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Whether a waterway is temporary or permanent influences regulatory protection guidelines, however, classification can be subjective due to a combination of factors, including time of year, antecedent moisture conditions, and previous experience of the field investigator. Our objective was to develop a standardized protocol using publically available spatial information to classify ephemeral, intermittent, and perennial streams. Our hypothesis was that field observations of flow along the stream channel could be compared to results from a hydrologic model, providing an objective method of how these stream reaches can be identified. Flow‐state sensors were placed at ephemeral, intermittent, and perennial stream reaches from May to December 2011 in the Appalachian coal basin of eastern Kentucky. This observed flow record was then used to calibrate the simulated saturation deficit in each channel reach based on the topographic wetness index used by TOPMODEL. Saturation deficit values were categorized as flow or no‐flow days, and the simulated record of streamflow was compared to the observed record. The hydrologic model was more accurate for simulating flow during the spring and fall seasons. However, the model effectively identified stream reaches as intermittent and perennial in each of the two basins.

Engineered floodways are floodplains managed by hydraulic controls that can be activated passively, whereby the floodway fills and empties with changes in channel stage, or through a rapid control action, such as the detonation of a levee. During May of 2011, the Birds Point-New Madrid Floodway (NMF) was activated through levee detonation and the performance of this approach is examined herein. A two-dimensional hydraulic flood model (LISFLOOD-FP) is applied to the NMF and calibrated for April and May of 2011 in order to recreate the levee detonation scenario (detonation control). Additionally, the model is applied to simulate flood impacts had the NMF been activated passively, without the deliberate breaching of the levees (passive control). Results show that detonation control reduced flood stages upstream of the activation site by 0.8 m (2.62 ft) without significantly altering overall flooding extent compared with the passive control scenario. Damage estimates from the US Federal Emergency Management Agency HAZUS-MH model indicate that detonation control slightly reduced losses associated with building replacement costs and damaged crops (4.0 % reduction). However, floodway and levee damages that occurred under the detonation control required over 50 million US$ in repairs, and these costs would have been greatly reduced under a passive control scenario. These results indicate that the detonation control effectively reduced flood stage and the risk of upstream levee failures without increasing flooding extent, building losses, and crop damages, but the potential for floodway erosion and deposition deserves additional consideration in the implementation of a rapid activation design.

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