AS Hydrology Links

This is one of the cornerstones of Geography and geomorphology, and was also one of the major parts of the final year of my degree - all those years ago. Water has shaped the world's surfaces for billions of years and continues to fascinate with each downpour, snowfall or frosty morning. You need to be able to understand the route-ways that water can take through the drainage basin hydrological cycle, and the ways in which water is used once it gets into river channels. Recently, there has been an increase in flooding of housing, perhaps because they aren't always built in the most suitable places. We are also apparently set for more extremes of rainfall. Check out the flooding risk for your property at the 'Environment Agency' website. A recent news story suggested that many of the planned new houses in the SE, particularly the Thames Gateway are may soon be uninsurable due to their position, and Norwich Union has built up a postcode database of houses. Also be aware of the various MANAGEMENT issues for drainage basins.

Pronounced meander in Stirling. Picture by Mister P, from the Wallace monument. Looks to be on its way to an ox-bow lake soon... let us know if you live in the area...

Has anyone ever ACTUALLY SEEN an ox bow lake being formed ? I don't reckon they exist....

FLUVIAL SYSTEMS LESSON PLANS

I also recommend you download this rather useful POWERPOINT by Ollie Bray from LT Scotland (Please note that I have now updated the link - those of you who tried to use the old link should try again...), which has some good resources. I met up with Ollie at the SAGT Conference I recently presented at, and look forward to perhaps working with him in the future. My students will have seen a similar version of this in their lesson. I added a few other images / slides to look at the issues of EFFICIENCY and the HJULSTROM CURVE, and also some starter images. It's important that you appreciate the factors that effect the shape of hydrographs, and that you realise that these factors also influence each other, and also change during the course of the year. Make sure that you refer to the effect that these factors have on SPECIFIC PARTS of the hydrograph, not just say for example that "the hydrograph will be different". Remember that a hydrograph which rises quickly to a high peak after rainfall is called 'FLASHY'. Remember also that if 2 rainfall events follow on from each other, the hydrograph response from the first storm will still be in recession when the second event begins to affect the river, and the rising limb will behave differently. It's a complicated business...

Students should be familiar with the idea that DRAINAGE BASINS vary in size tremendously. Imagine the difference between the drainage basin of the AMAZON and the BABINGLEY river (which runs under the road between Knight's Hill and Babingley in King's Lynn.

To find out the details of a range of UK rivers, you need to go to the

This is available at the pages of the Centre for Ecology and Hydrology (CEH Wallingford)

http://www.nwl.ac.uk/ih/www/index.html is a direct link to the page. This allows you to explore the drainage basins and flows of many rivers in the UK. Follow the obvious links - I'll try to put a worksheet about this here soon. It is important that students are fully au fait with all the terms involved, and all the factors which affect the response of the catchment to precipitation.

2. INTRODUCTION TO RIVERS

Head over to the WYCOMBE HIGH SCHOOL site for some illustrated notes. These will be ideal for revision purposes.

A stream channel is an open funnel along which water and sediment are transferred.

All natural streams have sinuous planforms: either meandering or braided or straight.

The total load a stream is capable of carrying at any specific discharge is called the CAPACITY.

The maximum size/weight of individual particles (CALIBRE) that can be entrained is known as the stream COMPETENCE.

Shape and dimensions of a river channel are influenced by a number of factors: volume and velocity of water, quantity and calibre of sediment load and materials which make up the bed and banks of the channel

The ideal shape is semi-circular or trapezoidal.

Shape of channel can be expressed by the FORM RATIO

Form Ratio = d / w (d = channel depth, w = channel width)

Recurrence interval for most rivers for bankfull discharge is around 1.5 years.

Based on a catchment in the USA, from Snobear. Looks at the effect of deforestation in a catchment. Need to be aware of the months when there is a SURPLUS or a DEFICIT of soil moisture.

Need to produce illustrated notes on the 3 types of precipitation, all of which require uplift: the mechanisms of uplift vary in each case: Relief (Orographic), Convectional and Frontal (Cyclonic). Need to explain how precipitation is formed. Do need to know how a raindrop is formed, and the role of condensation nuclei (aerosols)

Infiltration capacity - this is a rate in mm/hr rather than a capacity as the name suggests. Typical rates are as follows (see if you can explain this):

Old Pasture - 57 mm / hr

Grazed pasture - 19 mm / hr

Intensively grazed pasture - 13 mm / h

Bare ground - dried hard - 6 mm / hr

Sandy soils - 45 mm / hr

Clay Soils - 2 mm / hr

Infiltration capacity declines over a period of time. The plot of this decline is called the Phillip curve.

