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LAND & WATER 1 CONSERVATION

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I J NSW Department of Land and Water Conservation I I I I I

I Kew - Kendall Sewerage I Camden Haven River Tidal I Modelling Report I I

Estuary Management Group I October 1996 I I I I I I I

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I Contents I 1 Introduction 4 2 Methodology 5

I 3 Datasets 7

4 Hydraulic Modelling 8 I' 4.1 Calibration 11 4.2 Verification .... 12

I 5 Transport Dispersion Results 13 5.1 Continuous Effluent Discharge 16 I 5.2 Ebb Staged Effluent Discharge 19 5.3 Retention Time/ Transport Analysis 19 5.4 Region of Influence ...... 20 I 5.5 Interpreting the Model Results as Dilution 20 I 6 Discussion 21 I List of Tables 1 Model Characteristics . 9 I 2 Comparison of Tidal Harmonic Analysis for Amplitude 13 3 Location of Results and Site Descriptions ...... 15 4 Results of mean Concentration for 50% Base Flow . . . 17 I 5 Results of Mean Concentrations for Zero Base Flow . . 18 6 Results of Mean Concentrations for Ebb Only Release . 19 I 7 Distance Reached by Drogues after Release ...... 20

I List of Figures

1 Location and Study Area Details 5 2 . Location of Hydraulic Data .. . '. 7 3 Model Grid Used ...... 10 4 Location of Effluent Discharge Sites Modelled 14 I 5 Location of Concentration Results...... 16 6 Calibration Results - Entrance Water Levels . 26 I 7 Calibration Results - Hanleys Point Water Levels 26 8 Calibration Results ~ Queens Lake Water Levels 27

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I 9 Calibration Results - Rossglen (Highway Bridge) Water Levels 27

10 Calibration Results - Stingray Channel Water Levels 0 0 28 I 11 Calibration Results - Watson Taylors Lake Water Levels 28

12 Calibration Results - Entrance Discharge 0 0 0 0 29

13 Calibration Results - Hanleys Point Discharge 0 0 0 0 29

I 14 Calibration Results - Stingray Channel Discharge 0 0 0 0 30 15 Verification Results - Watson Taylors Lake Water Levels - Day 13

- 24 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 32 I 16 Verification Results - Watson Taylors Lake Water Levels - Day 23

- 34 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 32 I 17 Verification Results - Watson Taylors Lake Water Levels - Day 33 -44 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 33

18 Verification Results - Lower Rossglen Water Levels - Day 13 - 24 0 34

19 Verification Results - Lower Rossglen Water Levels - Day 23 - 34 0 34 I 20 Verification Results - Lower Rossglen Water Levels - Day 33 -44 35 21 Verification Results - Kendal Road Bridge Water Levels - Day 13 I - 24 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 36 22 Verification Results - Kendal Road Bridge Water Levels - Day 23

- 34 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 36 I 23 Verification Results - Kendal Road Bridge Water Levels - Day 33

-44 0 0 0 0 0 0 0 0 0 0 0 0 37 24 Concentration Profile - For Site 1 Release 39 I 25 Concentration Profile - For Site 2 Release 39 26 Concentration Profile - For Site 3 Release 40 27 Drogue Tracks - Site 1 Release - Day 0 - 14 42 I 28 Drogue Tracks ~ Site 1 Release - Day 14 - 28 42 29 Drogue Tracks - Site 2 Release - Day 0 - 14 43 30 Drogue Tracks - Site 2 Release - Day 14 - 28 43 I 31 Drogue Tracks - Site 3 Release - Day 0 - 14 44 32 Drogue Tracks - Site 3 Release - Day 14 - 28· 44 I 33 Drogue Tracks - Site 4 Release - Day 0- 14 45 34 Drogue Tracks - Site 4 Release - Day 14 - 28 45 01 I I I

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I 1 Introduction I The villages of Kew and Kendall are located in the catchment of the Camden Haven River system. The Camden Haven River lies approximately 350 km north I of Sydney on the coastal plain with a catchment area of approximately 720 km 2 2 square kilometres and a waterway area of approximately 27.8 km . The Camden Haven River entrance to the South Pacific Ocean is located at North Haven and I is trained with two breakwalls. The river is the tidal connection for two estuarine lakes, namely Queens Lake, through a relatively small side arm from the main river and Watson Taylors Lake located approximately 8 km upstream of the river I entrance. The river continues upstream through Watson Taylors Lake and onto Kendall approximately 10 km upstream from the lake. The tidal limit is located I 3 km upstream of Kendall. Figure 1 shows details of the study area. Tidal characteristics of the river system indicate that Queens Lake behaves as I a typical coastal lake at the end of an inlet channel with a very small tidal range. Watson Taylors Lake, although with a surface area similar to Queens Lake, maintains a significant tidal range which is then maintained throughout the I upper reaches of the river to Kendall. Because of the relatively shallow nature of Watson Taylors Lake (approximately 1.0 m depth), and a tidal range of half that depth, the lake is quite well flushed in terms of volume of water exchanged. I The river system as a whole though, exhibits ali unusual mix of different tidal hydraulic characteristics. The inlet channel up to Watson Taylors Lake behaves as a typical lake/inlet channel system where the velocities (and discharges) occur I in phase with the tidal water levels. However the upper reach from the Lake to Kendall (and the tidal limit) behave as a typical tidal river system where the I velocities occur 90 degrees out of phase with the water levels. This results in a situation which occurs every tide, ,,,here the upper reaches are ebbing irito the Lake while the inlet channel is still flooding into the lake. Under this situation, I the period of time where both the upper reach and inlet channel are flowing in the same direction is reduced considerably. This means that hydraulically the actual flushing of the upper reaches to the ocean will be of short duration and I very dependent on the tidal phasing of these different sub-systems of the river I system. It has been proposed to implement a sewerage scheme to cater for the villages of Kew and Kendall, and possibly take effluent from the expanding development I around Queens Lake, which currently is processed by the Dunboggan treatment plant. In conjunction with a treatment plant for Kew-Kenda11, effluent manage­ ment options under consideration include the discharge of treated effluent (either I totally or in part) to the Camden Haven River.

I 4 I I I I I I I I I I I Figure 1: Location and Study Area Details

I This Report outlines the results of a study into the characteristics of effluent discharge, for a number of discharge site options on the Camden Haven River. The study uses computer models to simulate the tidal and baseflow conditions of I the river and conservative tracers 'injected' into the model, along with simulated I drogues, to determine the movement and dilution of effluent in the river.

