Location

UMass Amherst

Start Date

29-6-2011 2:15 PM

End Date

29-6-2011 2:35 PM

Description

Flood frequency estimates are used to quantify the magnitude and frequency of relatively rare river discharges. Such estimates are necessary to design many fish passage projects. For projects that include constructing new infrastructure, or retrofitting existing infrastructure, flood frequency estimates are required to size the infrastructure to withstand floods of specified magnitudes (e.g., events expected to recur every 100 years). For projects where infrastructure is being removed and a natural channel restored, for example a dam removal, flood frequency estimates are also useful because stream channel geometry, process, and habitat are very closely linked with the magnitude of comparatively frequent flood events those with recurrence intervals between 1 and 5 years. Recent research documents increases in the magnitudes and frequencies of precipitation and flood events in New England over the last century, especially in recent decades, indicating a hydroclimatic shift. Flood records exhibiting hydroclimatic shifts require special treatment when used for statistical flood frequency analyses because these procedures assume stationary (nonvarying) climate. Flood frequency analyses also assume that hydro climatic conditions observed in the past provide reasonable guides to the future, an assumption challenged by anthropogenic climate change which has prompted calls to develop non-stationary estimation techniques that combine paleohydrologic and historical records with projections from multiple climate models. Since such techniques are not fully mature, and wide vailability/acceptance may be years away, an interim approach is proposed to help project teams avoid underestimating flood magnitudes at New England project sites. The suggested guidelines employ well established estimation techniques, encourage evaluation of an entire updated gauge record, and ensure that data representing the recent past and thus the modem hydroclimatic regime inform the analyses.

Comments

Matt Collins is a hydrologist and earth scientist with the NOAA Restoration Center in Gloucester, MA. He provides technical support for fish passage restoration projects throughout the Northeast United States and elsewhere, as well as support for large scale wetland restoration/lower Mississippi River diversion projects in southern Louisiana. His focus areas are fluvial sediment dynamics, long-term monitoring of stream restoration projects, and flood hydroclimatology. Mr. Collins has a master’s degree in geography and water resource management from the University of Wisconsin Madison.

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Jun 29th, 2:15 PM Jun 29th, 2:35 PM

Session A8- Flood frequency estimates for New England fish passage projects: Considering climate change in project design

UMass Amherst

Flood frequency estimates are used to quantify the magnitude and frequency of relatively rare river discharges. Such estimates are necessary to design many fish passage projects. For projects that include constructing new infrastructure, or retrofitting existing infrastructure, flood frequency estimates are required to size the infrastructure to withstand floods of specified magnitudes (e.g., events expected to recur every 100 years). For projects where infrastructure is being removed and a natural channel restored, for example a dam removal, flood frequency estimates are also useful because stream channel geometry, process, and habitat are very closely linked with the magnitude of comparatively frequent flood events those with recurrence intervals between 1 and 5 years. Recent research documents increases in the magnitudes and frequencies of precipitation and flood events in New England over the last century, especially in recent decades, indicating a hydroclimatic shift. Flood records exhibiting hydroclimatic shifts require special treatment when used for statistical flood frequency analyses because these procedures assume stationary (nonvarying) climate. Flood frequency analyses also assume that hydro climatic conditions observed in the past provide reasonable guides to the future, an assumption challenged by anthropogenic climate change which has prompted calls to develop non-stationary estimation techniques that combine paleohydrologic and historical records with projections from multiple climate models. Since such techniques are not fully mature, and wide vailability/acceptance may be years away, an interim approach is proposed to help project teams avoid underestimating flood magnitudes at New England project sites. The suggested guidelines employ well established estimation techniques, encourage evaluation of an entire updated gauge record, and ensure that data representing the recent past and thus the modem hydroclimatic regime inform the analyses.