Paleohydrologic reconstruction of flood frequency on the Escalante River, south-central Utah

Typical of many streams in the arid or semi-arid western United States, Escalante River floods have heretofore been documented by a fragmentary, short-term systematic record. Here in contrast, historical data, tree ring data, and SWD-PSI data is given for as many as 20 paleofloods. Hydraulic flow modeling procedures are used to calculate paleoflood discharges. Of particular interest are the silt lines that are interpreted as precise paleostage indicators for ancient floods. Channel stability for bedrock reaches of the Escalante River is demonstrated with historic photographs. Of considerable importance for the Escalante River is the apparent clustering of flood events. Large floods occurred approximately 1000 years ago, about 500 years ago, and in historic times. The largest flows in the last 2000 years were comparable to the largest floods observed on similar-sized drainage basins in the region. -from Editors