Water Pathways

Question 1

What do water pathways control

Answer 1

Denudation processes

Question 2

What are the denudation processes, starting from the smallest scale

Answer 2

Solution
Erosion (particles and aggregates)
Mass movement (landslides)

Question 3

What are the 2 stages of erosion

Answer 3

Detachment and transport

Question 4

What are the two controls of erosion

Answer 4

Erodibility

Erosivity

Question 5

What is erodibility

Answer 5

Properties of soil trying to keep it in one place

Question 6

What is erosivity

Answer 6

Kinetic energy of water flow, whatever is resisting erosion

Question 7

How to prevent erosion

Answer 7

Remediate

Question 8

Where are the locations f erosion on slopes

Answer 8

Soil pipes 
Gully’s 
Rills 
Rain splash 
Subsurface 
Sheet flow

Question 9

What is rainsplash erosion

Answer 9

What in rainfall hitting ground and dislodging particles and taking them with it in net transfer of material

Question 10

If raindrop hits the ground at terminal velocity how far can the particles move

Answer 10

1m

Question 11

How does sheetflow erode

Answer 11

Focused on a particular point giving you gully erosion

Question 12

What are direct evidence of rainsplash erosion

Answer 12

Soil pillars - what can’t be eroded

Question 13

What are the two ways rainsplash erosion effects the landscape

Answer 13

Detachment of particles wasn’t away from sheet flow and capping of soil which increases sheet flow

Question 14

How does capping of soil work

Answer 14

Lots of rainfall hits the surface of silty materials and the clay particles orientate horizontal and water fant get in

Question 15

How to protect against rainsplash erosion

Answer 15

Mulch tillage

Cover cropping

Question 16

What is mulch tillage

Answer 16

In between crops out dead vegetable matter to protect the soil this cuts off the evaporation from the soil a little bit

Question 17

What is cover cropping

Answer 17

Put another crop in between crops to stop erosion but don’t want this to take up too many water or nutrients

Question 18

What is surface sheetflow erosio

Answer 18

Uniform surface but water tends to move into tiny little channels called micro-rills rather than staying as a sheet. Goes from laminar into channels and becomes turbulent

Question 19

When does sheet flow by occur

Answer 19

Over cement or tarmac

Question 20

What equation is used to work out sheet flow

Answer 20

Reynolds Number (turbulence at depth) is VD/U. Velocity, depth of flow and kinematic viscosity

Question 21

What is the range of turbulence in Reynolds number

Answer 21

100-500

Question 22

What are the ways to reduce overland flow amount and velocity

Answer 22

Increase infiltration
Reducing flow velocity
Reduce net precipitation

Question 23

How to increase infiltration

Answer 23

Organic matter to improve soil structure - slow it down.

Plough surface induration - don’t allow compacted surface.

Question 24

What is induration due to

Answer 24

Capping
Dessication- hydrophobicitiy 
Burning
Salt precipitates
Salt defloculates
Trampling 
Vehicle compaction

Question 25

What makes deserts hydrophobic

Answer 25

Months of drying means water won’t go in. Setting fire to them also makes it hydrophobic and destroys soil structure

Question 26

How do salt precipitates cause induration

Answer 26

If you irritate some water is used by plants and some goes out of the water and it pulls salts in the profile to the surface. Sodium causes sobic souls which destroys the structure making it collapse.

Question 27

How does salt deflocculation occur

Answer 27

Clay deflocuates in sobic soils

Question 28

How to reduce flow velocity

Answer 28

Terracing - hold back water and slow it down. Contour bunds - lines of stones across hill slopes to slow the water down. Mulch tillage - rough vegetable matter resits and slows water.

Question 29

How to reduce net precipitation

Answer 29

Afforestation - reduce rainfall that gets to ground.

