DSE Geography | River Processes and Landforms Lesson-Prep Guide (Tutor Edition)

DSE Geography | River Processes and Landforms Lesson-Prep Guide (Tutor Edition) | Long Profile, Meanders, Floodplain

2026-11-02

Tutor lesson-prep guides · Secondary Geography

Students can chant that rivers erode upstream and deposit downstream, yet freeze when asked why the same river dumps its load on one bend and scours the next. This lesson ties every landform to one energy-versus-load comparison on a single long profile.

Objectives — Students can: (1) convert basin area and rainfall into annual runoff, and separate discharge from velocity; (2) apply one rule, that surplus energy erodes and surplus load deposits, to explain the division of work along a river; (3) label cut bank, point bar, floodplain and oxbow lake on a cross-section and justify each label with a velocity figure.

01 Prerequisites (3-minute check)

If any of these fails, fix it before the lesson starts.

Skill	Quick check	Pass mark
Water cycle	Name the three routes by which water leaves a basin	Evaporation, infiltration, surface runoff
Unit conversion	How many metres are in one kilometre	1000 metres
Map skills	What do closely spaced contour lines show	A steep slope

02 Lesson flow (60 minutes)

Time	Stage	Tutor does	Student does
0-5 min	Opening probe	Write 30 on the board and ask what that number could measure here	Answer aloud, one idea each
5-15 min	Prerequisite check	Hand out the three quick questions, mark live	Written answers, self-marked
15-37 min	Three acts	Teach basin and discharge, erosion and transport, meanders and floodplain	After each act, state the energy rule in one line
37-49 min	Worked tasks	Model four tasks, each starting with process, place, landform	Copy then rewrite from memory
49-55 min	Independent practice	Circulate and ask only: eroding or depositing, and how do you know	Three tasks, self-checked
55-60 min	Exit check	Collect papers and count errors on the spot	Written, no discussion

03 Teaching script (read it out)

Scene 1: Act one: basin, discharge and velocity

The basin covers 120 square kilometres and receives 2400 mm of rain a year, which is 2.4 m of water depth. Annual runoff is depth times area: 120 million square metres times 2.4 m, giving 2.88 hundred million cubic metres. Make students walk the unit chain out loud, millimetres to metres and square kilometres to square metres, because that is where most marks are lost. Discharge equals cross-sectional area times velocity: 20 square metres times 1.5 m/s gives 30 cubic metres per second. The channel runs 40 km with a fall of 800 m, an average gradient of 0.02, roughly 1 in 50. Gradient sets velocity, and velocity with discharge sets energy. Stream power rises roughly with the sixth power of velocity, so doubling velocity multiplies available work by about 64. Every landform question later in the lesson hangs on that number.

A narrow upstream section flows fast, a wide downstream section flows slowly. Which carries more energy, and what do you have to calculate?

Scene 2: Act two: the division of work

Give them one sentence to reason with: when energy exceeds load the river erodes, when the two match it only transports, and when load exceeds energy it deposits. Name the four erosion processes, hydraulic action prising grains loose, abrasion grinding the bed, solution in limestone country, and bank collapse once undercutting removes support. Name the four transport modes, solution, suspension, saltation and traction, and link each to grain size. Then make students state the conditions for deposition themselves: falling velocity, falling discharge, gentler gradient, and a river mouth meeting still water. The upstream-erodes-downstream-deposits slogan is only a trend; the real judgement is the local balance of energy against load. Every answer sentence should say what changed, how it changed, and which process followed.

After a dam is built, why does the channel below it erode more and deposit less?

Scene 3: Act three: meanders, floodplain and oxbow

Do not ask students to memorise meander formation; make them reason with inertia. Water entering a bend swings toward the outer bank, where velocity and erosion peak and a river cliff forms. Surface water then crosses toward the inner bank, where velocity drops and sediment builds a point bar. Measure the bend with sinuosity: a 3.2 km channel across a 2.0 km valley gives 1.6. Meanders migrate outward until the neck is cut, and the abandoned loop silts up at both ends into an oxbow lake. In flood, water overtops banks about 3.5 m high; coarse sand settles near the channel as levees while fine silt travels further out, laying the flat alluvium of the floodplain layer by layer. Answers must give place, process and name, since examiners award each separately.

