SECTION REPORT 2: CURRENT MEASUREMENTS IN THE SEA SCHELDT VERSION OKTOBER Kris Van Troos, Toon Goormans, Steven Smets, Roeland Notelé

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1 INVESTIGATING THE FEASIBILITY OF ENERGY HARVESTING USING POTENTIAL ENERGY AT THE TIDAL LOCK IN HEUSDEN AND USING KINETIC ENERGY AT SEVERAL LOCATIONS IN THE SCHELDT RIVER SECTION REPORT 2: CURRENT MEASUREMENTS IN THE SEA SCHELDT VERSION OKTOBER 2013 Kris Van Troos, Toon Goormans, Steven Smets, Roeland Notelé

2 Colophon International Marine & Dredging Consultants Address: Coveliersstraat 15, 2600 Antwerp, Belgium : : info@imdc.be Website: 2

4 Table of Contents 0 INTRODUCTION THE ASSIGNMENT AIM OF THE STUDY OVERVIEW OF THE STUDY STRUCTURE OF THE REPORT MEASUREMENT LOCATIONS INTRODUCTION JETTY OF LILLO PONTOON AT STEENPLEIN BRIDGE AT TEMSE CURRENT VELOCITY MEASUREMENTS MEASUREMENTS AT JETTY OF LILLO Measurement Set-up AADI RCM MEASUREMENTS PONTOON AT STEENPLEIN Measurement Set-up Teledyne ADCP workhorse sentinel MEASUREMENTS BRIDGE AT TEMSE Measurement Set-up DATA PROCESSING AND VISUALISATION JETTY AT LILLO PONTOON AT STEENPLEIN BRIDGE AT TEMSE DISCUSSION OF RESULTS MEASUREMENT RESULTS JETTY AT LILLO MEASUREMENT RESULTS PONTOON AT STEENPLEIN MEASUREMENT RESULTS BRIDGE AT TEMSE REFERENCE LIST List of Tables TABLE 1-1: ESTIMATION OF AVAILABLE DRAFT AT THE JETTY OF LILLO TABLE 1-2: ESTIMATION OF AVAILABLE DRAFT AT THE PONTOON AT STEENPLEIN TABLE 1-3: ESTIMATION OF AVAILABLE DRAFT AT THE BRIDGE AT TEMSE TABLE 2-1: MAIN CONFIGURATION SETTINGS OF ADCP DURING THE CAMPAIGN