The area above the WATER TABLE is called the VADOSE or AERATION zone - the zone below is the PHREATIC or SATURATION zone.

An important aspect of Hydrology is the investigation of those factors which affect the response of a catchment to a rainfall event. These are reflected in the shape of the hydrograph: which shows the discharge of a river over a period of time. There are different shapes which relate to differences in peak discharge and basin lag. A flood hydrograph is going to be like a fingerprint for any given year.

8. Groundwater: Soil Moisture - this has now been added to with additional notes, as well as some questions relating to the site of the Groundwater Foundation. Remember the importance of this in water supply and the synoptic paper..

11. ONLINE LECTURE courtesy of Bootham School's Geography Department - this has some excellent detail which could be used as a case study, or as the basis for further research, plus pictures of flood amelioration works in York.

INFILTRATION CAPACITY is a misleading term, as rather than a CAPACITY it is a RATE at which water enters the ground (mm / hr) - use an infiltrometer to measure the rate. This could be made from waste materials rather than purchased as long as the area and height is known.

13. FLOODING on the River DULAS. Go to THIS WEBSITE. Click on the Geography link, then lesson plans, and follow the link to the River lesson. There is a worksheet to fill in using the spreadsheet to calculate some key values. This is one of a selection of excellent worksheets on this site. The lesson is a River Discharge activity sheet.

This needs data on river flow data for 1996 for the River Dulas near Llanidloes. Figures show the total discharge in cumecs. Thanks to Paul Hunt for making this lesson available. The data is available in a spreadsheet file, but you can of course type in the values as there are only 12 of them.

This clearly shows a regime, or pattern of annual variation in discharge. Recommended. This is the sort of activity which will hopefully become more common with the arrival of Curriculum Online.

Log on to the HIGHDOWN website, and follow the links to CURRICULUM, GEOGRAPHY, HYDROLOGY.

The link opens up an online area which is sponsored by the NERC. This is a spreadsheet workbook with a number of sheets which can be opened and used to explore the comparisons between 2 rivers: the OCK and the LAMBOURN. There are also sections on the CHICHESTER FLOODS of 1994, and DROUGHT IN THE UK.

Choose one flood event: Lynmouth 1952 or Derwent floods 2000 (also Mississippi: 1993) - of course you may choose one closer to home or more recent, I would... YORK is particularly prone to flooding.

Rivers have an annual pattern of flow. This is known as the regime. This can be simple or complex depending on the size of the river network and the nature of the source. Go to the NATIONAL WATER ARCHIVE site where you can download the details of the River Tees at Barnard Castle. There is a chance to compare various places on the river.

River regimes are the pattern of flow of a river. These should be known for 2 contrasting rivers. A handout has been given to tell you about 4 of these: make sure that you have 2 of them which you can recreate.

18. COMPARING RIVERS

A splendid example of how to save others time!

There is a requirement to compare rivers in terms of their regimes, and also to compare rivers at different stages of their journey from Source to Mouth. There is an excellent site at the HIGHDOWN SCHOOL which is also linked to from elsewhere on the site. This allows you to compare the River Ock and the Lambourn. There are details on the catchments and some question tasks and spreadsheets to use.

This has a workbook which is called HYDROLOGY at HIGHDOWN. There are Spreadsheets to use and a series of questions which also involve some gridded catchment maps. There are 18 questions to answer using all the available information. This could also be adapted into an A2 Synoptic type activity. Recommended.

I will be adding a slimmed down version of this which my students had 1hour to tackle shortly.

Examples of the introduction of this idea to Urban areas in the UK. Water bills are going up. Anything we can do to save water would be good.

Another similar technology is that to be found at many TESCOs car parks. This is produced by FORM PAVE. The website has lots of images and also some movies showing the amazing speed at which the water drains away. These can be saved and used as a starter activity.

This is an often overlooked section of the topic. It's important that people appreciate the effects of drought, which is why you need to have some time to explore the site of the US DROUGHT MITIGATION CENTRE. The page HERE goes into the details on the IMPACTS OF DROUGHT. There are a range of details here which would be very useful: the effects are classified into 3 groups:

An Undergraduate level (but also has the information required for AS/A2) illustrated tutorial. The images alone make it worth checking out.

2 flood events, 52 years apart. Lynmouth 1952 and Boscastle 2004. A possible piece of work looking at the floods and comparing the two. The FLOODS page has some other relevant links. A good research task once the WATER CYCLE has been explained in depth.

A single flood event is needed for the exam. This should serve to illustrate the influence of both physical and human factors.

