Averting Failure Due to Spring Runoff - North Dakota's Historic Flood of 2009

摘要

In the Spring of 2009, an unprecedented convergence of meteorologic and hydrologic conditions occurred across a large portion of North Dakota, setting the stage for historic runoff and statewide flooding. The event was largely the result of heavy snowmelt and ultimately impacted dozens of dams and other hydraulic structures throughout the state. In addition to addressing the daunting regulatory task of responding to an event of this scale, the authors will present first-hand accounts of the emergency response at Cottonwood Creek Dam and Clausen Springs Dam. The vegetated auxiliary spillways at both of these earthen embankment dams were activated for the first time in April 2009 and experienced extensive headcutting and erosion. Significant intervention efforts were made to stop or slow spillway erosion at both dams, and residents downstream of Clausen Springs Dam were evacuated. Ultimately, neither spillway was completely breached, though both dams experienced major damage and required emergency modifications following the flood. During and after this exceptional flood, many lessons were learned spanning a broad range of topics from emergency planning and response to spillway evaluation and design. This presentation will focus on the most significant lessons learned and their applicability to regulators, dam owners, engineers and emergency responders.