Lecture panel 2

Question 1

What is hydrologic Science?

Answer 1

science of the waters of the Earth including:

• occurence/ origins
• distribution
• circulation
• physical and chemical properties
• reaction with the environment
• relationship to life

Question 2

Where do the physical, chemical, and biological components of the hydrologic cycle occur?

Answer 2

within all components of the Earth system

-Atmosphere, oceans, solid earth, Ice sheets, rivers, lakes, biosphere

Question 3

What must we know about to asses precipitation and evaporation?

Answer 3

climatology and meteorology

Question 4

What must we know to assess infiltration and evaporation?

Answer 4

soil physics

Question 5

What must we know to assess transpiration?

Answer 5

biological processes

Question 6

What must we know to assess groundwater flow?

Answer 6

geology

Question 7

What must we know to assess surface runoff?

Answer 7

geomorphology

Question 8

What must we know to assess streamflow?

Answer 8

fluid mechanics

Question 9

What are the two “states” of water in the hydrologic cycle?

Answer 9

reservoirs and fluxes

Question 10

Principal storages in hydrologic cycle

Answer 10

• interception storage
• snowpack
• surface detention
• soil moisture
• groundwater
• streams and lakes

Question 11

principal pathways of the hydrologic cycle

Answer 11

• precipitation
• throughfall and stemflow
• snowmelt
• infiltration
• percolation
• groundwater flow
• overland flow
• channel flow
• evapotranspiration

Question 12

Major reservoirs in hydrologic cycle

Answer 12

oceans
glaciers/snow
groundwater
lakes/rivers
atmosphere

Question 13

major fluxes in hydrologic cycle

Answer 13

evapotranspiration
runoff
precipitation
groundwater flow

Question 14

Global annual average water balance values given in units relative to 100 for rate of precipitation on land:

Answer 14

precipitation on land - 100
evaporation from land - 61
moisture over land - 39
surface discharge - 38
groundwater discharge - 1
evaporation from ocean - 424
precipitation on ocean - 385

Question 15

Where is Earth’s water stored?

Answer 15

97.22% Ocean
2.78% freshwater
for freshwater:
-77.78% surface (>99% in glaciers) (note: <1% of total water)
-11% GW, 11% deep GW
-0.18% soil moisture

Question 16

properties of large reservoirs

Answer 16

low variability and greater persistence

Question 17

residence time

Answer 17

(T) = average length of time a parcel of water spends in a particular reservoir. also called turnover time
T = Storage volume / flux
where flux is in units volume/time

Question 18

Continuity/ Water balance equation

Answer 18

dS/dt = Inputs - Outputs

• change in storage over time
• inputs and outputs depend on the reservoir

Question 19

What is a control volume?

Answer 19

“box model” - any substance that enters the control volume must leave at the same rate, or either accumulate or deplete supplies within
-steady state has no change in storage volume ie. fluxes are in balance

Question 20

Types of control volumes in hydrology

Answer 20

• Basin
• sub-basin
• landscape units
• fields, forest stands

Question 21

What scale is the concept of water balance useful at?

Answer 21

All scales:

• Macro-scale eg. continental watershed
• meso-scale eg. Grand River basin
• Micro-scale eg. leaf, field

Question 22

What is the typical area for the water balance equation to be applied to?

Answer 22

catchment or watershed

-watershed is defined topographically

Question 23

watershed definition

Answer 23

represents an area that will contribute all the water that passes through a given cross section of a stream (groundwater flow may be a separate source)

Question 24

Water balance limitations

Answer 24

-all processes operate at different spatial and temporal scales that may not coincide with our measurements - adds imprecision in our assumptions

Question 25

What is the general water year?

Answer 25

Oct 1 - Sept 30

-minimizes differences in storage (avoid spring surges, etc. i.e. calmest/steadiest time of year)