5 List of Figures FIGURE 1-1: OVERVIEW OF THE INITIALLY CONSIDERED LOCATIONS (YELLOW DOTS). THE SHORT-LISTED LOCATIONS ARE INDICATED WITH LABELS (SOURCE SATELLITE IMAGE: GOOGLE MAPS) FIGURE 1-2: THE JETTY OF LILLO. THE RED CROSS INDICATES THE SELECTED LOCATION FIGURE 1-3: TOP VIEW OF THE JETTY OF LILLO. THE RED CIRCLE INDICATES THE SELECTED LOCATION (SOURCE SATELLITE IMAGE: GOOGLE MAPS) FIGURE 1-4: EXTRACT FROM THE BATHYMETRY AROUND THE JETTY OF LILLO (AUGUST-OCTOBER 2012). EXPRESSED IN MLAT BELOW ZERO. THE RED CIRCLE INDICATES THE SELECTED LOCATION (SOURCE: AFDELING KUST VLAAMSE HYDROGRAFIE) FIGURE 1-5: MODELLED DEPTH AVERAGED FLOW VELOCITIES NEAR THE JETTY OF LILLO FIGURE 1-6: THE PONTOON AT STEENPLEIN. THE RED CROSS INDICATES THE SELECTED LOCATION FIGURE 1-7: TOP VIEW OF THE PONTOON AT STEENPLEIN. THE RED CIRCLE INDICATES THE SELECTED LOCATION (SOURCE SATELLITE IMAGE: GOOGLE MAPS) FIGURE 1-8: EXTRACT FROM THE BATHYMETRY AROUND THE PONTOON AT STEENPLEIN (JUNE-JULY 2012). EXPRESSED IN MLAT BELOW ZERO. THE RED CIRCLE INDICATES THE SELECTED LOCATION. SOURCE: AFDELING KUST VLAAMSE HYDROGRAFIE FIGURE 1-9: MODELLED DEPTH AVERAGED FLOW VELOCITIES NEAR THE PONTOON AT STEENPLEIN FIGURE 1-10: THE MEASUREMENT LOCATION NEXT TO THE BRIDGE AT TEMSE, INDICATED BY A BUOY FIGURE 1-11: TOP VIEW OF THE BRIDGE AT TEMSE. THE RED CIRCLE INDICATES THE SELECTED LOCATION (SOURCE SATELLITE IMAGE: GOOGLE MAPS) FIGURE 1-12: EXTRACT FROM THE BATHYMETRY AROUND THE BRIDGE AT TEMSE (30 APRIL AND 30 MAY 2012). EXPRESSED IN MLAT BELOW ZERO. THE RED CIRCLE INDICATES THE SELECTED LOCATION. SOURCE: AFDELING KUST VLAAMSE HYDROGRAFIE FIGURE 1-13: MODELLED DEPTH AVERAGED FLOW VELOCITIES NEAR THE LOCATION OF THE BRIDGE AT TEMSE FIGURE 2-1: RCM-9 CONNECTED TO THE BUOY FOR DEPLOYMENT AT THE JETTY OF LILLO FIGURE 2-2: RCM-9 ALONG THE MOORAGE CHAIN OF THE BUOY DEPLOYED AT THE JETTY OF LILLO FIGURE 2-3: BUOY WITH RCM-9 AT THE JETTY OF LILLO FIGURE 2-4: PRINCIPLE OF ADCP DEPLOYMENT FIGURE 2-5: ADCP MOUNTED ON BOTTOM FRAME. THE SIGNALISATION BUOY IN THE BACK IS MOORED WITH A SEPARATE ANCHOR STONE FIGURE 2-6: TELEDYNE ADCP WORKHORSE SENTINEL FIGURE 2-7: RCM-9 ALONG THE MOORAGE CHAIN OF THE BUOY DEPLOYED AT THE BRIDGE AT TEMSE FIGURE 3-1: TIME SERIES OF MEASURED VELOCITY (MAGNITUDE AND DIRECTION), TEMPERATURE, SALINITY AND SUSPENDED SEDIMENT CONCENTRATION (SSC) AT THE JETTY IN LILLO, FROM 24/06/2013 TILL 30/06/2013. THE GIVEN WATER LEVEL WAS CALCULATED FROM DATA MADE AVAILABLE BY FLANDERS HYDRAULICS RESEARCH FIGURE 3-2: TIME SERIES OF MEASURED CURRENT MAGNITUDE (TOP) AND DIRECTION (BOTTOM) ALONG DEPTH, AT THE PONTOON STEENPLEIN, FROM24/06/2013 TILL 30/06/ FIGURE 3-3: TIME SERIES OF MEASURED CURRENT MAGNITUDE (TOP) AND DIRECTION (BOTTOM), AVERAGED OVER THE FULL DEPTH, AND AVERAGED OVER THE UPPER (80-100%) AND LOWER 20% (0-20%) OF THE WATER COLUMN, FROM24/06/2013 TILL 30/06/ FIGURE 3-4: TIME SERIES OF MEASURED VELOCITY (MAGNITUDE AND DIRECTION), TEMPERATURE, SALINITY AND SUSPENDED SEDIMENT CONCENTRATION (SSC) AT THE BRIDGE AT TEMSE, FROM 02/09/2013 TILL 08/09/2013. THE GIVEN WATER LEVEL WAS CALCULATED FROM DATA MADE AVAILABLE BY FLANDERS HYDRAULICS RESEARCH

6 0 INTRODUCTION 0.1 THE ASSIGNMENT This assignment concerns the investigation of energy harvesting possibilities using potential energy at the tidal lock in Heusden and using kinetic energy at several locations in the Sea Scheldt river. Waterwegen en Zeekanaal nv is participating in the European project PRO-TIDE, funded by the Interreg IVB North-West Europe program. The main goal of this project is to increase the use of renewable energy by promoting innovative, sustainable and cost effective solutions for tidal energy through research, development, testing and comparison of different forms of tidal energy at different locations and circumstances, in coastal zones and estuaries. 0.2 AIM OF THE STUDY In a previous study the feasibility of harvesting tidal energy on the Sea Scheldt was considered in more general terms. Different techniques were described, that are applicable at several types of locations, such as tidal measuring stations, inlet-outlet structures or the lock to be constructed in Heusden, that has a downstream water level influenced by the tide (IMDC, 2011). In the framework of the feasibility study of harvesting tidal current energy in the Sea Scheldt, a measurement campaign was set up. The results of this campaign are described in this report OVERVIEW OF THE STUDY This section report 2 is part of a series of reports which together describe the complete study: Section report 1: Investigating the feasibility of energy harvesting from potential energy at the lock in Heusden (I/RA/11407/12.318/TGO). Section report 2: in the Sea Scheldt (I/RA/11407/13.217/KVT). Section report 3: Feasibility of harvesting tidal current energy in the Sea Scheldt (I/RA/11407/13.168/TGO). 0.4 STRUCTURE OF THE REPORT This report is the factual data report for current velocity measurements performed at three locations in the Sea Scheldt river: Jetty of Lillo Pontoon at Steenplein Bridge at Temse

