In the late fall of 2012, Continental Mapping was awarded a contract with the US Fish & Wildlife Service to acquire high accuracy aerial imagery and lidar for 76 sq. kilometers along the Kwethluk and Tuluksak Rivers in the Refuge.
The data was needed to model habitat and hydrological gradients to study surface and groundwater interactions and plan for restoration along these critical habitats due to concerns over leaching of historic mines located upstream.
The Yukon Delta National Wildlife Refuge covers more than 19.5 million acres and was established to conserve shorebirds, seabirds, and marine mammals. The delta includes Alaska’s two largest rivers and their tributaries, creating hundreds of miles of spawning and rearing habitat for 44 species of fish.
Aerial imagery and lidar acquisition are very difficult in Alaska due to its remote location, tight acquisition windows between snowmelt and leaf out conditions (inc/dec of 15 minutes of sun every day in the spring and fall), quick changing weather patterns, and highly variable water flow due to snow melt in the mountains. After unsuccessful attempts to acquire the data in the spring of 2013 due to these issues, Continental Mapping successfully acquired the data in the fall of 2013. The project schedule had these potential delays factored in. Data processing began in ernst shortly thereafter with delivery occurring in early 2014 - well ahead of schedule.
Continental Mapping developed and delivered a bare earth model, breaklines, DTM, and orthos. The accuracy of the deliverables exceeded the 0.60' vertical accuracy at a 95% confidence interval (per ASPRS accuracy guidelines). Imagery was delivered with a 2' pixel resolution.
Staff throughout the Refuge as well as other agencies working in the region - such as the Flathead Lake Biological Station at the University of Montana - now have a highly accurate and current data set to support their field studies and future evaluations.