I 2 Methodology

I' A computer model was developed for the whole of the Camden Haven River covering its region of tidal influence. The model used is Flo2D - a 2D mod­ elling system using curvilinear coordinate grid system, supporting calculation of I hydrodynamic characteristics, and transport dispersion processes amongst other features. This model has been used extensively in Estuary Management for more. I than ten years.

Using this model, complete tidal cycles are run to generate water velocities and I water levels throughout the tidal extent of the model. In effect these results are generated solely by defining an ocean water level (which is ·varying with time). Using these calculated velocities and water levels, a transport dispersion model I can be run which then simulates pver time the movement and dispersion of any

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I effluent that is released into the river. These model results can be used to show the expected dilution and regions of influence of effluent from given effluent discharge locations. The transport dispersion model is run with a conservative tracer. That I is, this tracer does not decay with time and helps to define the actual regions of influence clearly, giving a picture of worst case concentrations. The chemical I interaction that occurs in nature is not modelled. Another tool that is used, is the modelling of the movement of numerical drogues. Drogues are used extensively in field studies and are small floats whose locations are monitored and is recorded I over a period of time. This can be done in numerical models as well. The use of numerical drogues defines the flow paths and retention time in the estuary.

I The model must be calibrated against measured tidal data (1979 Gauging), and then verified against another set of independent data (1995 Water Levels). The I model geometry was based on a combination of survey data from different years, with the bulk of the data from the 1979 Camden Haven Survey.

I To determine the effects of various effluent discharge strategies, the model was then run for two fresh water baseflow conditions over a 30 day tidal period - 1) zero base flow and 2) a 50% base flow for both the Stewart and Camden Haven I Rivers. The 50% flow is that flow which is exceeded 50% of the time, and was determined from records provided by the Department of Land and Water Con­ servation. Using these hydraulic results, modelling for effluent discharge for four I possible sites were done. At each site the model was run for transport dispersion of a conservative tracer, for both zero and 50% base flow, and depending on the site an effluent discharge limited to only ebb tide flow conditions was also run. I The transport dispersion model runs were based on a 28 day hydraulic run but was cycled through this 3 times to give a total dispersion model run time of 84 I days (12 weeks) .. This time duration for the transport dispersion runs allowed '. the concentrations to stabilise and' reach pseudo steady state conditions. For each site drogue runs were undertaken to determine their extent of travel over I predetermined time periods.

The mouel assumes full mixing through the model cell at the discharge location I and hence represents far field results .. Instantaneous concentrations at actual discharge sites need to be determined with a near field model using the hydraulic. I and mixing characteristics of the discharge diffuser and local site condition~. The transport dispersion modelling could not be calibrated due to a lack of dilution or dye tracing data. However, the 2D model used in this study defines the physical I dispersion and mixing characteristics through the velocity variations and lateral shearing processes which are the mechanisms that provide' dispersion as part of the river processes. On this basis, 2D model calculated results are relatively I insensitive to the dispersion coefficients used. However,a 1D model in comparison

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I .... -.... ,-.. ,~.- I I I I I I I I I I Figure 2: Location of Hydraulic Data does not include these processes at all, and as such the reliance on the dispersion coefficients is very high. In a 1D model the dispersion and mixing are achieved I almost entirely through the dispersion coefficient based terms in the equations. The 2D dispersion coefficients used are based on values used in previous studies I and it is felt they are representative of the processes simulated by the models.

I .. 3 Datasets I A number of datasets were used to build, calibrate, verify and run the model. The following list outlines those items used in this study. Figure 2 shows the I location of all the hydraulic data.

• Geometry data was supplied by the Department of Public Works and Ser- . I vices Survey Group. All data downstream of and including both lakes was obtained from the 1979 Camden Haven Hydrographic Survey. This com­ prised of cross sectional data for the inlet channel above Hanleys Point I including Watson Taylors Lake and Queens Lake. The. data. did not cover upstream of the lakes (DPWS internal reference B12160, B12161, B12162). I Below Hanleys Point the main. inlet channel data was available as XYZ

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I data from a Hydrographic Survey (reference BXXXX). Survey data for up­ per reach of the Camden Haven River from Watson Taylors Lake to Kendall I was undertaken as part of this study, comprised 17 cross sections (reference BXXXX). I • Hydraulic data comprised of a main tidal gauging undertaken on the 9th August 1979 and a complementary water level survey over 3 months start­ ing in November 1995 in the upper reaches of the river. The 1979 data I set is made up of 3 gauging lines measuring velocities (discharge) and 7 water levels. The discharge lines were located in the inlet channel near the entrance and upstream of the Stingray Channel confluence in both the inlet I channel and Stingray Channel itself. The most upstream water level was located at the Pacific Highway Bridge. Other water levels included one up Stewarts River, and one located in each Lake. The 1995 data set was made I up of 3 water levels, Watson Taylors Lake, on the Camden Haven River approximately 1.5 kilometres upstream from Watson Taylors Lake, and at I Kendall just downstream of the road bridge. I I 4 Hydraulic Modelling The modelling was undertaken using the Department of Land and Water Con­ I servation's Fl02D Modelling System. . This system is a 2 Dimensional Hori­ zontal Modelling System based on a curvilinear grid approach developed by Stelling(1984) and used extensively around the world. The Department's system I incorporates a suite of numerical to.ols to simulate water flow, transport disper- ... sion and sediment transport in conjunctions with a complete set of routines for I input and output (graphics) processing. The mQdel is built, based on a combination of plan form details from maps and ,I geometry data available from hydrographic and cross section surveys. Using the plan form information, a model grid is 'drawn out' by the modeller and smoothed mathematically. The final model grid is shown in Figure 3. Once the grid is· finalised bed geometry values are interpolated from existing bed data onto the grid. The model is then calibrated using hydraulic data so that the model results agree with the measured data to a satisfactory level. Calibration is achieved by adjusting friction in the hydraulic model and possibly geometry adjustments. Geometry adjustments are only justified for cases where the grid generation or the survey data has missed important geometry features. This process of fixing geometry involves close inspection. of a combination of survey plans and a~rial .". -" I 8 I I I I I Characterisitc Values Overall Grid Size 247 x 57 I Active Cells 3705 min Cell Size 10m I Hydraulic Friction 0.020 Mannings n Dispersion Coefficient 0.5 m2 /s Time Step 1 minute I Transport Dispersion Dispersion Coefficient Longitudinal 1.0 m~ Is I Lateral 0.1 m2 /s Time Step 3 minutes

I Table 1: Model Characteristics

photographs. After calibration, verification runs are undertaken where the model I is run against other measured data sets, and the results are compared without any model parameter adjustments. The combined results from the calibration and the verification runs gives an indication of the degree of confidence that the I model can be used with ..

