Hydrogeology Exam 1 Review

reservoir

compartment that can be assumed to be literally homogeneous e.g. glaciers, oceans, atmosphere, groundwater, soil moisture

fluxes

rate of transport between reservoirs e.g.precipitation, runoff, evaporation, transpiration

change in storage equation

volume in-volume out = change in storage

watershed

a topographic area that drains to a point

runoff

volume of runoff per watershed area per time

porosity = ?

volume of water an aquifer could yield

equation for porosity

n = volume of voids/ total volume

What is the water the water cycle driven by?

sun and gravity

saturation humidity

air is holding mx. amt of water @ the temp

Hs = mass of water/volume of air

Absolute Humidity

actual amount of water vapor in the air @ a particular temp (vapor density)

mass of water vapor/volume of air

Relative Humidity

Hr = absolute humidity/saturation humidity %

dew point temperature

temperature @ which air can no longer hold water vapor; for a given water vapor content temperature @which Hr = 100%

specific heat capacity

heat required to increase per kilogram of weight by 1C

Does it require more specific heat to melt ice or convert it to steam?

convert it to steam, by one whole magnitude more

What holds more water, warm or cool air.

warm air holds more water than cool air

Does watershed area increase or decrease upstream?

Watershed area decreases upstream, and discharge increases downstream.

Does evaporation and melting collect or release energy?

It requires energy (latent heat of vaporization)

Does condensation and freezing release or collect energy?

It releases energy (latent heat of fusion)

convection

movement or transport created by the tendency of less dense material to rise and denser material to sink

pressure and temperature relationship in the atmosphere

pressure and temperature decrease going up in the atmosphere

formula for specific heat capacity (C)

change in heat (Q) = mass (M)(C)change in temperature(DELTA T)

Ideal Gas law

PV = nRT pressure x volume = moles x gas constant x temperatue

What does air do as vapor pressure increases?

air will become less dense

How much temperature will an air parcel in the atmosphere increase each 1000 m?

10*C

What pressure does air move along?

air moves from high to low pressure

Describe the orographic effect.

Air goes up the windward side of the mountain above the lifting condensation level and produces weather only on that side of the mountain.

Describe the convergence of wind.

Winds converge from opposite directions, which lifts air higher into the atmosphere above the lifting condensation level.

Describe localized convection.

The sun will heat up a more low density air, warming it further so that warm, moist air will now rise

Describe local convergence

When warm air is confronted by cold air, the cold air goes under the warm air and pushes it up further into the atmosphere above the lifting condensation level.

What is the recipe for precipitation?

• lifting moist air to temperature below dew point

• condensation nuclei (aerosols, particulates)

• coalesce water dropletss & overcome the force of gravity

Why is there so much rain at the equator?

air lift → solar radiation → warms water

What are the different ways to measure precipitation?

• tipping bucket rain guage (small local sensors)

• disdrometers (small local sensors)

• doppler (remote sensing satellite)

What is a rainfall over time plot called?

hyetograph

What did horton find?

Horton found that for a given soil, the rate of infiltration will decrease over time exponentially.

capillarity

surface tension, attraction of water to solid surfaces

Why does infiltration rate decrease over time? What forces are at time.

capilarity and gravity

what types of landscapes impact infiltration rate?

• bioturbation - increases infiltration rate

• plowing - increase infiltration

• grazing - decreases infiltration

• changing ground cover - decreases infiltration

• fire - decreases infiltration

How are cumulative infiltration and infiltration rate related?

The higher the infiltration rate, the higher the cumulative infiltration

What substance conditions would lead to higher cumulative infiltration?

larger pores and capillarity

Explain Horton Overland Flow

• rare in nature

• rainfall intensity or rate exceeds infiltration capacity

• ‘saturation from above’

• some water gets infiltrated into the subsurface, and some pools aboveground

Explain Dunne Overland Flow

• temporary transient water table

• water gets absobed into the subsurface until it hits a less permeable layer and that water flows into the pools- ponding and overland flow occur at the same time

• saturation from below

Explain Shallow Sub-Surface Stormflow Interflow

• dunne overland flow that doesn’t intersect w/ groundsurface

• transient/temporary water table and saturation flow towards stream

• the saturated water is the water that pools

Baseflow

• groundwater that feeds streams

• rainfall goes very deep into the subsurface

What graph measures runoff?

hydrograph

What is a spring?

groundwater that intersects with the ground surface

What is the relationship between groundwater and topography?

Groundwater tends to be a subdued replica of topography

What does bank storage help with?

flooding - bank storate is space to accomodate high flows transinity in the subsurface

How do you measure streams?

stage readers

What is a rating curve?

Measure stage on the x and discharge on the y

saturation

volume of water/volume of voids

volume water content

volume of water/total volume

groundwater

any water found in subsurface over atmospheric pressure

aquifer

a water bearing geologic formation that can store and transmit a usable amount of freshwater

What makes a good aquifer material?

• high porosity

• high permeability or high hydraulic conductivity

Artesian Conditions

Where water level in well rises above ground surface

head

the representation of energy in groundwater water will always flow from high to low head

What is a phreatic surface

where water rises above the water table