Hydrometric Data Review for 3 Sites Upstream of Okotoks, Alberta

Transcription

1 Prepared for AMEC Foster Wheeler Hydrometric Data Review for 3 Sites Upstream of Okotoks, Alberta 05BL012 Sheep River at Okotoks 05BL013 Three Point Creek at Millarville 05BL014 Sheep River at Black Diamond Greg MacCulloch P.Eng. 6/29/2015

2 Acknowledgements All data source for this review was provided by Environment Canada either through their publicly available HYDAT website ( the EC Data Explorer desktop application, or from personal correspondence with staff at the Water Survey of Canada, Alberta District Office in Calgary, Alberta. The author would, in particular, like to express his gratitude to Mr. Dennis Lazowski, Hydrological Services Supervisor, WSC-Alberta for his invaluable help and generous efforts in providing the data and associated information with speed and accuracy. i

3 Hydrometric Data Review for 3 Sites Upstream of Okotoks, Alberta 1 Introduction Subsequent to significant flooding that occurred in Southern Alberta during the month of June, 2013, a detailed look at the basic data used to compute peak flow risk is warranted. This report reviews the data provided by the National Hydrometric Program, a cost-shared program by the governments of Canada and the Provinces. It should be noted that throughout this review the terms flowrate and discharge are considered synonyms and are used interchangeably. Factors impacting the quality of the hydrometric record used in the risk assessment include: Proximity to the point of interest Length of record Range of observation Measurement frequency Rating stability Hydrograph Consistency: compare annual peak flows: Maximum Instantaneous, Maximum Daily, Event Volumes and other sites. The preferred variable for assessing flood risk is annual maximum instantaneous peak flowrate. It is important to understand that this fundamental piece of information relied upon to derive flood risk is also a derivation, not a measurement. In general hydrometric practice, a series of direct discharge measurements are used to establish a rating curve with volumetric discharge being the dependent variable and river stage being the independent variable. Stage is the value that is commonly measured on a more or less continuous basis; except in very rare instances where stage observations are augmented by near real-time velocity data, time varying stage data is the only parameter used to derive the corresponding streamflow rates.. The nature of streams that rise on the eastern slopes of the Canadian Rockies is such that annual peak flows are momentary in duration and often significantly larger in magnitude than the corresponding maximum daily mean flowrate, which is again often significantly larger in magnitude than the average flow for the year. Consequently, determining peak values is a challenge at best as the observational experience for such events is quite low. This is compounded further for extreme events such as those that occurred in the area in the early 1900s and again most recently in 1995, 2005, and Such extreme events create a demand for direct field observation over a large geographic area during difficult conditions. To further complicate the work the floods often cause the failure or destruction of gauging equipment at a time when accurate results are most in demand. The transitory nature of flood peaks results in an inability to revisit events to confirm results or check potential errors. 1

4 This review looks at the published hydrometric record for 3 sites at and upstream of the Town of Okotoks in the context of data suitability for high flow risk assessment. It includes a look at the basic data used for the derivation of stream flow provided by the Water Survey of Canada, Alberta District Office. 2 05BL012 Sheep River near Okotoks Proximity to point of interest: As noted in the WSC station description for this site: This station is located in the town of Okotoks. From the intersection of Hwy # 2A and Riverside Drive West, travel East for 0.7 km. The gauge is on the right side of the road, just past the intersection of Centre Ave and Riverside Drive West (also known as South Railway St). The gauge monitors flows in the largest stream to pass through the Town of Okotoks, Alberta. Any consideration of activity that might impact or be impacted by the Sheep River in the vicinity of the town should consider data from this site. Approximately 1/3 of the contributing drainage area to this point is captured at the gauging location on Threepoint Creek near Millarville, and another 1/3 is observed at the site on the Sheep River at Black Diamond Length of record Gauging has been sporadic at this site which was first established in For the 8 year period from 1908 to 1915 manual observations of stage were made during the open water season by a local observer, typically once per day (although the published record suggests less frequently as many concurrent days have the same value). From 1916 to 1920 manual observations continued on a year round basis. The operation of the gauge was discontinued for the first time after The gauge was re-established in 1965 and operated on a continuous basis with an automatic recording device until November 30, Continuous gauging was re-established once again in 2006 and the gauge continues to operate at the time of this review (2015); however, data computations are behind the standard and hydrometric results are only available up to December 31, Thus, peaks flows for the recent year of concern are not yet available, even on a tentative basis. Reference to nearby gauges (Bow at Calgary, Three Point Creek near Millarville, and Sheep River at Black Diamond) indicate some significant gaps exist in the record that will impact risk analysis if the record is not extended to consider these historic events. Notable peaks flows that are missing from the record for Sheep River at Okotoks include the years: 1915, 1916, 1923, 1929, 1970, 1990, 1995, and The last is a significant gap as peak flows for 2005 may have exceeded 2013 flows. It should be noted that for the only site in this review with data for 2013, the peak was lower than the peak for

5 Some significant years of low flow are missing from the record. Comparison with the same nearby sites suggests that significant years of low flow include: 1910, 1914, 1920, 1941, 1966, and the period from the late 1970s to the mid-1980s. Any analysis of risk should consider these gaps and efforts should be made to understand how the record at this site might relate to nearby sites with more data available Range of observation: Notwithstanding the relatively short period of record, stream gaugers were successful in making a direct discharge measurement of 452 m 3 /s on May 27, This is close to the maximum daily peak flow of 524 m 3 /s measured July 16, 1915, and exceeds the highest reported daily flow of 419E m 3 /s May 27, 2011, (note that this is an estimated value [see table7.1.1]). In 1915 the gauge was operated manually, so there was no way to determine the value or time of the instantaneous peak. Also, an instantaneous peak for the year 2011 is not part of the hydrometric record; speculating, this was likely due to do with a gauge failure at the time of peak flow. Although a mean daily value was estimated it was likely prudent for the Water Survey of Canada technologist to be conservative and not estimate the peak. Available record indicates that annual instantaneous peaks discharge for high flow events is in the order of a factor of 1.5 times the maximum daily mean for the year. [See ] This is consistent with the other two sites in the review. Considering that the sum of the maximum daily flow during the 2005 high water event for Three Point Creek at Millarville[see ], and Sheep River at Black Diamond [see ], are close to the peak value observed in 1915 it is fair to say that the hydrometric record of observations support the results at this site. The range of direct discharge measurement can be considered good for this site, although the record length is quite short and many important flows are absent from the record due to choices made by the Hydrometric Network Administrators regarding network extent Measurement frequency Direct discharge measurements are costly; however, they are the best way to be assured of the validity of the rating curve. A review of the station visits for this site (see7.1.3] shows that apart for the month of December, the stream gauge is visited on a monthly basis and during high conditions 2 to 4 times a month. This is well within the standard for hydrometric operations Rating stability Streams in this area typically run through glaciated material making the stream beds prone to aggradation and degradation of the loosely packed sands, gravels, and cobble. The rating curve shown [see 7.1.4] includes all recent measurements; however the points subsequent to May 10, 2007 have been adjusted by adding m to the gauge height to correspond to historic datum. Corrections such as this are common; the stage is generally referenced to an arbitrary datum plane and not linked to other references for elevation such as the Geodetic Survey of Canada. 3