I The model geometry was based on a combination of survey data from different years, with a large component of the data from the 1979 Camden Haven Survey. The 1979 data set essentially covers the lower reaches of the river system from I the ocean entrance to t~e lower parts of the upper river reach. The 1979 data includes cursory data for the geometry of both Watson Taylors and Queens Lakes. The upper river from Watson Taylors Lake to Kendall used survey data collected I .. in Jan 1996. More recent survey dat-a exists for the lower sections of the river but it was felt that it was better to have as consistent a data set as possible, and the I 1979 data set also corresponds closely with the· period that the main hydraulic data was collected over.

I The model was constructed with a few assumptions and simplifications. The exact planform for Queens Lake was not adhered to,. possibly generating a small error in the entrance reach. Also Gogleys Lagoon was not incorporated into the model· I at all. Both these decisions were made on the basis of keeping the model slightly smaller and therefore easier to run - while not incorporating significant errors in the main areas of interest - namely the Watson Taylors Lake and upstream to I Kendall.

I The model characteristics are shown in Table 1.

I 9 I I I I I I I I I I I I I I I I I I I Figure 3: Model Grid Used I

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I 4.1 Calibration

I The calibration of the model was made using the 1979 Manly Laboratory Tidal Gauging data. This gauging consisted of a number of discharge lines covering I the inlet channel near the entrance and both arms into the lakes. Water levels were monitored throughout the river system but only going upstream as far as I the Pacific Highway Bridge. The model calibration included testing the measured data against a range of model friction values. The model was run with a constant friction value over the I whole of the estuary. There was no spatial or temporal variation of friction. The final value used which gave the best agreement with the dataset was a Manning's N value of 0.020. This value is typical of 2D model friction values used in tidal I studies.

I A major discrepancy occurred with the ocean water level that was needed to be used to drive the model. Local ocean values were not available, particularly for the year 1979, the only available site was Fort Denison. Data was available as I one hour sampling which needs to be interpolated using cubic spline methods to generate 15 minute values for the model. Fort Denison is not really applicable for this part of the coast and it was found that better model results were obtained I when the Fort Denison water levels were lowered by 0.2 metres. this type of adjustment is justified as the exact relation of local AHD to remote locations (for I example Sydney and Fort Denison) is not precisely known. Some adjustment to the grid bed levels was also done. In the inlet channel near I the entrance the shallowest points ~nd the extent of the fairly severe shoaling 1 ... km from the entrance was schematised unsatisfactorily from survey spot depth with an automatic interpolation method. Direct definition of these bed levels I was needed. In Watson Taylors Lake, both maps and aerial photographs indicate shoals forming an effective channel edge where the inlet channel flows into the lake. The available survey data did not provide any information on the exact I shape, size or levels of these bed features. However due to the effects of tidal phasing it was found that it was necessary to include some presentation of these. shoals, otherwise unrealistic flow patterns resulted in the model. These shoals I were assumed to have a spatial extent depicted from aerial photos and a level of I zero AHD so that these shoals are covered at high tide but exposed at low tide. Comparison of the measured data against the modelled results is given in Figur~s 6 to 14 at the end of this report. Overall the behaviour exhibited by the model I corresponds well with that measu.red.· Water levels show tidal range consistency

I 11 I I I I I and reasonable correspondence in the phasing. There is some variation in mean water level over the period but some variation is expected due to survey errors. I Complete agreement with the discharge comparisons is not achieved and this lack of agreement is normal for older datasets. The accuracy of the gauging method is around 25%. However the result for the entrance discharge is considered reason­ I able as the grid developed for the model excludes Gogleys Lagoon which, given its location nearer the entrance can account for a drop in the entrance discharge. Gogleys Lagoon was left out of the schematisation in order to simplify the model, I as it would not significantly change the results which are focused on the upstream half of the river system. Overall in the areas of interest, that is Watson Taylors Lake and upstream, the water levels match very well, and in other areas agree­ I ment is good. This indicates that the model can represent the behaviour of the I river system to a satisfactory level. I 4.2 Verification

No verification data was available before this study commenced, so that a wa­ I ter/evel data collection exercise was initiated over a three month period from November 1995 to January 1996 as part of this study. This dataset is available I from Manly Hydraulics Laboratory from their database system. This dataset provided a twofold purpose - provide verification data and confirm model be­ haviour in the upper reaches of the river up to Kendall, where previous data was I not available. It was envisaged that some minor adjustments of the upper reach might be pecessary from the runs with this dataset. However modelling results showed that the upper river configuration represented the real behaviour well I without the need of further model adjustment.

Comparison of the measured data and model results is given in Figures 15 to 23 I in the back of this report. Some variation in the comparison is expected due to the rela~ively wet period that the data was collected in. These model runs were I undertaken with zero base flow specified. This was because the flow data available only specifies daily average flow. For the tidal behaviour and the peakiness of this relatively small catchment a much smaller flow specification is needed. However· I given this limitation the comparison is still very good.

