Provincial Runoff Highlights

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Provincial Runoff Highlights

Publié le : jeudi 21 juillet 2011
Lecture(s) : 994
Nombre de pages : 17
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Provincial Runoff Highlights   May 8, 2011 Both Round and Crooked Lakes are beginning to decline. Inflow to the Qu’Appelle from eastern tributary streams from melting of the recent snow pushed the levels of Crooked and Round lakes to second peaks. Both lakes have dropped since yesterday but remain at high levels. Coupled with the potential for wave damage this increases the risk for cottagers at these lakes. These peaks are expected to be of short duration as the melt water from the recent storm passes and the lakes will then return to levels prior to the snow storm. Pasqua, Echo, Mission and Katepwa lakes are continuing a slow decline. Sandbag berms and other protective measures will be needed for several weeks on the Qu’Appelle lakes including an allowance for wind and maintenance of the berms. Please refer to the Qu’Appelle Lakes flood peak section of this report for additional information. Releases from Rafferty Reservoir are at 83 m 3 /s. This flow is expected to be maintained over the weekend. Flooding of low lying areas and some roads can be expected. High flows are necessary due to the high runoff from the recent storm. Cypress Lake is at its highest level since 1971. The diversions from Battle Creek and tributaries of the Frenchman into Cypress Lake are closed to avoid overfilling the lake which is expected to finish filling from local runoff. A small release from Cypress lake of 1.4 m 3 /s has been initiated. The level of Lenore Lake is at a record level and continuing to rise. Flows on the Red Deer River at Archerwell and Steen remain very high but have levelled and are near their peak.    
Southwest Region Missouri Watershed  While runoff in the Frenchman has produced high volumes of water, the long slow melt has kept peaks down and the risk of very high peaks has declined.  Cypress Lake is at its highest level since 1971. The diversions from Battle Creek and tributaries of the Frenchman into Cypress Lake are being closed avoid overfilling the lake, which is expected to finish filling from local runoff.  Belanger Canal is closed. All Belanger Creek water is running East down the Frenchman River.  Cypress Lake East Outflow Canal gate was opened yesterday to a release of ~1.4 m 3 /s. Local inflows into Cypress Lake continue including Sucker Creek from the East side.  Frenchman River near Ravenscrag station running 19 m 3 /s this morning.  Eastend Dam passing 27 m 3 /s, up 1 m 3 /s from yesterday..  Huff Dam continues to fill (21 m 3 /s in and 10 m 3 /s out). Should be full tomorrow.  Newton Reservoir is nearly full and now passing inflow. Water level is being held around 0.175m below FSL.  Once Huff is full tomorrow, both dams will pass inflow.  Frenchman River at the International Boundary is down to 24 m 3 /s today.  The snowpack in the upper portion of the watershed remains heavy but much of the runoff from the lower areas is well underway or has occurred. Photos below show some of the snow conditions April 30.  Flows on Battle Creeks at the international boundary are up from 5 m 3 /s yesterday to 11 m 3 /s this morning.  A repair is necessary on a dyke along the Nashlyn Canal. Therefore, the diversion down the Nashlyn Canal has been shut off. A small diversion into Cypress Lake via the West Inflow Canal may be necessary to allow the work to be completed at Nashlyn.  Lodge Creek at the International Border is steady at 15 m 3 /s.  Middle Creek Reservoir is full and spilling. These photos in the Missouri Watershed were taken April 29 & 30, 2100. See larger view of photos and descriptions at the end of report.  
Southeast Region Souris River Watershed  The peak flow from recent snow melt has passed. Long Creek at Noonan has declined to 31 m 3 /s, which is still a very high flow, but it is declining indicating the peak of the snow melt is past.  Releases from Rafferty Reservoir are at 83 m 3 /s. This flow is expected to be maintained over the weekend. Flooding of low lying areas and some roads can be expected.  This outflow is necessary because of high inflows into Boundary and Rafferty reservoirs as a result of the weekend snowfall.  Rafferty Reservoir is currently at a record high of 553.825 metres above sea level. Its maximum flood elevation is 554.0. The reservoir rose 0.07 metres over the past 24 hours. Storage in Rafferty Reservoir has been used to significantly reduce downstream flooding from the spring melt. However, the large volume of runoff this year has filled the reservoir above its full supply level and it is nearing its maximum flood elevation leaving little remaining storage. Outflows will remain high until runoff inflows drop and some storage is available in the reservoir.  Boundary Reservoir is 0.05 metres above full supply level. Flows through the diversion channel to Rafferty will be reduced today from 46.5 m 3 /s as inflows to Boundary are dropping.  Flows into Alameda Reservoir this morning are steady at 61m 3 /s. The reservoir rose 18 cm over the last 24 hours. At 565.187 the reservoir is above full supply level but is 1.8 metres below its maximum flood elevation of 567 metres above sea level.  The release from Alameda will be increased today from 22 to 35 m 3 /s. Wascana Creek Watershed  The level of Wascana Lake is again declining. People are again walking on the lake shore path which was under water a few days ago. The lake will continue to fall slowly over the next few weeks as the large volume of water passes through the watershed.
    
