Hydrograph Revision

8/2/2019 Hydrograph Revision

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HYDROGRAPH REVISION 1

This question type asks you to analyse the parts ofthe hydrograph in order to find out about the riverbasin and its reaction to a storm event.

Try this example from 2006.

First, look at the rainfall event itself.


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Now the discharge.


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What is the question?


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See the two graphs together-

6


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Hintsto follow


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What does this question need from you?

Use technical terms as if you are comfortable withthem.

A description is needed- not too long-winded, butwhat you say must be accurate and meaningful to thequestion asked.

Quote some data- not too much- and make sure ithelps to illustrate the point you are making.Then try to give reasons for the changing levels.

You can of course mix up these four things- it mayflow better if you do; but make sure they are allthere before you finish the answer!


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Lag time of about30 hours.

Steady river

discharge at 0.8muntil peak rainfall isreached, at start of9th April.

Steep rising limbshowing quick risingof river level to2.8m during April9th into the 10th.

Fairly gentle returnto base flow by endof April 13th.

description

Lag time


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explanation

Long response time because ofinfiltration-filling pore spaces in

permeable/ porous soil or rock.Water in pores is called in storage.

Soil capacity reached by end April8th, so then river rises fast due tostorm flow-(throughflow, surfacerun-off, aka overland flow) as asteep rising limb.

Gentle recessional limb as raindrizzles for four days after peak,reaching the river as surface run-off.

Both description and explanation neededfor 6 marks.


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You should look up all the hydrograph past

paper questions and see how to tackle themusing this one as a blue print!

Now let us look at a mapping river question.


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HYDROGRAPH REVISION 2

This question type asks you to analyse a map sectionof a river and its valley to identify river landforms

and/or

To find out about the land use around the river.

Try this example from 2007- the Worcester map.

Look it up in your booklet, and collect a map.

First, find the section of the river indicated. Do notlook outside this section.


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a) Look for the PHYSICAL characteristics only ofthe river and its valley; do not include ANY man-made objects or land uses.

(The only exception could be if a river has areservoir or other water feature in it that mightaffect the river itself; but then mention it only asan added extra!)

There are 14 possible marks here, and at least TENpossible features you could mention.

Giving a reference and a name for seven of them will

get you full marks, as long as they are correct!

At least ONE reference MUST be a six figure one!


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Here are a list of ten- how many can you find andidentify accurately? Are there any others?

1. meander 2. oxbow lake

3. pond 4. flat valley floor

5. wide flood plain 6. braiding

7. low channel gradient. 8. gentle valley sides9. easterly river direction of flow

10. many tributaries- identify at least two

Note that the features you nameMUST be found mainly- or more likely- in

the LOWER stage of a river.

If there is a feature not normal for there,do not use it!

Remember todescribe!


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There is almost always a question asking to explainthe formation of a river feature. Look back in thepast papers to see which are the usual features

asked about.

There might be a nasty one, not asked for before,so be prepared!

Meander incised meander

Waterfall River gorge

Levee delta

Braiding river terrace

Oxbow lake estuary/firthAny others?


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Another question type asks you to describe thehydrological cycle.

This is often PART of a question.

The question here is looking to see if you canremember and include a lot of the more complexterms that you did not get in Standard Grade,

so include them particularly!


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You are often expected to produce a diagram.

Firstly read the question carefully to see if you onlyneed a diagram, or if they need text as well.

Do not duplicate the writing in both!

If you need both, the trick is to do good labels thatexplain what is going on in a concise way; thisreduces the need to explain too much in the text.


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This diagram is in the SQA marking scheme as anexample of an adequate diagram.

The labels are minimal- the text would need toinclude more detail!

You could add ADVECTION, THROUGHFLOW,

STORAGE, INFILTRATION, INTERCEPTIONand some other terms, too.

END

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Hydrograph Revision