7 Chapter 1 gives a description of the measurement locations. After that, Chapter 2 describes the set-up of the measurement equipment for each location. Chapter 3 explains how the data are processed. Finally, in Chapter 4, a concise interpretation of the results is given, together with a short discussion. References are listed in Chapter 5. 7

8 1 MEASUREMENT LOCATIONS After a short explanation on how the three locations were selected, this chapter describes those locations, on which current measurements have been performed. 1.1 INTRODUCTION In the framework of the feasibility study on harvesting tidal current energy in the Sea Scheldt, a preselection of possible locations for small scale tidal current turbines led to a long-list of 27 locations (IMDC, 2013). Later, an additional location on the Durme river a tributary of the Sea Scheldt river was considered as well. Figure 1-1 gives a geographic overview of these locations. Those 28 locations were further narrowed down to 8 locations, that were visited on Tuesday 12 February From that visit, a shortlist of 5 locations was defined, indicated on Figure 1-1 with labels. Investigation of the bathymetry led to a further narrowing down to three locations to perform current velocity measurements, with the objective to select the most suitable location for installing a test set-up of a tidal current turbine. The selected measurement locations for current velocity measurements are: 1. Jetty of Lillo 2. Pontoon at Steenplein 3. Bridge at Temse (indicated Railway bridge Temse in Figure 1-1). The locations Jetty Xella and Ferry Baasrode-Moerzeke appeared to be too shallow to easily install current turbines, especially compared to the other three locations. 8

9 Figure 1-1: Overview of the initially considered locations (yellow dots). The short-listed locations are indicated with labels (Source satellite image: Google Maps). 9

1.2 JETTY OF LILLO The jetty of Lillo is denoted location no. 1 in IMDC (2013). The jetty is owned and maintained by Waterwegen en Zeekanaal (W&Z) (Figure 1-2).

10 1.2 JETTY OF LILLO The jetty of Lillo is denoted location no. 1 in IMDC (2013). The jetty is owned and maintained by Waterwegen en Zeekanaal (W&Z) (Figure 1-2). Figure 1-3 shows a satellite image of the jetty, as well as an indication of the location. Water levels from the tide table of Liefkenshoek (Afdeling Kust Vlaamse Hydrografie, 2012), which is located at the left bank, opposite the jetty, together with bathymetry data made available by Afdeling Kust Vlaamse Hydrografie (Figure 1-4), are used to estimate the available draft at the jetty. The results are given in Table 1-1. Table 1-1: Estimation of available draft at the jetty of Lillo. ESTIMATION OF AVAILABLE DRAFT AT THE JETTY OF LILLO Point in tidal cycle Value [mtaw] Bottom depth [mtaw] Draft [m] Mean high water, spring tide Mean high water, neap tide to Mean low water, neap tide Mean low water, spring tide Figure 1-2: The jetty of Lillo. The red cross indicates the selected location.

11 11 Figure 1-3: Top view of the jetty of Lillo. The red circle indicates the selected location (Source satellite image: Google Maps).

12 12 Figure 1-4: Extract from the bathymetry around the jetty of Lillo (August-October 2012). Expressed in mlat below zero. The red circle indicates the selected location (Source: Afdeling Kust Vlaamse Hydrografie).

13 Trough tide measurements in the vicinity of the jetty, using an Acoustic Doppler Current Profiler (ADCP), from a measurement campaign of Flanders Hydraulics Research are available (Aqua Vision, 2009). From this campaign, velocities up to about 1.2 m/s were encountered. Also results from a 2D depth averaged model of the Sea Scheldt are available. Figure 1-5 shows the results of a simulation of a neap tide-spring tide cycle for a point as close as possible to the jetty. The maximum modelled velocities correspond quite well to the above measured ones. However, the model does not capture local effects occurring at the jetty; experience from skippers mooring at the location indicate above average velocities occurring at the jetty. Local measurements hence are indispensable to assess the location s suitability for installing a test turbine. 13 Figure 1-5: Modelled depth averaged flow velocities near the jetty of Lillo. It should be noted that the model was developed and calibrated to calculate water levels as accurately as possible, and not flow velocities. However the results can give an idea of the expected order of magnitude.

