EXAM 1: Water/ Hydrologic Cycle Part 2

What is overland flow?

this occurs whenever rate of precipitation is greater than the combined rate of evapotranspiration + inflitration

When is overland flow common? What location?

-during heavy rainfall events; after leaf fall

-arid areas, devoid/lacking to vegetation, etc

What is very important for causing overland flow?

the underlying geology

What is the average reservoir residence time in the atmosphere?

9 days

What is the average reservoir residence time in the rivers?

2 to 6 months

What is the average reservoir residence time in the deep groundwater?

10,000 years

What is the average reservoir residence time in the soil moisture?

1 to 2 months

What is the average reservoir residence time in the ocean?

3,200 years

What is the average reservoir residence time in Antarctica?

20,000 years

What is intensifying the hydrologic cycle?

climate change

What does warming global temperatures do?

raises the upper limit of moisture in the air.

What does climate change lead to?

greater intensity of heavy rain events, droughts, and heat waves

Where is climate change warming the strongest?

Arctic, on land, and in the Northern Hemisphere

Because of climate change, where is precipitation increasing? Where is it decreasing?

-increasing the most in high latitudes, tropics, and monsoon regions

-decreasing in the subtropics

What greenhouse gas is currently at its highest level?

data shows that CO2 levels are at the highest in the last 800,000+ years.

What is the most potent greenhouse gas? Why?

H2O

-water holds the most heat which insulates the earth

What does development lead to?

more impervious cover.

What is there more and less of when there is impervious cover?

-more runoff causing stream bank erosion and incision

-less evapotranspiration, shallow infiltration, and less infiltration

What is incision? What is this not a good zone for?

a downcut in the bank, the stream is eroding down.

-not a good riparian zone (transition between water and land)

Of the water on the earth, how much is on "land"?

2.5%

Of the water on the earth, how much is in rivers?

roughly 0.001%

Of the water on the earth, how much is in the air?

roughly 0.001%

Is there more water in lakes or rivers?

lakes

What are the inputs to lake basins?

-precipitation on lake surface

-land surface influents

-ground water

Do lake basins get most of their water from precipitation?

no, it is generally a small percentage of the total.

When is it important for lake basins to get water from precipitation? What is an example?

in large, shallow lakes.

-Lake Victoria in Africa receives roughly 84% of its water from precipitation (rainfall)

What are the land surface influents on lake basins? What are they affected by?

-streams, overland flow, etc (can be highly variable)

-largely affected by catchment basin topography, geology(desert, mountain, tropics), and vegetation

What are other names for catchment basins? What are they?

-watersheds or drainage basins

-area of land where surface water from rain, melting snow or ice converges to a single point at a lower elevation

What are watersheds usually the exit of?

usually the exit of basin or lake or some arbitrarily defined point in a river or stream

What two functions do ground water have on water and lake basins?

-seepage (important in rock basins where lake extends into water table)

-discrete springs

In the Florence area, how many inches of rain do we see a rain?

55-60 inches

What are open lakes?

lakes with water loss other than through evapotranspiration

What are the two kinds of open lakes?

drainage lakes

seepage lakes

What is a drainage lake? Where is an example?

-loss is from an outlet flow

-best known example are the finger lakes of New York

What is a seepage lake? Are there any in this area?

loss is from seepage into ground water. the water percolates or sinks down.

-none in this area.

What are closed lakes?

evapotranspiration is the only sources of loss for some lakes.

-very seasonal.

What is an example of a closed lake?

the Great Salt Lake, Utah