How to describe a river and its valley from an OS map

1. How to describe a river and its valley from an OS map

2. Mapwork A common question in the final exam is being asked to describe a river and its valley between two set points. You must remember to mention all of the following to gain maximum marks. First of all describe the river: > The direction of flow (remember a river normally gets wider as it flows downstream, so this can give you a clue here) > The width of the river and any changes that occur(use the scale on the map to help you here) > The speed of the river (this can be worked out by looking a the gradient over which it flows) > Sinuosity(how much the river meanders, with grid references) > Identify specific features(eg waterfalls, ox bow lakes – these may used later in the same question for feature formation)

3. Mapwork To get full marks you must mention the valley too! Now describe the valley: > Width of the valley (again use the scale to help here – look at the the distance between the first contours on each side of the river itself to get the valley’s width) > The shape of the valley(eg v shape with tight contours and steep slopes or a flatter valley with few contours) > The stage that the river is in(this is done by taking all of the information into account)

4. To get full marks you must mention the valley too! Question: Describe the river and its valley between GR 185 686 and GR 109 747. Point 1 : 185 686 Point 2 : 109 747 The question will give you the two points on the map between which you have to describe the river and its valley. Be careful to plot these accurately.

5. To get full marks you must mention the valley too! The direction of flow The River Nevis here flows in two clearly different directions. Firstly it flows westerly, then north-westerly… from GR 140 687. Use the grid references to show at which point the direction changes ie 140 687.

6. To get full marks you must mention the valley too! The width of the river and any changes that occur The width of the river stays virtually the same all along its source on the map and is 50m. Use the scale to help you to work out how wide the river is. Remember on this scale of map there is 1km segment which is divided into ten equal parts – each of these then is 100m (the length of a football pitch).

7. To get full marks you must mention the valley too! The speed of flow The speed of the river likely to be fast flowing.

8. To get full marks you must mention the valley too! Sinuosity with meanders (when the river “wanders” over flat land. The river flows between interlocking spurs in is first westerly flowing section from 185686 to 140 687. In second north-westerly flowing section from 140 687 to 109 747 there are a few meanders as the land is flatter eg at GR 133708. Remember not to mix up interlocking spurs (higher bits of land getting in the way of the river)

9. To get full marks you must mention the valley too! Identify specific features There are several tributaries joining the main river channel eg from GR 1469.

10. To get full marks you must mention the valley too! Identify specific features There is an island in the middle of the river at GR 140 687.

11. To get full marks you must mention the valley too! Identify specific features There are numerous waterfalls eg GR 183 683.

12. To get full marks you must mention the valley too! Identify specific features At the end if it course the river becomes tidal . The colour at the side of the river is normally dark blue, but where it changes to black this shows that the river is tidal ie the water level goes up and down with the tides.

13. To get full marks you must mention the valley too! The width of the valley Measure the width of the valley by looking at the distance between the first contours on each side of the river itself. Again use the scale to help here. If the contour pattern shows some “white” ie flat land then there is flat land beside the river ie a floodplain. If the contour pattern goes right to the edge of the river it will be a v-shape valley.

14. To get full marks you must mention the valley too! The width of the valley The valley width changes slightly from being close to the river ~ a v-shape valley generally the same width as the river: 50-100m wide. But in is north-westerly flowing section it widens and there is some flat land beside the river: 200-300m wide in places.

15. To get full marks you must mention the valley too! The shape of the valley The valley is a steep sided v-shape valley in it westerly flowing section. In its north-westerly flowing section it still has steeps sides but has a slightly wider and flatter valley floor.