Climate change, flow regulation and land-use effects on the hydrology of the Peace-Athabasca-Slave System; findings from the Northern Rivers Ecosystem Initiative.

The Northern Rivers Ecosystem Initiative (NREI) was established in the late 1990s to address important science questions resulting from previous studies undertaken by the Northern Rivers Basin Study (NRBS). This manuscript summarizes the results from a number of reports on hydrologic research conducted on the Peace-Athabasca-Slave river and lake systems. Specific concerns expressed by the NRBS and subsequent NREI focused on how these systems were being affected by climate change, flow regulation and land-use changes. Issues addressed in this report include: the fate of aquatic perched basins within the Peace-Athabasca Delta under historical and future climate trends; the sources of major floods that replenish these basins and how the frequency, magnitude and source areas of such events have changed over time; the synoptic weather patterns and atmospheric teleconnections that are responsible for the generation of major snowmelt runoff that drive major floods; the potential effect that climate and land-use changes might have on basin runoff and delta lake levels; the specific hydro-climatic conditions required to produce major ice-jam floods on the Peace River and how these may be altered by climate change; remote-sensing methods to document delta flooding and vegetation change; and the dual effect of climate and flow regulation on the water levels of Great Slave Lake and how these may affect other nearshore processes, particularly wind seiches, that influence flooding of the Slave River Delta. A review of the major findings and recommendations for future research concludes the report.

Hydrometeorological aspects of flood hazards in Canada

Floods are major disasters in Canada and worldwide. Although technology has reduced the flood hazard in many areas, the world death toll from floods in recent decades still has averaged 4680 per year. During the summer of 1993, flooding in the U.S.A. caused an estimated $12 billion damage. These statistics confirm that floods are a major natural disaster. This paper reviews the hydrometereological aspects of the hazard associated with rainstorm, urban, ice-jam, and snowmelt floods. The hazard element is highest for floods with rapid onsets such as rainstorm, urban, and ice-jam floods. Although snowmelth floods are common throughout Canada, their slower onset times reduce their risk potential. To reduce the risk of the flood hazard, society must have access to statistical information for adequate planning and design, and forecasts for issuing warnings and implementing evacuation strategies. Flood design statistics and forecast models are discussed relative to each major flood type. The paper also describes historical flood frequency trends and discusses the implications of climatic warning for future floods. The paper concludes with a brief discussion of some knowledge gaps and research needs.(AU)