6 How well individual measurements are fit to the rating curve are shown by the chart at (showing the departure of the measurement from the curve by stage), and the chart at (showing the same departures plotted by discharge). The charts demonstrate complete agreement with the rating when the measurements fall on the zero percent line. Negative values indicate the rating exceeds the measurement and positive values that the rating is less than the measured value. As can be seen for the gauge at Okotoks, measured values are rarely within 5% of the rating and values +- 20% are not uncommon. It would be fair to see the same random error about the rating throughout the range of stage or flow; however, as the higher values are much less common, there is no comparison to be made. Consequently, the ratings tend to fall directly on the upper measurements giving a false confidence in the accuracy of peak events. In this case the majority of the departures are negative suggesting that the rating may exceed an average result if many measurements were available. To make a general statement, this rating curve should not be used by those unskilled in its application except as a guide to the shape of a rating. Accurate results for this site can only be achieved through a consistent and frequent direct discharge measurement program (as is being done) and the judicious application of shifts to the rating or stage record Hydrograph Consistency: compare Max. Inst., Max. Daily, Event Volumes and other sites. The site at Okotoks is downstream of the other two sites in this review. As these gauging locations are hydraulically and hydrologically connected it is expected that upstream responses are also observed at the downstream location. A review of the annual peak hydrographs demonstrates that this is indeed the case. Although the Calgary gauge is not hydraulically connected and the Bow River is regulated to a large degree, the patterns of highs and lows are trackable in all sites giving us confidence in the results. 4

7 3 05BL013 Threepoint Creek near Millarville Proximity to point of interest: The gauge is located in a rural area at a major road crossing. A bridge immediately upstream of the gauge may restrict flows during times of high flow; however, the hydraulic control downstream of the gauge will not be significantly altered from the natural state. The gauge monitors flows in a rural area in the foothills of a stream that is a major tributary to the Sheep River upstream of the Town of Okotoks. It is located about 10 km upstream of Threepoint Creek s confluence with the Sheep River and about 30 km upstream of the town of Okotoks Length of record Of the three sites in the review Threepoint Creek has the longest period of record, although not significantly different from Sheep at Black Diamond. In total the gauge has been operated for 60 years over a span of 108 years, beginning in 1908 and continues today. The gauge is operated seasonally from March to October, typical of rural monitoring in Alberta. Although it lacks continuity, the summer season data is still valid for consideration of flood and drought risk. Looking at the annual extremes summarized in Table 8.1.1,early season (Feb/March) low flows are less than 100 l/s (0.1 m 3 /s), while maximum daily values range from a low of 3.18 m 3 /s in 1988 to a high of 229 m 3 /s in Curiously, for the years 1966 through 1989 daily values are available yet only maximum instantaneous peak discharges are reported. The maximum daily values reported here in Table were taken from the daily record available through HYDAT, the interactive archival record for Canada s National Hydrometric Program. This gauging site is the only one under review to present data for the 2013 year. Although 2013 is a year of interest due to the devastating flooding that occurred throughout southern Alberta, it is noteworthy that the peak flow for this site in 2013: a maximum instantaneous value of 289 m 3 /s is less than the maximum instantaneous value derived for the year 2005: 389 m 3 /s. The summer of 2005 is an important season that needs to be considered when making a risk assessment for this area. Looking through all hydrographs for this site ( through ) demonstrates a pattern of multiple peaks during a short period of time. Often the series of peaks are near coincident so that one augments others in the series. In the 2005 season [see Hydrograph ] 3 significant peaks were recorded in a span of 22 days. The maximum instantaneous value was recorded for the second peak on June 17 (229 m 3 /s), but the maximum daily value occurred 10 days earlier on June 7, yielding a peak of 389 m 3 /s. Subsequently, on June 28 a third event occurs yielding a mean daily flowrate of 140 m 3 /s. This value is the smallest of 3 peaks in a 22 day period, yet would have ranked 5 th overall for the 60 years of record. 5

8 Traditional risk analysis looks only at the single highest value in any given year; however, it is clear from this example that such an approach may under-estimate the magnitude of extreme conditions. As the hydrographs for this site often demonstrate two or more near concurrent events that make up a peak for any year, if these 3 separate events over 3 weeks during the summer of 2005 had been closer in time a more serious flood may have occurred. The three distinct peaks that occurred in June 2005 can be seen for many other gauging locations in the area, including Sheep River at Black Diamond, a gauge that is also subject of this review. Reference to nearby gauges (Bow at Calgary, Sheep River at Okotoks, and Sheep River at Black Diamond) indicate some gaps exist in the record that may impact risk analysis. Notable peaks observed at nearby sites that are missing from the record for Threepoint Creek near Millarville include the years 1923 and Some significant years of low flow are missing from the record, including1910, 1920, and Any analysis of risk should consider the record gaps and efforts should be made to understand how the record at this site might relate to nearby sites with a longer record available Range of observation: The highest historical direct discharge measurement on record occurred May 30, 1967 when 283 m 3 /s was gauged at this site. Reference to gauge height is no longer relevant so this number is of little use in establishing a rating except to suggest a range and general shape of the rating curve. The highest direct discharge measurement in recent times was 201 m 3 /s, June 28, The record shows 5 measurements between 150 m 3 /s and 200 m 3 /s suggesting that the rating is well supported by direct observations in that range. Of the 249 measurements available electronically since 1994, 234 of these are less than 50 m 3 /s. In the context of the derived maximum instantaneous peak of 389 m 3 /s, the peak measurement of 201 m 3 /s is marginally low to establish confidence in the rating. That said, typically peaks in the foothills region occur during flood events over a wide area at all times of the day and night and are of short duration. Annual flood durations range from 2 to 12 days with the median duration being 7 days. It is difficult to establish a measurement in the range of half an instantaneous peak. The difference between observation and derivation of approximately 100% is cause for concern in any risk assessment. However, it is commendable that a high measurement in a small channel was completed at all. Available records indicate that annual instantaneous peak discharge for high flow events is in the order of a factor of 1.5 times the maximum daily mean for the year [See ]. This is consistent with the other sites in the review. Understanding that peak flow determination without supporting direct discharge measurement is problematic, it would be of benefit to support the peak flow determination by indirect means (e.g., 6

