Mountains as Water Sources - Himalayan Expedition Part 1
When you climb out of the tent this morning, there is a blanket of snow on everything. How beautiful! Although you knew Mount Makalu would be covered in glaciers, you have to admit you're a bit surprised to see new snow. It is the dry season, after all. During the pre-monsoon season (April through early June) and the post-monsoon season (late September through November), the weather is preferable for expeditions. Although the summit has been hidden behind mist and clouds, you haven't experienced any of the torrential rains that plague expeditions during the monsoon season. This is what high-altitude mountains do, anyway--they act as a weather barrier, extracting large amounts of water from the atmosphere. It's one of the ways that the Himalayas are able to supply the streams, rivers, and lakes that 500 million people depend on for water.
Thinking back to the beginning of the expedition, when you crossed over the Arun River, you recall that 80 percent of the water humans use comes from mountain ranges like the Himalayas. Without mountains, people all over the world would not be able to drink, clean themselves, generate electricity, or water their crops. Back at the river you marveled at the different ways mountain people got across. Now, because it is the dry season, they are able to swim the pack animals to the other side. On some of the narrow stretches, you saw a single tree trunk stretching across. In other locations, several tree trunks were tied together to create a bridge. Some of the bridges have been washed away, probably from flash floods. In August, during the monsoon season and when snowmelt is at its maximum, the Arun River flows rapidly, forcing the people of Makalu-Barun to blow up dried animal skins like balloons and float them across the river, loaded down with supplies.
Where does this water go when it leaves the Himalayas? Ask the team Geographer to pull out the world map. Once you've located the Himalayas, try to determine where the water that falls on either side of Mount Makalu ultimately ends up.