2019 CSCE Annual Conference - Laval (Greater Montreal)

2019 CSCE Annual Conference - Laval (Greater Montreal) Conference

Preservation of ecological indices in downscaled climate data

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Ms. Diana Sankar
Dr. Joseph Daraio, Memorial University of Newfoundland (Presenter)

The effects of climate change are likely to have a significant impact on environmental flows, which are often represented by hydrologic and ecological indices.   These indices represent relationships between the ecology of a waterway and the five primary flow statistics: magnitude, frequency, duration, timing and rate of change.  Changes in flow regimes caused by climate change have implications for river ecology, and projections of future flow regimes must be reliable and uncertainty must be quantified in order to determine strategies to maintain environmental flow needs in the future.  To assess the potential impacts of climate change on important indices, downscaling of general circulation models (GCM) is required to use climate change projections in hydrologic models because of the spatial mismatch between GCM output data and meteorological data required to drive hydrological models.  There are a variety of downscaling methods and choice of method depends on the scale of the hydrologic application.   The objective of this research was to determine which downscaling method is most appropriate when determining environmental flows and ecological indices.

 Two watersheds in New Jersey located within the Pinelands ecoregion, an ecologically sensitive area with many endangered and threatened species, were used in the analysis. Ecological indices were calculated for the Batso River Watershed (a undeveloped watershed) and the Maurice River watershed (a developed watershed) and were analyzed using different downscaling methods, dynamic and statistical (change factors), to determine which downscaled method best preserved historical ecological indices and determined future indices. 

 Preliminary results using observed USGS stream flow data and the hydroecological integrity assessment process indicated that dynamically downscaled data does not preserve ecological indices.  Results also suggest that the change factor method, a simpler and less computationally intensive tool can be used instead when determining ecological indices for future conditions.