Erosion in the Himalayas
Erosion plays an important role in shaping the contrasting landscapes of the northern and southern slopes of the Himalayas, driven by climatic differences and other geographical factors. The Himalayas, the world’s tallest mountain range, span a region with very different climates on each side, resulting in varied processes shaping the landscape.
The southern slope of the Himalayas, which faces the Indian subcontinent, is exposed to the Indian monsoon. It receives heavy rainfall, especially during the monsoon season, with annual precipitation exceeding 5,000 mm in some areas. The humid and wet climate makes the southern slope prone to intense water-driven erosion processes, particularly:
• Fluvial erosion: Rivers fed by monsoonal rains carve deep valleys and gorges.
• Landslides: Frequent and heavy rains also trigger landslides, especially on the steep and rugged terrain of the southern slope.
• Glacial erosion: In higher altitudes, glaciers contribute to erosion through glacial scouring.
The combined effects of rainfall, river activity, and landslides create dramatic features on the southern slope, such as steep, forested valleys, and deep gorges.
The northern slope of the Himalayas, facing the Tibetan Plateau, experiences an arid, cold desert climate. The region lies in the rain shadow of the Himalayas and receives minimal precipitation, in some areas less than 100 mm. Here erosion is dominated by:
• Glacial erosion: large parts of the landscape have been formed by glaciers, as the moraines and glacial lakes show. However, with the retreat of the glaciers, their role as erosive power decreases.
• Wind erosion: In the dry, barren northern slope, wind erosion plays a significant role. Winds carry fine particles across the plateau, sculpting rock formations and creating vast expanses of sand dunes and gravel plains.
As a result, the northern slope features more gradual, expansive valleys with less dramatic relief compared to the southern side.
Satellites are used for monitoring erosion and landscape formation in the Himalayas. They provide valuable data on a large scale, offering insights into changes over time. Some key uses of satellite technology in this context include: topographic mapping, monitoring the vegetation cover, glacial monitoring, and detecting landslides e.g. for disaster relief support.
Exercises
- Satellite Map:
- Look at the satellite map and click on the layer selector in the upper right. Deactivate all satellite images (layer groups “N” and “S”) by unticking the respective boxes.
- Try to identify important land cover classes (e.g. bare land in the north, tree cover and agricultural land in the south, and ice/snow).
- What can you say about the relief of the terrain? Where is it rugged, where smooth?
- Which indicators support your findings? During which time of the year is the relief best visible in satellite images? Think about shadows and the sun position! Compare with the elevation maps by switching the respective layers on and off.
- Now zoom to the “S” section and look at the detail satellite image from 2023. Try to identify areas with recent landslides (small brownish areas directed downwards, often to rivers).
- Copernicus Browser:
- Open the case study area in the Copernicus Browser.
- Find the most recent Sentinel-2 data covering the case study area.
- Use a false colour infrared representation.
- Compare the land cover in the southern part with that in the latest satellite image in the case study. Can you detect changes? Which reasons can you imagine? Think about landslides.
Links and Sources
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PDF document of the case study (includes exercises): English, German, French, Italian, Spanish |
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This case study is covered on page 26 of the printed ESA Schoolatlas – download the PDF document of the page: English, German, French, Italian, Spanish |
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