Heavy precipitation associated with a large storm system resulted in major flooding in several areas of south-central Alaska during October 10-12, 1986. Flooding was particularly severe in the Seward area of the Kenai Peninsula and in tributaries to Susitna River from Telkeetna downstream. Flood damage has been estimated at $20 million and the region was declared a Federal disaster area. The report includes a brief discussion of meteorological conditions that caused the unusual amounts of precipitation, a summary of flood stages and discharges, a comparison to prior floods, flood-frequency estimates, a brief description of flood areas, and hydrologic data for each area.

Alaska↗

USGS1985

Water Resources Data for Alaska, Water Year 1984

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Water Data Report↗

USGS1984

Cost-effectiveness of the stream-gaging program in Alaska

This report documents the results of a study of the cost-effectiveness of the stream-gaging program in Alaska. Data uses and funding sources were identified for the 110 continuous stream-gaging stations that were being operated in September 1983 with a budget of about $1,700,000 per year. However, for the purposes of the report, only 98 stations were included in the analysis of cost-effectiveness. The current policy for operation of the 98-station program required $1,539,000 (1983 dollars) per year, which results in an average standard error of estimate of streamflow records for open-water periods of 18.4 percent. This overall level of accuracy at the 98 sites could be maintained with a budget of approximately $1,440,000 if the scheduling of visits and allocation of funds to the stations were changed. A minimum budget of $1,381,000 is required to operate the 98 stations; a budget less than this does not permit proper service and maintenance of the gages and recorders. At the minimum budget, the average standard error is 19.8 percent. Several other budgets were analyzed; the maximum budget analyzed was $2,500,000, which resulted in an average standard error of 11.9 percent. A significant portion of the standard error is attributable to loss of gage-height record, which is used to compute open-water discharge records. If gage-height record loss could be prevented, the average standard error could be reduced to 13.4 percent at the minimum operating budget of $1,381,000. It was determined that the standard error of estimate of streamflow records could be reduced by changing some operational policies and by reducing the amount of missing gage-height record. Since there is no method to determine standard errors of Alaska's winter records of streamflow, it was concluded that such a technique should be developed. More than half of western Alaska was identified as having insufficient streamflow data. It is suggested that steps be undertaken to remedy this situation as funds become available.

Alaska↗

USGS1979

Flood characteristics of Alaskan streams

Peak discharge data for Alaskan streams are summarized and analyzed. Multiple-regression equations relating peak discharge magnitude and frequency to climatic and physical characteristics of 260 gaged basins were determined in order to estimate average recurrence interval of floods at ungaged sites. These equations are for 1.25-, 2-, 5-, 10-, 25-, and 50-year average recurrence intervals. In this report, Alaska was divided into two regions, one having a maritime climate with fall and winter rains and floods, the other having spring and summer floods of a variety or combinations of causes. Average standard errors of the six multiple-regression equations for these two regions were 48 and 74 percent, respectively. Maximum recorded floods at more than 400 sites throughout Alaska are tabulated. Maps showing lines of equal intensity of the principal climatic variables found to be significant (mean annual precipitation and mean minimum January temperature), and location of the 260 sites used in the multiple-regression analyses are included. Little flood data have been collected in western and arctic Alaska, and the predictive equations are therefore less reliable for those areas. (Woodard-USGS)

Alaska↗