1995 Southcentral Flooding
Overview
September 1995 brought intense rain and heavy flooding to southcentral Alaska, especially the Kenai Peninsula. Coastal areas received between 10-20 inches of rain. Many rivers in southcentral exceeded flood stage. Major infrastructure such as roads, bridges and levees was damaged. Some personal residences near the Copper River were flooded. Some rivers stayed above flood stage for many days. A lack of historical flood data, as well as a limited number of river and rain gauges in the region, made it difficult to communicate the severity of the event.
Flooding on the Knik and Eagle Rivers was estimated to have been a once in a 500 year event by the U.S. Geological Survey.
Weather woes: orographic effect
In September, a persistent south-to-north storm track brought repeated storms, marked by excessive rainfall, to an already saturated area. The intensity and variability of rainfall was exacerbated by topography. The orographic effect (see graphic below) helps to explain the variability. On the windward side of mountains (i.e. Chugach and Kenai) moist air is pushed over the top. As the air moves up, it cools and condenses causing precipitation to fall. The relatively dry, and now warmer air, descends the mountain. During this event, liquid precipitation persisted at high elevations due to freezing levels above 5000 feet, further increasing rainfall totals influenced by the orographic effect.
Disaster declared
Sept. 22: Governor Knowles declared a state disaster for impacted communities
Oct. 23: President Clinton signed a federal disaster delcaration
Public assistance totals $7.97 million and individual assistance totals $700k disaster totals estimated at $10.5 million (in 1995 dollars).
Rainfall totals Sept. 18-22*
| Location | Rainfall (in) |
|---|---|
| Whittier | 20.75 |
| Seward | 14.12 |
| Cordova (north) | 10.78 |
| Exit Glacier | 10.54 |
| Alyeska | 9.44 |
| Copper Lake | 7.60 |
| Moose Pass (near) | 6.64 |
| Cordova Airport | 6.58 |
| Valdez | 3.78 |
| Glen Alps (south Anchorage Hillside) | 2.98 |
| Palmer AES | 2.56 |
| Homer | 1.82 |
*Data source: National Oceanic Atmospheric Association (NOAA).
Community specific impacts
Many rivers in southcentral Alaska exceeded flood stage. Most rivers and streams crested on September 20, 21 or 22. The Lower Kenai crested on September 24. The high volumes of water impacted bank stability and caused channel erosion. The floodwaters carried heavy sediment which limited the amount of additional water able to enter streams. Determining the exact river levels was difficult due to the lack of river and precipitation gauges in this region at the time of the storm.
Kenai: The Lower Kenai remained above flood stage for 10 days. River levels crested 2.1 feet above flood stage at Cooper Landing, 3.5 feet at Kenai Keys and 2.5 feet at Soldotna.
Resurrection River: The river rose over 8 feet. This was 4 feet above flood stage. Flood damage was reported at the airport, small boat harbor, sewage facility and power facility.
Knik River: Homes in the Windsong subdivision flooded. Sediment covered roads in some areas. Nearby Eklutna Lake overtopped the spillway for nearly a month.
Copper River: The lower Copper River reached record highs on September 23 and flooded some homes near Cordova.