Notes on Connecticut River data files related to the Elementa article:
“Quantifying flooding regime in floodplain forests to guide river restoration”
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The MS Access database of floodplain forest vegetation and topographic survey data
contains the information connecting the different file types. Specifically, if the database
tables are opened in design mode there is a description of what data each column
contains and the units of measurement. The following are some useful examples to help
navigate these files:
o The “transect” table has the “hydro file name” column with the name of the file
from the “calculated river stage history” file folder that corresponds to that
transect.
o The “transect” table also contains a column of the “zero reference” used for
reporting elevations at the site both in the database and the HEC-RAS model. In
some cases it is a local reference such as the stage at normal flow on the
downstream transect (T1), in other cases the reference is sea level in NAVD
1988. Daily stage data in the “hobo data logger” folder and “calculated river
stage history” folder use the same zero elevation reference. The HEC-RAS
models also use the same zero elevation reference.
o The names of the subfolders in the “HEC-RAS hydraulic model” folder
correspond to the site names in the “site” table in the database.
o Areas that can be used to calculate tree densities are listed in the “area” column
of the “subtransect” table.
o Latitude and longitude listed in the “subtransect” table are rounded off to one
decimal place obscure the locations slightly to protect landowner privacy.
Decimal degree location information is still sufficiently accurate for climate
analysis for example.
Database tables include the following:
o The “water” table lists field measurements of river stage that were used to help
calibrate the HEC-RAS models. Additional hydraulic model calibration came from
aerial photos showing extent of flooding during particular high flow events, but
these photos are not included with this database.
o The “vel&stage” table summarizes the HEC-RAS model results for each transect.
These results include stage and velocity as well as hydraulic measures calculated
from velocity such as stream power. For Hobo data logger sites the stage results
from the regression model are also summarized in this table.
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o The “status” table contains measurements on the individual trees on transects
such as circumference at the time of measurement. Tree species are listed in the
“location” table.
o The “seedling” and “ground” tables provide the shrub layer and herb layer
vegetation data associated with each location in the location table. Trees are
listed directly in the “location” table. The seedling data are all of the woody plant
species that occurred in a 1 meter radius plot around the base of the
tree/transect location. The ground table lists the dominant plant species in the
herb layer in this plot.
o The “rating curve” table summarizes the stage-velocity relationship calculated
with the models for each transect.
The ArcGIS giving transect locations that are on public land are provided in a separate
folder.
For HEC-RAS model sites, vegetation transects locations are the same as hydraulic
model valley elevation cross sections.
Data contained in all of these files are in metric units.
Locations along vegetation transects increase from left to right when looking
downstream, the same convention also used by the HEC-RAS model. Within sites,
transects were numbered “1” at the downstream end with numbers increasing
sequentially upstream.
All methods are described in greater detail in the methods section of the accompanying
open-access article titled “Quantifying flooding regime in floodplain forests to guide
river restoration” by C.O. Marks, K.H. Nislow, and F.J. Magilligan published in the journal
Elementa: Science of the Anthropocene, in 2014. Supplemental material table S1 is
particularly useful at summarizing the methods used for each site.
The “calculated river stage history” (in separate folder) uses the period of record from
nearby USGS stream gages (listed in the “site gages” table in the database and in table
S1 in the accompanying article). If there are upstream flood control dams, only the post
dam construction data are included in calculations. The return interval flows used by the
HEC-RAS model as inputs and summarized for each site in the “RIflows” table were also
calculated from these gages but using the annual maximum flows instead of average
daily flows. The watershed areas to linearly adjust flows between the gage and the site
are listed in the “site” and the “USGS gages” tables in the database.
The HEC-RAS hydraulic model folder contains a document with additional notes on the
HEC-RAS models.
Looking at the relationships among tables under “database tools” in MS Access can be
useful in helping to build custom queries of the data. Several queries used in the
analysis of these data are included in the database for convenience.
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We respectfully request that any researcher making use of these data or models
acknowledge the original authors and cite the associated article.