9 slope- area measurement conducted after the fact); nevertheless having a measurement (200 m 3 /s ) that is 70% of the maximum daily value (229 m 3 /s) is very good. However, flood risk is generally considered using maximum instantaneous values, and in this case the highest measurement (200 m 3 /s) is only 51% of the peak (389 m 3 /s). Further, the standard field practice of demonstrating consistency by repeating any measurement that results in a total discharge that is more than 10% off the rating curve (always the case for unknown peaks values during flood events) is rarely done in practice (certainly not demonstrated for any of the 3 gauges in this review). During a flood event, the hydrographer must balance the demands form streamflow forecasters to collect data from as many sites as possible rather than making double measurements to satisfy rating curve development criteria. As is appropriate, concern over lives and property risk trumps science concerns when floods are happening. The range of direct discharge measurement can be considered good for this site; however, the uncertainty of peak flow determination should be taken into consideration when determining flood risk Measurement frequency A review of the station visits for this site [see 8.1.3] demonstrates that the stream gauge is visited on a monthly basis and during high conditions 2 to 4 times a month. This is well within the standard for hydrometric operations Rating stability Streams in this area typically run through glaciated material making the stream beds prone to aggradation and degradation of the loosely packed sands, gravels, and cobble. The rating curve shown [see 8.1.4] includes all recent measurements. Looking at the available measurement data (i.e., since 1994), results prior to the 2005 high water event do not relate to current conditions. This could be due to a variety of factors including changes to the channel by natural means, highway and bridge construction, or by loss of original reference points due to bank erosion and the consequent need to establish a new gauge datum. There is no sense speculating on the cause for the change in datum as there are sufficient measurements to show a stable rating between 2005 and As mentioned above there is some concern that the magnitude of the highest measurement is only half the peak determined from this curve, but we have some confidence that the general shape of the high curve is more or less parallel to high measurements observed at this site in How well individual measurements are fit to the curve are shown by chart showing the departure of the measurement from the curve by stage, and chart showing the same departures plotted by discharge. The charts demonstrate complete agreement with the rating when the measurements fall on the zero percent line. Negative values occur when the rating exceeds the measurement and positive values occur when the rating is less than the measured value. As can be seen on the charts and 8.1.6, the gauge near Millarville of the 70 values plotted only 7 are within +-5% of the rating curve. Measured values for this gauge are rarely within 5% of the rating and values +- 20% are not uncommon. 7

10 It is expected that some systematic errors are at play to explain some of the large departures of measurements from the rating curves. If the differences are due to random error, it would be fair to see the same random error about the rating throughout the range of stage or flow; however, as the higher values are much rarer, there is no comparison to be made. The lack of experience at peak flowrates for a rating curve generally leads to the common approach of forcing the rating through the few peak values that are available giving a false confidence in the accuracy of peak events. In the case of Threepoint Creek near Millarville, for flows exceeding 5 m 3 /s up to 50 m 3 /s it appears equally likely that the rating and the measurement to disagree by as much as 50%. For values higher than 50 m 3 /s there is not enough information to make a valid judgement. As is the case for many hydrometric sites, this rating curve should not be used except as a general guide to the shape of a rating by experienced practitioners. Accurate results for this site can only be achieved through a consistent and frequent direct discharge measurement program (as is being done) and the judicious application of shifts to the rating or stage record Hydrograph Consistency: compare Max. Inst., Max. Daily, Event Volumes and other sites. The site near Millarville is the most upstream of the three sites in this review. All three gauging locations are hydraulically and hydrologically connected so it is expected that upstream responses are also observed at the downstream location. A review of the annual peak hydrographs demonstrates that this is indeed the case. Although the Calgary gauge is not hydraulically connect and is regulated to a large degree, the patterns of highs and lows are trackable in all sites giving us confidence in the results. 8

11 4 05BL014 Sheep River at Black Diamond Proximity to point of interest: The gauge is located on the floodplain downstream of a major highway bridge at the town of Black Diamond, Alberta. The watershed to this point is predominately rural ranging from alpine to foothills to rolling prairie, much like the watershed leading to the gauge near Millarville. The highway bridge is large and robust and would not likely restrict flow except during the most extreme conditions. The contributing drainage area to this location is about 1/3 of the drainage to the Town of Okotoks. Another 1/3 contributes to the gauge location on Threepoint Creek near Millarville. The gauge is located about 10 km upstream of the confluence with the Threepoint Creek and 25 km upstream of the town of Okotoks. Any considerations of the impact of the communities upstream of Okotoks on the rivers, or the impact of waterways on infrastructure in the vicinity of Okotoks, should utilize data from this site Length of record Gauging for Station 05BL014 began in 1908 as Sheep River at Turner Valley. Records at the WSC District Office in Calgary describe the original location as 1 km west of Black Diamond. The station was moved and renamed under the same station number approximately 3 km downstream in October In 1997 the datum was lowered by 1 meter. The gauge was destroyed during the 2013 flooding and relocated below the highway bridge, approximately 100 m downstream of its previous location. In the 108 intervening years since gauging was first established in the vicinity of the Town of Black Diamond, the gauges have been operated for 57 years with the longest contiguous period of record being from 1968 to present (2015). At the time of this review, only data to 2012 is computed and available: a 45 year period. A summary of station information and data collection history can be found at The same effect of 3 significant peaks during the summer of 2005 for Threepoint Creek is also observed in the data for the Sheep River at Black Diamond and is worthy of special note. These 3 events are significant and need to be considered specifically when making a risk assessment for this area. Looking through all hydrographs for the station demonstrates a pattern of multiple peaks during a short period of time and often the events are near coincident so that one peak augments the other. In the 2005 season [see Hydrograph ], 3 significant peaks were recorded in a span of 22 days. The maximum instantaneous value for the second peak was computed for June 17 (380 m 3 /s), but the maximum daily value determined to occur 10 days earlier on June 7 yielding a peak of 245 m 3 /s. Subsequently, on June 28 a third event yielded a mean daily flowrate of 118 m 3 /s. This value is the smallest of 3 peaks in a 22 day period, yet it would have ranked 11 th overall for the 57 years of record. As for the station Threepoint Creek near Millarville, if these events had occurred closer in time so as to compound each other there exists the potential for much more serious flood. 9

12 Reference to nearby gauges (Bow at Calgary, Sheep River at Okotoks, and Threepoint Creek near Millarville) indicate some gaps exist in the record that may impact risk analysis. Notable peaks that have been recorded elsewhere yet are missing from this site include 1923, 1929 and Further, the year 1993 has a significant maximum daily flow but the corresponding maximum instantaneous value for that year is missing from the record. Also, some significant years of low flow are missing from the record. Comparing the same nearby sites suggest that significant years of low flow include 1910, 1920, and Any analysis of risk should consider the record gaps and efforts should be made to understand how the record at this site might relate to other nearby sites with a longer record available Range of observation: The highest historical direct discharge measurement available electronically (i.e., since 1994) occurred June 7, 2005 when 277 m 3 /s was gauged at this site (see Table 9.1.2). Comparing this to the reported maximum annual instantaneous peak of 380 m 3 /s June 17, 2005 [see Table 9.1.1] it can be easily calculated that the highest measurement is 73% of the peak value(note 2012 was last year available at the time of this review). This is a reasonable departure from a peak for the flashy streams that rise on the eastern slopes. As for most eastern slopes streams, the majority of the measurements are during low flow conditions. Of the measurements taken since 1994, 62.9% (185 measurements) occur for discharge quantities less than 1% of the peaks discharge reported (i.e., less than 3.8 m 3 /s). Further, 40.8% (120 measurements) are less than 0.5% of the reported peak. The fact that there is so little experience at the higher flow rates needs to be understood when assessing flood risk. The top 10 measurements have the following magnitudes in m3/s: 277, 173, 154, 146, 96.4, 95.5, 84.3, 78.3, 72.2, and Comparing these to the list of top 10 annual peak discharges (also in m 3 /s): 380, 366, 259, 207, 195, 185, 185, 150, 126, and 121 demonstrates that the range of flows is well covered; however, there are only single observations during the extreme high flow events. Therefore, the only corroborating evidence of validity of a singular events relating to a rating is the degree of linearity among the elements in the series. Looking at the measurements as plotted against the rating curve [see 9.1.4] suggests good linearity above a stage of 2.5 meters. Looking at the same information plotted as departures from the curve [see and 9.1.6] indicates that although the range in stage is well covered, departures from the rating are almost all greater than +- 5% with many being +- 50% or greater Measurement frequency A review of the station visits for this site (see 9.1.3] demonstrates that the stream gauge is visited on a monthly basis and during high conditions 2 to 4 times a month. This is well within the standard for hydrometric operations. 10

