Beak Creek Hydrologic Assessment,...

BEAK CREEK WATERSHED

Hydrologic Assessment and ECA Evaluation

(Including Application of the Ministry of Forests’ Extension Note 67)

Prepared for

By

March 2005

Beak Creek Hydrologic Assessment

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TABLE OF CONTENTS

1 INTRODUCTION ......................................................................................... 1

2 HYDROLOGY RESEARCH.............................................................................. 2

2.1 RESEARCH FINDINGS....................................................................................... 2

2.2 APPLICATION TO WATERSHED MANAGEMENT......................................................... 3

2.3 LIMITATIONS ................................................................................................ 4

3 SNOW SENSITIVE ZONE DETERMINATION ................................................... 4

4 MOUNTAIN PINE BEETLE INFESTATION ....................................................... 5

4.1 SCENARIO 1 – LOSS OF ALL MATURE LODGEPOLE PINE IN THE SNOW SENSITIVE ZONE.... 5

4.2 SCENARIO 2 – LOSS OF CURRENTLY INFESTED LODGEPOLE PINE IN THE SNOW SENSITIVEZONE TO DECEMBER 31, 2004.......................................................................... 6

5 CURRENT WATERSHED CONDITION (to December 31, 2004)......................... 7

5.1 CHANNEL MORPHOLOGY................................................................................... 7

5.2 PEAK FLOWS................................................................................................. 9

5.3 SURFACE EROSION ......................................................................................... 9

5.4 RIPARIAN FUNCTION ..................................................................................... 10

5.5 LANDSLIDES................................................................................................ 10

6 PEAK FLOW RISK ANALYSIS ...................................................................... 11

6.1 SUB-BASINS................................................................................................ 12

7 RISKS FROM HARVESTING BEETLE INFESTED LODGEPOLE PINE.................. 13

8 AVAILABLE DEVELOPMENT........................................................................ 15

9 CONCLUSIONS.......................................................................................... 16

10 RECOMMENDATIONS ................................................................................ 16

11 LITERATURE CITED .................................................................................. 18


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TABLES

TABLE 1ECAs for the Beak Creek watershed assuming mortality of all lodgepole pine

TABLE 2Proposed development and ECAs in the Beak Creek watershed

TABLE 3Current ECAs for the Beak Creek watershed

TABLE 4Peak flow hazards/risks and associated ECAs for the sub-basins and the residual area

TABLE 5Proposed development and ECAs in the infested pine dominated stands of the snow

sensitive zone

TABLE 62004 available development in the snow sensitive zone of the Beak Creek watershed

TABLE 7

Total supply of mature timber in the Beak Creek watershed

FIGURES

FIGURE 1 Maximum changes in daily peak flows with increasing harvest level in the 241 Creek

watershed


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APPENDICES

Appendix AWatershed Condition Summary Table, Available Development, and Licensee Areas

Appendix BPeak flow and Water Level Analysis

Appendix CField Photos

Appendix DWatershed Condition Map

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BEAK CREEK WATERSHED

Hydrologic Assessment and ECA Evaluation

1 INTRODUCTION

The following report was completed by Dobson Engineering Ltd. (Dobson) at therequest of Riverside Forest Products (Riverside) to estimate the hydrologic impactof the current and anticipated mountain pine beetle infestation. The evaluationutilizes the results of the Ministry of Forest’s Forest Sciences Program ExtensionNote 67 investigating the influence of forest development on the quantity of flowsin a snowmelt hydrologic regime (Schnorbus et. al. 2004).

This report summarizes the results of loss of forest cover and peak flow impactsfrom two unique scenarios. Scenario 1 illustrates the “worst case” for peak flowsshould all the susceptible pine succumb to the mountain pine beetle and assumesthe loss of all mature (age class 4+) lodgepole pine leading stands within the snowsensitive zone of the Beak Creek watershed. Scenario 2 illustrates what theexpected impact will be as a result of the loss of currently identified infestedlodgepole pine within the timber harvest landbase portion of the snow sensitivezone.

The reader is reminded that this is an assessment of the loss of the mature pinedue to insects. The impacts on peak flow have been assessed based on the lossof forest cover and the resulting increase in water yields due to changes in waterbalance (i.e. increases to snow accumulation and snowmelt). Timber harvesting oflodgepole pine leading stands is not considered in the initial assessments since it isnot the cause of the loss of forest cover. The impacts of harvesting beetleinfested stands are considered independently.

Conclusions arrived at within this report are based on modeling which incorporatesrecently acquired information. The first is the results of snowline research basedon several years of snowline information analyzed by Dobson for the Chase Creek,Mission Creek, Peachland Creek, Trout Creek, and Shingle Creek watersheds. Inthese watersheds, the snow sensitive zone was mapped for up to five consecutiveyears. Each year, a series of mapped snowlines was evaluated against the streamflow hydrograph to determine the snowline position that corresponds to the startof the peak flow period. All snowlines were then plotted on a topographical mapof the watershed and selecting the lowermost segments from all the survey yearscreated a composite snowline. As a result of this research, a more refineddetermination of the snowline position was achieved. The snowline delineates theportion of the watershed with a melting snowpack during the peak flow period(addressed in greater detail in the following section titled Snow Sensitive Zone


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Determination). This research confirms that the recently revised snow sensitivearea is smaller (see section 3) than that originally suggested by the H60 lineproposed in the Interior Watershed Assessment Procedure. The second piece ofinformation is the Ministry of Forests Forest Sciences Program Extension Note 67released in 2004 that summarizes the results of research into the impacts oftimber harvesting on peak flows in the Upper Penticton Creek researchwatersheds. The results of this article suggest that increases to peak flows relatedto ECA are less than previously suspected for watersheds with similar morphologyand geographical setting.

2 HYDROLOGY RESEARCH

2.1 Research FindingsExtension Note 67 (Schnorbus et. al. 2004) presents the results ofstreamflow modeling that used the Distributed Hydrology-Soil-VegetationModel (DHSVM). The study investigates the influence of forest harvestinglevels on streamflows in the Upper Penticton Creek (UPC) watershed,specifically 241 Creek. This watershed is small (~500ha) with asnowmelt-dominated hydrologic system. Elevations range fromapproximately 1600m to over 2000m.

Extension Note 67 defined the increase in peak flow discharge by eventreturn period. The model results show that peak flow discharge increaseswith increasing harvest level. For presentation, the graph from Figure 2in the extension note is reproduced in Figure 1 below.

The results show that the larger, less frequent flood events are affectedby changes in harvest level (percent of watershed area cut) to a greaterextent than the smaller, more frequent events. At 20% harvest level,peak flows are increased by 0, 4, and 10% for return period events of 2,10, and 50 years, respectively. At 40% harvest level, peak flows areincreased by 4, 10, and 19%, respectively. These results suggest that,for watersheds in the Southern Interior with similar morphology to UpperPenticton Creek, the average peak flow event (approximate 2-year returninterval) may be increased by a maximum of 5% and the smallestchannel forming event (approximate 10-year return interval) may beincreased by up to 10%.


