National Geographic : 1989 May
TERRIFYING FLOODS in the Reuss River Valley historically forced peo ple to build homes close to the foot of the moun tains to avoid the river in rage. They trusted in the Bannwalder to guard them from falling rock and avalanches. Forests also play a crucial part in flood control: Leaves and needles break the impact of hard rains and prevent erosion, while spongy soil with a fine network of roots soaks up a large amount of water. In August 1987, after heavy rains in the sparsely forested Andermatt region, floodwaters jumped the river's banks, a rare occurrence in modern times. Water spread over fertile farm land (right), the Gotthard highway was badly damaged, railway tracks washed out, and all traffic stopped for several days. Damage came to more than half a billion Swiss francs (320 million dollars). At Gurtnellen the Reuss near ly doubled its width, shattering homes and ripping away part of the massive stone church and its centuries-old graveyard (below). If Alpine valleys become more severely deforested, the destruc tive effects of hard rains could reach far into Switzerland's flatlands.