A long straw as a glacial flooding solution

University of Alaska Southeast geophysics professor Jason Amundson controls a research drone surveying Suicide Basin on Aug. 13, 2025. (Jasz Garrett / Juneau Independent)

By Art Petersen

Drilling a tunnel into Suicide Basin would drain it from below.

But how about draining it from the top?

Imagine the Basin is a 450-foot water town on a stand of rock. From the bottom of the rock to the top edge of the tank is 1,368 feet high over the distance of about a mile. Now imagine a 6,300-foot garden hose fed over the top of the tank and down 300 feet into the water. Finally, imagine someone at the long end of the hose sucking water until it begins gravity flow down the 6,000 feet of hose. The person steps back as the hose expels water until the supply of water drops to 150 feet. In this way, the tank could be drained of 300 feet of water.

With a garden hose, however, that drop could not occur as the tank is filling with water at a faster rate than the hose can remove it.

But what if instead of a garden hose, it was a 6,300-foot pipe of 30 inches in diameter. The quantity of water times the distance coming down the pipe would produce a destructive amount of pressure. But with a valve, the gravity flow could be adjusted to about five feet per second (fps), the amount about equal to the pressure in a fire hydrant. That would evacuate 11,016 gallons per minute (gpm) or 660,960 gallons an hour. And instead of someone sucking up water to prime a hose, a suction pump would prime the pipeline for gravity flow to commence. The flow at five fps would draw down 15,863,040 gallons of water every 24 hours.

If that rate of removal were not enough to keep the basin from bursting, a second pipe could be installed. And another if needed.

The cost of one pipeline possibly would come in at about $4 million. For 6,300 feet of stainless steel 30-inch pipe, the cost might run $1,800,000 ($1,500 per five feet). Engineering, transportation, valves, pump, other parts and installation would account for the rest.

A pipeline for water longer than 6,300 feet to the Mendenhall Lake area was completed once before in 1914. It ran 6,900 feet to supply a power-generating plant, about where the visitor center is now, until 1943. Reasons for closure included an irregular water flow and a high silt content that damaged equipment.

An efficient suction evacuation system would need engineering and planning for an effective type of pipe and size, assembly with controls, and release schedule, but the concept is simple: evacuate accumulating water in Suicide Basin by means of a gravity flow pipe.

This might be a semi-permanent and relatively immediate solution to the 16.65-foot and possibly higher flood levels along the heavily inhabited Mendenhall River. Nature and physics cause the damaging outbursts. Given a long straw, physics could provide a solution.

• Art Petersen is a retired UAS Professor of English and a 50-year resident of Juneau.