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0

5

10

15

20

25

30

35

40

45

50

0 10 20 30 40 50 60 70 80 90 100

% of Watershed Area Cut

% I

ncre

ase

in D

aily

Pea

k Fl

ow

Tr = 2 years

Tr = 10 years

Tr = 50 years

FIGURE 1Maximum changes in daily peak flows with increasing

harvest level in the 241 Creek watershed(Extracted from Scnorbus et. al. 2004; Tr refers to return period of flow)

2.2 Application to Watershed ManagementWithin the context of water resources management and communitywatersheds in the Southern Interior, 241 Creek constitutes the snowsensitive zone of the Penticton Creek watershed: that portion of thewatershed with melting snowpack during the peak flow period (addressedin greater detail in the following section titled Snow Sensitive ZoneDetermination). As a result, in applying the study findings to otherregional watersheds, the harvest levels and associated flow impactspresented in the research should be compared to harvest levels withinthe snow sensitive zone only and not to harvest levels within the entirewatershed. In terms of peak flow levels, the predicted harvest impacts(e.g. peak flow percentage increase) outlined in the research areconsidered maximum impacts when extrapolating the results to the entirewatershed. This is based on the rationale that, during the peak flowperiod, streamflow contributed from areas outside of the snow sensitivezone are from the draining of soils (i.e. matrix flow) as opposed tosnowmelt, which is affected by harvesting to a lesser extent thansnowmelt. In addition, most of the flow volume during the peak flowperiod is generated directly from melting snow in the snow sensitivezone.

The research article investigates the impacts of forest harvesting onstreamflow assuming that all harvesting is completed at one point in timewith negligible hydrologic recovery. In most watershed managementscenarios, watersheds contain multiple polygons in various stages of


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hydrologic recovery. Because of this, ECA is considered to represent theequivalent watershed area that would be in a non-recovered state. Inorder to apply the research findings to watershed management, ECA isused instead of harvest level (non-recovered harvest area).

2.3 LimitationsIn applying this research information to the management of otherwatersheds in the Southern Interior, the limitations of the research andits extrapolation must be clearly recognized. First, the research is basedon modeling and, as such, the results are only as accurate as the modelrepresents the true watershed characteristics and processes. Second, theaccuracy of the research results for high return periods is limited by theinherent lack of field data for comparison. Third, the extrapolation of theresults to other regional watersheds assumes that the watershedcharacteristics and hydrologic processes are similar. In general, this thirdassumption is likely reasonable for most high elevation watersheds in theregion, but should be evaluated for each watershed individually

The modeling, including the results presented in Figure 1, does notaccount for roads as part of forest development. Because of this, anyintercepted subsurface flows that are directed into the channel networkwould effectively increase the length of the channel network and wouldlead to greater peak flow impacts than are suggested by the researchresults. As long as the majority of intercepted flows are drained onto theforest floor through cross-drains and subsequently infiltrate, the overallimpacts of roads on peak flows would be negligible.

Because of these limitations, forest development direction in the followingsections is more conservative in terms of ECA than the research suggestsis reasonable.

3 SNOW SENSITIVE ZONE DETERMINATION

For the purposes of assessing ECA levels and associated peak flow impacts, anassumed snow sensitive zone was delineated for the Beak Creek watershed based,in part, on the results of several years of snowline information analyzed by Dobsonfor the Chase Creek, Mission Creek, Peachland Creek, Trout Creek, and ShingleCreek watersheds. In these watersheds, the snow sensitive zone was mapped forup to five consecutive years. Each year, a series of mapped snowlines wasevaluated against the stream flow hydrograph to determine the snowline positionthat corresponds to the start of the peak flow period. These snowlines, unlike theH60 line proposed in the Interior Watershed Assessment Procedure, can transversecontour lines and their location is influenced by a number of attributes such asslope aspect, forest cover, microclimates, and topography. The snowline wascreated by overlaying all 5 years of snowline data and selecting the lowest mostline segments as the representative snowline (refer to map in Appendix D). Theentire area above this selected snowline is considered the portion of the watershed


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that is sensitive to forest development in terms of impacting snow melt and peakflow generation. For the five watersheds noted above, the snow sensitive zoneconstitutes the upper 43, 30, 22, 36, and 26% of the watershed, respectively.

Since there were no snowline data for the Beak Creek watershed, a cautiousapproach was taken to use a snowline that comprises the upper 40% of thewatershed. The snowline was then adjusted either up or downslope based onantidotal information provided by Riverside staff and on slope aspect (refer to mapin Appendix D).

The snowline mapping process and extrapolation to nearby watersheds has beenpeer reviewed in detail and is considered to adequately represent the snowsensitive zone (Rita Winkler and Dave Gluns, Ministry of Forests, personalcommunication).

4 MOUNTAIN PINE BEETLE INFESTATION

Based on discussions with Riverside staff, it is understood that mountain pinebeetle infestations are a concern in the Beak Creek watershed and that most ofthe proposed development for the next several years will be aimed at beetleinfested stands. In terms of hydrologic impacts, any activity that causes treemortality has the potential to affect the watershed hydrology (i.e. timing andvolume of flows) through a variety of mechanisms such as reducedevapotranspiration, loss of interception, and increased solar radiation exposure.Peak flows are a product of snowmelt and respond to changes in forest cover inthe snow sensitive zone. As such, loss of forest cover within this zone for anyreason, such as mortality from mountain pine beetle, can affect peak flows byincreasing ECAs.

4.1 Scenario 1 – Loss of All Mature Lodgepole Pine in the SnowSensitive Zone

In the Beak Creek watershed, approximately 60% of mature forest in thesnow sensitive zone is lodgepole pine (lodgepole pine leading stands at40% or greater only). If, as a worst case scenario, all of the remainingmature lodgepole pine leading stands in the snow zone are attacked andkilled by beetle, the snow zone ECAs would be 66, 95, 79, and 80% for theStuart sub-basin, Treadgold sub-basin, the residual area and entirewatershed, respectively (Table 1). These ECA levels are considered highhazards (as outlined in Table 4) for all units. Peak flow impacts may beexpected in the high hazard sub-basins and in the residual area. Such ascenario may result in increases to the Beak Creek 10-year peak flow by23%, 37%, 29%, and 30% respectively, for the Stuart and Treadgold sub-basins, the residual area, and the watershed. For the 50-year event thepeak flows would increase by 31%, 44%, 37%, and 38%, respectively.


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TABLE 1Scenario 1 - Mortality of all mature lodgepole pine leading stands

in the snow sensitive zone

Drainage Area ofMature Pl

(ha)1

Current +Proposed AreaDecember 31,

2004(ha)

CombinedArea(ha)

ECA inthe Snow

zone(%)

Stuart 293 197 490 66Treadgold 625 239 864 95Residual 1510 500 2010 79

Watershed 2427 936 3364 801. Area of Pl leading stands in the snow zone not currently identified as infested or proposed for

harvest.

