L13: Hydrologic Cycle

Question 1

Define polar

Answer 1

More negative charge near the oxygen, more positive near the hydrogen

Question 2

How is the water molecule formed

Answer 2

Formed by the covalent bond of 2 hydrogens to an oxygen; bent molecule at 104.5 angle

Question 3

Phases of water

Answer 3

Ice, water vapour, liquid water

Question 4

Transitions between phases _______ or _______ energy

Answer 4

• Absorb

- Release

Question 5

When is energy absorbed by water?

Answer 5

While going from a more ordered to a less ordered phase

Question 6

Properties of liquid water

Answer 6

• Polarity makes water an excellent solvent for ionic and polar substances, including many minerals
• Polarity causes water molecules to form hydrogen bonds with other water molecules in a solution; this is how it achieves high surface tension

Question 7

How do water molecules achieve high surface tension?

Answer 7

Polarity causes water molecules to form hydrogen bonds with other water molecules in a solution

Question 8

Properties of ice

Answer 8

• Ice is a mineral

- Expands as it freezes; ice has an open crystal lattice, which causes it to have a lower density than liquid water

Question 9

Mineral properties

Answer 9

Fixed composition
Defined structure
Inorganic
Naturally occurring
Solid

Question 10

What are some consequences of ice properties?

Answer 10

Ice is able to float in liquid water; expansion of freezing water can cause physical weathering (ex. The fracturing of rocks

Question 11

Define hydrologic reservoirs

Answer 11

• Places in the water cycle where water is stored

Ex. Oceans, the atmosphere, lakes, rivers, etc.

Question 12

Freshwater

Answer 12

• Useful for consumption and agriculture; 2.5% of all water on earth
• Of this, 75% is locked in ice

Question 13

Where does water reside on the earth

Answer 13

Notebook

Question 14

Define residence time

Answer 14

The average amount of time that a water molecule stays in a particular reservoir

Question 15

Surface water bodies

Answer 15

• Lakes, rivers, wetlands

- Less than 0.01% total water on Earth

Question 16

Define flux

Answer 16

• The rate at which water moves between reservoirs

- Earths reservoirs have hugely different reservoir times; check in notebook

Question 17

Define hydrologic balance

Answer 17

Reservoir sizes, residence times, and fluxes combined

Question 18

How does water flow at the surface?

Answer 18

• Overland flow

- Stream flow

Question 19

Overland flow

Answer 19

• The initial sheet-like movement of water downhill with gravity
• Ex. Some of the rainfall and meltwater on the landscape begin to flow across the surface once the soil is saturated

Question 20

Stream flow

Answer 20

• Once the flow of water occurs in an established channel

- Overland flow becomes channelized due to erosion, typically over relatively short distances

Question 21

What are the 2 major sources of the flow of water in streams

Answer 21

1. Overland flow contributions

2. Baseflow

Question 22

Baseflow

Answer 22

The input of groundwater through the bed of a river, contributing to its flow

Question 23

Streams are organized into _________

Answer 23

River systems

Question 24

Define tributaries

Answer 24

Small streams; typically merge downstream

Question 25

Define drainage basin

Answer 25

Area drained by a major river and its tributaries

Question 26

How are drainage basins separated?

Answer 26

• By drainage divides

- Topographic highs (ex. Continental divides) typically separate water drainage basins that flow into different oceans

Question 27

What is river behaviour controlled by?

Answer 27

• Width/depth of the channel: Both increase downstream as tributaries join
• Channel gradient: Or the steepness of the channel decreases downstream
• Average velocity: The average speed of the water in the channel increases downstream
• Discharge: The flux of water moving through the river at any given point, increases downstream

Question 28

River behaviour properties change along the channel as . . .

Answer 28

We go from headwaters (upstream) to the mouth (downstream)

Question 29

Discharge

Answer 29

• Determined by calculating the cross-sectional area of a river
• Notes

Question 30

Why are river systems important?

Answer 30

• Important in physical erosion and weathering, as well as global transport routes for:
  - Dissolved ions in solution
  - Suspended sediments
  - The bed load of a stream or a river
• Intimately tied to the four physical properties

Question 31

What is a dissolved load?

Answer 31

Major ions in rivers; primarily come from the dissolution of minerals

Question 32

Suspended load

Answer 32

• Compromised of particulate matter (ex. clays) that remains in suspension in a river or stream
• Smaller particles settle more slowly than larger ones and so are transported farther
• Water often appears cloudy and opaque due to suspended load

Question 33

Bed load

Answer 33

Compromised of the typically larger particle in a river system that are transported by moving along the bed

Question 34

Hydrographs

Answer 34

A record of river discharge at one point in the river continuously over many years

Question 35

What are particles in the bed load able to do?

Answer 35

• Roll: Rotate along the bed without leaving it
• Slide: Move along the bed without leaving it
• Move by saltation: Hopping along the bed, leaving it for short periods of time

Question 36

Short periods of ______________ in a river, often cause most of the ______ transport over a year

Answer 36

• High discharge

- mass

Question 37

Trends in the river mass transport

Answer 37

Notebook

Question 38

How do we calculate discharge?

Answer 38

Width x depth x velocity of water

Question 39

Faster flow = moves _______ particles

Answer 39

Larger