Re-evaluating Dam Spillway Design Using Current Data and Methods

Re-evaluations of the spillway design capacity using current data and methods can indicate the need for spillway modifications to meet current hydraulic design criteria. For example, dam spillways designed using methods and data available 30 or more years ago may not meet current hydraulic design criteria when evaluated using current data and methods. For example, hydrologic methods of the 1980s using HEC-1 and revised using HEC-HMS versions and data not available in the 1980s may provide significantly different expectations for dam design. For the specific site investigated, HEC-HMS provides an opportunity to better represent the surface water runoff and ground water flow components not considered in an analysis of 1987. The resulting change in the estimated water levels and river flows could have a significant impact on the estimated spillway capacity of the existing dam.