor wind flies over top, snow more affected by wind than rain.
*wind almost always makes measurements too low.

3. spaial patterns of precip through RADAR (Patterns, patterns of lo and high intensity precipitation, 3 and 4)
4. Satellite
5. Each day image updated, have to record every morning but shows actual precip for te day in different place of the country from normal peoplereprting
6. Prism model – good source of info for MONTHLY and ANNUAL total precip

?Tipping Bucket: Rain gauge that measure precipitation – continuously measures quantity of rain
?Belford Gauge: Weighs – can also continuously monitor accumulation of precipitation and is wind protectant.
?Precipitation Gauge: Weights how much – better because snow could accumulate on top of tipping bucket.

o Why are each of the following precipitation statistics important for watershed management?:? Storm depth
? Storm intensity
? Storm duration
? Storm frequency
? Monthly total
? Annual total
? Annual average


? Storm depth
total depth of precip during a storm
( a storm affects soil absorbtion depth)
? Storm intensity
Depth per length of time( depth/lenth of time of storm)
? Storm duration
length of time of a storm
? Storm frequency
how often a storm of particular duration occurs
? Monthly total
Monthly Total: Defines climate.
? Annual total
Annual Total: Defines climate.
? Annual average (end of individual term efects)
Annual Average: Defines climate.
o How/why do precipitation statistics vary over time and space?
Proximity to oceans, humidity, temperature, topography, global circulation
Seasonal Snow Cover: High latitudes and high elevations
o Where do you find seasonal snow cover?
locations where snow lasts though the winter, found at high latiduteds* ex poles, and high elevations*

2. PERMANENTLY SNOW COVERED REGIONS form glaciers->moving!! (compacted snow–>ice!

o Define snow water equivalent, and describe how it can be measured
SWE depth of liquid water in snowpack.

Measure it to predict stream flow for the next year,
done using

1. Snow pit. Done near peak snow.
How? Measure mass (known volume), figure out Volume of core
Density of water=1000kg/m^3 or 1g/cm^3
(Density of ice Density of aged snow=500kg./m^3
Density of fresh snow=100kg/m^3


2. Snow Pillow. Pad in the middle of high forest open ground, viscous fluid inside, as snow accumulates it keeps track then relate mass to SWE

Depth of liquid water in snow pack. It can be measure by knowing the density of water and density of snow and taking out wedges from the snow. Snow Pillow helps forecast.

o Define interception and the factors that affect it
Part of the precipitation does not hit the ground because it his caught first by tree branches or litter or forbs, shrubs grasses ect. It is hard to quantify but trees release their interception as throughfall or stemflow.
According to the graph, highest percent precipitation intercepted is alfalfa crops 36%, Coniferous forests 28%, Grasses 10-20%, Corn 16%, Deciduous forests 13%, Oats 7%.

Precipitation that does not reach the soil, but is instead intercepted by the leaves and branches of plants and the forest floor.
?Affected by: Vegetation

Latent heat flux over land surfaces.
o Define the land surface energy budget, and explain how it relates to evapotranspiration
How Available energy (Rn)(net radiation) is used at the lands surface
1. LE- Latent heat flux (amount of heat that GOES INTO A PHASE CHANGE OF WATER) ex evaporation *Laten heat flux AKA Evapotranspiration ET!!
2. H- Sensible Heat flux (Energy to HEAT AIR coming from the LANDS SURFACE) ex pavement radiation heats you and the air around it
3. G- Ground heat flux (Energy to heat the ground)

-Almost all Rn is used for LE (in open water!) (Irrigated crop! Because it has plenty of water most of the net radiation is used for LE)
-Rn used for H, no water available for LE (paved surface)
-Available water used for LE, Rest of Rn becomes H or G ( SHRUBS AND GRASSES because when they transpire, they evaporate water out of their leaves to photosynthesize)

