Discerning periglacial drainage evolution using historic satellite-imagery-derived digital elevation models
Abstract
Over the past several decades, geomorphic processes in the Arctic have been changing and intensifying due to region-wide warming and thawing of permafrost. Permafrost depth and extent control sediment and hydrologic pathways in Arctic landscapes, and, permafrost degradation by even modest temperature changes can severely alter tundra landscapes and ecosystems. Much is still unknown about the nature of feedbacks within Arctic landscapes, though the expansion and contraction of river networks is expected to be a first order control on the routing of water, sediment, nutrients, and carbon from headwaters to the ocean. This study investigates the propagation of channel heads in Imnavait Creek, the headwaters of the Kuparuk River, Alaska, over the last half century. Analysis of gradient versus contributing area at the pixel scale is often used to identify the transition from diffusive (hillslope) to advective (fluvial) transport. These slope-area plots demonstrate a threshold between transport regimes, which defines the channel head in a watershed. It has been argued that in periglacial watersheds, fluvial erosion is restricted by permafrost on the hillslope, and therefore the contributing area at the channel head represents the area in a watershed dominated by periglacial processes. The channel head location and contributing drainage area can be identified through time series analysis using historic 1960-1970's CORONA data and modern 2000's-present ArcticDEM and Alaska IFSAR elevation data. We expect that with the degradation of permafrost since the 1960's, the contributing area for the channel head will decrease due to an increase in fluvial erosion, enhanced by more mobile soil on the hillslope. Saturated zones on the hillslope will become connected to channels, and the drainage network will expand. Preliminary Google Earth Engine imagery time series analysis of Imnavait Creek shows an increase of hillslope-channel connectedness from 1990-2016. Slope-area results will identify the locations of channel heads, identify rates of expansion of the drainage network, and provide insight into areas at risk for erosion.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.C51C1067M
- Keywords:
-
- 0702 Permafrost;
- CRYOSPHEREDE: 0710 Periglacial processes;
- CRYOSPHEREDE: 1625 Geomorphology and weathering;
- GLOBAL CHANGEDE: 1807 Climate impacts;
- HYDROLOGY