Bathymetry for Six Lakes on Calvert and Hecate Islands, BC

Bathymetric surveys were completed for six lakes on Calvert and Hecate Islands as part of the Kwakshua Watersheds Program. The surveys were conducted at different times from May to July 2016 using a canoe-mounted, location-aware depth sounder and by taking random manual depth measurements.

All depth recordings are referenced to a survey benchmark and have been quality controlled, cleaned and processed in a 3D GIS environment. For each lake, bathymetry has been modeled by means of a 1m Natural Neighbours raster generated from a Triangulated Irregular Network (TIN) using survey data. The high water mark is used as reference for full lake volume calculations. The lake outline has been manually digitized from high resolution orthophotos.

Bathymetry TIN models have been produced for each lake by using the manually digitized lake outlines as a “hard clip” interpolator of depth = 0, and using normalized (referenced on the vertical to a common benchmark) pre-processed and cleaned depth sounder and manual depth-reading survey data (depth) as mass points.

The surveyed lakes are the following: Major lake within watershed 708 on Calvert Island. Major lake within watershed 1015 on Hecate Island. A system of four interconnected lakes within watershed 693 on Calvert Island.

This dataset contains two layers of information: 1m depth contours for all lakes merged into the same layer to allow for symbolization and comparison of all lakes on the same vertical scale Surveyed lake outline polygons manually digitized from high resolution (25cm) orthophotos acquired in 2012.

The following attributes are provided in each layer:

1m Depth Contours CONTOUR: An integer value representing the depth value for that contour line. Contours have been derived from a 1m Natural Neighbours raster generated from a Triangulated Irregular Network (TIN) using normalized (referenced on the vertical to a common benchmark) survey data. Contours were derived by means of the “Contour” tool in ESRI’s 3D analyst extension.

Digitized Surveyed Lakes’ Outlines FID: Internal GIS primary key identifier ID: Hakai Lake ID. All lake IDs are internal to Hakai Research Institute. This 3 character ID corresponds to the BC Waterbody Identifier.
Area_M2: Full lake area in square meters computed by the GIS. Perimeter: Lake outline perimeter (in meters) computed by the GIS. Area_Ha: Full lake area in Hectares computed by the GIS. Int_ID: Temporary internal ID used during lake surveys. Flk_Vol: Volume of full lake in cubic meters. Lake volume has been calculated by taking the Sum of all pixel values from a 1m x 1m Natural Neighbours raster generated from a Triangulated Irregular Network (TIN) using normalized (referenced on the vertical to a common benchmark) survey data. The Sum of pixel values was obtained by means of the “Zonal Statistics” tool in ESRI’s spatial analyst extension using the lake outline’s envelope as a zone. Avg_dpth: Mean depth (relative to full lake levels) in meters. Mean depth has been calculated by taking the Average of all pixel values from a 1m x 1m Natural Neighbours raster generated from a Triangulated Irregular Network (TIN) using normalized (referenced on the vertical to a common benchmark) survey data. The Average of pixel values was obtained by means of the “Zonal Statistics” tool in ESRI’s spatial analyst extension using the lake outline’s envelope as a zone. Max_dpth: Maximum depth (relative to full lake levels) in meters. Maximum depth has been calculated by taking the Maximum of all pixel values from a 1m x 1m Natural Neighbours raster generated from a Triangulated Irregular Network (TIN) using normalized (referenced on the vertical to a common benchmark) survey data. The Maximum of pixel values was obtained by means of the “Zonal Statistics” tool in ESRI’s spatial analyst extension using the lake outline’s envelope as a zone. SD_dpth: Standard deviation of depth (relative to full lake levels) in meters. This statistic has been calculated by taking the Standard Deviation of all pixel values from a 1m x 1m Natural Neighbours raster generated from a Triangulated Irregular Network (TIN) using normalized (referenced on the vertical to a common benchmark) survey data. The Standard Deviation of pixel values was obtained by means of the “Zonal Statistics” tool in ESRI’s spatial analyst extension using the lake outline’s envelope as a zone.

All data processing has been undertaken using ESRI’s ArcGIS 10.3 platform (ArcMap and ArcScene).

For stage-volume tables, volume equations and further details on the methodologies employed in the survey and processing of the data please contact data@hakai.org

Author Contributions: Santiago Gonzalez Arriola did all geospatial data processing and produced the final data and map products. Maartje Korver lead the the field data collection and initial data management. Wayne Jacob developed the depth sounder instrument and data logger. Ian Giesbrecht co-conceptualized the project with Suzanne Tank and Allison Oliver, and supervised implementation of field and geospatial aspects. Several members of the Hakai Geospatial Technologies team made important contributions, including Will McInnes, Matt Foster, Ray Brunsting and Keith Holmes.

Suggested citation: Gonzalez Arriola, S., M. Korver, W. Jacob and I. Giesbrecht. 2016. Bathymetry for six lakes on Calvert and Hecate Islands, British Columbia. Hakai Institute Data Package. DOI: pending.

Access and Use

Licence: Appropriate credit must be given to Hakai Institute and the authors of the dataset.

Data and Resources

Dates

Metadata Created October 26, 2018, 22:48 (UTC)
Metadata Updated October 26, 2018, 22:48 (UTC)
Reference Date(s) 2016-08-14 (Creation)
2016-08-14 (Publication)
Frequency of Update
Metadata Date October 17, 2018, 22:40 (UTC)

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Additional Info

Field Value
Contact Email data@hakai.org
encoding utf8
metadata-language eng
progress completed
resource-type dataset
Responsible Party Hakai Institute (Point of Contact, Processor)
spatial-reference-system 3857