The peak flow results suggest that, based on the channel dimensions atsites visited, water depth in the mainstem channel during a 50-year peakflow event would be 34cm greater (1.897m versus 1.560m) at an ECA of70% compared to an ECA of 0% (i.e. fully recovered sub-basin). Theshear stress on the bed substrate would be approximately 22% greater.

4.2 Scenario 2 – Loss of Currently Infested Lodgepole Pine in theSnow Sensitive Zone to December 31, 2004

This scenario illustrates the impact on peak flows from the loss of all of thecurrently identified infested lodgepole pine in the snow sensitive zone as ofDecember 31, 2004. Combining the current estimates of the infestedstands with previous harvesting (assuming that these stands would bedead by December 31, 2004), the ECAs would increase to 26.7, 26.3, 19.7,and 22.4% for the Stuart sub-basin, Treadgold sub-basin, the residual areaand watershed respectively (Table 2). Applying these ECAs to the curves inFigure 1 suggest that the impact on the mean daily peak flows would be toincrease the 10-year peak flows by 6%, 6%, 4%, and 5% respectively, forthe Stuart and Treadgold sub-basins, the residual area, and the watershed.For the 50-year event the peak flows would increase by 12%, 12%, 9%,and 11%, respectively.

Appendix A contains hydrologic recovery projections that can be used tocalculate actual ECAs as development is planned in the future.


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TABLE 2Scenario 2 - ECAs assuming Loss of all Currently Infested Lodgepole Pine by

December 31, 2004 in the Snow Sensitive Zone

Current ECA with proposeddevelopment

Drainage Current ECA(%)

(nodevelopment)

ProposedFDP -

above andbelow SSZ

(%)

Current +Proposed -above andbelow SSZ

(%)

Snow Zone

(%)

Below SnowZone

(%)

Stuart 19 17 36 27 43Treadgold 39 3 42 26 79Residual 25 9 34 20 44Watershed 26 13.0 39 22 47� Refer to Appendix A for more ECA details� SSZ = Snow sensitive zone

5 CURRENT WATERSHED CONDITION (to December 31, 2004)

A ground-based field review was conducted in the Beak Creek watershed inOctober of 2004. The results of the field investigations and subsequent analysesare provided below.

5.1 Channel Morphology

The Beak Creek mainstem channel and many of its tributaries wereexamined for disturbances such as bank erosion, bed scour, avulsions, andrecently formed LWD jams.

The Beak Creek mainstem channel flows in an east to west direction,starting from Stuart Lake (in the Stuart Sub-basin, reaches H, I, and J) andcontinues, along a series of benches and steps, through the residual areato the Nicola River. Average gradients through the benches (which formwetland areas) range from 0.5% in reach D to 1% in reaches C, F, H, andJ. The steps between the wetlands ranged from 3 % in reaches A, E, andG (reach B was 4%) to 7% in reach I.

The steps, reaches B, E, and G (A and I were not assessed in the field)were characterized as having a stable to partially aggraded cascade-poolmorphology (boulder/cobble dominated). Boulders were moss covered andbanks were slightly undercut with minor localized bank scour. A few logjams were noted along sharp bends in the creek (refer to photos 1 to 6).

The benches, C, D, F, H and J were characterized as having a stable topartially aggraded riffle-pool morphology through wetlands ranging in widthfrom 5m to 400m (refer to photos 7 to 17). Sands and gravels dominatedbed and bank materials, some cobbles and boulders were noted. Beaver


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activity was noted in these areas and anecdotal evidence of flooding wasprovided in personal communications with Riverside staff.

The mainstem channel in the Treadgold sub-basin (Treadgold Creek,tributary #13) is characterized as having a stable riffle-pool morphology inthe upper and lower reaches with sections of ribbon type wetland (refer tophotos 18 to 20). Sands and gravels dominate bed and bank materials. Alongitudinal profile (Appendix B) of Treadgold Creek was used to determineaverage gradients. Reach TA is 1% (wide wetland at confluence with BeakCreek), the lower and upper reaches ranges from 2.5% to 4% (TB, TC, TE,TF). Reach TD, the middle reach, has an average gradient of 8%, andalthough not field checked, likely has a cascade-pool morphology. Noevidence of peak flow disturbance was identified at the sites visited. Abeaver dam was noted approximately 75m upstream from Beak Main FSRthat has caused overbank flow. Cattle trampling of the banks above andbelow Beak Main FSR was also noted (refer to photo 21).

Although the Beak Creek mainstem channel through the residual area isdiscussed above, disturbances noted in the tributary channels warrantfurther discussion. The residual area, as mentioned earlier, is bisected byBeak Creek and has virtually all of the past harvesting occurring on oneside, the north. Disturbances were encountered along tributary 2 and 7(refer to map) where gradients are lower and channels are less defined,and included: severe bed scour, overbank sediment deposition, andchannel widening (Tributaries 2 and 7, photos 22, 25 to 29). Although thecause of some of the disturbances noted might be related to peak flows,confounding issues such as cattle trampling of banks (photo 23), roadcrossings (photo 24) and riparian harvesting negate a direct link. It shouldbe noted that these disturbances were noted in a fish inventory reportcompleted for Riverside Forest Products that identified an extremehydrological event (rainstorm) as the likely cause. Although might be aplausible reason we were unable to confirm this hypothesis. Channelmorphology for the tributaries on the north side range from riffle-pool tocascade-pool in the lower reaches dominated by sands and gravels withsome cobbles, to step-pool dominated by cobbles and boulders in theupper reaches.

On the south side of Beak Creek, in the residual area, tributary channelsgenerally appeared more robust. Morphology ranges from cascade-pool tostep-pool and are dominated by mossy cobbles and boulders with somegravel and sands (refer to photos 37 to 43). Disturbances, such as bankscour and overbank deposition of sediment (refer to photos 44 to 46) werenoted in Venturi Creek above Venturi Main. These disturbances areconsidered natural due to the lack of development in the area and mightsupport the theory that an extreme hydrological event recently occurring inthe residual area.


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5.2 Peak Flows

ECA’sBased on the research findings discussed above and the current ECA valuescalculated for the snow sensitive zone (Table 3) potential increases to peakflow events can be extrapolated for each of the sub-basins and the residualarea. Past harvesting in the Beak Creek watershed may have increasedpeak flows from the Stuart and Treadgold sub-basins, and from theresidual area by approximately 3, 5, and 2% in terms of contributing to the10-year peak flow event, respectively. Contributions to the 50-year peakflow event from these basins may be elevated by 8, 12 and 7% due to pastharvesting, respectively.