As this data extended over a reasonably long period, it was possible to run a I tidal harmonic analysis on both the results and the data. This method allows the statistics of the tidal behaviour to be compared giving a clearer indication of the overall tidal behaviour - and is less subjective. The harmonic analysis I has as its output, the phasing and amplitude of the constituents of the tide

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I Tide Board Source Tidal Constituent Location M2 I S2 K1 01 I Watson Taylors Lake meas. 0.103 0.022 0.052 0.049 (Site 1 - 96) model 0.126 0.027 0.064 0.048 Camden Haven River meas. 0.103 0.022 0.052 0.049 I (Site 2 - 96) model 0.123 0.026 0.060 0.047 Kendal Road Bridge meas. 0.107 0.023 0.052 0.049 I (Site 3 - 96) model 0.133 0.028 0.065 0.048 I Table 2: Comparison of Tidal Harmonic Analysis for Amplitude record. This means that by comparing harmonic results, it is possible to compare the base components of the tide rather than subjectively comparing level and I time offsets for long time period records. Harmonic Analysis provides a better method than standard statistical methods as it takes into account the periodic nature of the record. Table 2 shows a comparison of the amplitude of the 4 main I tidal constituents (the M2, S2, K1 and 01 constituents) for both the measured and modelled water levels. See Figure 2 for the locations of these sites. This comparison indicates that the modelled results are generally 20% larger. This I is not unexpected due to the length of time between the survey data for the entrance channel and the time of this data collection - 16 years later. The 1979 I survey was also undertaken only 1 year after a significant flood on the river and as such it could be expected that the river in 1979 would still be adjusting itself back to its 'normal' geometry'. Both data and model results show that there is I slight amplification as you move upstream towards Kendall. I Transport Dispers'ion Results I The transport dispersion modelling was undertaken for 4 effluent discharge sites along the river. These are referred to as Sites 1 to 4 respectively (shown in I Figure 4). Site 1 represents a location north of Kendall, Site 2 is immediately downstream from Kendall, and Site 3 is located at Rossglen, downstream of. I the Pacific Highway bridge. The last location, Site 4 was chosen to sho.w the influence of Watson Taylors Lake on the dilution and transport times of the I effluent although it is not an actual discharge location option. As described in the methods section above, the transport dispersion modelling I was simulated using a 28 day ocean tide. 28 days is used as this represents it lunar month. The 28 day hydrodynamj~ result was then used for the dye dispersion

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I I I I I Figure 4: Location of Effluent Discharge Sites Modelled runs to drive the transport and dispersion processes. Due to the relatively long I times involved in these processes in the Camden Haven River system, a single transport dispersion run of 28 days is not long enough as the system is still influenced by the start up conditions. The approach taken was to rerun the I transport dispersion runs using the previous results as the starting conditions - this was d~ne with 2 extra runs each starting from the results of the previous run I - this effectively gives a total runtime of 3x28 days or 12 weeks . . .. The discharge inflow is not directly modelled, as the actual flow is insignificant in the river system with respect to both the tidal and base flow conditions. The I model inputs the mass inflow of tracer at the effluent discharge sites. As discussed earlier, .~ith a conservative tracer there is no need to work with explicit tracer I concentrations or mass flows, unless the actual effluent flow rates become signif­ icant with respect to the river flows. The conservative tracer under low effluent discharge flow rates becomes scalable - in the sense that the river concentrations. I are directly proportional to the ratio of the modelled mass rates and the required mass rates. Under a restricted discharge policy - for example discharge under ebb tidal flow conditions in the river only, it is necessary to adjust the mass inflow I for the effluent. This is done so that the concentrations from model results are comparable. The adjustment is such that the total flow from the discharge site I over a complete tidal period remains constant. So that if flow is restricted only to ebb, then during the ebb period. . the mass inflow is increased to ensure. that the

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I _...... ~.' I I I River Chainage from Site Description Tidal Limit (km) I 0.0 North Kendall - Site 1 Discharge Point 2.3 Kendall Road Bridge 3.1 Downstream Kendall - Site 2 Discharge Point I 4.7 River Elbow 6.4 River Constriction I 8.7 Rossglen - Site 3 Discharge Point 9.8 Rossglen - 2/3 Downstream 11.6 Rossglen - 1/3 Downstream I 13.8 Watson Taylors Lake - Upstream - Entrance to Stewart River 16.8 Watson Taylors Lake - Downstream I 17.0 Inlet Channel - Site 4 Discharge Point 21.0 Hanleys Point I 22.0 Stingray Channel Confluence I Table 3: Location of Results and Site Descriptions combined flood and ebb portions of the discharge is released over the shorter time period. This is equivalent in practice to discharging a larger quantity of effluent I over the restricted period. The model was run with an equivalent continuous I effluent mass flow of 100 units per second. The cases. that were mo'delled are Discharge Site Baseflow 50% Zero I Discharge Cont. Ebb Cont, North Kendall X X I Kendal X X X Rossglen X X X I Inlet Channel X X X

Table 3 gives the river chain age of each result location. Figure 5 shows these· I result locations. I I

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I WatsonTaylors Lake - Upstre I ~N:i!.-f.'.l..ce to Stewarts River I Figure 5: Location of Concentration Results I 5.1 Continuous Effluent Discharge The continuous effluent discharge is the case where the effluent is discharged at I a continuous rate. In the case of this modelling work, the actual flowrate is not modelled but the infeed'of the mass of tracer is maintained at a constant rate.

I Continuous effluent discharge was modelled at all sites. It was modelled under 2 ' .. flow conditions - namely 50% base flow and zero base flow, both in conjunction I with full tidal flow. The results obtained for a 50% base flow are shown in Table 4. These values are I based on the statistical analysis of the 3rd 28 day model run where results have reached pseudo steady state. Figures 24 to 29 show profiles of these results in I the upper reaches for Release Sites 1 to 3. These results indicate that effluent discharges into the upper river sections pre­ I dominantly remain in that section of the river, while also raising the concentra­ tions in the Watson Taylors Lake. The trend indicated is that the further up the river that the discharge site is located, then the higher the concentrations ob­ I tained and those concentrations occur. over a longer section of river. This would

I 16 I. I I I I Chainage from Concentration (units/m3) Tidal Limit (km) Site 1 Site 2 Site 3 Site 4 I 0.0 290 0 0 0 2.3 266 0 0 0 I 4.7 266 135 0 0 Camden 6.4 265 135 1 0 Haven 8.7 262 134 104 0 I River 9.8 257 132 132 0 11.6 215 112 119 1 13.8 56 30 40 4 I I Stewart RIver I 15 9 18 5 Camden 16.8 16 9 15 15 I Haven 21.0 5 3 6 7 Inlet 22.0 2 1 3 4

