GEOMORPHOLOGY APPLIED TO FLOODING PROBLEMS OF CLOSED-BASIN LAKES - SPECIFICALLY GREAT-SALT-LAKE, UTAH

Closed-basin lakes fluctuate in level and area in response to variations in the climate over their drainage basins. Rises of the level of these lakes present severe flooding hazards to developments on the lake bed. Effective planning for development of these lake beds requires a knowledge of the lake-level fluctuations that should be anticipated and also the effect of wind, earthquakes, and human activity on flooding. The historic record of fluctuations of the closed-basin lakes of the Great Basin of the western United States is too short to adequately define the recurrence intervals of high lake levels. Geomorphic evidence can supplement the historic record. Great Salt Lake is the largest closed-basin lake in the Great Basin and its lake bed has been the most extensively developed. In the 1980s the level of Great Salt Lake rose dramatically in response to a period of much above-average precipitation. The resulting flooding caused extensive damage to developments on the lake bed and posed serious dilemmas to Federal, state and local governments. Studies subsequent to the flooding reveal how geomorphic evidence can supplement the historic record and provide sufficient understanding of the lake's flooding hazard to guide development and planning. Under the climatic conditions that have existed for the past several thousand years, the still-water level of Great Salt Lake can be expected to rise to near the historic highstand, or slightly above, about once every one hundred years. Wind action extends flooding in some locations to elevations 2 m above the still-water elevation of the lake. If an understanding of flooding hazards guides the planning and engineering of developments on and around the lake, losses from future high-lake cycles can be significantly reduced.