The Himalayas' permanent ice cover is around 97,000 sq.km. with 12,930 sq.km. volume of ice and snow: 10-20 % are covered by glaciers and 30-40% are seasonal snowfalls. The Himalayan streams and rivers are fed by the melting of snow and ice of approximately 500 sq.km / year.
The Himalayan rivers yield much more water per unit area and for longer periods of time as compared to the southern, peninsular rivers. This is because they are fed by the Himalayan glaciers throughout the year, while the peninsular rivers largely depend on the rainfall received in the catchment areas.
The Himalayan watersheds are already affected due to the rapid population growth and the resulting pressures on land-use, dependences of forests and timber and growth of cities and urbanization in these areas. Existing deforestation and other pressures on the Himalayan regions have resulted in floods, siltation, erratic rainfall patterns etc.
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