13 4.1.5 Rating stability Streams in this area typically run through glaciated material making the stream beds prone to aggradation and degradation of the loosely packed sands, gravels, and cobble. The rating curve shown [see 9.1.4] includes all recent measurements. Measurements prior to 1997 have been adjusted by 1 m to accommodate the change made to the datum in Measurements plotted on the rating curve show good agreement with the general shape of the curve. However apart from the highest measurements, for which there is scant experience, the individual measurements around the curve vary widely, in particular for flows less than 100 m 3 /s or stages below 2.5 m. Of the 294 measurements available for review, only 4 measurements have been made above 2.5 m in stage and no check measurements have been possible to validate the curve. How well individual measurements are fit to the curve are shown by the Chart showing the departure of the measurement from the curve by stage, and Chart showing the same departures plotted by discharge. The charts demonstrate complete agreement with the rating when the measurements fall on the zero percent line. Negative values are when the rating exceeds the measurement and positive values are when the rating is less than the measured value. As can be seen on the charts, of the 63 values plotted only 9 are within +-5% of the rating curve. For this site, measured values are rarely within 5% of the rating and values greater than +- 30% are not uncommon. It would be reasonable to see the same random error about the rating throughout the range of stage or flow; however, at high values of stage it is rare to find two proximal measurements for which a comparison can be made. It is not likely that measurements made during high flow should demonstrate less scatter about the mean than measurements made at lower flowrates. In hydrometric determinations some systematic error exists in all measurements, the degree of which is not understood for this site. As is the case for most gauge locations, the lack of experience at peak flowrates for a rating curve generally leads to the common approach of forcing the rating through the few peak values that are available giving a false confidence in the accuracy of peak events. If we consider that the discharge measurements at the top end of the rating curve are much more difficult to measure and subject to rapidly changing conditions, it is likely that peak flows determined by hydrograph extension are subject to large errors. As is the case for many hydrometric sites, this rating curve should not be used except as a general guide to the shape of a rating by experienced practitioners. Accurate results for this site can only be achieved through a consistent and frequent direct discharge measurement program and the judicious application of shifts to the rating or stage record Hydrograph Consistency: compare Max. Inst., Max. Daily, Event Volumes and other sites. The site at Black Diamond has a relatively long period of record and although the gauge has often been damaged and failed to work during the most extreme flooding, it has been operated through some of 11

14 the most serious high water events in the last 100 years. Such longevity makes this site very important as a reference for hydrology in the vicinity of the Town of Okotoks. Comparing this site to nearby locations demonstrates no obvious abnormalities. 12

15 5 Conclusions This review observes good consistency among the sites. This is to be expected as hydrometric records are rarely produced independently and comparison between sites is part of the process applied in the derivation of streamflow from stage data. In terms of suitability to task of this information for high flow risk assessment proximal to the Town of Okotoks the following generalizations can be made: 1. All 3 sites should be used in any decision making on the risk of high flow occurrences. 2. The record for the two upstream sites includes some significant and recent high flow events, making these sites most valuable in the risk assessment. 3. It is known that the peak flows for the 2013 year are significant and important in the assessment of risk for this area. At a minimum the peak flows for the 2013 year should be obtained prior to the assessment of flood risk. 4. Rating curves should not be employed without an understanding of the data used in their derivation. In general, accurate results are dependent on a consistent and frequent direct discharge measurement program and the judicious applications of shifts to the rating or stage record. The frequency of station visits suggests that this is well understood and is being done by the Water Survey of Canada. 5. Caution should be employed in application of derived peak flowrates. The review of rating curve stability indicates significant variability at low flows and the fact that opportunities for high flow measurements are rare makes it difficult to establish accurate ratings curves by direct discharge measurements alone 6. Although not specifically germane to the context of this review, efforts should be made to influence the National Hydrometric Program Partners (Province of Alberta and Government of Canada) to work towards peak flow validations for gauge locations on the eastern slopes of the Rocky Mountains. Techniques such as double measuring when results are more than 10% off the rating curve, post-facto determination of peak flow by indirect means, flood routing with HEC- RAS, etc. are well established and should be considered as fundamental to peak flow determination. 7. Special attention should be made to the 2005 summer season. At the only site for which 2013 data is available, peak flows for 2005 were higher than the peak derived for More importantly, 3 peaks occurred in 22 days during 2005, each of which could have been in the top 10 occurrences for the gauge sites. As the hydrographs demonstrate that annual peaks are commonly the result of the superposition of one or more peaks, the risk of flows similar to 2005 occurring in closer proximity resulting in compounding flows should be considered in the analysis of risk. 13

16 14

17 6 Station Record Summary 15

18 6.1 SHEEP RIVER AT OKOTOKS (05BL012) [AB] Station Information No table of figures entries found. Active or discontinued: Active Province / Territory: Alberta Latitude: 50 43' 26'' N Longitude: ' 24'' W Gross drainage area: km 2 Effective drainage area: N/A Record length: 27 Years Period of record Regulation type: Natural Regulation length: N/A Real-time data available: Yes Sediment data available: Yes Type of water body: River Reference Site (RHBN): No EC Regional Office: CALGARY Data contributed by: N/A Datum of published data: ASSUMED DATUM Data Collection History Period of operation Type Operation schedule Gauge type Flow Seasonal Manual Flow Continuous Manual Flow Continuous Recorder Flow Continuous Recorder Flow & Level Date modified: Continuous Recorder 16

19 6.2 THREEPOINT CREEK NEAR MILLARVILLE (05BL013) [AB] Station Information Active or discontinued: Active Province / Territory: Alberta Latitude: 50 46' 16'' N Longitude: ' 43'' W Gross drainage area: km 2 Effective drainage area: N/A Record length: 60 Years Period of record Regulation type: Natural Real-time data available: Yes Sediment data available: Yes Type of water body: River Reference Site (RHBN): No EC Regional Office: CALGARY Data contributed by: N/A Datum of published data: ASSUMED DATUM To convert to APPROXIMATE GEODETIC SURVEY OF CANADA DATUM, add 1155 m Regulation length: N/A Data Collection History Period of operation Type Operation schedule Gauge type Flow Miscellaneous Manual Flow Seasonal Manual Flow Seasonal Recorder Flow & Level Date modified: Seasonal Recorder 17

20 6.3 SHEEP RIVER AT BLACK DIAMOND (05BL014) [AB] Station Information Active or discontinued: Active Province / Territory: Alberta Latitude: 50 41' 16'' N Longitude: ' 37'' W Gross drainage area: km 2 Effective drainage area: N/A Record length: 57 Years Period of record: Regulation type: Natural Regulation length: N/A Real-time data available: Yes Sediment data available: Yes Type of water body: River Reference Site (RHBN): No EC Regional Office: CALGARY Data contributed by: N/A Datum of published data: ASSUMED DATUM Data Collection History Period of operation Type Operation schedule Gauge type Flow Miscellaneous Manual Flow Seasonal Manual Flow Continuous Recorder Flow & Level Date modified: Continuous Recorder 18

