Flood hydrology of the Peace‐Athabasca Delta, northern Canada

Abstract

Abstract:This study conducted a systematic examination of the flood hydrology of the Peace-Athabasca Delta (PAD), a complex and internationally important freshwater ecosystem located in northwestern Canada. Three distinct zones of floodwater origin within the PAD were discerned on the basis of the dominant hydrology and the topography represented by a digital-elevation model (DEM): (1) perimeter Peace Delta, (2) perimeter Athabasca Delta, and (3) central delta lakes. Analysis of the satellite image and DEM-derived flood maps of historically significant events, combined with field data of open-water and ice-influenced flood stages, revealed that ice-jamming was the most effective and likely the only mechanism capable of recharging the highly elevated perimeter areas in the Athabasca and Peace Deltas. This supports the conclusion of previous studies that used hydrometric data external to the delta to infer inter-delta flood conditions. By contrast, even the record open-water flow to the Peace Delta could not generate overbank flow. Hydraulic simulation of the naturalized system (no dam & no weirs) suggests that overbanking of the lower Peace River would have been a rare occurrence without the effects of regulation. Both ice-jam induced and open-water high waters were found to recharge perched basins in the Athabasca Delta. Enlargement of the central delta lakes beyond the shoreline was determined to be an effective flood mechanism for filling low to mid-elevation wetlands. Comparison of the observed and naturalized lake levels indicates that flow regulation of the Peace River and addition of the weirs on delta outflow channels has, depending on the year, led to an increase or a reduction in the annual maximum potential of inland flooding via lake expansion.

Resistance and Resilience of A Stream Salamander To Supraseasonal Drought

“…In the case of flow increases on the Eurasian rivers, potential controlling factors, such as ice melt from permafrost, forest-fire effects and dam storage variations, have been eliminated as being responsible (McClelland et al, 2004), and one modelling study suggests that anthropogenic climate forcing factors have played a role. Evaluating the effects of climate and other factors on the largest Arctic-flowing river in North America, the Mackenzie River, has proven particularly difficult because of the large dampening effects on flow created by natural storage-release effects of major lakes and reservoirs (e.g., Gibson et al, 2006;Peters et al, 2006). [WGI 9.5.4;WGII 15.4…”

Flood Frequency Variability During the Past 80 Years in the Slave River Delta, NWT, as Determined from Multi-Proxy Paleolimnological Analysis

“…Conversely, major flooding results from high snow accumulation and a rapid spring melt in the Smoky River Basin. A major ice-jam flood occurred in the PAD in 1974 (Peters et al, 2006b), which likely extended downstream to the SRD (Figure 8), was generated by extremely high discharge on the Peace River (8700 m 3 /s, Water Survey of Canada, 2006) as a result of historical maximum peak snow accumulation in the Smoky River catchment . The strong correlation between Peace and Slave River discharge (Brock et al, 2008) is also evident in the sediment records of flood-dominated lakes in both deltas.…”

Streamflow input to Lake Athabasca, Canada

“…Lake Athabasca forms a large, natural reservoir of freshwater in the upper reaches of the 1.8 × 10 6 km 2 Mackenzie River basin, thus influencing the timing and amount of pan-Arctic river discharge (e.g., McClelland et al, 2006). It is the site of the ecologically sensitive Peace-Athabasca Delta (PAD) that depends on spring flood events for freshwater recharge (Peters et al, 2006;Smith and Pavelsky, 2009;Wolfe et al, 2008a,b). The Athabasca River, the longest river entirely within Alberta, is especially important for societal needs and economic development such as for domestic water consumption and for irrigation of agricultural lands.…”