Challenge of Mapping Complete River Networks and Salmon Habitats in Southeast Alaska and in Adjoining Canadian Trans-Boundary Watersheds
Across the 80,000 square mile U.S. and Canadian Trans-Boundary region, analysis of existing cartographic map products and river networks that can be delineated from regional digital elevation models (DEMs) reveal that they may be missing about half or more of salmon streams in southeast Alaska and in British Columbia, or collectively about 50,000 miles (80,000 km), a length of unidentified and unmapped salmon streams that would stretch around the world two times.
The extent of all unmapped streams in this region maybe underestimated by about 200,000 miles (320,000 km), a length almost to the distance to the moon.
Powerpoint presentation summarizing analysis (short version, 12 slides). Updated May 9, 2016.
Powerpoint presentation summarizing analysis (long version, 23 slides). Updated May 9, 2016.
See Poster describing the crowdfunding campaign: Salmonidae Incognito Crowdfunding Campaign
The U.S.–Canada Trans Boundary Region (158,000 km2) encompassing islands and coastal areas of southeast Alaska (SE AK) and rivers extending into British Columbia (BC) (Taku, Stikine and Unuk) constitutes one of the last strongholds of five species of wild Pacific Salmon. The region faces increasing development including large open pit mines, hydro projects, logging and road building. We investigated whether existing river network maps and those that could be developed from digital elevation models could accurately identify locations and abundance of salmon habitats that could be at risk. Existing cartographic maps containing salmon designations include the Alaska Department of Fish and Game Anadromous Waters Catalog (AWC), the U.S. National stream layer (SEAK-Hydro), and BC’s 1:50,000 and 1:20,000 scale Provincial hydrography. River networks were also delineated using a range of DEMs in SE AK, including 1m LiDAR and regional 5m and 20m, and a Provincial 17m in BC. Thresholds of channel steepness, including waterfalls, and salmon habitat models were applied to identify potential habitats and suitability. In SE AK, the LiDAR DEM (limited to 720 km2) produced the most accurate and complete river networks and salmon habitat distribution and it revealed that as much as 60% and 50% of salmon habitats could be missing from the AWC and SEAK-Hydro maps, and that 50% to 80% of salmon habitats would be omitted from river networks derived from existing 20m and 5m DEMs. In BC, we infer that greater than 90% of salmon habitats could be missing from the Provincial 1:50,000 hydrography and up to 40% of salmon habitats would be omitted from river networks derived from the 1:20,000 hydrography and delineated from the 17m DEM. We estimate that as much as 350,000 km of all streams, and up to 80,000 km of salmon streams, remain unidentified and unmapped in the Trans-Boundary region.