TABLE 3Current ECAs for the Beak Creek watershed

Current (Dec 31, 2004)Equivalent Clearcut Area (%)

Drainage

Entire Basin Snow Zone Below Snow Zone

Stuart 19 15 22Treadgold 39 24 73Residual 25 12 35Watershed 26 15 35� The regeneration heights are modeled using Variable Density Yield Predictor (VDYP) and site

index values.� Site index values were updated using the BC Ministry of Forest’s Site Index estimates by Site

Series (SIBEC) - Second Approximation published in 2003.� All stands �12m in height are considered to be fully recovered, hydrologically, and have

been excluded from the ECA calculations.� Snow zone ECA is calculated as the non-recovered area in the snow zone divided by the

total area of the snow zone.� Refer to Appendix A for more ECA details

RoadsRoads were generally in good condition and do not appear to be a concernwith regards to increasing peak flows. Typically, vegetation was wellestablished along ditchlines and not conveying flows over long distances.The majority of roads are situated along the contours resulting in a rollinggrade that can limit conveyance distance.

5.3 Surface Erosion

The forestry roads throughout the watershed are generally stable and wellmaintained. Surface erosion along the road prism was considered low inproduction class and delivery on the north side of Beak Creek where roadsystems have been established for many years. Only one small section ofroad (Stuart FSR near the cattle guard, refer to photo 47) was considered amoderate production class, but still low for delivery as the sediment wasdeposited on the forest floor. Roads located on the south side of BeakCreek are more recent have not had time to stabilize through vegetative


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cover of ditches and cut banks. On these sections of road recent cutslopeerosion and sediment transport was noted, however, was considered lowfor production class and delivery potential.

Potential sediment sources, in the form of failing wood culverts, wereidentified on a semi-permanently deactivated road off Beak Main (nearCP175-1). These wood culverts are at the end of their usable life span andcontribute sediment directly to the stream network. Other problems notedwere related to cattle trampling stream banks and ditchlines at streamcrossings (refer to photos 20, 23, and 27), and poor armouring of streamcrossings after culvert removal (refer to photo 24).

With the current road construction and deactivation practices, prudentcontrol of surface drainage using frequent cross-drains, and aggressiverevegetation practices, the likelihood of watershed disturbance caused byforest development related surface erosion is low. Based on thesepractices, surface erosion is a low concern for future development in thesub-basins and residual area.

5.4 Riparian Function

No riparian harvesting was noted along the Beak Creek mainstem channel.Minimal amounts of riparian harvesting were observed in the Treadgoldsub-basin directly above Beak Main FSR. Impacts to Treadgold Creek arelargely the result of beaver and cattle activity and are not directly related tothe removal of riparian vegetation.

Considerable riparian harvest has occurred along the tributaries on thenorth side of Beak Creek in the residual area, and impacts were noted insome of the tributaries but could not be directly linked to riparian harvestas discussed in Section 5.1.

In terms of future forest development, riparian areas are protected throughlegislation. The likelihood of additional watershed disturbance related tofuture riparian harvesting is low given the current standards for riparianmanagement practices. Riparian function is a low concern for future forestdevelopment in the sub-basins and the residual area.

5.5 Landslides

A review of air photos as well as a field reconnaissance assessment did notidentify any significant landslides in the Beak Creek watershed. It shouldbe noted that aerial photos were unavailable for the upper portions of theTreadgold sub-basin and the residual area on the North side of thewatershed.


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6 PEAK FLOW RISK ANALYSIS

The primary factor in determining reasonable levels of development for awatershed is the robustness of the mainstem channels to elevated peak flows;increases in harvesting leads to increased rates of snowmelt and runoff resulting inpeak flow increases. As flow volumes increase, so do water depth and the levelsof shear stress on the bed substrate and channel banks. Shear stress increasescan lead to greater rates of bank erosion and sediment transport. Peak flows inthe watershed and sub-basin mainstem channels are generated by flows from thesnow sensitive zone (i.e. higher elevations in the watershed). Loss of forest coverin areas below the snow sensitive zone have only minor impacts on peak flows.

The following sections outline, for the sub-basins and the residual area, snow zoneharvest levels (ECAs) associated with low, moderate, and high peak flow hazardratings. Peak flow risk ratings are also presented. The risk ratings are determinedby combining the hazard ratings with the consequence rating. The consequencerating is considered moderate due to Fisheries values1. The approximate increasesin flows contributed to the Beak Creek 10-year and 50-year peak flow events,based on the data presented in Figure 1, are also presented.

For the purposes of this assessment, low peak flow hazard means that peak flowdisturbance caused by loss of forest cover is unlikely. Moderate peak flow hazardmeans that loss of forest cover related peak flow disturbance may occur, butwould be generally limited to localized bank scour in channel sections with aboveaverage sensitivity. High peak flow hazard means that loss of forest cover relatedpeak flow disturbance is likely with potential impacts ranging from localized toextensive.

The ECA guidelines (Table 4) presented in the following sections are based on thereconnaissance level watershed assessment conducted in October 2004 and not adetailed channel assessment. The ECA guideline levels were determined byanalyzing the peak flow increases and associated increases in water depth andshear stress on the channel bed. For five sites in the watershed, peak flows wereestimated for snow zone ECA levels of 0, 30, 50, and 70% and return period flowsof 2, 10, and 50 years. Annual maximum daily discharge frequency analysis datafor Beak Creek2 and the results summarized in Extension Note 67 were used forestimating flows. Based on the channel observations at each site, Manning’sEquation was used to approximate the flow depths and channel bed shear stresswas subsequently calculated. The results of these analyses are in Appendix B.Interpretations of the results are provided in the following sections.

In terms of selecting ECA values associated with low, moderate, and high peakflow hazard levels, channel sensitivity in each of the Beak Creek watershed sub-units was evaluated independently. Because the sub-basins exhibit similar,channel conditions, morphologies and sensitivities, a single ECA guideline for peak

1 fish values as related by Glenn Smith, Wildstone Engineering Ltd. personal comm. – natural rainbowtrout2 WSC Station 08LG064 - Beak Creek at the Mouth, period of record 1982 to 2001.


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flow management may be applied. It is for this reason that Table 4 has combinedthe two sub-basins to report on peak flow hazards and risks. Typically in the past,the ECA levels associated with low, moderate, and high peak flow hazards wereconsidered <20, 20-30, and >30%, respectively. The results presented inTechnical Note 67 suggest that the ECA levels should be higher for this particularwatershed. Other studies provide similar direction (Rita Winkler, Ministry ofForests, personal communication).

It should be recognized that there are limitations to the following ECA guidelinesdue to the reconnaissance level of the channel assessment and the modelinglimitations addressed previously. Because of these limitations, the provided ECAdirection is more conservative than what the research and field observationssuggest is reasonable.

6.1 Sub-basins

The Stuart sub-basin and Beak Creek mainstem channels (refer toAppendix D – Maps) consist of two channel types; sections of low gradientriffle-pool morphology dominated by sands and gravel flowing throughwetland areas that may act as buffers to peak flows, separated by sectionsof cascade-pool dominated by boulder and cobbles that are moderatelyrobust to peak flows. Based on the Beak Creek channel conditions and thepeak flow results presented in Appendix B, snow zone ECA levelsassociated with low, moderate, and high peak flow hazard levels (i.e.moderate and high risk levels) are presented in Table 4.

