Preprints
https://doi.org/10.5194/hess-2020-613
https://doi.org/10.5194/hess-2020-613

  04 Jan 2021

04 Jan 2021

Review status: a revised version of this preprint was accepted for the journal HESS and is expected to appear here in due course.

The Spatial Extent of Hydrological and Landscape Changes across the Mountains and Prairies of Canada in the Mackenzie and Nelson River Basins Based on Data from a Warm Season Time Window

Paul H. Whitfield1,2,3, Philip D. A. Kraaijenbrink4, Kevin R. Shook1, and John W. Pomeroy1 Paul H. Whitfield et al.
  • 1Centre for Hydrology, University of Saskatchewan, Saskatoon, SK, S7N 1K2, Canada
  • 2Department of Earth Sciences, Simon Fraser University, Burnaby, BC
  • 3Environment and Climate Change Canada, Vancouver, BC
  • 4Geosciences, Utrecht University, Utrecht, The Netherlands

Abstract. The cold interior of Western Canada, east of the Continental Divide, has one of the world's most extreme and variable climates and is experiencing rapid environmental change. In the large Mackenzie and Nelson River basins, the warming climate is changing the landscape, vegetation, cryosphere, and hydrology. This is a study of a large number (395) of natural (unmanaged) gauged basins where streamflow may be continuous or temporary, and observed streamflow records had been collected either year-round or during only the warm season. Each station may have records for a different series of years between 1910 and 2012. Instead of a common period of years and a small number of stations, as in many trend studies, an annual warm season time window where observations were available across all stations is used to classify [1] streamflow regime using dynamic time-warping, and [2] seasonal trend patterns with k-means clustering. The trends in seasonal streamflow patterns were compared to changes in satellite Normalized Difference Vegetation, Water, and Snow Indices (NDVI, NDWI, and NDSI) for each gauged basin using Landsat 5 TM imagery between 1985 and 2010.

Twelve streamflow regime types were identified using dynamic time-warping which overcomes timing differences in streamflow generation due to latitude or elevation. These streamflow regime types exhibit a strong connection to location; the spatial distribution follows ecozones and shows a strong distinction between mountains and plains in the study area. Clustering of seasonal trends using the annual common time window resulted in six trend patterns that also have a strong and distinct spatial organization. The trend patterns include one with decreasing streamflow, four with different patterns of increasing streamflow, and one with stations without trend structure. Trends in the mean, minimum, and maximum of three satellite indices were determined; the spatial patterns of trends in NDWI and NDSI were similar to each other, but different from NDVI trends. Streamflow regime types, the trend patterns, and satellite indices trends each showed spatially coherent patterns reflecting the influence of sources in the Canadian Rockies and other range in the west and poorly defined drainage basins due to post-glacial topography in the east and north. The overlap between hydrological and satellite index trends were not consistent across the study area. Three particular areas of change were identified: [i] in the mountains or lake-dominated, cold taiga-covered subarctic, north of 60° N, streamflow and greenness were increasing while wetness and snowcover were decreasing, [ii] in the forested Boreal Plains, particularly in the mountain west, streamflows and greenness were decreasing but wetness and snowcover were not changing, and [iii] in the semi-arid to sub-humid agricultural Prairies three patterns of increasing streamflow and an increase in the wetness index were observed. The largest changes in streamflow occurred in the eastern Canadian Prairies, where there were only a few increases in greenness and snow indices.

Paul H. Whitfield et al.

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2020-613', Mehdi Bahrami, 01 Feb 2021
    • AC1: 'Reply on RC1', Paul Whitfield, 10 Feb 2021
  • RC2: 'Comment on hess-2020-613', Anonymous Referee #2, 04 Feb 2021
    • AC2: 'Reply on RC2', Paul Whitfield, 18 Feb 2021
  • RC3: 'Comment on hess-2020-613', Anonymous Referee #3, 10 Feb 2021
    • AC3: 'Reply on RC3', Paul Whitfield, 24 Feb 2021
  • RC4: 'Comment on hess-2020-613', Anonymous Referee #4, 24 Feb 2021
    • AC4: 'Reply on RC4', Paul Whitfield, 25 Mar 2021
  • RC5: 'Comment on hess-2020-613', Anonymous Referee #5, 01 Mar 2021
    • AC5: 'Reply on RC5', Paul Whitfield, 25 Mar 2021

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2020-613', Mehdi Bahrami, 01 Feb 2021
    • AC1: 'Reply on RC1', Paul Whitfield, 10 Feb 2021
  • RC2: 'Comment on hess-2020-613', Anonymous Referee #2, 04 Feb 2021
    • AC2: 'Reply on RC2', Paul Whitfield, 18 Feb 2021
  • RC3: 'Comment on hess-2020-613', Anonymous Referee #3, 10 Feb 2021
    • AC3: 'Reply on RC3', Paul Whitfield, 24 Feb 2021
  • RC4: 'Comment on hess-2020-613', Anonymous Referee #4, 24 Feb 2021
    • AC4: 'Reply on RC4', Paul Whitfield, 25 Mar 2021
  • RC5: 'Comment on hess-2020-613', Anonymous Referee #5, 01 Mar 2021
    • AC5: 'Reply on RC5', Paul Whitfield, 25 Mar 2021

Paul H. Whitfield et al.

Paul H. Whitfield et al.

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Short summary
Using partial year streamflow records a regime and change classification were produced for ~400 watersheds in the Nelson and Mackenzie River basins, and trends in water storage and vegetation were detected from satellite imagery. Three areas show consistent changes; north of 60° [increased streamflow and basin greenness], in the western Boreal Plains [decreased streamflow and basin greenness], and across the Prairies [three different patterns of increased streamflow and basin wetness].