Transcript: Water Erosion

Torrential storms are common here, and annual totals are often measured in hundreds of inches.

Rain can be both nourishing… and destructive.

On these mountainous islands, water is always on the move, and it moves fast.

Waterlogged hillsides eventually give way, with disastrous results.

On Oahu, one community found itself in peril after tons of rock rolled down from the hills above.

Boulders narrowly missed the houses, and residents took the warning seriously, evacuating their homes.

To help prevent further disasters, crews went to work on the nearby slopes.

The loose rocks can’t simply be removed… but with luck and skill, they might be held in place.

The best solution is a veil of steel mesh to contain the hillside. Helicopters do the heavy lifting, but a crew of scalers has to rappel down the uneven face of the slope, and stitch the net together.

Their work may keep the rocks in check here… for a time. But in Hawaii, erosion is part of the natural order. What the volcanoes have built up, wind, water, and seismic forces will inevitably tear apart.