Restoring Ice-jam Floodwater to a Drying Delta Ecosystem

Pietroniro³

et al. 2006

Hydrological Processes

Self Cite

104

100

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.

Section: Historical Flood Eventsmentioning

confidence: 97%

Section: Historical Flood Eventsmentioning

confidence: 98%

Section: Historical Flood Eventsmentioning

confidence: 99%

See 1 more Smart Citation

Flood hydrology of the Peace‐Athabasca Delta, northern Canada

Peters

Pietroniro³

et al. 2006

Hydrological Processes

Self Cite

104

100

“…Prowse and Conly (1998) suggested that reservoir operation has helped generate Q M in the lower Peace River. In particular, following the recommendations of the NRBS (1996), reservoir releases were briefly enhanced in the spring of 1996 to increase potential flooding of the Prowse et al, 2002). Overall, more than half of Q M , on average, originated from above the town of Peace River (¾66%) under both flow regimes.…”

Section: Annual Eventsmentioning

confidence: 99%

Generation of streamflow to seasonal high waters in a freshwater delta, northwestern Canada

Peters

2006

Hydrological Processes

Self Cite

Abstract:Shallow lakes and wetlands in the Peace-Athabasca Delta (PAD), one of the world's largest freshwater deltas located in northwestern Canada, are dependent on occasional flooding to replenish evaporated water. The hydrology of the PAD has experienced natural and human induced changes in recent times. Since the early 1970s, there has been a desire to restore water to perched wetlands by managing inundation of the perimeter deltas. Before such plans are implemented, it is important to understand the generation of annual peak ice-induced and open-water floodwaters to this Nordic delta. The hydroclimatology, physiography, size, and relative locations of sub-basins exert a strong control on the runoff response. Ice-jam floods in the lower Athabasca and Peace Rivers are generated by large snowmelt runoff from 'trigger tributaries' located in the downstream (foothills and plains) portions of the basin. Flood flows during the open-water period are primarily generated by heavy rainfall runoff originating from the more elevated foothill/mountain regions where the precipitation process is enhanced by orography. In general, storage of alpine runoff in the headwaters of the Peace River places an increased dependence on downstream tributaries of the system to produce extreme flow events to the delta. Recommendations are made for additional hydrological modelling studies to assess the potential change to generation of extreme events from additional water retention/diversion schemes, land-use change, and a changing hydroclimate within the upstream contributing basins of the PAD.

“…Detailed analysis of the event using the calibrated RIVJAM model revealed that the flow addition increased the flood level at the PAD by some 0.27 m at its peak effect. Proposal of this method as an adaptation strategy for dealing with the effects of climate change is described in Prowse et al (2002b).…”

Section: Resultsmentioning

confidence: 99%

Climate Change, Flow Regulation and Land-Use Effects on the Hydrology of the Peace-Athabasca-Slave System; Findings from the Northern Rivers Ecosystem Initiative

Beltaos

Gardner

et al. 2006

Environ Monit Assess

Abstract. 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.