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 variatio ns in the climate over their drainage basins. Rises of the level of th ese 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 an d 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 d efine the recurrence intervals of high lake levels. Geomorphic evidenc e can supplement the historic record. Great Salt Lake is the largest c losed-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 precipitat ion. The resulting flooding caused extensive damage to developments on the lake bed and posed serious dilemmas to Federal, state and local g overnments. Studies subsequent to the flooding reveal how geomorphic e vidence can supplement the historic record and provide sufficient unde rstanding of the lake's flooding hazard to guide development and plann ing. Under the climatic conditions that have existed for the past seve ral thousand years, the still-water level of Great Salt Lake can be ex pected to rise to near the historic highstand, or slightly above, abou t once every one hundred years. Wind action extends flooding in some l ocations to elevations 2 m above the still-water elevation of the lake . If an understanding of flooding hazards guides the planning and engi neering of developments on and around the lake, losses from future hig h-lake cycles can be significantly reduced.