21 6.4 BOW RIVER AT CALGARY (05BH004) [AB] Station Information Active or discontinued: Active Province / Territory: Alberta Latitude: 51 03' 00'' N Longitude: ' 05'' W Gross drainage area: km 2 Effective drainage area: N/A Record length: 115 Years Period of record: Regulation type: Regulated Regulation length: N/A Data Collection History Period of operation Type Operation schedule Real-time data available: Yes Sediment data available: Yes Type of water body: River Reference Site (RHBN): No EC Regional Office: CALGARY Data contributed by: N/A Datum of published data: ASSUMED DATUM To convert to GEODETIC SURVEY OF CANADA DATUM, add m Gauge type Level Seasonal Manual Level Seasonal Manual Level Seasonal Recorder Level Seasonal Recorder Flow Seasonal Manual Flow Continuous Manual Flow Continuous Recorder Flow Seasonal Recorder Flow Continuous Recorder Flow & Level Date modified: Continuous 19 Recorder

22 6.5 BOW RIVER BELOW GHOST DAM (05BE006) Station Information Active or discontinued: Discontinued Province / Territory: Alberta Latitude: 51 12' 50'' N Longitude: ' 40'' Gross drainage area: 6550 km 2 Effective drainage area: N/A Record length: 52 Years Period of record: Regulation type: Regulated Regulation length: N/A Real-time data available: No Sediment data available: No Type of water body: River Reference Site (RHBN): No EC Regional Office: CALGARY Data contributed by: N/A Datum of published data: ASSUMED DATUM Data Collection History Period of operation Type Operation schedule Gauge type Flow Seasonal Recorder Flow Continuous Recorder Flow Continuous Recorder Flow Seasonal Recorder Date modified:

23 6.6 Preliminary Review of Period of Record and Hydrographs 21

24 6.6.1 Long Term Comparison of Proximal Hydrographs 22

25 6.6.2 Period of Record Hydrograph for 05BL012- Sheep River at Okotoks 23

26 6.6.3 Period of Record Hydrograph for 05BL013- Three Point Creek at Millarville 24

27 6.6.4 Period of Record Hydrograph for 05BL014- Sheep River at Black Diamond 25

28 6.6.5 Period of Record Hydrograph for 05BH004 Bow River at Calgary 26

29 7 05BL012-Sheep River at Okotoks 27

30 7.1.1 Summary of Peak Flow Data for 05BL012 Sheep River at Okotoks Year of Record Instantaneous Peak Flow (m3/s) SYMBOL B=ice, E=Estimate Time of Peak Flow HH:MM CODE Time Zone Instantaneous Peak Month of Occurrence (MM) Instantaneous Peak Day of Occurrence (DD) Maximum Annual Daily Mean Flow (m3/s) SYMBOL B=ice, E=Estimate Maximum Daily Mean Month of Occurrence (MM) Maximum Daily Mean Day of Occurrence (DD) Minimum Annual Daily Mean Flow (m3/s) SYMBOL B=ice, E=Estimate Minimum Daily Mean Month of Occurrence (MM) Minimum Daily Mean Day of Occurrence (DD) B B B B B A 23:00 MST A :16 MST B

31 Year of Record Instantaneous Peak Flow (m3/s) SYMBOL B=ice, E=Estimate Time of Peak Flow HH:MM CODE Time Zone Instantaneous Peak Month of Occurrence (MM) Instantaneous Peak Day of Occurrence (DD) Maximum Annual Daily Mean Flow (m3/s) SYMBOL B=ice, E=Estimate Maximum Daily Mean Month of Occurrence (MM) Maximum Daily Mean Day of Occurrence (DD) Minimum Annual Daily Mean Flow (m3/s) SYMBOL B=ice, E=Estimate Minimum Daily Mean Month of Occurrence (MM) Minimum Daily Mean Day of Occurrence (DD) :01 MST B :01 MST B :31 MST B E B A B

32 7.1.2 Recent Direct Discharge Measurements: 05BL012 Sheep River at Okotoks 05BL012 - SHEEP RIVER AT OKOTOKS 05BL012 - SHEEP RIVER AT OKOTOKS 05BL012 - SHEEP RIVER AT OKOTOKS Date Discharge (m^3/s) Stage (m) Date Discharge (m^3/s) Stage (m) Date Discharge (m^3/s) Stage (m) 01/01/ /11/ /03/ /02/ /12/ /03/ /03/ /01/ /04/ /03/ /02/ /05/ /04/ /03/ /06/ /05/ /03/ /06/ /06/ /04/ /07/ /06/ /04/ /08/ /06/ /05/ /10/ /06/ /07/ /10/ /07/ /08/ /11/ /07/ /09/ /01/ /08/ /10/ /02/ /09/ /11/ /02/ /10/ /12/ /03/ /12/ /01/ /04/ /01/ /02/ /05/ /02/ /02/ /06/ /02/ /03/ /06/ /03/ /04/ /08/ /03/ /05/ /10/ /04/ /06/ /10/ /05/ /07/ /12/

33 05BL012 - SHEEP RIVER AT OKOTOKS 05BL012 - SHEEP RIVER AT OKOTOKS 05BL012 - SHEEP RIVER AT OKOTOKS Date Discharge (m^3/s) Stage (m) Date Discharge (m^3/s) Stage (m) Date Discharge (m^3/s) Stage (m) 10/05/ /08/ /01/ /05/ /09/ /02/ /06/ /10/ /02/ /06/ /10/ /03/ /06/ /11/ /04/ /07/ /01/ /06/ /08/ /02/ /06/ /09/ /03/ /06/ /11/ /03/ /07/ /12/ /04/ /08/ /01/ /04/ /09/ /02/ /05/ /10/ /03/ /05/ /11/ /03/ /05/ /12/ /05/ /06/ /01/ /05/ /08/ /02/ /05/ /08/ /02/ /06/ /10/ /03/ /07/ /11/ /04/ /08/ /01/ /05/ /10/ /01/

34 7.1.3 Station Visit Frequency: 05BL012 - Sheep River at Okotoks 32

35 7.1.4 Rating Curve No. 5 Showing Recent Measurements: 05BL012-- Sheep River at Okotoks 33

36 7.1.5 Measurement Departure from Rating Curve by Stage: 05BL012 Sheep River at Okotoks 34

37 7.1.6 Measurement Departure from Rating Curve by Discharge: 05BL012 Sheep River at Okotoks 35

38 7.1.7 Duration of Annual Flood from Peak Hydrographs: 05BL012 - Sheep River at Okotoks 36

39 7.1.8 Annual Flood Volume Vs. Annual Max. Inst Flow: 05BL012 - Sheep River at Okotoks 37

40 7.1.9 Annual Flood Volume Vs. Annual Max. Daily Flow: 05BL012 - Sheep River at Okotoks 38