14 1.3 PONTOON AT STEENPLEIN The pontoon at Steenplein is denoted location no. 5-1 in IMDC (2013) (Figure 1-6). The pontoon is owned by W&Z and operated by the Port of Antwerp (Gemeentelijk Havenbedrijf Antwerpen, GHA). Figure 1-7 shows a satellite image of the pontoon, as well as an indication of the proposed location. Water levels from the tide table of Antwerp (Afdeling Kust Vlaamse Hydrografie, 2012), which is located about 600 m further downstream, together with bathymetry data made available by Afdeling Kust Vlaamse Hydrografie (Figure 1-8), are used to estimate the available draft at the pontoon. The results are given in Table 1-2. Table 1-2: Estimation of available draft at the pontoon at Steenplein. ESTIMATION OF AVAILABLE DRAFT AT THE PONTOON AT STEENPLEIN Point in tidal cycle Value [mtaw] Bottom depth [mtaw] Draft [m] Mean high water, spring tide Mean high water, neap tide Mean low water, neap tide Mean low water, spring tide

15 15 Figure 1-6: The pontoon at Steenplein. The red cross indicates the selected location.

16 16 Figure 1-7: Top view of the pontoon at Steenplein. The red circle indicates the selected location (Source satellite image: Google Maps).

17 17 Figure 1-8: Extract from the bathymetry around the pontoon at Steenplein (June- July 2012). Expressed in mlat below zero. The red circle indicates the selected location. Source: Afdeling Kust Vlaamse Hydrografie.

18 No trough tide measurement data are available in the proximity of the pontoon. Results from the 2D depth averaged model of the Sea Scheldt are shown in Figure 1-9. The figure shows the flow velocities during a neap tide-spring tide cycle for a point as close as possible to the pontoon. The maximum modelled velocities are in the order of 1 m/s. However, as with the jetty of Lillo, the model does not capture local effects occurring at the pontoon. Moreover, as stated before, the model was developed to reproduce water levels rather than flow velocities. Common knowledge indicate that flow velocities near the quay wall of Antwerp can be quite high. Again, the local measurements will clarify this ambiguity. 18 Figure 1-9: Modelled depth averaged flow velocities near the pontoon at Steenplein.

19 1.4 BRIDGE AT TEMSE The bridge at Temse is denoted location no. 8-3 in IMDC (2012). The bridge is co-owned and co-maintained by W&Z and the NMBS (the governmental railway company of Belgium) (Figure 1-10). Figure 1-11 shows a satellite image of the bridge, as well as an indication of the proposed location. Water levels from the tide table of Temse (Afdeling Kust Vlaamse Hydrografie, 2012), together with bathymetry data made available by Afdeling Kust Vlaamse Hydrografie (Figure 1-8), are used to estimate the available draught at the bridge. The results are given in Table 1-3. Table 1-3: Estimation of available draft at the bridge at Temse. ESTIMATION OF AVAILABLE DRAFT AT THE BRIDGE AT TEMSE Point in tidal cycle Value [mtaw] Bottom depth [mtaw] Draft [m] Mean high water, spring tide Mean high water, neap tide to Mean low water, neap tide Mean low water, spring tide Figure 1-10: The measurement location next to the bridge at Temse, indicated by a buoy.

20 20 Figure 1-11: Top view of the bridge at Temse. The red circle indicates the selected location (Source satellite image: Google Maps).

21 21 Figure 1-12: Extract from the bathymetry around the bridge at Temse (30 April and 30 May 2012). Expressed in mlat below zero. The red circle indicates the selected location. Source: Afdeling Kust Vlaamse Hydrografie.

22 In the framework of the design of the new bridge at Temse (the most western one of the current two bridges), Flanders Hydraulics Research performed velocity measurements near the already existing bridge (WL, 2005). Maximum measured velocities were about 1.5 m/s and 1.9 m/s during an average neap tide and spring tide respectively. Comparing these results with the results of the 2D depth averaged model (Figure 1-13), the model seems to underestimate flow velocities. The maximum modelled velocities are about 1.25 m/s. It should be noted however, that the presence of the bridge that results in a narrowing of the stream section and hence an increase in velocity is not taken into account in the model. Moreover, as stated before, the model was developed to reproduce water levels rather than flow velocities. 22 Figure 1-13: Modelled depth averaged flow velocities near the location of the bridge at Temse.