Question 30

What are the odd circumstances where sub surface erosion occurs

Answer 30

Sapping at seepage face | Piping

Question 31

What is sapping at seepage edge

Answer 31

If water is going through ground it may come out near the river and as it comes out it accelerates and takes some particles with it

Question 32

What is piping

Answer 32

Soil pipes where turbulent flows generate natural tunnels underground - can cause pipe collapse (middle) and pipe emergence (end)

Question 33

Where is the perfect environment for pipes

Answer 33

Silty soils don’t have enough cohesion to maintain the integrity of a pipe whereas clays have too much resistance to form a pipe. Silt has perfect structure for them

Question 34

How to protect against piping

Answer 34

Very difficult Afforestation Controlled drainage

Question 35

How does controlled drainage protect against pipes

Answer 35

Try to get some water out of the soil. Put drains in terraces so the water doesn’t fall into any subsurface drainage

Question 36

How does gully erosion form

Answer 36

From subsurface flows and surface flows

Question 37

What are the kinds of gully erosions

Answer 37

Rill enlargement | Undercutting by scour

Question 38

What is rill enlargement

Answer 38

Little channel gets deeper until it can be called a gully

Question 39

What is undercutting by scour

Answer 39

Overland flow runs off top of gully and botched under the material will cause collapse. Aided by soil fall and Knickpoint lip erosion

Question 40

How to protect against gully erosion

Answer 40

Stop sheet flow | Bunds e.g wire bolsters and log dams

Question 41

How to stop sheet flow and protect gully’s

Answer 41

Obstructions above the gully to stop overland flow to stop enlargement

Question 42

What is the case study for water pans

Answer 42

Borneo

Question 43

What percentage of precipitation in Borneo is hortonian overland flow

Answer 43

1%

Question 44

What is the topography of Borneo

Answer 44

V-shaped so limited saturation excess overland flow

Question 45

Why is their enormous drainage density in Borneo

Answer 45

It’s a young landscape

Question 46

What does the sharp topography in Borneo mean

Answer 46

There’s opportunities for water to come out of the soil before it gets to the river

Question 47

What is the main water pathway in Borneo

Answer 47

Subsurface flow

Question 48

What is the exception in Borneo of HOF

Answer 48

39% of rainfall over these surfaces

Question 49

How to measure sediment load

Answer 49

Measure the rapidity of water to measure the concentration of sediment in water. Take a sample and figure out the mass

Question 50

How much sediment being eroded in Borneo’s roads

Answer 50

600 tonnes per km squares of catchment per year. Natural slopes are only 30-40tonnes per year

Question 51

In Borneo where is sediment production higher

Answer 51

On tracks | 643t/km^2/yr (some only 81). Not predictable

Question 52

Where is most sediment in natural catchments coming from

Answer 52

River banks where water is interacting with sediment constantly

Question 53

What erosion do undisturbed catchments in Borneo favour

Answer 53

Channel bank erosion

Question 54

What does logging in Borneo lead to

Answer 54

Landslides during extreme events as logging adds instability

Question 55

Example of landslide in Borneo

Answer 55

1996. 67t in 1 day

Question 56

What is the annual rate of erosion in Borneo

Answer 56

1467 tonnes

Question 57

What is the average erosion rate in the uk

Answer 57

50 tonnes

Question 58

What is the most extreme erosion rate in New Zealand

Answer 58

10,000 tonnes

Question 59

What did the landslide in Borneo lose in one year

Answer 59

49% of all sediment lost from Baru

Question 60

What does cut and fill timber haulage roads lead to

Answer 60

Landslide impacts seen downstream as they are intrinsically unstable in material

Question 61

What is an important aspect of sustainable forestry

Answer 61

Trying to ensure subsurface hydrology not changed by road construction

Question 62

What did Borneo do to try and create sustainable forestry

Answer 62

Add drain under road which means water percolates into drainage and changes the properties of the soil to which the small rainfall events caused it all to collapse. Done bc it’s essential to how they might finesse their forestry practices so they don’t generate as much sediment