41 Rank of Annual Extremes by Peak and by Volume: 05BL012 -Sheep River at Okotoks 39

42 Compare Annual Maximum Instantaneous Peak to Maximum Daily: 05BL012 Sheep River at Okotoks 40

43 Combined Annual Peak Hydrographs: 05BL012 Sheep River at Okotoks 41

44 Sheep River at Okotoks

45 Sheep River at Okotoks

46 Sheep River at Okotoks

47 Sheep River at Okotoks

48 Sheep River at Okotoks

49 Sheep River at Okotoks

50 Sheep River at Okotoks

51 Sheep River at Okotoks

52 Sheep River at Okotoks

53 Sheep River at Okotoks

54 Sheep River at Okotoks

55 Sheep River at Okotoks

56 Sheep River at Okotoks

57 Sheep River at Okotoks

58 Sheep River at Okotoks

59 Sheep River at Okotoks

60 Sheep River at Okotoks

61 Sheep River at Okotoks

62 Sheep River at Okotoks

63 Sheep River at Okotoks

64 Sheep River at Okotoks

65 Sheep River at Okotoks

66 8 05BL013 Three Point Creek at Millarville 64

67 8.1.1 Summary of Peak Flow Data for 05BL013 Three Point Creek at Millarville Note: Data for cells shaded in blue have been taken from daily record for years where the data was absent from the Peaks file in HYDAT. Year of Record Instantaneous Peak Flow (m3/s) SYMBOL B=ice, E=Estimate Time of Peak Flow HH:MM CODE Time Zone Instantaneous Peak Month of Occurrence (MM) Instantaneous Peak Day of Occurrence (DD) Maximum Annual Daily Mean Flow (m3/s) SYMBOL B=ice, E=Estimate Maximum Daily Mean Month of Occurrence (MM) Maximum Daily Mean Day of Occurrence (DD) Minimum Annual Daily Mean Flow (m3/s) SYMBOL B=ice, E=Estimate Minimum Daily Mean Month of Occurrence (MM) Minimum Daily Mean Day of Occurrence (DD) : :00 MST :00 MST :15 MST :25 MST :35 MST :00 MST :00 MST :00 MST :30 MST :00 MST :00 MST

68 Year of Record Instantaneous Peak Flow (m3/s) SYMBOL B=ice, E=Estimate Time of Peak Flow HH:MM CODE Time Zone Instantaneous Peak Month of Occurrence (MM) Instantaneous Peak Day of Occurrence (DD) Maximum Annual Daily Mean Flow (m3/s) SYMBOL B=ice, E=Estimate Maximum Daily Mean Month of Occurrence (MM) Maximum Daily Mean Day of Occurrence (DD) Minimum Annual Daily Mean Flow (m3/s) SYMBOL B=ice, E=Estimate Minimum Daily Mean Month of Occurrence (MM) Minimum Daily Mean Day of Occurrence (DD) :30 MST :00 MST :00 MST :30 MST :30 MST :12 MST :29 MST :00 MST :07 MST :18 MST B :52 MST :47 MST :15 MST B A B B :02 MST B : A B

69 Year of Record Instantaneous Peak Flow (m3/s) SYMBOL B=ice, E=Estimate Time of Peak Flow HH:MM CODE Time Zone Instantaneous Peak Month of Occurrence (MM) Instantaneous Peak Day of Occurrence (DD) Maximum Annual Daily Mean Flow (m3/s) SYMBOL B=ice, E=Estimate Maximum Daily Mean Month of Occurrence (MM) Maximum Daily Mean Day of Occurrence (DD) Minimum Annual Daily Mean Flow (m3/s) SYMBOL B=ice, E=Estimate Minimum Daily Mean Month of Occurrence (MM) Minimum Daily Mean Day of Occurrence (DD) A B :30 MST :15 MST B B :20 MST :00 MST :40 MST :00 MST :30 MST :45 MST :16 MST :31 MST :16 MST :03 MST :33 MST :33 MST

70 8.1.2 Recent Direct Discharge Measurements: 05BL013 Threepoint Creek near Millarville 05BL013 - THREEPOINT CREEK NEAR MILLARVILLE 05BL013 - THREEPOINT CREEK NEAR MILLARVILLE 05BL013 - THREEPOINT CREEK NEAR MILLARVILLE Date Discharge (m^3/s) Stage (m) Date Discharge (m^3/s) Stage (m) Date Discharge (m^3/s) Stage (m) 30/05/ /06/ /06/ /05/ /07/ /07/ /02/ /08/ /07/ /03/ /09/ /08/ /03/ /10/ /10/ /03/ /03/ /03/ /03/ /04/ /03/ /03/ /04/ /03/ /03/ /04/ /05/ /04/ /06/ /05/ /05/ /06/ /05/ /06/ /07/ /06/ /06/ /09/ /06/ /06/ /11/ /07/ /06/ /03/ /08/ /06/ /03/ /09/ /06/ /04/ /11/ /07/ /04/ /03/ /08/ /05/ /03/ /10/ /06/ /04/ /10/ /06/ /04/ /02/ /07/ /05/ /03/ /07/ /07/

71 05BL013 - THREEPOINT CREEK NEAR MILLARVILLE Date Discharge (m^3/s) Stage (m) 05BL013 - THREEPOINT CREEK NEAR MILLARVILLE Date Discharge (m^3/s) 69 Stage (m) 05BL013 - THREEPOINT CREEK NEAR MILLARVILLE Date Discharge (m^3/s) 15/03/ /09/ /08/ /03/ /10/ /09/ /03/ /11/ /10/ /04/ /03/ /11/ /04/ /03/ /02/ /04/ /03/ /03/ /05/ /04/ /04/ /05/ /05/ /05/ /06/ /07/ /05/ /06/ /07/ /06/ /06/ /08/ /07/ /08/ /09/ /08/ /08/ /10/ /09/ /02/ /02/ /10/ /03/ /03/ /10/ /03/ /03/ /03/ /03/ /03/ /03/ /04/ /04/ /04/ /04/ /05/ /04/ /05/ /05/ /05/ /06/ /06/ /05/ /07/ /07/ /05/ /09/ /08/ /06/ /10/ /09/ /08/ Stage (m)

72 05BL013 - THREEPOINT CREEK NEAR MILLARVILLE Date Discharge (m^3/s) Stage (m) 05BL013 - THREEPOINT CREEK NEAR MILLARVILLE Date Discharge (m^3/s) 70 Stage (m) 05BL013 - THREEPOINT CREEK NEAR MILLARVILLE Date Discharge (m^3/s) 28/02/ /10/ /08/ /03/ /03/ /10/ /03/ /03/ /03/ /04/ /04/ /03/ /05/ /05/ /04/ /07/ /06/ /05/ /08/ /06/ /06/ /09/ /06/ /06/ /10/ /06/ /07/ /02/ /06/ /08/ /03/ /06/ /10/ /03/ /07/ /10/ /04/ /08/ /02/ /05/ /08/ /03/ /05/ /09/ /04/ /07/ /09/ /05/ /07/ /09/ /06/ /08/ /10/ /06/ /09/ /02/ /08/ /11/ /03/ /10/ /02/ /04/ /10/ /03/ /05/ /02/ /04/ /06/ /03/ /05/ /06/ /04/ Stage (m)