TABLE 4Peak flow hazards/risks and associated ECAs for the sub-basins and the

residual area

Approximate FlowIncrease (%)1

Basin Hazard Consequence RiskSnow

Zone ECA(%)

10-year 50-year

Low Low <30 <7 <14Moderate Moderate 30-50 7-14 14-23

All sub-basinsand residualarea High

ModerateHigh >50 >14 >23

1. Approximate increases in the 10-year and 50-year peak flow events compared to a baseline of 0% ECA.

The peak flow results presented in Appendix B suggest that, based on thechannel dimensions at site 11 (located on Treadgold Creek near beak mainFSR), water depth during a 50-year peak flow event would beapproximately 11cm greater (1.09m versus 0.985m) at an ECA of 30%compared to an ECA of 0% (i.e. fully recovered sub-basin). The shearstress on the bed substrate would be approximately 11% greater. Waterdepth and bed shear stress is of equal importance in the Treadgoldmainstem channel since bed scour and bank erosion are both relevanthazards. A water depth increase of 11cm and an increase in bed shear


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stress of ~11% (from 193N/m2 to 214N/m2) may exacerbate the channelcondition since the bed and banks are dominated by sands and gravel’s.The potential for bank erosion and bedload transport increases withincreasing water depth.

Flows through the residual area are influenced by forest development inthe snow sensitive zones of the sub-basin and the residual area. Becauseof this, the management of peak flows (i.e. ECAs) in the sub-basins needsto account for the sensitivity of the Beak Creek mainstem. Water depthand shear stress along the Beak mainstem need to be evaluated based onthe combined impacts from the sub-units units. The flow analysis presentedin Appendix B incorporates contributions from all areas upstream from site5 (located on Beak mainstem within the residual area) and the followingparagraph discusses the results.

The peak flow results suggest that, based on the channel dimensions atsite 5, water depth during a 50-year peak flow event would beapproximately 15cm greater (1.71m versus 1.56m) at an ECA of 30%compared to an ECA of 0% (i.e. fully recovered sub-basin). The shearstress on the bed substrate would be approximately 10% greater. A waterdepth increase of 15cm and an increase in bed shear stress of ~10% (from612N/m2 to 671N/m2) are not likely to exacerbate the channel conditionsince the bed and banks are dominated by boulder and cobble material.The potential for bank erosion and bedload transport increases withincreasing water depth.

7 RISKS FROM HARVESTING BEETLE INFESTED LODGEPOLE PINE

Proposed harvesting by the licensees for 2004 and beyond is designed primarily totarget beetle infested stands. The objective for harvesting has been to balancethe risks to all watershed resources. A summary of the proposed developmentand associated ECAs (assuming that all proposed development occurs in 2004)within the snow sensitive zone in the watershed is presented in Table 5.

TABLE 5Proposed development and ECAs in the infested pine dominated stands

of the snow sensitive zone

ECAs of Mature PineDrainage

Snow Zone(ha)

Snow Zone

(ECA %)

Stuart 88 27Treadgold 17 26Residual 209 20

Watershed 314 221. Refer to Appendix A for more ECA details


544-014/24028/March 2005 Page 14

Appendix A contains hydrologic recovery projections that can be used to calculatethe ECAs as development is planned in the future. Based on the hazard/riskdirection provided in the previous sections, the peak flow hazards for the proposeddevelopment would be Low for all the sub-basins, and the residual area. Theoverall watershed hazard rating would be low.

As has been previously stated it is the loss of forest cover as a result of the beetlethat has the greatest impact on peak flows. The removal of mountain pine beetleinfested stands by harvesting would have very limited additional impacts on peakflows, as a stand dominated by dead trees would function hydrologically similar toa clear-cut.

Construction of access roads can increase stream flows due to the interception ofsubsurface drainage, however if the natural drainage patterns are maintained bydirecting runoff from the ditchlines onto the forest floor rather than into thechannel system, the impacts of roads on peak flows would be minimal.

Harvesting beetle infested trees can provide measurable benefits. Early andaggressive harvesting of infestations might suppress the rate of expansion ofbeetle populations and subsequently reduce the overall amount of harvesting. Theremoval of beetle killed trees reduces the risk of wildfire by reducing the fuel load.Since reforestation is scheduled within 1 – 2 years after harvesting, logging wouldalso increase the rate of hydrologic recovery in the watershed. It has beenestimated that hydrologic recovery can be advanced by up to 30 years throughharvesting and timely silviculture operations.

Due to the increased level of mountain pine beetle infestation in the Beak Creekwatershed, harvesting should be planned at the basin level with all options forminimizing hydrologic and landslide impacts considered. This is particularlyimportant in those sub-basins with high ECAs/peak flow levels or where harvestingmay be proposed on gentle over steep terrain.

Based on Dobson field investigations throughout the province, most forestryrelated hydrologic impacts in BC have resulted from either terrain instability or lossof riparian vegetation. The impacts of terrain instability can include channelaggradation and increased rates of bank erosion. Riparian harvesting can lead tochannel instability through the loss of large wood recruitment to streams andthrough the loss of bank stabilizing vegetation. Large wood creates channelroughness, which slows the flow of water, reduces erosion, and traps sediment.Dead trees (e.g. dead lodgepole pine) are valuable for short-term recruitment tostreams as large wood. Live trees provide long-term recruitment. Tree rootsincrease the strength of soils, thereby, increasing the stability of channel banks.The bank and floodplain roughness that the trees provide reduces flow velocitiesduring flood events, thereby, reducing erosion. Maintaining riparian vegetation isimportant, particularly for basins with high ECAs and highly mobile, alluvialchannel substrate. It is not necessary to retain all trees in the riparian zone forsufficient protection. It is important to assess the need for wood recruitment on a


544-014/24028/March 2005 Page 15

reach basis. In terms of retained stem sizes, the larger the stream, the larger thediameter the wood to maintain channel stability and function.

8 AVAILABLE DEVELOPMENT

ECAs for the period of December 31, 2004, to December 31, 2014, illustratinghydrologic recovery of the watershed without consideration for future forestdevelopment are provided in Appendix A. Based on maintaining the guidelineECAs outlined in Table 4, the analysis of hydrologic recovery leads to adetermination of the available development in the snow zone at low, moderate,and high hazard levels (i.e. low, moderate, and high risk levels).

As explained previously, the development in the areas below the snow zone isconsidered to be more constrained by other resource values than by potential peakflow impacts. Because of this, direction regarding ECA levels and availabledevelopment are not provided. Lower elevation development does advance thetiming of the early portion of the spring freshet, but development below the snowsensitive zone has a low likelihood of impacting peak flows and channel conditions.Other forest management concerns may be more constraining in these areas (e.g.visual quality objectives, biodiversity, surface erosion potential hazards).

The available development results are presented in Appendix A for years 2004through 2014 and summarized for 2004 in Table 6 below. Table 7 presents thetotal supply of mature timber as of December 31, 2004 (current condition).

