*WINNER* Flash Flooding Prediction of Cummins Falls State Park

Abstract

Cummins Falls State Park has become a popular attraction since being named as one of America’s Secret Swimming Holes by the Travel Channel. Located in southern Jackson County, the park is visited by thousands of people each year. While a beautiful place, the falls also are subject to flash flooding like the arroyo flash floods of the western U.S. In response, the state has installed gauging and rainfall monitoring in the watershed. Our research focuses on comparing observed data with model output using the USACE’s Hydraulic Engineering Center River Analysis System (HEC-RAS). The objective is to determine how much rainfall can cause dangerous increases in stream level, and how much time elapses between a rainfall and the increased stream level. Observations from the rain gauges indicate that rainfall amounts over 0.04 inches in 5 minutes can cause unsafe rises in the stream depth. The time from rainfall at the far reach of the watershed to the Cummins Bridge Road station appears to range from 2-3 hours. The time between the stream rising at the West Fork gauge and the East Fork Gauge to reach the bridge is about 45 minutes. Further modeling of the watershed may provide more details of stream behavior and answers to questions of rainfall and timing.