I Table 4: Results of mean Concentration for 50% Base Flow

appear be due to the relatively low transport rates in those parts of the river. I This is directly linked to the relative sizes of the tidal prism at the discharge sites - negligible at Site 1 and increasing with sites downstream. The tidal prisms I are relatively small due to the effect of the lake on the overall tidal behaviour. However in the lower sections of this reach above Watson Taylors Lake the con­ I centrations remain at higher values. The effect of the lake on the tidal currents and their phasing must contribute considerably to the overall flushing behaviour. This effect is quite important. I What is happening is that the lower part of the river represented by the Inlet Channel effectively acts in a coastal lake configuration where the currents are in phase with the water levels - that is peak flood and ebb velocities occur at high I and low water respectively. However, the upper section of the river from Watson Taylors"Lake to Kendall acts as a river type estuary where the water levels and I currents are approximately 90 degrees out of phase - that is peak velocities occur around mid-tide and slack water occurs close to the high and low waters. What this means is that the ebb flow can be flowing out of the upper reach into the· I lake at the same time that the Inlet Channel is still flowing into the lake .on its flood cycle. This gives the situation where for approximately a quarter of the tide cycle both reaches are flowing into the lake, another quarter where both are I flowing out of the lake and half the time actually flowing in the same direction, either both in ebb or flood. I

I 17 I I I I I Chainage from Concentration (units/m3) Tidal Limit (km) Site 1 Site 2 I Site 3 Site 4 I 0.0 290 0 0 0 2.3 266 0 0 0 I 4.7 267 136 0 0 Camden 6.4 274 146 2 0 Haven 8.7 279 167 109 0 I River 9.8 267 175 140 0 11.6 194 148 135 1 13.8 39 35 45 5 I I Stewart RIver I 5 6 18 6 Camden 16.8 7 8 17 15 I Haven 21.0 2 2 7 8 Inlet 22.0 1 1 3 4

I Table 5: Results of Mean Concentrations for Zero Base Flow

It is most probable that it is this effect that produces the relatively low con­ I centration results for an effluent discharge at Site 4, compared to the results for discharges into upper reach of the river. Though, it is not that Site 4 has low con­ I centrations but that they are considerably lower than Site 3, most probably due to the effect of the mis-matched phasing restricting the flushing and exchange of the upper reach with the Inlet Channel. Comparison of Site 4 and Site 3 results show I that Site 4 has minimal impact on the river and the lake. Although the results for the "~ake Downstream" (chain age 16.8km in Table) location show similar concentrations for Site 3 and 4, the "Lake Upstream" (13.8km) and "Stewarts I River" locations have concentratioI2:s, factors of 3 or more lower for the. Site 4 . '. case compared to those for Site 3. These latter results indicate the overall lake concentrations are considerably lower for a discharge at Site 4. In the case of Site I 4, the "Lake Downstream" (16.8 km) location could be lowered by moving the discharge site further down the inlet channel. I The results obtained for zero base flow are shown in Table 5 represent a worst I case under tidal flow flushing. . These results for a zero base flow mimic the results for the 50% baseflow with a minor change in the concentrations which from a practical point of view are I negligible. I

I 18 I I I I I Chain age from Concentration (units/m3) Tidal Limit (km) Site 2 Site 3 Site 4 I 0.0 0 0 0 2.3 0 0 0 I 4.7 133 0 0 Camden 6.4 133 1 0 Haven 8.7 133 103 0 I River 9.8 131 131 0 11.6 III 118 1 13.8 30 40 5 I I Stewart RIver I 9 18 5 Camden 16.8 9 15 15 I Haven 21.0 3 6 7 Inlet 22.0 2 3 4

I Table 6: Results of Mean Concentrations for Ebb Only Release I 5.2 Ebb Staged Effluent Discharge

Table 6 presents the results for the case where the effluent discharge at the site I is only released during the ebb tide cycle at that site. Site 1 did not have this I option run for it as there was effectively only ebb flow present at that location. These results for a zero' base flow mimic the results for the 50% base flow with a minor change in the concentrations which from a practical sense are negligible. I This is because all the discharge sites are appreciable distances from any ph.ysical . feature that will induce increased mixing within the region that is encompassed by one ebb cycle transport from the site. The concentrations remain effectively I the same because the mixing over a number of tidal cycles compensates for the increased discharge rates and increased local concentrations for the staged case. I Locally"the concentration does increase in the region of the discharge point but this difference diminishes over the following half tidal cycle. I I 5.3 Retention Time/ Transport Analysis The retention time and transport analysis is based on model runs using numerical I drogues. The drogues are released in the model at the Site of the effluent discharge

-. -'. I 19 I I I I I Time After Release Distance Reached from Tidal Limit (Days) Site 1 Site 2 I Site 3 I Site 4 I 14 Ocean I ~:~ I 6.9 I 11.6 I I 28 9.9 Ocean Ocean Table 7: Distance Reached by Drogues after Release

I and are tracked through the river system. At specific time intervals a plot of the tracks are produced to indicate the largest extent of travel of the drogues. Chosen I times to plot the results are at 14 days and 28 days after release.

The results of the drogue modelling is presented in Figures 27 to 34. These results I are summarised in Table 7. This table shows that the upper discharge sites have a low transport component which results in the drogues only migrating as far as Site 3 discharge location over 28 days. When combined with the Site 3 results I (which indicate transport to the river entrance in 28 days), Sites 1 and 2 have a retention time of the order of 60 days in the river system with approximately 40 I days before leaving the upper river. In comparison a release at Site 4 below the lake, reaches the river entrance inside I the first 14 days. I 5.4 R~gion of Influence I ... Based on the tables presented above it is possible to determine the region of influence of the various modelled options. In effect the further up the river the I discharge site the larger the effective region of influence there is. The results show that the upper reach of the river from the respective discharge site downstream to Watson"Taylors Lake, effectively sees a concentration that mirrors the discharge I site concentration. There is very little fall off in concentration till just upstream of the Lake. I I 5.5 Interpreting the Model Results as Dilution

The model results are based on a mass flux input into the river at each discharge I site. This mass flux can be convert.ed into a concentration given the discharge. flow

