SECTION A

Hydrology and fluvial geomorphology 1 Fig. 1.1 shows the relationship between velocity and size of particles eroded, transported and deposited within a river.

(a) Using Fig. 1.1: (i) state the minimum velocity needed for particles of 0.1mm to be eroded; [1]

11-13

(ii) state the minimum size of particle deposited at a velocity of 1.0cm/sec. [1]

0.15-0.2

(b) With reference to Fig. 1.1, describe the relationship between velocity and size of particles deposited. [3]

• River no long has energy and is deposites at settling velocity curve
• No settling velocity curve for clay and slits as they are transporer they will continue to be transported and will not be depositied

The following points are worthy of credit: • The basic relationship – as velocity decreases, the particle size which can be transported and not deposited decreases / or alternative way to describe it. • Reference to two sets of data to substantiate the general relationship, e.g. at velocities of 100 cm / sec particles above 100 mm are deposited (settling velocity) and all others carried or eroded. • Note the position of clay. • Non-linear nature of the relationship.

(c) Explain why the velocity needed to pick up particles varies with their size. [5]

• Critical velocity- Show the realtionshio between material size and the energy needed to transport/erode them
• The larger the particles the more energy is needed to erode/transport therefore higher velocites needed.
• Clay and slits bond together meaning it is harder to break the particles up to erode/transport hence higher critical velocity

Explanations should involve: • Larger particle sizes require higher velocities to be picked up because they are heavier. • Sand (0.1–1.0 mm) requires the lowest velocity for entrainment because of its small size and non-cohesive nature (granular nature). • Clays have a more cohesive nature, which requires higher velocities for entrainment.

[Total: 10]

Atmosphere and weather 2 Fig. 2.1 shows annual precipitation totals across a mountain range. (a) Using Fig. 2.1: