DOI: 10.25921/9xw0-h868
title: NOAA/WDS Paleoclimatology - Lake Athabasca 200 Year Water Level Reconstruction

description: Tree-ring data were analyzed for a long-term perspective on ecological and hydroclimatic variations on the Peace-Athabasca Delta (PAD). The ecosystem of this Ramsar Wetland of International Importance in northeastern Alberta is sensitive to fluctuations in water levels of the numerous lakes, channels and perched basins, and attention has been focused in recent decades on the possibility of deleterious effects from climatic change and regulation of the Peace River by W.A.C. Bennett Dam. A network of eight Picea glauca tree-ring chronologies was developed, time series features of growth variation were summarized, and the chronologies were applied in a regression model to reconstruct an annual time series of early summer (July 11 to 20) water levels of Lake Athabasca for the period A.D. 1801-1999. Though statistically weak (R2 = 0.36), the reconstruction verifies adequately in cross-validation and is consistent with anecdotal written records of a dramatic decline in water levels in 1879-81. Correlation of reconstructed and observed water levels improves with smoothing. Gaussian smoothing (ten years and longer) identifies a major low centred on 1890. The differential growth responses among the sites as well as evidence from other tree-ring studies suggest the 1890 low was associated primarily with diminished Peace River flows. The 20th century is unusual in a long-term context for high-amplitude multi-decadal variations in tree growth and reconstructed water levels, but the timing of these more recent fluctuations appears unrelated to the building of the W.A.C. Bennett Dam. Further research is needed to better discriminate the tree-ring signal for lake-level variation from the signal due to localized precipitation.
description: Tree-ring reconstructed water level of Lake Athabasca at Ft. Chipewyan, Alberta Province, Canada. Reconstructed variable is the 10-day-average water level for the period July 11-20.
Tree rings of white spruce (Picea glauca) have previously been used to reconstruct annual variations in Lake Athabasca water level back to the early 1800s (Stockton and Fritts 1973). 
	This study includes an updated reconstruction of Lake Athabasca water level, and extends the earlier tree-ring work in several ways: 
	1) improved tree-ring site coverage of the delta with additional chronologies, 
	2) increased sample depth at existing tree-ring chronologies, 
	3) analysis of the statistical relationship between tree-ring indices and climatic, 
	4) analysis of stable-isotope variations in cellulose of tree rings, 
	5) placement of the delta chronologies in the context of tree-ring variations over a much larger region of western Canada, 
	6) reconstruction of annual streamflow of the Peace and Athabasca Rivers, and 
	7) statistical testing of differences in tree-ring data and reconstructed water-level before and after construction of W.A.C. Bennett Dam.	
Supplementary information can be found in the Meko (2002) BC Hydro report at:
	ftp://ftp.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/canada/meko2002.pdf

	Original data file format is available here:
	https://www.ncei.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/canada/athabasca-lakelevel2006.txt
	
	Tree ring data available from the International Tree Ring Data Bank:
	https://www.ncei.noaa.gov/products/paleoclimatology/tree-ring

Files cana212.rwl - cana219.rwl were used for the reconstruction.  These data include 
	1970 collections by Fritts and Stockton, and new 2001 collections or recollections by Meko:
cana212.rwl - Point Providence 2001 Recollection
cana213.rwl - Quatre Fourches 2001 Recollection 
cana214.rwl - Horseshoe Slough
cana215.rwl - Revillon Coupe 2001 Recollection 
cana216.rwl - Peace/Rouchers 2001 Recollection
cana217.rwl - Athabasca River 2001 Recollection
cana218.rwl - Birch River
cana219.rwl - Mamawi Lake