Quiz 8+9

Question 1

Stream flow responde determined by

Answer 1

-spatial and temporal variability in rain
-travel time from watershed area to stream
-travel time from channel entrance to outlet
-slope
-watershed shape
-drainage patterns
-soils and geology

Question 2

Measurement of stage

Answer 2

-height of water surface above arbitrary datum
-manual: staff gauge
-automated: sitting well float

Question 3

Measurement velocity

Answer 3

-distance traveled per unit time
-standard is a six tenths depth

Question 4

Measurement discharge

Answer 4

-rate at which water passes through a given cross section
-destermined using velocity area method

Question 5

Measurement rating curve

Answer 5

-relationship between stage and discharge to each stream.
-uses non linear regression

Question 6

Rational method

Answer 6

-used to predict peak flow rates in small watersheds

Question 7

Runoff generation

Answer 7

-factors affecting
1.precipitation form and intensity
2.storage/soil moisture
3.spatial distribution
4.covergence of flow pathways
5.land use or land disturbance

Question 8

VSA (variable source area)

Answer 8

-most of the storm flow by interflow and saturation Overland flow to stream channel
-infiltration not a limiting factor
-watershed area not a direct index of flow response
-assumes only part of a watershed is making direct contribution to storm flow
Primary contributors
1.interflow
2.saturation excess Overland flow

Question 9

Vsa vs partial

Answer 9

Spatial
1.partial-fixed in area space
2.VSA-expand and contract overtime
Source if water
1.)partial
-INFILTRATION excess Overland flow
2.)VSA
-interflow and saturation excess

Question 10

Erosion

Answer 10

-detachment and transport of unconsolidated material from one place to another

Question 11

Erosion impacts

Answer 11

-nutrient loss
-reduce infiltration
-fills resevoirs
-affects aquatic organisms
-drinking water quality
-carries toxins
-
-

Question 12

Erosion phases

Answer 12

-detachment
Rain drops falling on ground and flowing to dislodge material E=(M)(Vt^2)/2
-transportation
Detached particles moved down hill
-depostion
Particles eventually accumulate somewhere (sedementation)

Question 13

Sheet erosion

Answer 13

-relatively uniform erosion over entire soil surface
-requires Overland flow and is often exacerbated by raindrop impact

Question 14

Rill erosion

Answer 14

-most common form of soil erosion
-occurs when Overland flow breaks up into small channels or microrills

Question 15

Gully erosion

Answer 15

-when depth of a rill is greater than .3m

Question 16

Surface erosion in forest

Answer 16

-high infiltration and interception makes erosion generally not an issue in forest

Question 17

Mass movement commonality

Answer 17

-most common in OR, WA, AND CA in coastal and mountain areas

Question 18

Mass movement factors

Answer 18

-vegetation, topography, land use, precipitation.

Arid, sparse veg = mudflows/debris

Humid/dense veg = earthflows/soil creep

Question 19

Mass movements slide hazar

Answer 19

-slope > 80% except 75% in tyce core area
-headwall configuration
-geology: coast range sandstone with sequences of turbiditbeds

Question 20

Mass movement slides

Answer 20

-down slope movement of soil or rock on a surface of rupture
-occur in response to extreme rain events, snowmelt, grading, adding loads to top slope
Two types
1.translational:movement along a roughly planar surface
2.rotational: curved concavely upward

Question 21

Forces promoting failure

Answer 21

F = resistance of soil to failure / forces promoting failure
Safety factor
- _< 1 imminent failure
->_1 increasing slope stability

Question 22

Debris flow

Answer 22

-form of rapid mass movement in which loose materials flow downslope
-source area: steep gullies

Question 23

Soil creep

Answer 23

-very slow (mm/yr)
-caused by sheer force not great enough to cause failure
-evidence is curved trees

Question 24

Erosion measurements

Answer 24

-silt fences
-erosion pins
-rainfall simulator

Question 25

USLE

Answer 25

-provides an estimate of sheet and rill erosion from rainfall elements on up land areas: principally ag land

Question 26

MUSLE

Answer 26

-Adds vegetation management factor to equation which is why it’s used for forestry

Does it work? Not usually

Question 27

WEPP water erosion prediction project

Answer 27

Used for small scale watersheds.