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I rate at the discharge site. Using the maximum daily outflow of 833 kL/d (Year 2025 prediction for Kew /Kendall effluent volume - source DPWS) gives an outflow I concentration that was modelled as 10000 units/m3 (based on a model mass flux discharge of 100 units/sec). Using this outflow concentration the following table of dilutions apply to the model concentration results. Similar calculations can be I made for the Year 2000 predicted discharges - 434 kL/d. The effective dilution for this situation is also included in the table. I I Model Concentration (units/m3) I 300 I 200 I 100 I 50 I 20 I Effective Dilution for 833 kL/d (yr 2025) 33 50 100 200 500 Effective Dilution for 434 kL/d (yr 2000) 66 100 200 400 1000 I Table 8 Dilution Rates based on an Effluent Volume of 833 kL/d (yr 2025) and I 434 kL / d (yr 2000) The technique can also be applied to determine approximate in-river concentra­ tions given a design discharge concentration at the discharge site. The model I results can be scaled against the inflow concentration of 10000 for a discharge of 833kL/d. For other discharge volumes this concentration needs to recalculated. I I 6 Discussion

I The modelling study shows that the dilution results relate to the distance of the discharge site from· the river ocean entrance. That is, the North Kendall Site has the lowest dilution, followed by the Downstream Kendall, Rossglen sites I and then the hypothetical Inlet Chc:nnel site. Lower relative dilution rates mean .. that the concentration of constituents in the effluent discharge must be lower for the upper discharge points to obtain similar in-river concentrations. For I example the comparable discharge concentration for the North Kendall site would be approximately 1/2 that of the Rossglen site. Importantly the modelling shows the marked effect that Watson Taylors Lake has on the river concentrations, I with a significant reduction in concentrations for a site downstream of the lake I compared to those upstream. The study results are applicable under tidal conditions and low river flow. The modelling is based on a 50% base flow but these results are expected to extend I to higher flows as the comparison with no base flow model runs show that tl!.e 50% flow has negligible effect on the in river concentrations indicating that the dilution processes are tidally dominated. Similar results are expected up to at I least double the 50% base flow w~ich represents a 32% flow (that is flow which

I 21 I

I .. --~ I I

I least double the 50% base flow which represents a 32% flow (that is flow which I is present 2/3 of the time). The upper river reach is relatively poorly flushed by tidal influences because of the nature of the tidal hydraulics created by the presence of Watson Taylors I Lake. The lake creates a situation where the tidal flow for the inlet channel and upper river are 90 degrees out of phase resulting in a considerably short period of effective flushing (or exchange) between the upper river and the inlet channel I (and hence the ocean). This is in spite of the fact that the lake has a significant tidal range compared to its overall depth. The comparison of results between Site I 3 (Rossglen) and Site 4 (Inlet Channel) discharges help to show the influence that 'Yatson Taylors Lake has on the flushing of the upper river reach.

I The retention time of the river system for the various discharge sites is relatively long, being nearly 30 days for the Site 3 and 60 days for the upper river Sites 1 I and 2. I I I I I I I I I

-. --. I 22 I I I I

I References I Manly Hydraulics Laboratory - "Camden Haven River Tidal Data - 9th August 1979", Report MHL440, September 1989.

Public Works Department - "Camden Haven Flood Study", Report No PWD I 88039, ISBN 0730551792, February 1989.

G .S.Stelling - "On the Construction of Computational Methods for Shallow Water I Flow Problems", Rijkswaterstaat Communications no 35/1984, 1984. I I I I I I I I I I I I

I 23 I I I 1 1 I 1 1 1 1 1 1 1- Figures I I 1 I I 1 I I

1 24

1 .. ··· .. ·-·~f·~~,..·· I I I I I I I I I I I Model Calibration Results I I I I I I I I

I 25 I I I I

1 Wedel Calibration Run, - 1979 I 2 WHL Dat.a - 1979 I

I .4 ~

E- .2

I I

-1.0 '--_'--_L-_..L-_-'--_-'--_-"-_ _'__---L_---'-_---"-_~ _ _'___ _'__ __'__ ___'_ __' I 9:08:00 9: 10:00 9: 12:00 9: 14:00 9: 16:00 9: 16:00 9:20:00 9:22:00 10:00:00 TIME Fig 6 - Model Calibration I Entrance Water Levels I

1 Model Clllibralion Runs -.1979 I 2 Mffl. Data - 1979 I .s .6 I .4 E- .2 I

I -.4 I -.s -.6

I -19~06L,0~0-..L--.~'1-'-0'-00--'--.-'1...L2'-00--'--.'-"14-'0-0---'~-'---'---'---'---::--:~--'--:-9:2=2-=-:OO-:---'--1~0'~OO:OO TIME Fig 7 - Model Calibration I Hanleys Point Water Levels 26

Plotted on Thll Jul 18 1~:02:3" I~. I I I I

1 Yodel Cal ibralion Runs - 1979 I 2 IdtD.. Dala - 1979 1.0 r----r----r----r----r----r----r----r----r----r----r-,---r----,-,---r----r-,---r---, I .6 r-

.6

I .4

~( I-=- I ,- I -.4

I -.6 -

-.6 r-

I -10 ~ ___L ____ ~ ___L ____ ~~-L----L----L----L----L----L----L----L----L----L----L--~ 9;08:00 9: 10:00 9: 12:00 9: 14:00 9: 16:00 9: 18:00 9:20:00 9:22:00 10:00:00 TIME I Fig 8 - Model Calibration Queens Lake Water Levels I

1 Yodel Calibration Run. - 1979 I 2 MHL Dala - 1979

.6

.6

I .4 E ., I I -.4 I -.6 -.6

-1.0 L-__-L ____ L- __-L ____ L- __-L ____ L- __-L ____ L- __-L ____ L- ___L ____ L- ___L ____ L- ___L __ ~ I 9:08:00 9: 10:00 9: 12:00 9: 14:00 9: 16:00 9: 18:00 9:20:00 9:22:00 10:00:00 TIME I Fig 9 - Model Calibration Rossglen Highway Bridge Water Levels 27 I Plott,d on ihu Jul III 1$:02:38 11»98. I I I

1 Model Calibration Runs - 1979 I 2 WfU. Data - 1979 I.0r---.----,--~----r_--.----r_,--~--_.---.----r_,--~--_.---.----,_--~--_, I .8 - I :c~~ #~~ I or------~~~------~~,L-/'------__i "~ /1 I ~,// -.4 I -.. - -.8 -

_I. 0 '--__-'- __---L __ --'- ____L-, __ -'- __-'-- __~ ____"__ __ _'_ __ _'__ __ ~ ____"__ __ _'_ ___ "__ ,---'----' I 9:08:00 9:10:00 9:12:00 9:14:00 9:16:00 9:1B:00 9:20:00 9:22:00 10:00:00 TIME Fig 10 - Model Calibration I Stingray Channel Water Levels I

1 Model Calibration Runs -.1979 2 MIL Datc - 1979 I 1.0 ,---.----,--~----r---.---_, __~----r_--.---_,---.----r_--~--_,--_, ____, I .8 .. - ..