73 05BL013 - THREEPOINT CREEK NEAR MILLARVILLE Date Discharge (m^3/s) Stage (m) 05BL013 - THREEPOINT CREEK NEAR MILLARVILLE Date Discharge (m^3/s) Stage (m) 05BL013 - THREEPOINT CREEK NEAR MILLARVILLE Date Discharge (m^3/s) 04/06/ /06/ /04/ /06/ /06/ /05/ /08/ /07/ /06/ /09/ /08/ /07/ /11/ /09/ /08/ /02/ /11/ /09/ /03/ /02/ /10/ /03/ /03/ /11/ /03/ /03/ /02/ /04/ /04/ /03/ /05/ /05/ /04/ /05/ /06/ /05/ Stage (m) 71

74 8.1.3 Station Visit Frequency: 05BL013 Threepoint Creek near Millarville 72

75 8.1.4 Ratings Curves No.9 and no. 11 Showing Recent Measurements: 05BL013 Threepoint Creek near Millarville 73

76 8.1.5 Measurement Departure from Rating Curve by Stage: 05BL013 Threepoint Creek near Millarville 74

77 8.1.6 Measurement Departure from Rating Curve by Discharge: 05BL013 Threepoint Creek near Millarville 75

78 8.1.7 Duration of Annual Floods from Peak Hydrographs: 05BL013 Threepoint Creek near Millarville 76

79 8.1.8 Annual Flood Volume VS Annual Max. Inst. Flow: 05BL013 Threepoint Creek near Millarville 77

80 8.1.9 Annual Flood Volume VS Annual Max. Daily Flow: 05BL013 Threepoint Creek near Millarville 78

81 Rank of Annual Extremes by Peak and by Volume: 05BL013 Threepoint Creek near Millarville 79

82 Compare Annual Maximum Instantaneous Peak to Maximum Daily: 05BL013 Threepoint Creek near Millarville 80

83 Combined Annual Peak Hydrographs: 05BL013 Threepoint Creek near Millarville 81

84 Threepoint Millarville

85 Threepoint Millarville

86 Threepoint Millarville

87 Threepoint Millarville

88 Threepoint Millarville

89 Threepoint Millarville

90 Threepoint Millarville

91 Threepoint Millarville

92 Threepoint Millarville

93 Threepoint Millarville

94 Threepoint Millarville

95 Threepoint Millarville

96 Threepoint Millarville

97 Threepoint Millarville

98 Threepoint Millarville

99 Threepoint Millarville

100 Threepoint Millarville

101 Threepoint Millarville

102 Threepoint Millarville

103 Threepoint Millarville

104 Threepoint Millarville

105 Threepoint Millarville

106 Threepoint Millarville

107 Threepoint Millarville

108 Threepoint Millarville

109 Threepoint Millarville

110 Threepoint Millarville

111 Threepoint Millarville

112 Threepoint Millarville

113 Threepoint Millarville

114 Threepoint Millarville

115 Threepoint Millarville

116 Threepoint Millarville

117 Threepoint Millarville

118 Threepoint Millarville

119 Threepoint Millarville

120 Threepoint Millarville

121 Threepoint Millarville

122 Threepoint Millarville

123 Threepoint Millarville

124 Threepoint Millarville

125 Threepoint Millarville

126 Threepoint Millarville

127 Threepoint Millarville

128 Threepoint Millarville

129 Threepoint Millarville

130 Threepoint Millarville

131 Threepoint Millarville

132 Threepoint Millarville

133 Threepoint Millarville

134 Threepoint Millarville

135 hreepoint Millarville

136 Threepoint Millarville

137 Threepoint Millarville

138 9 05BL014 Sheep River at Black Diamond 136

139 9.1.1 Summary of Peak Flow Data for 05BL014 Sheep River at Black Diamond Year of Record Instantaneous Peak Flow (m3/s) SYMBOL B=ice, E=Estimate Time of Peak Flow HH:MM CODE Time Zone Instantaneous Peak Month of Occurrence (MM) Instantaneous Peak Day of Occurrence (DD) Maximum Annual Daily Mean Flow (m3/s) SYMBOL B=ice, E=Estimate Maximum Daily Mean Month of Occurrence (MM) Maximum Daily Mean Day of Occurrence (DD) Minimum Annual Daily Mean Flow (m3/s) SYMBOL B=ice, E=Estimate Minimum Daily Mean Month of Occurrence (MM) Minimum Daily Mean Day of Occurrence (DD) E :59 MST :00 MST B :00 MST :00 MST :59 MST :30 MST :00 MST :30 MST :59 MST :00 MST :30 MST :00 MST B

140 Year of Record Instantaneous Peak Flow (m3/s) SYMBOL B=ice, E=Estimate Time of Peak Flow HH:MM CODE Time Zone Instantaneous Peak Month of Occurrence (MM) Instantaneous Peak Day of Occurrence (DD) Maximum Annual Daily Mean Flow (m3/s) SYMBOL B=ice, E=Estimate Maximum Daily Mean Month of Occurrence (MM) Maximum Daily Mean Day of Occurrence (DD) Minimum Annual Daily Mean Flow (m3/s) SYMBOL B=ice, E=Estimate Minimum Daily Mean Month of Occurrence (MM) Minimum Daily Mean Day of Occurrence (DD) :51 MST B :26 MST :19 MST B :09 MST B :29 MST B :37 MST B :02 MST B :58 MST B :00 MST B :50 MST B :12 MST B B :49 MST B :54 MST B :00 MST B :50 MST B :50 MST B :00 MST B :00 MST

141 Year of Record Instantaneous Peak Flow (m3/s) SYMBOL B=ice, E=Estimate Time of Peak Flow HH:MM CODE Time Zone Instantaneous Peak Month of Occurrence (MM) Instantaneous Peak Day of Occurrence (DD) Maximum Annual Daily Mean Flow (m3/s) SYMBOL B=ice, E=Estimate Maximum Daily Mean Month of Occurrence (MM) Maximum Daily Mean Day of Occurrence (DD) Minimum Annual Daily Mean Flow (m3/s) SYMBOL B=ice, E=Estimate Minimum Daily Mean Month of Occurrence (MM) Minimum Daily Mean Day of Occurrence (DD) :50 MST B :55 MST B :25 MST B :00 MST B :05 MST B :35 MST B :50 MST B :15 MST B :55 MST B :45 MST B :15 MST B :15 MST B

142 9.1.2 Recent Direct Discharge Measurements: 05BL014 Sheep River at Black Diamond 05Bl014 - Sheep River at Black Diamond 05Bl014 - Sheep River at Black Diamond 05Bl014 - Sheep River at Black Diamond Date/Time Discharge (m^3/s) Stage (m) Date/Time Discharge (m^3/s) Stage (m) Date/Time Discharge (m^3/s) Stage (m) 04/01/ /07/ /02/ /01/ /09/ /03/ /02/ /10/ /03/ /03/ /12/ /05/ /03/ /01/ /05/ /03/ /01/ /05/ /04/ /03/ /06/ /05/ /04/ /07/ /06/ /04/ /08/ /06/ /06/ /09/ /06/ /06/ /11/ /06/ /07/ /12/ /06/ /09/ /01/ /07/ /11/ /02/ /08/ /11/ /03/ /10/ /12/ /03/ /10/ /01/ /04/ /11/ /01/ /04/ /12/ /03/ /05/ /01/ /03/ /07/ /01/ /04/ /08/ /02/ /05/ /09/ /03/ /06/ /10/