TABLE 62004 available development in the snow sensitive zone

of the Beak Creek watershed

2004 Available Development (ha)1Drainage

Low Risk2 ModerateRisk3

High Risk4

Stuart 47 77 106Treadgold 35 97 160Residual 279 430 581Watershed 362 604 847

1. Presents the potential development if moderate, high, or very high risks areconsidered acceptable.

2. Assumes 30% ECA3. Assumes 40% ECA4. Assumes 50% ECA


544-014/24028/March 2005 Page 16

TABLE 7Total supply of mature timber in the Beak Creek watershed

Mature Timber (ha)Drainage

Snow Zone Below SnowZone

Total

Stuart 578 679 1257Treadgold 670 76 746Residual 2198 2016 4214

Watershed 3446 2772 62171. Includes all areas within the watershed (private land, THLB, NTHLB,

OGMAs, terrain class V, etc.)

9 CONCLUSIONS

� Extension Note 67 can be applied to the Beak Creek watershed since thebasin morphology is similar to that of the Penticton Creek watershed.

� Based on the results summarized in the extension note, ECA levels and peakflow hazard levels for Beak Creek have been revised and are proposed as;<30 % ECA = low hazard, 30 to 50% ECA = moderate hazard, and >50%ECA = high hazard.

� Peak flow related channel disturbance was not observed in the Beak Creekwatershed.

� Surface erosion and riparian function are low concerns for future forestdevelopment.

� The proposed development would result in Low peak flow hazards for allsub-basins, and for the residual area (low risk).

� The loss of forest cover due to mountain pine beetle infestations (excludingharvesting) can affect the watershed hydrology and is considered to impactECAs.

� The harvesting of dead or dying stands should have negligible additionalpeak flow impacts.

� Maintenance of riparian vegetation is important, particularly for basins withhigh ECAs and highly mobile, alluvial channel substrate.

10 RECOMMENDATIONS

� It is recommended that the results summarized in Extension Note 67 beapplied to the snow sensitive zones of the Beak Creek watershed since thebasin morphologies are similar to Upper Penticton Creek.

� The acceptable level of risk for peak flow increases due to harvestingproposals should be determined based on a combination of the loss of forestcover levels in the snow sensitive zone portions of the watershed and thechannel sensitivity.


544-014/24028/March 2005 Page 17

� In order to minimize the potential impacts of roads on peak flows, naturaldrainage patterns should be maintained. Runoff in ditches should bedispersed onto the forest floor frequently using cross drains. Ditches thatare directly connected to the channel network should not extend beyond theimmediate gully sidewall. Roads should be deactivated as soon as possiblefollowing development.

� All options to aggressively suppress beetle expansion should be consideredto minimize the future spread of beetles and subsequent peak flow impactson Beak Creek.

� Where ECAs are moderate or high, consideration should be given, whereverpractical, to leaving those stands that are not Pl leading in the snow sensitivezone that will emulate an undisturbed stand with regards to canopy closureto reduce the peak flow impacts. These stands might also form WTPs orstream buffers as appropriate.

� When allocating stand level WTP hectares, where ECA's are moderate tohigh, consideration should be given to applying WTP's in those stands in thesnow sensitive zone that are not Pl leading that will emulate an undisturbedstand with regards to canopy closure to reduce the peak flow impacts.Where it exists and is practical stream buffers would be considered a suitablearea for this type of retention.

� In basins with high ECAs or where reaches may have highly mobile alluvialsubstrate, riparian vegetation should be retained to maintain channelstability and to emulate an undisturbed stand with regards to canopyclosure.

� For beetle suppression activities in riparian areas, the need for woodrecruitment as in-stream large wood should be considered at the site planstage.

� During Terrain Stability Assessments, careful attention should be given to flatover steep scenarios to minimize potential impacts on soil moisture levels(eg. CP 178-KB1007)

� Consideration should be given to completing a more detailed assessment ofwood function in streams to mitigate the potential affects of peak flows.

Please call me if you have questions or concerns.

Respectfully submitted,

Original signed by: Brian Gaucher

Original signed by: M.E. Noseworthy, P.Geo.Senior Reviewer

Attach.


544-014/24028/March 2005 Page 18

11 LITERATURE CITED

Schnorbus, M.A., R.D. Winkler, and Y. Alila. 2004. Modeling Forest HarvestingEffects on Maximum Daily Peak Flows at Upper Penticton Creek. BC Ministry ofForest Extension Note No. 67.

APPENDICES

APPENDIX AWatershed Condition Summary Table,

and Available Development

Watershed Report Card for Beak Creek 2004*

Basin Gross Area (ha)

TotalHarvested

AreaHa%

ECAha%

ECAbelow

Snowlineha%

ECAAbove

Snowlineha%

Stuart Sub-basin 1,735.1 359.7

20.7

331.6

19.1

222.6

22.3

109.1

14.8

Treadgold Sub-basin 1,287.7 515.0

40.0

497.7

38.6

275.9

72.6

221.7

24.4

Residual 6,052.1 1,566.2

25.9

1,521.7

25.1

1,230.3

35.0

291.4

11.5

Watershed 9,075.0 2,440.9

26.9

2,351.0

25.9

1,728.8

35.4

622.2

14.9

November 8, 2004 Page 1 of 1* Includes all blocks cut or projected to be cut in 2004

Beak Creek 10 year ECA Recovery*Values in ha and %

Basin 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014GrossArea(ha)