East Central Region Qu’Appelle Watershed   Inflow to the Qu’Appelle from eastern tributary streams from melting of the recent snow pushed the levels of Crooked and Round lakes to second peaks. Both lakes have dropped since yesterday but remain at high levels. Coupled with the potential for wave damage this increases the risk for cottagers at these lakes. These peaks are expected to be of short duration as the melt water from the recent storm passes and the lakes will then return to levels prior to the snow storm.  The tributary streams which were impacted by the recent storm are receding.  Pasqua, Echo, Mission and Katepwa lakes are continuing their slow decline.  Flow on the Qu’Appelle River at Lumsden and at Craven continues to drop.  Last Mountain Lake continues to rise. The lake is expected to peak in about a week approximately 10 cm above its current level. The rate of increase is declining as combined inflows to the lake from 2 major sources, the Qu’Appelle and Lanigan Creek, have dropped to 33 m 3 /s Saturday from 43 m 3 /s yesterday.  Wave action is now a major risk on the Qu’Appelle Lakes and caused significant problems over the past weekend. Flood protection measures such as sandbag berms should be built to provide 0.6 metres of protection above the expected flood peak to allow for wind and wave action. On Last Mountain Lake, due to its larger size, protection works should be 1.0 metres above the projected peak to allow for wave action. This level will provide protection for normal winds, but will still be over topped in an extreme wind situation. Additional height will be required if extreme winds, such as those observed during the past weekend, occur again.  T here are large volumes of water moving through the Qu’Appelle system.   The decline in lake levels will be gradual. Sandbag dikes and other protective measures need to be maintained for several weeks. Sandbag dikes require continuing maintenance or they may fail. Seepage under dikes will require pumping until lake levels drop.  The large volumes of water will mean high river flows through the summer and a slow recession. The best estimates of the rate of recession can be obtained by consulting the hydrographs from previous high water years. For example, examination of the hydrograph for Echo Lake (at the end of
this report) shows that that lake levels dropped at about the same rate following the two previous record events from 1974 and 1996. This gives some guidance to the rate of decline that may occur now, although Echo Lake is starting its decline from a much higher level. The rate of decline of the lakes will, of course, be highly influenced by summer precipitation. For example, the Crooked Lake hydrograph shows how the levels rose in mid-summer following rainfall vents in both 1955 and 1976.  The following table indicates current levels, projected peak levels and flows as of May 8, 2011. The levels of some lakes are now declining. The observed peak and the decline from the peak level are shown in red. Note that we do not have gauges providing daily levels for Mission and Pasqua lakes as they are virtually the same as the levels on Echo and Katepwa lakes. Lake j Current Level Projected Expected date Present Trend Pro ected or observed peak increase to or of peak level (in meters (Metres observed above sea level)  above sea decrease from level) peak (meters)  492.0 491.90 0.10 Mid May Rising  April 27 Declining 480.97 480.76 0.21 April 27 Declining  April 30 Declining 479.58 479.43 0.15 April 30 Declining 453.84 453.71 0.13 May 5 Declining 445.11 445.02 0.09 May 6 Declining
Last Mountain Pasqua Echo Mission Katepwa Crooked Round    Hydrographs for Echo, Katepwa, Crooked, Round and Last Mountain lakes are located at the end of this report.  Assiniboine Watershed  Flow of the Assiniboine River at Kamsack is 275 m 3 /s this morning, down from 291 m 3 /s yesterday.  The Whitesand is declining and is now at 162 m 3 /s.
 Fishing Lake fell 2 cm over the past 24 hours. The lake is now 9 cm lower than its peak level. Flood protection works are protecting the communities.  Good Spirit Lake rose another 2 cm over the past 24 hours, and, barring further precipitation, should be near its peak.  Melt from the recent snow storm is creating significant local flooding in the Yorkton area and east of Yorkton. Yorkton Creek is steady at 43 m 3 /s and appears to be at its peak flow. Smith Creek peaked May 5 at 19.7 m 3 /s, only 5.3 m 3 /s below its highest recorded peak, and is now declining. Stony Creek is also past its peak from the snowstorm and is now declining. Quill Lakes Watershed  Quill Lakes continue to rise although inflows are dropping. As these basins have no outlet, water will continue to rise and reach elevations not seen since the 1920s over the next few weeks. Northeast Region Carrot River Watershed  The level of Lenore Lake is at a record level and continuing to rise. The lake is about 7.5 cm higher than the peak reached last year. Red Deer Watershed  Flow of the Red Deer River at Archerwill remains steady at 60 m 3 /s this morning.  The Red Deer River at Steen remains at 90 m 3 /s and is near its peak.  Nut Lake is about 0.8 m above normal levels. Flows downstream remain very high.  Marean Lake at Greenwater Provincial Park is high, 0.09 metres below the peak observed in 2007. With wave action, this level may create a risk to properties that were impacted in 2007. The lake level has reached its peak.   Northwest Region  
 Local flooding issues continue to cause problems in the RMs of Corman Park, Vanscoy, and Grant.
 A forecast of up 2.5 cm of rain in the next few days will, if it occurs, further impact flooding in the closed basins and local flooding issues in Corman Park and other areas.  LAKE HYDROGRAPHS
The following graphs present water levels on some of the Qu’Appelle Lake s through the spring and compares them with two previous flood years.  
 
 
 
 
 
 
 
Update
W
atershed Authority will update this
runoff report
on May
9.
 
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