ABSTRACT: Dendrohydrological reconstruction of flooding in the Red River Valley, Canada.

CGRG Bibliography of Canadian Geomorphology
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Abstract

The Canadian portion of the Red River Valley has been affected by severe flooding several times in the 20th Century, with particularly damaging floods occurring in 1950 and 1997. However, instrumental hydrological data is limited both in length and spatial coverage, with records spanningonly the latter part of the 19th and the 20th century. In 1999, the Geological Survey of Canada and Manitoba Geological Services Branch initiated a multi-disciplinary research program that will reconstruct the pre-instrumental flood history of the Red River. Tree-ring analysis will (i) provide annual reconstructions of important hydroclimatic variables within the Red River Valley over the last 350-400 years; (ii) identify large Red River floods prior to instrumental and historical records; and (iii) place the flood of 1826 (the largest known historical flood) within a context of over 500 years. The current network of bur oak (Quercus macrocarpa) along the Red River includes 9 living tree sites, 10 mid-19th century buildings and numerous subfossil logs from Red River alluvium. The network follows a 100-km north-south transect from Winnipeg to the Manitoba-USborder and spans the period 1463 to 1997. Red River oaks have significant common variance at high frequencies (> 32 years) that likely reflects the influence of a valley-wide environmental control. Several oaks damaged by the flood of 1826 contain a flood ring distinguished by greatly reduced earlywood vessel size, poorly developed latewood and a lighter colour. Radiocarbon dates of up to 1500 years ago for selectedsubfossil samples indicate considerable potential for developing millennial-length chronologies for southern Manitoba.

Bibliography of Canadian Geomorphology