Dataset DOI: 10.5061/dryad.nvx0k6f6m

Description of the data and file structure

This data was collected in field assessments, obtained from constructed wetland design plans or related material, and measured in laboratory tests, including particle size analysis (PSA) and loss on ignition (LOI). Accumulated mass depths were measured by collecting 'soil' cores (1-ft long core) at the same point until the original or characteristic soil layer was reached (i.e., red clay found in Raleigh, NC) and measuring with a ruler into the hole that was created. Sampling locations were also surveyed using a laser level to obtain elevations. Samples were collected in transects throughout a wetland site; the number of transects depended on the site's size and channel bends, though inlet (forebay usually) and outlet samples were always taken. Some watershed and wetland areas were obtained using Google Earth Pro if they were not provided in design plan materials. Other related sources are provided in variable descriptions. 

Files and variables

File: Dryad_mass_accum_data.csv

Description: 

Dataset containing field-collection, laboratory-process, and obtained data for analysis of stormwater wetland maintenance and accumulation. 'NA' denotes missing values.

Variables

• FULL_ID: Full sample ID
• SITE_ID: Site/wetland ID
• DATE_ID: Date sample was obtained in MMDDYY format
• SECTION_ID: Wetland 'section' or transect/location sample was collected from, specific to the sample number (3 samples obtained per section usually)
• wetland_section: Wetland section (or transect/location) where sample was collected from labeled forebay or 'f', middle sections first (mf), second (ms), and third (mt), and outlet or 'o'
• city: City where site/wetland was located in North Carolina
• land use: Predominant land use type in the watershed of the site/wetland
• region: Geographic region in North Carolina the site is located in
• age: Age in years of the site since initial construction
• num_transects: Number of transects or locations sampled in a particular wetland site
• sat_level: Saturation level with respect to how recent rainfall occurred, with 'wet' indicating rainfall the day prior, 'normal' indicating rainfall within or past the 2-5 day drainage window, and 'dry' indicating a lack of rain for 10+ days
• veg_density: Vegetation density compared to other sites, where high vegetation density was thick and tall vegetation that was difficult to navigate and low vegetation density was sparse vegetation that was more comparable to a pond's vegetation density; medium vegetation density was in between the two extremes
• mosquitos: General assessment after several hours at the site on the frequency of mosquito encounters
• woody_herbaceous: Predominant vegetation type at a site/wetland, either woody (trees, bushes, etc.) or herbaceous (rushes, soft-stemmed vegetation, etc.), with 'no' indicating the site was mostly unvegetated and 'mixed' indicating both woody and herbaceous vegetation was found in about the same quantities
• maintenance: Whether or not maintenance was performed regularly (annually or biannually for vegetation maintenance, at least once for dredging) including vegetation trimming, invasive vegetation removal, sediment accumulation dredging, etc.
• watershed_area_ac: Watershed area in acres
• wetland_area_ac: Wetland/site area in acres
• percent_developed: Percent developed land in watershed, as determined by StreamStats or design plans/materials
• percent_impervious: Percent impervious land cover in watershed, as determined by StreamStats or design plans/materials
• predom_soil_type: Predominant hydrologic soil group from Web Soil Survey (A through D soils)
• CN: Curve Number calculated using NRCS Curve Number Method
• 2yr_24hr_rainfall_in: 2-year, 24-hour rainfall in inches from NOAA Atlas 14
• approx_Q_cuft: Approximate runoff volume (Q) in cubic feet calculated using SCS Runoff equation (obtain Q in inches) and watershed areas 
• section_atr: Wetland/site section (transect/sampling location) attribute including 'temp' or the sample was collected from the wetland's temporary inundation zone, 'shallow' or the sample was collected from the wetland's shallow water zone, and 'deep' or the sample was collected from the wetland's deep pools or deep water zone
• prev_section: An estimation of what section attribute the sampling location used to be at site installation, found by comparing design plans/as-built plans to sampling location (documented using Survey 123 for coordinates) 
• accum_sed_ft: Depth of accumulated mass measured in feet collected from sampling points; accumulation was defined as any material built upon original soil characteristic for a site's location (like red clay found commonly in Raleigh, NC)
• original_storage_depth_ft: Approximate intended event storage depth in feet obtained from design plans (outlet structure designs, berm elevations, etc.); adjusted if in-field observations suggested diversion from design plans (as-built different from design plans)
• original_normal_pool_ft: Approximate normal pool depth noted in design plans; as-built depths were not able to be confirmed for most sites 
• accum_deter: Accumulation determination ('accum.' or accumulation, 'scour', 'none' or no change) comparing design plan/as-built elevations to elevations measured in the field to determine accumulation had built up at a particular location since construction ('accum.') or if the area had scoured out 
• bulk_density: Bulk density in grams/cubic cm measured by the NC Department of Agriculture and Consumer Service's Agronomics lab using standard procedures; three samples taken from a particular wetland section/transect were mixed together for this measurement
• percent_organic: Percent organic material/content measured by the loss on ignition (LOI) laboratory method
• porosity: Porosity calculated using Schjonning et al. (2017)'s particle density (Dp) and soil organic matter (SOM) relationship (Dp = 2.686- (2.649 x SOM)) to obtain a particle density from percent organic material (above) and bulk densities (above)
• phos_index: Phosphorus index value measured by the NC Department of Agriculture and Consumer Service's Agronomics lab using standard procedures (Mehlich-3 extractant); three samples taken from a particular wetland section/transect were mixed together for this measurement
• original_soil: Original soil type or the characteristic soil type found in a site's location (i.e., red clay, or 'clay', in Raleigh); sites with 'clay/sand' designations were along region borders where both soil types were predominant
• assumed_original: Original soil type/characteristic soil type assumed from sample/core bottom (deepest point) soil type
• num_layers: Number of layers in accumulation cores/samples distinguished by prominent shifts in material, color, and particle size, similar to how soil science distinguishes soil layers (though accumulation was considered different than soil due to the unnatural nature of how it built up)
• prop_detritus: Proportion of detritus material in samples/cores defined as organic material undergoing some level of decomposition 
• prop_sed: Proportion of sediment material in samples/cores (i.e., sand, clay, silt)
• prop_mixed: Proportion of well mixed sediment/detritus material in samples/cores that could not be separated by a distinct layer
• layer_order: Order from left to right (corresponding to top to bottom of the core) of materials in each layer where 's' is sediment, 'd' is detritus, and 'm' is mixed
• original_collected: Assessment ('yes' or 'no') of whether the original soil/characteristic soil layer was reached through field methods (coring); at times accumulation was too compacted to collect
• percent_clay: Percent clay material measured by particle size analysis (PSA) using the ASTM Hydrometer Method; organics were removed from samples prior to PSA with hydrogen peroxide
• percent_sand: Percent sand material measured by particle size analysis (PSA) using the ASTM Hydrometer Method; organics were removed from samples prior to PSA with hydrogen peroxide
• percent_silt: Percent silt material measured by particle size analysis (PSA) using the ASTM Hydrometer Method; organics were removed from samples prior to PSA with hydrogen peroxide
• percent_over2mm: Percent of material over 2mm that was separated from sample during particle size analysis (PSA) using the ASTM Hydrometer Method

Code/software

Excel, Google Sheets, or other spreadsheet viewer is needed to view.

Access information

Data was derived from the following sources:

• Web Soil Survey (no license)
• Google Earth Pro (free with license code GEPFREE)
• StreamStats (license CCO 1.0)
• NOAA Atlas 14 (no license)