Flood Control

A routine question I get when discussing our Corps of Engineers Flood Control infrastructure within NAE is: ...what level of protection do they provide... Here is a brief explanation that I normally use:

Flood Control Dams: All NAE owned and operated flood control dams were designed for as follows:

Hurricane Barriers: All NAE owned and operated hurricane barriers provide a level of protection up to approximately a 500-year tide elevation. The designs were based on a simulated hurricane that would produce between a 10 and 13 ft storm surge at Stamford and New Bedford, respectively.

Channel Capacity/Ramping at Corps Dams: When each dam was designed, a non-damaging downstream channel capacity was established. Channel capacity, along with the storage capacity of the dam, was incorporated into each design and used to determine the dams effectiveness during minor to major flood events. Basically the storage and channel capacity are hydrologic/hydraulic components of the dam's design. The rate of opening and closing the flood control gates during a flood event, was, however, established for purposes of defining how each dam should be operated during a flood event. The rates were based on available storage, watershed response time, and downstream channel conditions as well as engineering judgment, and made part of the operational plan developed for each dam.

Over the years, flood control ramping rates have been modified slightly by reservoir regulation personnel. In addition to flood control concerns, these rates have been established to avoid a major 'slug' of water being released downstream without warning. For example: people fishing in the river below the dam may be effected by too rapid a rise in river stage or debris piles near bridge crossings, etc. may restrict the river flow resulting in an abrupt change in stage. For the most part, the current ramping rates used at each dam appear to be effective and do not seem to inhibit flood control effectiveness. However, circumstances may warrant deviations from these established rates. These deviations are made at the discretion of reservoir regulation personnel with project personnel input. Keep in mind that reservoir regulation personnel have the authority to deviate from the established rates with appropriate justification.

Paul Marinelli, P.E.
Chief, Reservoir Control Center
New England District
Corps of Engineers