~ I E .2 ...l C4 > C4 I . ...l 0:: C4 <-... -.2 ~ I -.• r- I -.• r- -..

-1. 0 L-__-'- __---L_--'- ____'-- __-'- __-'-- __--'- ____1-- __--'- __-'-- __~ ____"__ __ _'_ __ _'_ __ __' __ __l I 9:08:00 9:10:00 9:12:00 9:14:00 9:16;00 9:18:00 9:20:00 9:22:00 10: 00: 00 TIME I Fig 11 - Model Calibration Watson Taylors Lake Water Levels 28 I Plolted on Thu lui Ie 15:02:40 lega.· I I I

1 Wedel Calibration Runl - 1979 I 2 YHL Dala - 1979

I 600

I ~ '" "­C"l I E. 200 '"E." to .c () I a'" -200 I -400

I 9: 10:00 9: 12:00 9:14:00 9: 16:00 9: 18:00 9:20:00 9:22:00 10:00:00 TIME I Fig 12 - Model Calibration Entrance Discharge I

I Idodel Calibration Run, -. 1979 I 2 IdHL Data - 1979

I 600

.00 I '" "-C"l S 200 ~

I '"....OIl to .c () I a'" -200

I -400

". ~' ..

-800 I 9:08:00 9:10:00 9:22:00 10:00:00 TIME I Fig 13 - Model Calibration Hanley Point Discharge 29 I PloUed. on Tbu Jul 18 15:02:42 19118_ I I I

Illodel CalibrrrotionRuns - 1979 I 2 WHL Dall!. - 1979

I 600

I 400 - ~ CIl '-.. '"E 200 r ~ I OJ ....bIl -='" "CIl , is ~2----~-' -200 r I -400

, -800 I 9:08:00 9: 10:00 9: 12:00 9: 14:00 9; 18:00 9: 18:00 9:20:00 9:22:00 10:00:00 TIME Fig 14 - Model Calibration I Stingray Channel Discharge I I I I I I I I

I 30 I Plolhd on Thu Jul 18 15:02:"'" 1998_ I I I I I I I I I I I Model Verification Results I I I I I I I I " .....

I 31 I I I I

I Model Verifice.lIon - 1995 I 2 wtn.. Date - 1995 I .. . 4

.3 I ., S ~ ....l .1 W > I ~ Or+.+---~r---~----~----+r-+r-~-fl--k-~~~~~~~~+*-4~

~ ~ -.1 E­ <1: I ~ -.,

-.3

I -.4

-.5

_.. ~-L---L--,-,.--L--'-----"'---L---L--'--'---'-----' __'---'----L-----'------'----L~'---L---'----'----,-----,---,---, I 13;08:00 14:04:00 15:00:00 15:20:00 -18:18:00 17:12:00 18:08:00 19:04:00 20:00:00 20:20:00 21:16:00 22:12:00 23:08:00 24:04:00 TIME Fig 15 - Verification - Water Level I Watson Taylors Lake I

1 MDdel Verll iClllion - 1995 I 2 MFn.. DGla - 1995 ., I

.3

~ ., I E I I -.3 I -.4 -.'

_. 6 L--'---'---'----L---'-__L...--'---'---'-,.--L--'---' __ -'----L--'--'---'-----' __ '---'----L----'-:---'----L __ ~ I 23:08:00 24:04:00 25:00:00 25:20:00 26:UI:OO 27:12:00 28:08:00 29:04:00 30:00:00 30:20:00 31:16:00 32:12:00 33:08:00 34:04:00 TIME Fig 16 - Verification - Water Level I Watson Taylors Lake 32 Plolllld on TIlu Jul 18 1:1:07:30 199h-

I "'--~'."'-.-r.' I I I I I .. I .3 E .2 ~ ...J .1 r:J I > ~ O~~-+~~~~~~~~~~-,~~~~~~4-~-r~~~~~~~ a: W -.1 E-< .,; I ;;: -.2

-.3

I -.4 -.. I _.6 '---'----'-----'---L---'_'---7--'---'-__L~___'_.L.__'_____'___L~____'_'___'_____'___'__:_'_~~----.-J 33:08:00 34:04:00 35:00:00 35:20:00 "36:16:00 37:12:00 38:08:00 39:04:00 40:00:00 40:20:00 41:16:00 42:12:00 43:08:00 44:04:00 TIME I Fig 17 - Verification - Water Level Watson Taylors Lake I I I I I I I I "" -. I 33 I Plothd on "'U Jill 111 15:07:35 1I~ge. I I I

1 Model Verification - 1995 I 2 WHL DaLe. - 1995 I .4 I .3 .2 E ~ ...l .1 C:J I > C:J ...l t>: C£I -.1 E-« I ~ -.2

-.3

I -.4

-.5

I _6L-~-L~~ __~~~~~ __L-~-L~~ __~~~~ __~~~-L~ __L-~~ 13:08:00 14;04:00 15:00;00 H5:20:00 "18:16:00 17:12:00 18:08:00 19:04:00 20:00:00 20:20:00 21:16:00 22:12:00 23:0B:00 24:04:00 TIME I Fig 18 - Verification - Water Level Rossglen I

1 Ilodel Verification - 1995 I 2 }Iffi. Datil. - 1995 I .5

.3

I .2 S .1 ...l C:J > C:J I ...l t>: W -.1 E-« I ~ -.2

-.3 I -.'

-.5 '". ~'-

_6L-~-L~~ __~~~~~ __L-~-L~~ __~~~~ __~~~-L~ __L-~ I 23:08:00 24:04:00 25:00:00 25:20:00 28: 16:00 27: 12:00 28:08:00 29:04:00 30:00:00 34:04:00 TIME Fig 19 - Verification - Water Level I Rossglen 34 I Plotted on Tbu Jut 18 11):08:48 19941_ I I I

I Medel Verification - 1995 I 2 WHl. Oat.e - 1995 .. I ..

.3

I .2 E ~ .1 -l I >"" ""-l c:: -.1 E-"" ~ I -.2

-.3 I -.' -.'