Why is the floodplain sediment coarse next to the channel and fine further away?

04 Question types and worked steps

Type	Example	Steps	Answer
Data calculation	Basin 120 square kilometres, rainfall 2400 mm, find annual runoff.	Convert mm to m, km squared to m squared, multiply, then state cubic metres.	Example: 2.88 hundred million cubic metres.
Process decision	Velocity falls from 1.5 m/s to 0.6 m/s in one reach. Decide the dominant process.	Name the velocity drop, note falling energy, compare with load, conclude deposition and give one landform.	Example: point bar on the inner bank.
Cross-section labelling	Label cut bank, point bar, river cliff and thalweg on a meander section.	Mark flow direction first, then outer and inner bank, then match each to erosion or deposition.	Example: cut bank carries the fastest flow.
Formation account	Explain how a floodplain forms.	Overtop, sudden velocity drop, coarse near channel and fine far out, repeated layers.	Example: one flood, one layer.

Sanity check (teach this): Check the arithmetic before teaching: 2.88 hundred million cubic metres follows only from 120 square kilometres times 2.4 m. A student answering 2.88 hundred million millimetres has not converted. A gradient of 0.02 written as 1 in 50 must not become 1 in 2. Discharge of 30 cubic metres per second comes from area times velocity, never area times gradient. Doubling velocity raises stream power about 64 times, not twice, because the relation is a sixth power. Sinuosity must exceed one; any figure below one means the division was inverted.

05 Independent practice (3 questions)

Question	Answer	What to watch
Name three erosion processes and one landform each.	Hydraulic action gives potholes, abrasion gives V-shaped valleys, solution gives limestone gorges.	Watch for transport processes listed as erosion.
Which process dominates the outer and inner bank, and why?	Outer bank erodes because velocity peaks there; inner bank deposits because velocity falls.	Watch for the two banks being swapped.
Why does deposition fall below a reservoir?	Sediment is trapped behind the dam, so the load drops and the clear water erodes the bed.	Watch for answers that stop at the water being clear.

06 Common mistakes and what to say

Mistake	Student writes	Say this
Multiplying before converting	Answering runoff as 120 times 2400 equals 288000 cubic metres.	Millimetres become metres and square kilometres become square metres first. Skip that and the answer is off by orders of magnitude.
Treating power as linear	Saying doubling velocity doubles the work a river can do.	Stream power scales with the sixth power, so doubling gives about 64 times. That figure explains why one storm reshapes a bed.
Swapping the banks	Writing that the outer bank deposits and the inner bank erodes.	Trace the flow with a finger around the bend: the outer bank takes the impact, the inner bank receives the slack water.
Mismatching form and process	Calling an oxbow lake an erosion feature.	An oxbow is an abandoned loop sealed by deposition at both ends, so the sequence of events must be written in order.

07 Homework (paper, section and question numbers)

Secondary geography chapter index: finish the three tasks here, then compare rainfall and runoff in the weather and climate chapter — Tasks 1-3 on this page

08 Exit check (last 5 minutes)

Question	Answer	Decision
Which two quantities multiply to give discharge?	Cross-sectional area and velocity	Wrong means reteach act one
Which process dominates the outer bank of a meander?	Erosion	Wrong means reteach act three
Doubling velocity multiplies stream power by roughly what?	About 64 times	Wrong means reteach act one

09 Tutor FAQ

Which year group is this for?

Mainly S4 river units; S5 groups revising dynamic landforms can use it as a summary lesson with map questions.

Must students memorise four erosion and four transport names?

Yes, but every answer also needs the place and the landform, because names alone earn little credit.

Will numbers really be examined?

Data questions are common in the rivers unit, so basin-to-runoff and area-to-discharge calculations are both fair game.

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A TutorZone lesson-prep guide. Written by the TutorZone team; questions and lesson flow are original and are not taken from any school or publisher material.