Analyzing the Multi-scale Heterogeneity of Wood Depositional Environments in the Mackenzie River Delta

The Mackenzie River Delta is a unique Arctic landscape that processes globally significant amounts of sediment, carbon, and other nutrients. Comprising complex lakes and channel networks that span multiple spatial scales, the delta also contains some of the worlds largest deposits of large wood. This wood serves as a source of carbon storage in this cold environment. It also interacts with the hydrology and geomorphology of the region to create a rich mosaic of depositional environments in the delta. Understanding these environments would provide insight into delta evolution and wood and carbon residence times. However, the large spatial and temporal heterogeneity of these features make this analysis a challenge. To address this, we use extensive field and remote sensing-derived datasets to systematically analyze wood depositional patterns in the Mackenzie River Delta. Using very high-resolution satellite imagery with a machine learning classification approach, we obtain the location of all wood deposits in the delta. We further partition this dataset by region (river, coast, etc.) and depositional environment to find broad spatial patterns of wood deposition. We couple this information with regional field datasets of wood diameter, radiocarbon age, and tree ring analysis to characterize wood residence times and fill in gaps for under-canopy deposits. We find distinct patterns in deposition timing and process both within jams and across the region. This multiscale spatial heterogeneity reflects the complex processes of river flow, ice breakup, coastal waves, and wind that act to transport wood in this system.