_.6 L-~ __L-~ __~~ __~~ __-L __ ~-L __L--L __ ~~ __~~ __~~ __~ __L--L __ L-~ __L-~~ I 33:08:00 34:04:00 3:5:00:00 36:20:00 ·38:16:00 37:12:00 38:08:00 39:04:00 40:00:00 40:20:00 41:18:00 42:12:00 43:08:00 44:04:00 TIME Fig 20 - Verification - Water Level I Rossglen I I I I I I I I ". -"

I 35

PIQthd on Thu Jul 18 15:08:52 1998.

I ..... -...... ~... . I I I .

1 Yodel Veri! icelion - 1995 I 2 lIHL Dilla - 1995

.5

I .4 I .3 I I

I -.4

-.5

-.6 '----'----'---'--'---'--'---'---"-----'---~-'---'---'----'---'---'------'-"---'-----'------'---' I 13:08:00 14:04:00 l~:OO:OO 1!5:20:00 -18:16:00 17:12:00 18:08:00 19:04:00 20:00:00 20:20:00 21:18:00 22:12:00 23:De:OO 24:04:00 TIME Fig 21 - Verification - Water Level I Kendall I

1 Yodlll Verification - 1995 I 2 WHL DatI!. - 1995 I I I

I -.4 - .. -.6 ~~-'-----'----'--~.. -'---'----. --'----'--'-'---'--'--'--~---'----' I ~:06:00 ~:04;OO ~:OO:OO ~:20:00 28:16:00 ~:12:00 ~:M:OO ~:~:OO 30:00:00 30:20:00 31:18:00 ~:12:00 ~:OO:OO M:~:OO TIME Fig 22 - Verification - Water Level I Kendall 36

Plotted on Thu lui 18 18:09:0tI 19118_

I •••••••• _•• ••• __ ....' .. ~~r .," • '1· .. ·' "":1:'""1IIQfII'.1· I I I

1 Model Verification - 1995 I 2 MHL Date. - 1995 ..

I . 4

.3

I ~ .2 E ~ ...J .1 W > I ~ O~~-+~~~~Hr4-~4-~~~~rM~~~~~~-+4-~~~~~~ 00: ,...~ -.1 «: I '"' -.2

-.3

I -.4

-.5

_., '--_'__-'----_'___--'-__'__'--_'__-'--~___'____'______"_ _'____'__~_'___L._'_'___'___'__'_____'___'__<___J I 33:06:00 34:04:00 35:00:00 35:20:00 '36:16:00 37:12:00 38:08:00 39:04:00 40:00:00 40:20:00 41:16:00 42:12:00 43:08:00 44:04:00 TIME Fig 23 - Verification - Water Level I Kendall I I I I I I I I

I 37 I Plott.

I Transport Dispersion Results I Upper River Concentration Profiles 50% Baseflow Continuous Release I I I I I I I I I 38 I I I I

I ". 2'. 2 •• I 24. 22. e a 2 •• lB. ~ I L I •• e ". •u e 120 a I •• U .~ I Vl B• •• •• I 2 •

• 2000 3000 4000 5000 9000 10r/100 11000 12000 14000 • Hila" 0003 7000 802:" I Chainage 1m) Figure 24: Concentration Profile - For Site 1 Release I I

K."dal Sit. :2 R.I.,ne - 5ex e••• flo_ 41.2301110.00 3 •• I 2B. 2 ••

2'. I 220 e N a 2.' II) lB. V.i ~ - L I •• ~ I •e " . u e 120 a u I •• B• V" I •• •• 2 •

• 1000 5000 11000 12000 132100 14000 I • 2000 4000 b0e0 7000 8000 leeae Chainage I m I

I Figure 25: Concentration Profile - For Site 2 Release I I

I 39 I I I I I I I I

Ro •• gl .... Site J R.I ..... - 50X a••• f! 41.23.""0130 I 3 •• 2 ••

2 •• I 24. 22. C 2 •• 0 ,.. ~ L ,.. I ~ C 14 • u• 12. C 0 U ,.. I •• o. 4.

2 • I • • 1000 2000 4000 b000 7000 BIlI00 GlIl00 100"0 11000 12000 13000 Chainage 1m)

I Figure 26: Concentration Profile - For Site 3 Release I I I I I I

I 40

I .,~ ...... ~ .. . I I I I II I I I I I I Drogue Track Results I I I I I I I I

I 41 I I I

I 16000 I

I 10000 I 8000 6000

I 4000 I 2000 0 ~ 2~~~ 4~~~ 6~0~ 8~~~ 1 ~~~~ 1 2~~~ 1 4~~~ 16~~~ I Figure 27 Drogue TracKs for Site 1 0 1 4 Days I

I 16000 I 14000 12000

I 10000 I 8000 6000

I 4000 I 2000 0 ~ 2~~~ 4~~~ 6~~~ 8~~~ 1 ~~~~ 12~~~ 14~~~ 16~~~ I Figure 28 Drogue TracKs for Sit e 1 4 28 Days I I

I 42 I I I I I I I I I

Figure 29 Drogue TracKs for Site 2 I o 14 Days I I I I I I

I 0L-~~~-L~~~~~~L-~~~-L~~ o 2000 4000 6000 8000 10000 12000 14000 16000 Figure 30 Drogu~ TracKs for Site 2 I 14 28 Days I I

I 43

I . ,'-.,- ...... , ...... I I

I 16000 I 14000 12000

I 10000 I 8000 6000

I 4000 I 2000 0 0 2000 4000 6000 8000 10000 12000 14000 16000 I Figure 31 Drogue TracKs for Sit e 3 0 1 4 Days I

I 16000 I I I I I 0 0 2000 4000 6000 8000 10000 12000 14000 16000 I Figure 32 Drogue TracKs for Sit e 3 1 4 28 Days I I

I 44 I I I I 16000 I I I 8000 6000

I 4000 I 2000 0 0 2000 16000 I Figure 33 Drogue Tracks for Sit e 4 I2l 1 4 Days I I 16000 I I I I I 2000 0 0 2000 4000 6000 8000 10000 12000 14000 16000 I Figure 34 Drogue Tracks for Sit e 4 14 28 Days I I -'.

I 45

I ,·t'''';·''J~.·· I I I I I I I I

LAND & WATER I CONSERVATION I

I I I I I NSW Department of Land and Water Conservation I I