Marine Waters in the Cascadia Bioregion

A comprehensive list of marine waters, bays, inlets, and channels in the Cascadia bioregion.

Introduction

Marine waters are the most abundant on the Earth, comprising 97% of the Earth's surface waters. They are home to all kinds of diverse lifeforms and provide very important ecological functions, goods, and services. Marine waters extend far out into the midst of the oceans but up close to the land, it's important to map and identify the marine waters which surround the coast, and what type it might be as they are usually the receiving body of water from which freshwater streams and rivers discharge to.

Marine bays and inlets can be nested within larger channels, creating a network of different kinds of marine systems at different scales. This dataset is a list of all the different kinds of marine waters, including channels, bays, estuaries, and oceans in the Cascadia bioregion. It was created using data collected from the United States Geological Survey (USGS) National Hydrography Dataset (NHD) and the British Columbia Freshwater Atlas.


Methods

Three datasets were obtained from the NHD, one covering coastal waters from Northern California to the tip of the Olympic Peninsula in Washington. Another covered the Puget Sound and Salish Sea up to the Canadian border, and the last covered the southern stretch of Alaska that is adjacent to Canada. These three datasets had multiple layers that were merged together for a total of 5 layers into one large dataset. Since the NHD combined dataset includes all kinds of waters, both freshwater and marine water, the layer had to be queried to show just the marine waters.

All the attribute fields were the same in each NHD dataset, so it was easy to merge. One of the attribute fields in the NHD combined dataset contained a Feature Code which described the type of water body each entity was. It ranged from reservoirs, to lakes, to rivers, to bays, to estuaries. The Feature Code was used to make different classes or a water type which was written out using the Feature Code key. This key can be found on the USGS website ( here ). Included in the Query was Bay/Inlet, Estuary, and Sea/Ocean. These are the only marine water types included in the NHD dataset.

For the British Columbia Freshwater Atlas, the Bays and Channels dataset was used. This dataset contains freshwater channels and bays as well as marine channels and bays on the British Columbia coast. The dataset was queried to just show the marine channels and bays. Both attribute fields in the NHD combined dataset plus and the BC Freshwater Atlas layer were changed so they could be merged together, creating a layer that displayed different bays/inlets, channels, estuaries, and seas/oceans ranging from Alaska down to California.

The area in square kilometers of each marine water entity is displayed.


Results

Cascadia Marine Waters

This map is portraying the different types marine waters and their area along the coastal Cascadia Bioregion. There is a complex structure of marine waters within the BC coastal region and in the Puget Sound. These include bays/inlets, channels, and estuaries. Along the United States Pacific Coast and the upper reaches in Alaska, the waters are fairly uniform and comprise mostly of sea/ocean.

Frequency of Marine Water Type in the Cascadia Bioregion

It can be seen that the Bay/Inlet marine water type is the most abundant in the Cascadia Bioregion. Channels also have a significant count of occurrence, while estuaries and sea/ocean waters appear quite a bit less. It is important to note that the frequency of the different water types may be affected by the georeferencing choices of the analyst working on the dataset. Some of the entities have been identified by water type and area, but do not contain a Geographic Names Information System (GNIS) ID or name.

Average area in square kilometers of each each marine water type in the Cascadia Bioregion

It can be seen that the sea/ocean area is the largest compared to the averages of the other marine water type. Note that bays/inlets contains the largest frequency of occurrence but have the smallest average area. Channels also have a noticeably higher average area than compared to other marine water types.


Data

USGS National Hydrography Dataset

Pacific Coast Dataset:

U.S. Geological Survey, National Geospatial Program, 2020/12/03, USGS National Hydrography Dataset Best Resolution (NHD) for Hydrologic Unit (HU) 4 - 1710 (published 2020/12/03): U.S. Geological Survey. Link:  https://www.sciencebase.gov/catalog/item/5a4cc64ae4b0d05ee8c4c8d0 

Puget Sound Dataset:

U.S. Geological Survey, National Geospatial Program, 2020/12/02, USGS National Hydrography Dataset Best Resolution (NHD) for Hydrologic Unit (HU) 4 - 1711 (published 2020/12/02): U.S. Geological Survey. Link:  https://www.sciencebase.gov/catalog/item/5a58a57be4b00b291cd6906a 

Alaska Dataset:

U.S. Geological Survey, National Geospatial Program, 20201201, USGS National Hydrography Dataset Best Resolution (NHD) for Hydrologic Unit (HU) 4 - 1901 (published 20201201): U.S. Geological Survey. Link:  https://www.sciencebase.gov/catalog/item/5a58a57de4b00b291cd69093 

British Columbia Freshwater Atlas

Ministry of Forests, Lands, Natural Resource Operations and Rural Development, British Columbia, Canada. (2021/06/03). Freshwater Atlas Bays and Channels - Data Catalogue. Link:  https://catalogue.data.gov.bc.ca/dataset/freshwater-atlas-bays-and-channels 

Cascadia Bioregion Boundary

Aquila Flower. 2020. Cascadia Bioregion Boundary. Feature Layer. Link:  https://wwu.maps.arcgis.com/home/item.html?id=c6497941559d433da98e286fb3f63551 

This Story Map is part of a project for Western Washington University's GIS IV course to create a Cascadia Bioregion Atlas. This Marine Waters section is part of the Hydrology Chapter.

Cartography

Brenden Murphy

Frequency of Marine Water Type in the Cascadia Bioregion

Average area in square kilometers of each each marine water type in the Cascadia Bioregion