Stuart Sub-basin 331.6

19.1

324.4

18.7

324.3

18.7

324.1

18.7

324.1

18.7

324.1

18.7

318.2

18.3

318.2

18.3

310.8

17.9

310.0

17.9

287.9

16.6

1,735.1

Treadgold Sub-basin 497.7

38.6

497.7

38.6

497.2

38.6

497.2

38.6

497.2

38.6

477.4

37.1

477.1

37.1

477.1

37.1

477.1

37.1

472.9

36.7

457.0

35.5

1,287.7

Residual 1,521.7

25.1

1,519.0

25.1

1,519.0

25.1

1,478.4

24.4

1,478.4

24.4

1,446.1

23.9

1,425.1

23.5

1,396.6

23.1

1,327.9

21.9

1,311.8

21.7

1,249.7

20.6

6,052.1

Watershed 2,351.0

25.9

2,341.0

25.8

2,340.5

25.8

2,299.7

25.3

2,299.7

25.3

2,247.5

24.8

2,220.4

24.5

2,191.9

24.2

2,115.8

23.3

2,094.7

23.1

1,994.6

22.0

9,075.0

November 8, 2004 Page 1 of 1* ECA values calculated for December 31 of each year

Beak Creek 10 year ECA Recovery*

Values in ha and %Area below Snow Line


Stuart Sub-basin

222.6

22.3

222.6

22.3

222.6

22.3

222.4

22.3

222.4

22.3

222.4

22.3

222.4

22.3

222.4

22.3

222.4

22.3

222.4

22.3

209.4

21.0

997.8

Treadgold Sub-basin

275.9

72.6

275.9

72.6

275.5

72.5

275.5

72.5

275.5

72.5

255.7

67.3

255.4

67.2

255.4

67.2

255.4

67.2

251.1

66.1

247.8

65.2

380.0

Residual 1,230.3

35.0

1,227.6

35.0

1,227.6

35.0

1,195.3

34.0

1,195.3

34.0

1,163.0

33.1

1,142.0

32.5

1,116.8

31.8

1,083.4

30.9

1,073.8

30.6

1,018.2

29.0

3,511.5

Watershed 1,728.8

35.4

1,726.1

35.3

1,725.7

35.3

1,693.2

34.6

1,693.2

34.6

1,641.0

33.6

1,619.9

33.1

1,594.6

32.6

1,561.2

31.9

1,547.4

31.6

1,475.4

30.2

4,889.3


Beak Creek 10 year ECA Recovery*

Values in ha and %Above Snow Line


Stuart Sub-basin 109.1

14.8

101.8

13.8

101.7

13.8

101.7

13.8

101.7

13.8

101.7

13.8

95.8

13.0

95.8

13.0

88.4

12.0

87.6

11.9

78.5

10.6

737.3

Treadgold Sub-basin 221.7

24.4

221.7

24.4

221.7

24.4

221.7

24.4

221.7

24.4

221.7

24.4

221.7

24.4

221.7

24.4

221.7

24.4

221.7

24.4

209.2

23.0

907.7

Residual 291.4

11.5

291.4

11.5

291.4

11.5

283.1

11.1

283.1

11.1

283.1

11.1

283.1

11.1

279.7

11.0

244.5

9.6

238.0

9.4

231.5

9.1

2,540.7

Watershed 622.2

14.9

614.9

14.7

614.8

14.7

606.5

14.5

606.5

14.5

606.5

14.5

600.6

14.3

597.2

14.3

554.7

13.3

547.3

13.1

519.2

12.4

4,185.6


Available Development

Available Harvest: Moderate Risk ScenarioDrainage Guideline ECA 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 Total

Stuart above snowline 30 47 0 0 0 0 2 0 3 0 4 57Treadgold Above Snowline 30 35 0 0 0 0 0 0 0 0 9 44Residual Above Snowline 30 279 0 6 0 0 0 2 21 3 5 316Watershed 30 362 0 6 0 0 2 2 24 3 17 416

Available Harvest: High Risk ScenarioDrainage Guideline ECA 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 Total


Available Harvest: Very High Risk ScenarioDrainage Guideline ECA 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 Total


544-014/24028/November 2004

APPENDIX BPeak flow and Water Level Analysis

Beak Creek Longitudinal Profile

1000

1100

1200

1300

1400

1500

0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000

Distance along Mainstem (m from POI)

Elev

atio

n (m

)

A3%

B4%

C2%

E3%

F1%

G3%

H1%

I7%

J1%

Confluence with the Nicola River

Forest License Boundary

Trib 1 (Venturi Creek)

Trib 7

Trib 11Trib 13 (Treadgold Creek)

Venturi Main

Outlet of Stuart Lake

D0.5%

Trib 2 - Site 6 Site 5

Trib 7Trib 7 Trib 7

Trib 7

Site 7

Site 16a, b, c

Site 12

Treadgold Creek Longitudinal Profile

1250

1300

1350

1400

1450

1500

0 1000 2000 3000 4000 5000 6000

Distance along mainstem (m)

Elev

atio

n (m

)

Beak Main crossing - Site 11TA1%

TB4%

TC2%

TD8.5%

TE2.5%

TF4%

Treadgold Lake

Confluence with Beak Creek

Site 15

Peak flow and water level Analysis

Beak Creek Mainstem at site 5

Width (m) 6.75Slope (%) 4Roughness 0.270

2 Year Flow

ECA(%)

Flow Increase(%)

Flow(m3/s)

Depth(m)

Calculated Flow(m3/s)

Shear Stress(N/m2)

Shear Stress(lb/ft2)

Increase in Depthand Shear Stress

(%)

Tractive force (1000*D*S)

(kg/m2)0 0.0 1.45 0.504 1.45 198 4.13 0.0 20.230 1.0 1.46 0.505 1.46 198 4.14 0.2 20.250 6.8 1.55 0.525 1.55 206 4.30 4.2 21.070 18.4 1.72 0.560 1.72 220 4.59 11.1 22.4

10 Year Flow

ECA(%)

Flow Increase(%)

Flow(m3/s)

Depth(m)


Shear Stress(N/m2)



(%)


(kg/m2)0 0.0 2.60 0.730 2.60 286 5.98 0.0 29.230 6.8 2.78 0.763 2.78 299 6.25 4.5 30.550 13.9 2.96 0.794 2.96 312 6.51 8.8 31.870 24.2 3.23 0.841 3.23 330 6.89 15.2 33.6

50 Year Flow

ECA(%)

Flow Increase(%)

Flow(m3/s)

Depth(m)


Shear Stress(N/m2)



(%)


(kg/m2)0 0.0 3.50 0.887 3.50 348 7.27 0.0 35.530 14.2 4.00 0.968 4.00 380 7.93 9.1 38.750 23.3 4.32 1.018 4.32 399 8.34 14.8 40.770 32.7 4.64 1.067 4.64 419 8.74 20.3 42.7

1 Tractive force can be used to approximate the maximum bedload particle size that is subject to incipient motion; force = Diameter (cm)

544-014/24028/November 2004

Peak flow and Water Level Analysis

Beak Creek Mainstem at site 6


2 Year Flow

ECA(%)

Flow Increase(%)

Flow(m3/s)

Depth(m)


Shear Stress(N/m2)



(%)

Tractive force

(1000*D*S) (kg/m2)

0 0.0 1.70 0.663 1.70 65 1.36 0.0 6.630 1.0 1.72 0.666 1.72 65 1.36 0.5 6.750 6.8 1.81 0.690 1.81 68 1.41 4.1 6.970 18.4 2.01 0.738 2.01 72 1.51 11.3 7.4

10 Year Flow

ECA(%)

Flow Increase(%)

Flow(m3/s)

Depth(m)


Shear Stress(N/m2)



(%)

Tractive force

(1000*D*S) (kg/m2)

0 0.0 3.10 0.959 3.01 94 1.96 0.0 9.630 6.8 3.31 1.020 3.31 100 2.09 6.4 10.250 13.9 3.53 1.065 3.53 104 2.18 11.1 10.770 24.2 3.85 1.125 3.83 110 2.31 17.3 11.3

50 Year Flow

ECA(%)

Flow Increase(%)

Flow(m3/s)

Depth(m)


Shear Stress(N/m2)



(%)

Tractive force

(1000*D*S) (kg/m2)

0 0.0 4.10 1.177 4.10 115 2.41 0.0 11.830 14.2 4.68 1.286 4.68 126 2.63 9.3 12.950 23.3 5.06 1.355 5.06 133 2.78 15.1 13.670 32.7 5.44 1.424 5.44 140 2.92 21.0 14.2

1 Tractive force can be used to approximate the maximum bedload particle size that is subject to incipient motion; Tractive force = Diameter (cm)

