A topographic map accurately represents the physical features of an area at a specific scale. Contour lines are lines drawn on a topographic map that join points at the same elevation. Contour lines are important because they make it possible to represent the Earth’s 3-dimensional physical features on a 2-dimensional topographic map.
Making sense of contour lines doesn’t have to be complicated. This post will explain how to read contour lines and outline things to remember if you’re new to contour lines.
Key Elements of Contour Lines
- Contour lines connect points with equal elevation
- Contour lines never intersect
- Contour lines are close together in steep terrain and further apart in flat areas
- A hill or mountain is represented by circular contours
- A contour that closes with hachures is a depression-with the hachures pointing inward
- Contour lines create ‘V’ or ‘U’ patterns when they cross a valley or river
The most important thing to remember about contours lines is they represent the natural terrain or bare earth. This means that the height of objects, e.g.
Index vs. Minor Contours
On most topographic maps, you’ll notice that some contour lines are darker brown, thicker, and labelled with the elevation. These are called index or major contours. At the same time, other contour lines are lighter, thinner and have no label. These are known as minor contours.
Contour Interval
Contour interval is the difference in elevation between one contour and the next. In the absence of a legend, pick two contour lines that are next to each other. In the above image, the vertical interval (V.I.) is 20 metres. Note: Different topographic maps use different units of measurements. Some are in feet while others are in metres.
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If the numbers on the contour lines increase in value, the elevation of the terrain is rising.
Interpreting Contour Lines
Knowing how to interpret the distance between contour lines will help you make sense of topographic maps. Contour lines may be evenly or unevenly spaced; close together or far apart. If the contour lines are close together, the horizontal distance is smaller, and the elevation change is steeper.
You can identify different land features by looking at the shape of contour lines on topographic maps.
Common Land Features Depicted by Contour Lines
- Mountain: A mountain is a large area of land that rises above the surroundings. Mountains and hills are represented by circular or oval contour lines.
- River valley: Usually, rivers run through valleys.
- Ridge:
- Saddle:
- Depression:
Reading contour lines is pretty simple. The catch? That’s it. The next time you have a topographic map, see if you can employ some of these insights.
How To Read Topographic Maps
The Geography of Kenya
The Geography of Kenya is diverse, varying amongst its 47 counties. Kenya borders South Sudan to the northwest, Uganda to the west, Somalia to the east, Tanzania to the south, and Ethiopia to the north.
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Kenya has a coastline on the Indian Ocean, which contains swamps of East African mangroves. Inland are broad plains and numerous hills. Central and Western Kenya is characterized by the Kenyan Rift Valley and central Province home to the highest mountain, Mount Kenya and Mount Elgon on the border between Kenya and Uganda. The Kakamega Forest in western Kenya is a relic of an East African rainforest.
Kenya Topography Map
Kenya's terrain is composed of low plains that rise into central highlands that are, in turn, bisected by the Great Rift Valley. The lowest point on Kenya is at sea level on the Indian Ocean. 9.8% of the land is arable; permanent crops occupy 0.9% of the land, permanent pasture occupies 37.4% of the land; forest occupies 6.1% of the land. Other uses make up the rest of Kenya's land.
There is limited volcanic activity in the country. Barrier Volcano (elev. 1,032 m) last erupted in 1921. Note: Kalukwakerith Mountain is in the disputed Ilemi Triangle region.
Climate
The climate of Kenya varies by location, from mostly cool every day, to always warm/hot by mid afternoon. The climate along the coast is tropical. This means rainfall and temperatures are higher than inland throughout the year. At the coastal cities, Mombasa, Lamu and Malindi, the air temperature changes from cool to hot, almost every day.
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The further inland one is in Kenya, the more arid the climate becomes. An extremely arid climate is nearly devoid of rainfall, and temperature varies widely according to the general time of the day/night. Elevation is the major factor in temperature levels, with the higher areas, on average, about 11 °C (20 °F) cooler, day or night. The many cities over a kilometre in elevation have temperature swings from roughly 10-26 °C (50-79 °F).
There are slight seasonal variations in temperature, of 4 °C or 7.2 °F, cooler in the winter months. On the high mountains, such as Mount Kenya, Mount Elgon and Kilimanjaro, the weather can become bitterly cold for most of the year.
The Great Rift Valley
The Great Rift Valley (a massive fracture line in the earth’s surface which runs 5000km from Jordan in the north through Kenya to Mozambique in the south) is perhaps the most outstanding. The Great Rift Valley, which enters Kenya from its southwestern neighbour, Tanzania, continues on to its northern neighbour, Ethiopia, and divides the Kenyan highlands into east and west, creating another very striking feature of Kenya’s geography.
Within the kenya rift valley lies a chain of eight lakes of various forms and composition, including the alkaline waters of an inland sea in the far north, Lake Turkana which has the popular name The Jade Sea because of its greenish colour. In addition to Lake Victoria, Kenya is well endowed with small and large lakes, which dot the floor of the Rift Valley from Lake Amboseli in the south to Lake Turkana in the north.
Land Use
9.8% of the land is arable; permanent crops occupy 0.9% of the land, permanent pasture occupies 37.4% of the land; forest occupies 6.1% of the land. Other uses make up the rest of Kenya's land.
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