Option A 1

Question 1

Drainage Basin

Answer 1

An area of land drained by a river and its tributaries, its boundary marked by high land, known as a Drainage divide or watershed.
Inputs: precipitation of varying types of intensity.
Outputs: evaporation and transpiration
Flows: infiltration, throughflow, overland flow and base flow
Stores: vegetation(interception), soil, aquifers and cryosphere.

Question 2

Overland Flow

Answer 2

does not have a permanent channel
forms when the intensity and amount overtake the infiltration rate/capacity.

Question 3

Infiltration

Answer 3

The process by which water soaks into or is absorbed by the soil.
1. vegetation increases infiltration efficiency
2. affected by soil type, land use, gradient and antecedent moisture.

Question 4

Base flow

Answer 4

flow of groundwater

Question 5

Aquifer

Answer 5

A body of saturated rock or sediment through which water can move easily

Question 6

River Discharge

Answer 6

The volume of water that flows past a given cross-sectional area in a unit of time (m^3/sec)

Question 7

Hydraulic Radius

Answer 7

The ratio between the area of the cross-section and the length of the wetted perimeter.

Question 8

Suspension

Answer 8

Fine particles (clay and silt) are dislodged and carried by turbulence in a fast-flowing river.

Question 9

Solution

Answer 9

Water flowing in a river channel CONTAINS ACIDS. If the bedrock is readily soluble, such as limestones, are constantly dissolved in running water and removed in solutions.

Question 10

Saltation

Answer 10

When pebbles, sand and gravel are temprorarily lifted up by the current and bounced along the bed in a hopping motion.

Question 11

Traction

Answer 11

when the largest cobbles and boulders roll or slide along the bed.

Question 12

Hydraulic Action

Answer 12

The force of air and water on the sides of rivers and in cracks. It includes the direct force of flowing water and cavitation force of air exploding.

Question 13

Abrasion

Answer 13

The wearing away of bed and bank by the river load. It is a mechanical impact produced by the debris eroding the river’s bed and bank.

Question 14

Solution

Answer 14

The removal of chemical ions, especially calcium. The key factors controlling the rate of solution are bedrock, solute concentration of the stream water, discharge and velocity.

Question 15

Base level

Answer 15

The lowest limit a stream can erode. SEA LEVEL IS CONSIDERED ULTIMATE LEVEL

Question 16

Bar

Answer 16

A ridge of sediment, usually sand gravel, is deposited in the middle or along the banks of a stream. Bars are formed by deposition when a stream’s discharge or velocity decreases.

Question 17

Braided Stream

Answer 17

Consists of complex network of converging channels
interwoven in appearance (wide and shallow)
develop as the river carries HIGH LOAD with COARSE MATERIAL and has highly VARIABLE DISCHARGE

Question 18

Natural Levees

Answer 18

The area behind a levee is poorly drained
(water cannot flow over the levee and into the river)

Question 19

Back Swamps

Answer 19

Formed after flooding

Question 20

Meanders

Answer 20

Outside concave bank: 阻挡河流流动
Inside convex bank (内凹)
Development of River Meanders
Point Bar: the low velocity on the inside of a curve promotes sediment deposition, creating a bar.
- Rarely fixed in position(Migrate back and forth across a flat valley floor because of contiued erosion and deposition)

Question 21

Oxbow Lake

Answer 21

Formation: The old meander is abandoned. Sediments separate it from the new. Shorter channel.
An Oxbow may be filled with sediment and vegetation.

Question 22

Floodplain

Answer 22

A broad strip of land built up by sedimentation on either side of a river channel
some are dominated by meanders shifting back and forth

Question 23

Interception (vegetation store)

Answer 23

Water that is retained by plant surfaces and which is later evaporated away or absorbed by the plant.