How can relief be shown on a map

They enable the map user to easily recognize the highest elevation in a given area. They show the highest elevation in an area which cannot be shown but contours due to the limitation of vertical interval. They can be used without obscuring other features. They have physical evidence on the grounds they appear in.

A trigonometric point on a map indicates the presence of a trigonometric station on the ground. Spot heights also called spot elevations are conventional dots used to show the exact elevation of points on the map. They are used to indicate the elevation of the ground at ruling points on the surface such as the top of hills. Spot heights are depicted by using a dot together with a number which indicates the exact elevation of the given point on the map.

However, unlike trigonometric points, spot heights do not have physical evidence in the fields they appear. The use of spot heights has the following advantages;. They provide accurate elevation of given points on the map.

They may be used to show a point of higher elevation which cannot be shown by contours due to the limitation in the vertical interval.

The methods can be easily used without obscuring other features. They do not provide much information about the relief of the land. Benchmarks are also useful in map analysis since they show the exact elevation of a given point on the map.

In surveying, they are used as reference points from which the elevations of other objects on the ground are determined. On maps, it is usually indicated by a dot followed by the elevation value of the given point on the map together with letters BM. This figure shows how benchmarks are shown on maps. It means that the given benchmark is at the elevation of meters above mean sea level.

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Layer Colouring is a method showing relief in layers and each layer is given a different colour. Physical maps in atlas and wall maps use this method to show relief features. Ocean depth is also shown in various shades of blue. There is an international recognition for colours used in these maps. Accordingly blue represents water bodies, green for plains, various shades of brown for highlands and white for snow covered peaks. Contour is universal method to show the relief.

The unit of measurement of contour is generally metres above the mean sea level. Contour has an advantage that it does not hide the other features drawn on the toposheet. Reading contours is a skill that helps us to understand the actual landscape.

The skill can be obtained by understanding the salient features of contours. They are as follows:. Generally 20m interval is followed in , and m interval in , toposheet. In case of water fall and cliffs contours almost ouch a same point or a line. In over hanging cliff the contours cut each other.

Figure The following figure shows the way two adjacent hills are shown by contours. Drawing cross section of the contours allows one to know the exact landform depicted in the toposheet.

Drawing cross section involves selecting a section within the portion of the contour, marking the intersections of these selected contours on suitable vertical scale and joining these points to indentify the land form. Generally closely spaced contours indicate that the slope is steep, and widely spaced contours indicate that the slope is gentle. The following pictures show contours and cross sections of a hill and a depression.

Draw the contours in brown colour. Draw a line AB for which the cross section has to be drawn. Click on it to enlarge! Remark: At a distance of meters, topographic map shading is most effective to be recognised for human eyes.

Remark: The shading layer is still the base layer for a topographic map. Furthermore, this expensive method can only be produced by specialists: the painter has to use graphical tricks to give steep rocks depicted on a map equivalent visual importance compared to that observed in nature. During the last two centuries, cartographers have developed different cliff representation styles. On the following slide show, some of those methods are presented.

The two following pictures and animations are good examples to visualise the relation between relief here represented using a Digital Elevation Model and contour lines. Created with World Construction Set 4 by M. Dobler IKA. Raw Data used:. Press left mouse button in the image and move the mouse in a direction you want. In the following exercise, you have to find out which topographic isolines representation matches which profile. Drag the isolines on the bottom to the white rectangle corresponding to the correct profile.

Try to be precise when dropping your isolines! Update: 9. Relief Representation Relief is so perfectly and precisely represented on topographic maps that if you look on them at a distance of 1 meter you will see crests and valleys, as on a thermoformed map. Contour lines Contour lines are an effective device for representing relief on topographic maps. Discover graphically the relation between contour lines and relief.