LOCAL TOPOGRAPHY

ANTECEDENT CONDITIONS

LOCAL GEOGRAPHY

THE PRECIPITATION EVENT WHICH CAUSED THE FLOOD

THE EFFECTS

THE CLEAR UP...

Students need to know the ways in which a river changes with increasing distance from the source.

We use the example of the river Ystwyth, which has its mouth at Aberystwyth. This has a range of human influences, notably adit mining for lead in the area which has affected both the water quality and the sediment load in the area. Braid bars and point bars have built up in the channel.

Students need to make notes on the following processes which are required by the specification. You should be aware of the nature of the processes, the effect they have on the river, and the variation both within the river and also over time...

A range of particle sizes and velocities. Give the students 10 seconds then they have to shout out / hold up a card / runaround stylee run to a corner of the room... whether they think the particle is going to SINK or SWIM !!

25. FILTER: FLUVIAL GEOMORPHOLOGY RESOURCE

This is an excellent resource: produced by Dr. Tim Stott, at the University of Bristol. It is designed for undergraduates, but most of the material in the early part of each unit is relevant to 'AS', and there are some useful images and examples to use. The structure is nicely laid out.

I would encourage you to head over to the index page HERE and work through the first 3 or 4 units. Try some of the assessments. If you find these manageable you should be fine for 'AS'.

Recommended.

That's the title of an article I wrote for KEYFILE, which is now available on the GEO PROJECTS website. This is a SUBSCRIPTION website.

27. QUESTIONS FROM A POWERPOINT SLIDE I USE

a) Define what is meant by the term 'drainage basin' (2 marks)

b) Outline the circumstances under which water would run off the surface of the ground rather than infiltrating (5 marks)

c) What is meant by the term 'infiltration capacity' (2 marks)

d) How and why do the processes of evaporation and interception vary throughout the year ? (4 marks)

This is a rather nice set of photos which asks students to consider the possible hydrograph shapes which would result from 2 contrasting catchment conditions. There are pictures and details of 2 locations and students need to relate these to the response of the catchment to a precipitation event.

Need to identify the 3 main types, and appreciate how raindrops are formed around condensation nuclei.

All air contains water in the form of vapour. Make sure that you know the difference between ABSOLUTE and RELATIVE humidity.

When RH is 100%, air has reached its carrying capacity and is said to be saturated. This point can be referred to as:

- the altitude at which this temperature is reached (condensation level) and where clouds will start to form (the cloud base)

Cloud droplets form around a condensation nuclei (CCN) - which will tend to be within the range 0.01 - 0.04mm in diameter

Cloud droplets need to grow to the size of 0.25mm to be classed as drizzle, or 1.5-2.5mm in diameter for raindrops.

There are 3 key mechanisms for raindrop formation: coalescence, Bergeron Findeisen process & seeder-feeder

30. A MODULE ON THE WATER CYCLE

http://techalive.mtu.edu/meec/module01/title.htm

Thanks to Terry Jones for letting me know about this site. It's got some lovely animations to take students through the processes involved in the Drainage Basin water cycle, and in particular has an excellent animation to show what a WATERSHED is, which is always a tricky thing to explain.

This is a critical part of the work on rivers. Students must appreciate how this operates within the river channel.

This is now doing the rounds thanks to a mention on SLN, and is on Paul Williams' blog too.

Go to RICHARD ALLAWAY's GEOGRAPHY ALL THE WAY blog for an extension of this task complete with activity cards.

32. YOUR ENVIRONMENT: an Environment Agency publication

http://www.environment-agency.gov.uk/aboutus/275292/668256

I recommend you subscribe to this, or at least download the PDF - very useful supplement in the May 2007 issue

The river is heavily managed as the water has to be used by a huge area of the USA. One of the world's greatest engineering challenges was the building of the HOOVER DAM.

The COLORADO is featured in the 3rd edition of Waugh's GAIA book which is used in many geography departments as a set text.

Check out a timely new resource on the Geographical Association's website...

34: BOSCASTLE FLOODS

Boscastle : August 2004

FLASH game introduction

DEFENCE DYNAMICS resources: new site from Ministry of Defence.

Richard Allaway's site has great RESOURCES.

CHECK OUT ROB CHAMBERS' RESOURCES !

Click the picture or HERE to go to the page.

This features links to some excellent materials for our specification: these include a COURSE OVERVIEW, and details on each of the MODULES at AS which have games, notes, activities etc.

New materials now available

Month	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Discharge	5910	7326	4687	3199	2993	1121	174	166	178	3484	7753	4064

'AS' HYDROLOGY LINKS

FLUVIAL SYSTEMS LESSON PLANS