Characteristics Of River Regimes

Question 1

Define Discharge

Answer 1

Rate of flow of a river at a particular destination at a particular time

Question 2

What is the river discharge measured in?

Answer 2

Cubic metres per second or cumecs.

Question 3

How do you measure the discharge?

Answer 3

Multiply cross sectional area (in m2 X by velocity (m/s)

Question 4

What is a river regime

Answer 4

The changing pattern of a river discharge over a period of time usually a year.
Use mean daily or mean monthly figures used.

Question 5

Competence of a river

Answer 5

A measure of the amount of material it can carry= total volume of load.

Question 6

Capacity of the river

Answer 6

The diameter of the largest particle that can be carried for a given velocity.

Question 7

Attrition

What happens to the pebbles?

Answer 7

Reduction in size of particles in transport ad they strike one another and beds and banks of the channel.
As particles are moved downstream, they are made smaller. In addition, angular edges of particles become more rounded, as more exposed.

Question 8

Corrosion or solution

Answer 8

Most important on carbonate rocks such as limestone and chalk where carbonic acid (rainwater dissolved rock, carried away in solution.

Question 9

What is the bedload?

Answer 9

The load transported by traction and saltation.

Question 10

Baseflow?

Answer 10

The movement of water through porous or permeable rock deep underground towards the river influenced by gravity

Question 11

Aquifer?

Answer 11

Aquifer is a water bearing rock that stores waters and allows water to pass through like limestone.

Question 12

How are potholes formed?

Answer 12

Potholes are formed when pebbles get stuck in slight hollow of river bed.
Swirling water around the pebble known as verticals eddies strong enough to allow pediment to grind a hole into the rock by abrasion.
Attrition rounds and smooths the pebbles caught in hole, helping to reduce bedload.

Question 13

Levees - where do they take place in river (upper, lower ect ?)

Answer 13

Middle / lower course.

Question 14

What are the two main origins of the alluvium flood plain.

Answer 14

1. Over bank deposition

2. Channel deposits point bar in migrating meanders

Question 15

What is the rising limb and what does it depend on?

Answer 15

Initial curve on a flood hydrographic. Steepness of the curve depends upon intensity of rainfall and character of the basin.

Question 16

Definition of through flow?

Answer 16

The downslope lateral movement of water, through the soil matrix, roughly parallel roughly parallel to the surface, similar to inter flow but at shallower depth.

Question 17

Definition of overland flow?

Answer 17

Movement of water over earths surface, - surface run off, arises from rainfall or snowmelt not been evaporated or infiltrated into the soil.

Question 18

Impervious ?

Answer 18

Rocks or soils which will not allow water to pass through them because they lack joints and cracks.

Question 19

What will cause a rock to be impermeable?

Answer 19

If it is impervious - no joints or cracks or it is not porous

Question 20

What is the rising limb and what does it depend on?

Answer 20

Initial curve on a flood hydrographic. Steepness of the curve depends upon intensity of rainfall and character of the basin.

Question 21

Definition of through flow?

Answer 21

The downslope lateral movement of water, through the soil matrix, roughly parallel to the surface, similar to inter flow but at shallower depth.

Question 22

Definition of overland flow?

Answer 22

Movement of water over earths surface, - surface run off, arises from rainfall or snowmelt not been evaporated or infiltrated into the soil.

Question 23

Impervious

Answer 23

Rocks or soils which will not allow water to pass through them because they lack joints and cracks.

Question 24

What will cause a rock to be impermeable?

Answer 24

If it is impervious - no joints or cracks or it is not porous

Question 25

Interception

Answer 25

The process by which vegetation prevents rain from reaching surface directly; intercepted water temporarily held as interception storage. Either then falls to the ground by processes such as leaf drip and stem flow or is evaporated back into atmosphere.

Question 26

Watershed

Answer 26

Dividing line between two basins

Question 27

Non porous

Answer 27

Rocks which contain no pore spaces and therefore cannot absorb water, although water may be able to pass through rock joints.

Question 28

What is the other name for overland flow?

Answer 28

Surface run off

Question 29

Percolation

Answer 29

The process by which surface water moves downwards through pores and joints in the soil and rocks to deeper stores such as groundwater store.

Question 30

Recharge?

Answer 30

The process by which water is added to an aquifer or to soil, particularly following a dry season or drought.