Mapping wood deposits across the Mackenzie River Delta: Towards an understanding of delta-scale transport processes
Abstract
Large wood transport and deposition in river deltas is governed by processes such as river discharge and wind that influence its delivery and residence time in the system. In Arctic deltas, ice breakup and jam formation may also have a strong control on wood transport. Wood deposition can also influence local hydrology by altering flow dynamics and serving as sites of enhanced biogeochemical processing. Many of these feedbacks have been identified at the reach scale, yet the identification of broader patterns of wood deposition across a larger domain would allow a deeper understanding of delta scale transport processes. This kind of understanding is difficult to achieve using previous approaches to wood mapping, such as aerial imagery, which generally covers a smaller spatial area.
In this work, we use high resolution (50cm) satellite imagery to classify large wood deposits across several locations in the Mackenzie River Delta, a 14,000 km2 delta in the Northwest Territories, Canada. The delta is characterized by a range of distributary channels, over 40,000 lakes, and maintains natural wood dynamics. Using remote sensing tools such as machine learning and principal component analysis (PCA), we identify and map wood deposits across multiple locations in the delta, spanning from the head of the delta at the confluence of the Mackenzie and Arctic Red Rivers, to the outlet of the delta at the coast. We compare the extent of wood deposition at different locations and distinguish deposits within channels, lakes, and in vegetated areas. A field campaign that measured deposits at several locations is used to estimate wood volumes at several locations and connect deposit location to the primary process influencing its transport. This coupled remote sensing and field analysis provides a large scale estimate of wood transport and storage in the delta. We also discuss tracking these deposits over time and the role of deposits as agents of geomorphic change.- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMEP41D2387S
- Keywords:
-
- 0410 Biodiversity;
- BIOGEOSCIENCES;
- 1813 Eco-hydrology;
- HYDROLOGY;
- 1825 Geomorphology: fluvial;
- HYDROLOGY;
- 1862 Sediment transport;
- HYDROLOGY