OPEN-WATER AND ICE-JAM FLOODING OF A NORTHERN DELTA

Citation
Td. Prowse et V. Lalonde, OPEN-WATER AND ICE-JAM FLOODING OF A NORTHERN DELTA, Nordic hydrology, 27(1-2), 1996, pp. 85-100
Citations number
19
Categorie Soggetti
Water Resources
Journal title
ISSN journal
00291277
Volume
27
Issue
1-2
Year of publication
1996
Pages
85 - 100
Database
ISI
SICI code
0029-1277(1996)27:1-2<85:OAIFOA>2.0.ZU;2-X
Abstract
Flooding is critical to the ecosystem health of many river-delta envir onments, particularly to perched-ponds and lakes that are vertically s eparated from the open-water flow system. This is the case for the Pea ce-Athabasca Delta in northern Canada, one of the world's largest, fre shwater deltas. Unfortunately, this delta has not experienced a major flood since 1974. As a result, significant drying has occurred in the higher-elevation portions of the Delta landscape. This has led to sign ificant changes in, for example, the vegetation regime and the related small-mammal habitat. For almost two decades, popular belief was that drying of the Delta was due to a reduction in the size of open-water floods resulting from upstream flow regulation and/or changes in clima te. Following a historically high flood in 1990, however, it was reali zed that open-water floods were relatively ineffective in flooding the perched bases. A historical analysis of hydrometric records revealed that the major peak-water levels have been produced at the time of bre ak-up. The spring flow driving such events are more related to downstr eam tributary runoff than flow produced within the headwaters, above t he point of regulation. Other ice factors, however, such as thickness, strength, and winter levels, may also have been important in controll ing break-up severity.