Hillslope processes

Question 1

Watershed definition

Answer 1

topographic catchment that drains all water received from an upstream area to a single point downstream

Question 2

What area of land containing mountain ranges links all biophysical processes?

Answer 2

Watersheds

Question 3

Climate regimes of BC

Answer 3

• different in coastal to interior to eastern as well as at different elevations
• climate governs how much of whats there and the form and timing of it

Question 4

What is a hydrograph?

Answer 4

a graph showing rate of flow vs. time

Question 5

What will a hydrograph have?

Answer 5

• river characteristics of the physiographic region

- periods of natural high flows, natural low flows and natural flood

Question 6

What will cause a hydograph to show river characteristics that are out of regime?

Answer 6

• major event of normal flooding, natural disturbance, climate change
• controlling discharge (lowered peak) reducing overall flow of channel (i.e. dam)

Question 7

What are the 3 main streamflow regimes of BC

Answer 7

1) Pluvial (rain driven)
2) Nival (snowmelt dominant)
3) Glacial supported

Question 8

What is characteristic of a pluvial streamflow? what area is it most common?

Answer 8

• follows rainfall closely
• highest discharge in Nov-Dec

-coastal lowlands and lower elevations of coast mountains

Question 9

What is characteristic of a nival streamflow? what area is it most common?

Answer 9

low flows through winter
high flows in May-July (freshet-spring thaws)

• interior plateau and mountain regions
• higher elevaitions of coastal mountains

Question 10

What is characteristic of a glacially supported streamflow? what area is it most common?

Answer 10

follows nival pattern-snowmelt spring-glacial melt summer
high flows may-Aug/sept
low flows Dec March (accumulation in snow pack)

occurs in high relief areas with >2-5% glacial cover
i.e. lillooet

Question 11

What 2 overarching controls govern peak flows (flood) in area?

Answer 11

Physiography

Climate

Question 12

Order Coast mountains, cascades, interior plateau and eastern mountains in order of highest annual flow

Answer 12

• Coast and Eastern similar but eastern high flows are only during snowmelt
• cascades
• interior (much drier and cooler than cascades)

Question 13

What are some natural disturbances within a watershed?

Answer 13

landslides
debris flows
earth creep
floods
wind
fire
insects
human disturbances

Question 14

How does a fan occur in a river? how does it affect its stability?

Answer 14

Adds additional sediment from side of slope causing a lateral movement of the river
widen of river causing It to become unstable

Question 15

What impact does a fire have on slope stability?

Answer 15

roots have a 3-4 year window to decompose and cause hillslope failure

Question 16

Mass movements are classified by

Answer 16

1) material type
2) speed
3) water content

Question 17

What are falls?

Answer 17

movement of rock/debris via gravity - no water, very fast

i.e. rock fall

Question 18

What are flows?

Answer 18

movement of soil or rock - lots of water, fast

i.e mud flow, debris flow

Question 19

What are heaves/creeps?

Answer 19

slow and long term mass movement.

movement of material up to the surface of a slope and down a slope - some water, slow

Question 20

What are slides?

Answer 20

an entire mass of material moving along a slip plane - some water, slow