Multi-Decadal Surface Water Dynamics in North American Tundra

Mark Carroll,Tatiana Loboda

doi:10.3390/rs9050497

Abstract

Over the last several decades, warming in the Arctic has outpaced the already impressive increases in global mean temperatures. The impact of these increases in temperature has been observed in a multitude of ecological changes in North American tundra including changes in vegetative cover, depth of active layer, and surface water extent. The low topographic relief and continuous permafrost create an ideal environment for the formation of small water bodies—a definitive feature of tundra surface. In this study, water bodies in Nunavut territory in northern Canada were mapped using a long-term record of remotely sensed observations at 30 m spatial resolution from the Landsat suite of instruments. The temporal trajectories of water extent between 1985 and 2015 were assessed. Over 675,000 water bodies have been identified over the 31-year study period with over 168,000 showing a significant (p < 0.05) trend in surface area. Approximately 55% of water bodies with a significant trend were increasing in size while the remaining 45% were decreasing in size. The overall net trend for water bodies with a significant trend is 0.009 ha year−1 per water body.

Highlights

The North American tundra is a complex landscape where vegetation is interspersed with over one million water bodies, the majority of which are much smaller than 100 hectares [1,2].Understanding where the water is located and how it is changing over time is a critical component of understanding the role of water in the carbon cycle [3,4], albedo [5,6], energy balance [7,8,9], and quantifying habitat for migratory wildlife [10,11]
The results of the accuracy assessment show that the annual water maps for year 2010 compared to WorldView-2 data represent water distribution of the tundra landscape of Northern Canada with the overall accuracy of 95% (Table 1)
(87%), visual inspection of the erroneous pixels shows that the misclassified pixels occurred at the edge of a water body or in a pond smaller than one Landsat pixel

Summary

Introduction

Understanding where the water is located and how it is changing over time is a critical component of understanding the role of water in the carbon cycle [3,4], albedo [5,6], energy balance [7,8,9], and quantifying habitat for migratory wildlife [10,11]. The Arctic has a greater proportion of terrestrial surface occupied by surface water than lower latitudes [2,15,16]. Given the higher proportion of surface water in the Arctic, the large amount of carbon in the terrestrial Arctic, and the observations of changes in surface water it is important to understand the extent of surface water in the Arctic and how that surface water is changing through time

Objectives

Results

Discussion

Conclusion