544-014/24028/November 2004

Peak flow and Water Level Analysis

Teradgold sub-basin at Site 11


2 Year Flow

ECA(%)

Flow Increase(%)

Flow(m3/s)

Depth(m)


Shear Stress(N/m2)



(%)


(kg/m2)0 0.0 0.25 0.310 0.25 61 1.27 0.0 6.230 1.0 0.25 0.310 0.25 61 1.27 0.0 6.250 6.8 0.27 0.325 0.27 64 1.33 4.8 6.570 18.4 0.30 0.345 0.30 68 1.41 11.3 6.9

10 Year Flow

ECA(%)

Flow Increase(%)

Flow(m3/s)

Depth(m)


Shear Stress(N/m2)



(%)


(kg/m2)0 0.0 0.44 0.450 0.44 88 1.84 0.0 9.030 6.8 0.47 0.470 0.47 92 1.93 4.4 9.450 13.9 0.50 0.485 0.50 95 1.99 7.8 9.770 24.2 0.55 0.520 0.55 102 2.13 15.6 10.4

50 Year Flow

ECA(%)

Flow Increase(%)

Flow(m3/s)

Depth(m)


Shear Stress(N/m2)



(%)


(kg/m2)0 0.0 0.58 0.540 0.58 106 2.21 0.0 10.830 14.2 0.66 0.590 0.66 116 2.42 9.3 11.850 23.3 0.72 0.625 0.72 123 2.56 15.7 12.570 32.7 0.77 0.653 0.77 128 2.68 20.9 13.1


544-014/24028/November 2004

Peak Flow and Water Level Analysis

Stuart sub-basin at Site 13


2 Year Flow

ECA(%)

Flow Increase(%)

Flow(m3/s)

Depth(m)


Shear Stress(N/m2)



(%)


(kg/m2)0 0.0 0.13 0.210 0.13 103 2.15 0.0 10.530 1.0 0.13 0.210 0.13 103 2.15 0.0 10.550 6.8 0.14 0.220 0.14 108 2.25 4.8 11.070 18.4 0.15 0.230 0.15 113 2.36 9.5 11.5

10 Year Flow

ECA(%)

Flow Increase(%)

Flow(m3/s)

Depth(m)


Shear Stress(N/m2)



(%)


(kg/m2)0 0.0 0.23 0.310 0.23 152 3.18 0.0 15.530 6.8 0.25 0.325 0.25 159 3.33 4.8 16.350 13.9 0.26 0.335 0.26 164 3.43 8.1 16.870 24.2 0.29 0.360 0.29 177 3.69 16.1 18.0

50 Year Flow

ECA(%)

Flow Increase(%)

Flow(m3/s)

Depth(m)


Shear Stress(N/m2)



(%)


(kg/m2)0 0.0 0.31 0.380 0.31 186 3.89 0.0 19.030 14.2 0.35 0.410 0.35 201 4.20 7.9 20.550 23.3 0.38 0.435 0.38 213 4.46 14.5 21.870 32.7 0.41 0.455 0.41 223 4.66 19.7 22.8


544-014/24028/November 2004

Peak Flow and Water Level Analysis

Venturi Creek (residual area) at Site 17


2 Year Flow

ECA(%)

Flow Increase(%)

Flow(m3/s)

Depth(m)


Shear Stress(N/m2)



(%)


(kg/m2)0 0.0 0.20 0.225 0.20 243 5.07 0.0 24.830 1.0 0.20 0.225 0.20 243 5.07 0.0 24.850 6.8 0.21 0.230 0.21 248 5.18 2.2 25.370 18.4 0.24 0.255 0.24 275 5.75 13.3 28.1

10 Year Flow

ECA(%)

Flow Increase(%)

Flow(m3/s)

Depth(m)


Shear Stress(N/m2)



(%)


(kg/m2)0 0.0 0.33 0.310 0.33 335 6.99 0.0 34.130 6.8 0.35 0.325 0.35 351 7.32 4.8 35.850 13.9 0.38 0.345 0.38 372 7.78 11.3 38.070 24.2 0.41 0.360 0.41 388 8.11 16.1 39.6

50 Year Flow

ECA(%)

Flow Increase(%)

Flow(m3/s)

Depth(m)


Shear Stress(N/m2)



(%)


(kg/m2)0 0.0 0.44 0.380 0.44 410 8.56 0.0 41.830 14.2 0.50 0.410 0.50 442 9.24 7.9 45.150 23.3 0.54 0.435 0.54 469 9.80 14.5 47.970 32.7 0.58 0.455 0.58 491 10.25 19.7 50.1


544-014/24028/November 2004

APPENDIX CField Photos

PHOTO 1. Site 5, Beak Creek - Oct 2004. Downstream view of Beak Creek at theconfluence of Tributary 7

PHOTO 2. Site 5, Beak Creek - Oct 2004. View of Beak Creek upstream of confluencewith Tributary 7

PHOTO 3. Site 5, Beak Creek - Oct 2004. Upstream view of Tributary 7 at its confluencewith Beak Creek

PHOTO 4. Site 5, Beak Creek - Oct 2004. Downstream view of Beak Creek below theconfluence of Tributary 7

PHOTO 5. Site 7, Beak Creek - Oct 2004. Upstream view of Beak Creek near theconfluence of Tributary 11

PHOTO 6. Site 7, Beak Creek - Oct 2004. Downstream view of Beak Creek near theconfluence of Tributary 11

PHOTO 7. Site 6, Beak Creek - Oct 2004. Upstream view of Beak Creek above theconfluence of Tributary 2

PHOTO 8. Site 6, Beak Creek - Oct 2004. Downstream view of Beak Creek above theconfluence of Tributary 2



PHOTO 11. Site 6, Beak Creek - Oct 2004. Downstream view of Beak Creek theconfluence of Tributary 2

PHOTO 12. Site 16a - October 2004. Upstream view of Beak Creek upstream ofconfluence with Treadgold Creek

PHOTO 13. Site 16b - October 2004. Upstream view of Beak Creek upstream ofconfluence with Treadgold Creek

PHOTO 14. Site 16b - October 2004. Downstream view of Beak Creek upstream ofconfluence with Treadgold Creek

PHOTO 15. Site 16c - October 2004. Downstream view of Beak Creek upstream ofconfluence with Treadgold Creek

PHOTO 16. Site 12 - October 2004. Beak Creek, upstream view 75m above bridge crossingon Venturi Main

PHOTO 17. Site 12 - October 2004. Beak Creek, Downstream view, 75m above bridgecrossing on Venturi Main

PHOTO 18. Site 15 - October 2004. Downstream view of Treadgold mainstem

PHOTO 19. Site 15 - October 2004. Upstream view of Treadgold mainstem

PHOTO 20. Site 11 - October 2004. Tributary 13, Downstream view, 75m below bridge onBeak Main

PHOTO 21. Site 11 - October 2004. Tributary 13, Upstream view, 75m above bridge onBeak Main. Beaver activity

APPENDIX DWatershed Condition Map

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