| Title | Reconstruction of past hydrology in the James Bay Hydroelectric Complex over the past 200 years |
| |
| Author | Bégin, Y; Nicault, A; Arseneault, D; Bégin, C; Savard, M M ; Berninger, F; Boreux, J -J; Guiot, J; Perreault, L; Roy, R; Chartier, I |
| Source | ArcticNet Third Annual Scientific Meeting (ASM2006): proceedings; 2006, 31 pages  Open Access |
| Links | Online - En ligne
|
| Links | Abstract - Résumé (pages 14-15)
|
| Image |  |
| Year | 2006 |
| Alt Series | Earth Sciences Sector, Contribution Series 20090060 |
| Meeting | ArcticNet Third Annual Scientific Meeting (ASM2006); Victoria, BC; CA; December 12-15, 2006 |
| Document | serial |
| Lang. | English |
| Media | on-line; digital |
| File format | pdf (Adobe® Reader®) |
| Subjects | Nature and Environment |
| Program | Hydro-Québec, Programme de financement |
| Program | Ouranos - Consortium on Regional Climatology and
Adaptation to Climate Change |
| Program | NSERC Natural Sciences and Engineering Research Council of
Canada |
| Program | ArcticNet |
| Abstract | In the last two centuries, we have witnessed a change in the water supply in the watersheds of northern Quebec. This change is recorded in the natural archives such as dendrochronological indicators
derived from lake shore trees. In order to retrace the evolution of the hydrological regime parameters with time, we have reconstructed the main hydroclimatological variables used in forecast models. The study was conducted in the region of the James
Bay hydroelectric complex of La Grande. Three types of proxies were used. The first one was the position of the tree line on the lakes shores. This position indicates that lake levels have been rising due to higher precipitation. The episodes of
colonization and retreat indicate that prolonged episode of low water levels have occurred seven times in summer in the
last two centuries. However, these summer low levels are only a negative incursion in the positive trend towards higher lake
levels mainly related to higher snow precipitation. This last information is inferred from ice-scarred trees, the second type of proxy studied. Ice scars allow the dating and evaluation of the amplitude of high snow levels in the last centuries.
River floods are explained by different hydrological processes but can be dated with the same method demonstrating the same rising trend for the last two centuries. In the absence of instrumental data, the use of discrete events give the possibility
of dating hydroclimatological extremes, detecting changes in
the precipitation regime and evaluating the range of variability in time and space. The third type of proxy comes from dendroclimatology. Trees occupying sites sensitive to water
availability variations (xeric, mesic and hygric sites) and those sensitive to thermal conditions (depending on exposition) give the opportunity to reconstruct climate variability between years. A calibration period with instrumental data is
essential and it is also important to verify the models relating rings to climate with independent data. A widespread network of measuring sites allows the evaluation of the spatio-temporal variability of these indirect climate markers. More than
one hundred treering
series covering more than 180 years, tens series of more than 250 years and two series covering almost one thousand years have been reconstructed. These tree-ring series cover an area of 320 000 km2 (800 km in longitude x 400
km in latitude). Our aim was to reconstruct quantitatively the main variables used in hydrologic forecast models as identified by a research team from Ouranos and Hydro-Quebec. The main variables are summer temperatures, snow precipitation and
seasonal water supply. The tree-ring proxies used were ring width, density (9 derived variables) and the ratios of the stable isotopes of oxygen and carbon. The first step of the study consisted in finding and analyzing all instrumental data
available for the area. This first step had double results. It permitted to obtain all validated data used in the calibration of tree-ring series and in the construction of the models relating tree-rings, hydrological conditions and climate. It also
allowed
establish the scientific basis of a northern network of hydroclimatological data taking into account the spatio-temporal representativeness of the available data. The second step of the study was to unravel the meaning of each proxy and
model the relationship between tree-rings, hydrological conditions and climate. Finally, the third step consisted in using all proxies to reconstruct past conditions for the period
before the availability of instrumental data. We could in this way
determine the evolution of hydrological and climatological conditions for the last two centuries. |
| GEOSCAN ID | 247407 |
|
|