Grass that is well watered- most of Rn used in LE (latent heat flux ) irrigated
Grass that is not well watered- plants cant transpire, lower LE

o What atmospheric factors affect potential evapotranspiration?
Evapotranspiration: Latent heat flux over land surfaces.
Potential Evapotranspiration (atmospheric factors affecting): Available energy (net radiation), humidity (HIGH HUMIDITY IS LOW ET), wind (INCREASES ET) transports water vapor.
o What is the difference between potential and actual evapotranspiration?
Difference between Potential and Actual Evapotranspiration: Potential ET is the amount of ET if water is unlimited and actual ET is the amount of ET given the amount of water available. PET depends on available energy (net radiation), humidity, wind. Actual ET depends on soil drying (limits movement through water pores), plants (open/close stomata to control water loss)
Subsurface Flow
Water moving from surface to subsurface, passage of water through the land surface into the subsurface or unsaturated vadose zone
DOWNWARD movement of water
movement of water IN ANY DIRECTION
Unsaturated zone
Part of the Subsurface where pores aren’t completely filled with water,
VADOSE ZONE. inbetween surface an zone of saturation
Saturated Zone
pore spaces completely filled with water, ground water-water in the saturated zone. NOT a big underground lake
Water Table*
in between vadose(unsaturatedzone)and saturated zone.
Top of saturated zone (ground water)
Top surface of saturated zone, below is water, groundwater
Capillary Fringe
Ability of liquid to flow in narrow spaces in opposition to gravity.
HIGHEST with small pores, in clay
LOW in sand
where infiltrating and percolaing water raises the water table, good graph on page 6 of notes for 3B feb 2
Medium that can easily transmit water, a loam (sands)

-not free flowing as youd see ina river
-water flowing throughthe pore spaces of different types of materials

(aquitard) Medium that is a barrier to waterflow, Silts CLAYS at bottom f lake WALL!!!
unfonfined aquifer, in the saturated zone below the water table but above the rock barrier aquiclude that seperates it from the confined aquifer below

connected to surface waterand atmospher
-material that easily transmits water

disconnected from atmosphere due to an impeeding layer (aquiclude or aquitard!)
Volume of pore (void) space/total volume. Large/connected means it will be easy to flow and more storage space.
Increasing infiltration, holes in soil that are much bigger than ones we looked at before, lead to “preferential pathways, and Preferential flow of water” created by root holes, worm, animal burrowing, soil cracking.
Combination of particle sizes in a porose medium. Loam = good for drainage.
o What properties of a soil affect the storage and flow of water?
Texture, structure, pore space, field capacity/wilting point, rain intensity, vegetation, soil wetness, infiltration.
o What soil and land cover conditions favor low/high infiltration?
Integrating factors for infiltration
1. affected by general soil texture and macropores and structure
2. affected by soil wetness, how much water is already there

high infiltration
-high for Coarse material like SAND
– if you have macropores
-Land surface roughness, vegetation, if it is more rough it holds water longer, more infiltration
ex. on vegitated surface, carse soil particles, macroores, dense vegetation or surface litter layer

Low infiltration,
-Fine soil particles,
-on road,
-few macropore, low vegetation, surface compaction EX compacted road surface
– if you already have saturated soil, a higher rain intensity will have low infiltration because the soil cant take anymore on at that point.

o What types of materials make good aquifers, and why?
Coarse sediments, fracured or soluble bedrock, water not free flowing but flowing through pore spaces of different types of materials
o What is the difference between a confined and an unconfined aquifer?
Confined is an aquifer that is connected to surface water and atmosphere whereas the unconfined is disconnected from the atmosphere due to an impeding layer.
Water that reaches a stream by ways ofthe 4 potential pathways.
o What are the potential pathways for water to reach a stream?
1. Infiltration Excess
2. Saturated Overland Flow
3. Shallow Subsurface Flow
4. Groundwater Flow

1. Horton, oerland flow, water that flows on lands surface because RAIN INTENSITY is greater than INFILTRATION RATE
2. water that flows on lands surface because GROUND WATER is SATURATED. Ground water table has risen to the surface
3. Flow through/near the surface layer, SLOWER, usually with high organic matter or MACROPORES
4. Water that travels SLOWLY through the saturated zone. Supplies the BASEFLOW(low flow) in streams.

o Explain which types of land surface and soil conditions favor infiltration excess overland flow.
Overland flow- flowing on the land surface due to infiltration or saturation excess
Subsurface flow- in permeable surface layers or through unconfined aquifers
Saturation overland flow in seeps or springs,