HR: 17:05h
AN: GC52B-05    [PDF]
TI: Long-Term Variability in River Flow and Associated Lake Levels in the Canadian Prairie Provinces: Applied Dendrohydrology
AU: * MacDonald, G M
EM: macdonal@geog.ucla.edu
AF: Department of Geography UCLA, 405 Hilgard Ave, Los Angeles, CA 90095 United States
AU: Meko, D M
EM: dmeko@ltrr.arizona.edu
AF: Laboratory of Tree-Ring Research, The University of Arizona, Building 58T, Main Office Room 105 West Stadium, Tucson, AZ 85721 United States
AU: Case, R A
EM: rcase@mclam.com
AF: McDaniel Lambert Inc, 1608 Pacific Ave., Venice, CA 90291 United States
AB: Understanding natural variability in river flow and lake levels is a major concern in water policy formulation and the development of resource management strategies in the prairie provinces of Canada. Two particularly high profile concerns are: 1. The natural variability in flow of the Saskatchewan River system, and 2. The natural variability in flooding of the Peace-Athabasca Delta system. The Saskatchewan basin recently experienced a severe multi-year drought between 2000 and 2003 that saw annual river flows decrease by 25 percent from their 20th century averages and precipitated sharp exchanges between the provinces regarding water rights. The Peace Athabasca-Delta is one of the largest freshwater delta systems in the world and of international importance under the Ramsar Convention. Pronounced dry periods over the past 30 years have led to debates and concerns regarding the natural variability of the delta hydrologic regime and the detection and management of the impact of W.A.C. Bennett Dam which was built on the Peace River in the 1960's. Instrumental records of river flow, floods and lake levels in western Canada extend back only about 100 years, are discontinuous, and insufficient for assessment of long-term variability for planning purposes. Tree-ring records from the southern and central portions of Alberta and Saskatchewan provide reconstructions of river flow in the Saskatchewan River system that extend back from 300 to 1100 years. The records indicate that 20th century mean flows were 6.5 to 8.6 percent higher than long-term means. Multi-annual to multi-decadal periods of low flow, without analogues in the last 100 years, occurred during the mid 1800's and early 1700's. The period of 900 to 1300 was typified by consistently low flows including multi-decadal periods in which flows did not reach long-term or 20th century mean values. The policy difficulties experienced during the most recent drought suggest an inability of present water management strategies to cope with the potentially more severe and prolonged droughts that are a natural part of the system. A reconstruction based on tree-ring chronologies from throughout western Canada indicates that the Athabasca River experienced flows that were 32 percent below the long-term mean during an extended period of low flow in the mid 1800's. This dry period corresponds with the episode of low flow evident in the adjacent Saskatchewan River system. In contrast, a similar reconstruction for the more northerly Peace River does not exhibit any evidence of prolonged or severe low flows during the mid 19th century. An episode of low flow on the Athabasca and Peace rivers, and portions of the Saskatchewan system, during the late 1880's and early 1890's corresponds to a prolonged period of low water levels on Lake Athabasca that appears longer in duration and similar in magnitude to the epiode of initial low lake levels and delta drying that was experienced following completion of Bennett Dam.
DE: 1620 Climate dynamics (3309)
DE: 1812 Drought
DE: 1821 Floods
SC: Global Climate Change [GC]
MN: 2003 Fall Meeting