143 05Bl014 - Sheep River at Black Diamond 05Bl014 - Sheep River at Black Diamond 05Bl014 - Sheep River at Black Diamond Date/Time Discharge (m^3/s) Stage (m) Date/Time Discharge (m^3/s) Stage (m) Date/Time Discharge (m^3/s) Stage (m) 21/03/ /06/ /11/ /03/ /07/ /12/ /04/ /07/ /01/ /04/ /09/ /02/ /04/ /10/ /02/ /05/ /10/ /03/ /06/ /11/ /04/ /06/ /01/ /05/ /06/ /02/ /06/ /06/ /03/ /07/ /06/ /03/ /08/ /08/ /04/ /10/ /08/ /05/ /10/ /09/ /07/ /11/ /01/ /08/ /01/ /01/ /09/ /02/ /02/ /10/ /03/ /03/ /12/ /03/ /03/ /01/ /04/ /04/ /02/ /04/ /04/ /02/ /05/ /05/ /03/ /05/ /06/ /04/ /05/ /07/ /05/ /06/

144 05Bl014 - Sheep River at Black Diamond 05Bl014 - Sheep River at Black Diamond 05Bl014 - Sheep River at Black Diamond Date/Time Discharge (m^3/s) Stage (m) Date/Time Discharge (m^3/s) Stage (m) Date/Time Discharge (m^3/s) Stage (m) 03/09/ /06/ /08/ /10/ /07/ /08/ /10/ /08/ /10/ /11/ /09/ /11/ /12/ /10/ /01/ /01/ /12/ /01/ /01/ /01/ /03/ /02/ /02/ /03/ /03/ /03/ /04/ /03/ /03/ /05/ /03/ /04/ /06/ /04/ /05/ /06/ /05/ /06/ /07/ /07/ /06/ /08/ /08/ /06/ /10/ /09/ /06/ /10/ /10/ /06/ /11/ /12/ /07/ /01/ /01/ /08/ /02/ /02/ /08/ /02/ /02/ /08/ /03/ /03/ /09/ /04/ /04/ /10/ /05/ /05/ /12/ /08/

145 05Bl014 - Sheep River at Black Diamond 05Bl014 - Sheep River at Black Diamond 05Bl014 - Sheep River at Black Diamond Date/Time Discharge (m^3/s) Stage (m) Date/Time Discharge (m^3/s) Stage (m) Date/Time Discharge (m^3/s) Stage (m) 28/05/ /01/ /08/ /06/ /01/ /10/ /06/ /02/ /10/ /07/ /03/ /10/ /07/ /04/ /12/ /09/ /05/ /01/ /11/ /06/ /02/ /11/ /06/ /02/ /01/ /07/ /03/ /02/ /08/ /04/ /03/ /09/ /06/ /04/ /10/ /06/ /05/ /12/ /06/ /06/ /01/ /07/ /06/ /02/ /07/ /08/ /02/ /08/ /09/ /03/ /09/ /11/ /03/ /10/ /11/ /04/ /11/ /01/ /05/ /12/ /02/ /06/ /01/ /02/ /07/ /02/ /03/ /08/ /02/ /03/ /09/ /03/

146 05Bl014 - Sheep River at Black Diamond 05Bl014 - Sheep River at Black Diamond 05Bl014 - Sheep River at Black Diamond Date/Time Discharge (m^3/s) Stage (m) Date/Time Discharge (m^3/s) Stage (m) Date/Time Discharge (m^3/s) Stage (m) 01/05/ /11/ /03/ /05/ /12/ /04/ /06/ /01/ /05/

147 9.1.3 Station Visit Frequency: 05BL014 Sheep River at Black Diamond 145

148 9.1.4 Rating Curve No. 16 Showing Recent Measurements: 05BL014 Sheep River at Black Diamond 146

149 9.1.5 Measure Departure from Discharge by Stage: 05BL014 Sheep River at Black Diamond 147

150 9.1.6 Measurement Departure from Rating by Discharge: 05BL014 Sheep River at Black Diamond 148

151 9.1.7 Duration of Annual Flood from Peak Hydrographs: 05BL014 Sheep River at Black Diamond 149

152 9.1.8 Annual Flood Volume Vs. Annual Max. Inst. Flow: 05BL014 Sheep River at Black Diamond 150

153 9.1.9 Annual Flood Volume Vs. Annual Max. Daily Flow: 05BL014 Sheep River at Black Diamond 151

154 Rank of Annual Extremes by Peak and Volume: 05BL014 Sheep River at Black Diamond 152

155 Compare Annual Maximum Instantaneous Peak to Maximum Daily: 05BL014 Sheep River at Black Diamond 153

156 Combined Annual Peak Hydrographs: 05BL014 Sheep River at Black Diamond 154

157 Sheep River Black Diamond

158 Sheep River Black Diamond

159 Sheep River Black Diamond

160 Sheep River Black Diamond

161 Sheep River Black Diamond

162 Sheep River Black Diamond

163 Sheep River Black Diamond The Symbol A indicates Partial Day Record. The Symbol E indicates an estimated value.

164 Sheep River Black Diamond

165 Sheep River Black Diamond

166 Sheep River Black Diamond

167 Sheep River Black Diamond

168 Sheep River Black Diamond

169 Sheep River Black Diamond

170 Sheep River Black Diamond

171 Sheep River Black Diamond

172 Sheep River Black Diamond

173 Sheep River Black Diamond

174 Sheep River Black Diamond

175 Sheep River Black Diamond

176 Sheep River Black Diamond

177 Sheep River Black Diamond

178 Sheep River Black Diamond

179 Sheep River Black Diamond

180 Sheep River Black Diamond

181 Sheep River Black Diamond

182 Sheep River Black Diamond

183 Sheep River Black Diamond

184 Sheep River Black Diamond The Symbol A indicates Partial Day Record. The Symbol E indicates an estimated value.

185 Sheep River Black Diamond

186 Sheep River Black Diamond

187 Sheep River Black Diamond

188 Sheep River Black Diamond

189 Sheep River Black Diamond

190 Sheep River Black Diamond

191 Sheep River Black Diamond

192 Sheep River Black Diamond

193 Sheep River Black Diamond

194 Sheep River Black Diamond The Symbol A indicates partial day record.

195 Sheep River Black Diamond

196 Sheep River Black Diamond

197 Sheep River Black Diamond

198 Sheep River Black Diamond

199 Sheep River Black Diamond

200 Sheep River Black Diamond

201 Sheep River Black Diamond

202 Sheep River Black Diamond

203 Sheep River Black Diamond

204 Sheep River Black Diamond

205 Sheep River Black Diamond

206 Sheep River Black Diamond

207 10 Water Survey of Canada Station Descriptions 205

208 Station Description for 05BL012 Sheep River at Okotoks 206

209 207

210 Station Description for 05BL013 Threepoint Creek near Millarville 208

211 209

212 Station Description for 05BL014 Sheep River at Black Diamond 210

213 211

214 212