Storm Surges
Since the Gold Rush days of 1898, at least 90 storm surges have battered Alaskan coastal villages and towns to cause damage running into the hundreds of millions of dollars, at today's costs.
Storm surges are temporary abnormal changes in sea level that accompany storms in shallow coastal waters. Storm surges can be either positive or negative, that is, a positive surge is one where the height of sea level increases, and a negative surge is one where the level decreases from normal. Strong onshore winds or winds parallel to the shore, where the shore is to the right of the wind flow, cause positive storm surges Offshore winds or winds parallel to the shore, where the shore is to the left of the flow, cause negative storm surges.
When the wind blows parallel to the shore the reason why the shore being to right or left of the wind flow is important is the Coriolis effect. Wind blowing across water drags on the water and forces it to move in the direction the wind is blowing. But because of the earth's rotation on its axis, a moving fluid at the earth's surface experiences another force directed at right angles to the motion. This Coriolis force is to the right in the northern hemisphere, and to the left in the southern hemisphere. The Coriolis force increases in importance away from the Equator and toward the poles.
Storm surges occur when a strong wind blows over a long fetch of water, perhaps several hundred miles, in a generally constant direction, and where there is gently sloping, shallow offshore water. Rugged coastlines with deep offshore waters do not suffer from storm surge effects.
A just-completed study of Alaskan storm surges, conducted by James L. Wise, Albert L. Comiskey and Richard Becker, Jr. of the University of Alaska's Arctic Environmental Information and Data Center, shows that positive storm surges up to 13 feet in height have occurred during the past four decades. This study, funded by the Alaskan Council on Science and Technology, has resulted in a predictive scheme that can be used to reduce losses caused by future storm surges. Loss can be minimized by knowing which coastal regions are most susceptible to storm surge flooding, and by being able to use weather observations to give a few hour's warning of impending surges.
Typical losses are those involving destruction of boats in harbors, damaged dock and warehouse facilities, destruction of homes and other structures, and washing out of roads and runways. Even wildlife suffers: storm surge floodings during early summer in the Yukon-Kuskokwim delta region have, at times, destroyed 80 to 90% of the production of nesting ducks. If a storm surge occurs at the time of high tide the damage, of course, tends to be the greatest.
The areas of Alaska having the combination of wind and topography that are conducive to strong storm surges include lower Cook Inlet, the north shore of the Alaska Peninsula, Bristol Bay, the Yukon-Kuskokwim delta region, Norton Sound, the Seward Peninsula and, going northward, much of the Chukchi Sea and Beaufort Sea coastlines. Thus, a great part of the Alaskan coastline is susceptible to storm surges. Since ice cover dampens the development of storm surges, the most severe surges generally occur only in summer in the most northern areas.
Among the more well known storm surges are those that have struck the Nome area in the years 1913, 1945, 1946, 1960, 1967, 1974 and 1978. But over the years, towns such as Kodiak, Dillingham, Port Heiden, Shishmaref, Barrow, Barter, Gambell, Seldovia, Homer and Unalakleet have had their share of storm surge problems too.