23 2 CURRENT VELOCITY MEASUREMENTS This chapter explains the measurement set-up at each location, as well as the used equipment. 2.1 MEASUREMENTS AT JETTY OF LILLO MEASUREMENT SET-UP A measurement device has been installed at the jetty in Lillo on Tuesday 18/06/2013. Since it is known from shipper s experience that the flow near the jetty is parallel along the jetty, an RCM-9 (Recording Current Meter, see 2.1.2), connected to a buoy, was considered sufficient for this location. The instrument was placed along the chain connecting a buoy and its moorage stone. This way, the device measured at a depth of 2.7 m below the water surface. Figure 2-1 and Figure 2-2 illustrate the used set-up, and Figure 2-3 shows the buoy at the jetty, after deployment. It was retrieved on Tuesday 16/07/ Figure 2-1: RCM-9 connected to the buoy for deployment at the jetty of Lillo.

24 24 Figure 2-2: RCM-9 along the moorage chain of the buoy deployed at the jetty of Lillo.

25 Figure 2-3: Buoy with RCM-9 at the jetty of Lillo. 2.1.

25 25 Figure 2-3: Buoy with RCM-9 at the jetty of Lillo AADI RCM-9 All sensors (temperature, pressure, conductivity, turbidity, tilting) except the Doppler Current Sensor were set to record once every 10 minutes. The Doppler Current Sensor sent 600 pings during every 10-minute interval and calculated the average value for current speed and direction over this interval. Data storage units in the instruments logged all the measured values. More information on the AADI RCM-9 can be found in Annex A.

2.2 MEASUREMENTS PONTOON AT STEENPLEIN 2.2.1 MEASUREMENT SET-UP At the pontoon, shipper s experience tells that flow direction is not always parallel along the quay.

26 2.2 MEASUREMENTS PONTOON AT STEENPLEIN MEASUREMENT SET-UP At the pontoon, shipper s experience tells that flow direction is not always parallel along the quay. Therefore it was decided to perform 2D profiling of the velocity field using an ADCP (Acoustic Doppler Current Profiler, see 2.2.2), deployed on a bottom frame. Figure 2-4 illustrates how the ADCP is deployed to the bottom of the Scheldt. A signalisation buoy is connected as well. Figure 2-5 shows the actual deployment of the frame with the mounted ADCP. The height of the bottom frame was 0.8 m and the first measurement bin started at 1.6 m above the bottom. The ADCP was deployed on Tuesday 18/06/2013 and was retrieved about a month later, on Tuesday 16/07/ Figure 2-4: Principle of ADCP deployment.

27 27 Figure 2-5: ADCP mounted on bottom frame. The signalisation buoy in the back is moored with a separate anchor stone.

2.2.2 TELEDYNE ADCP WORKHORSE SENTINEL The current measurements near the pontoon at Steenplein were conducted using a Teledyne RD Instruments ADCP 1200 khz Workhorse Sentinel (Figure 2-6).

28 2.2.2 TELEDYNE ADCP WORKHORSE SENTINEL The current measurements near the pontoon at Steenplein were conducted using a Teledyne RD Instruments ADCP 1200 khz Workhorse Sentinel (Figure 2-6). This ADCP system was mounted in a gimball to ensure the beams will point vertically upwards. Every 10 minutes a signal was sent to the logger. The main settings are given in Table 2-1. More information on this instrument can be found in Annex A Table 2-1: Main Configuration Settings of ADCP during the campaign. MAIN CONFIGURATION SETTINGS OF ADCP DURING THE CAMPAIGN Vertical bin size [m] 0.25 Number of currents measures in 1 hour 6 Number of pings to measure currents Figure 2-6: Teledyne ADCP Workhorse Sentinel.

2.3 MEASUREMENTS BRIDGE AT TEMSE 2.3.1 MEASUREMENT SET-UP At the bridge in Temse an RCM-9 was installed on Tuesday 20/08/2013, with a similar set-up as for the jetty of Lillo ( 2.1.1), as can be seen in Figure 2-7.

29 2.3 MEASUREMENTS BRIDGE AT TEMSE MEASUREMENT SET-UP At the bridge in Temse an RCM-9 was installed on Tuesday 20/08/2013, with a similar set-up as for the jetty of Lillo ( 2.1.1), as can be seen in Figure 2-7. At this location the RCM-9 was recording data at a depth of 1.1 m below the water surface 1. The RCM-9 was retrieved on Thursday 19/09/ Figure 2-7: RCM-9 along the moorage chain of the buoy deployed at the bridge at Temse. 1 Because this location is situated further upstream a different ship, with smaller buoys, was used to deploy the device.

30 3 DATA PROCESSING AND VISUALISATION This chapter describes how the measurement data are processed and visualised. 3.1 JETTY AT LILLO Current measurement datasets have been visualised in graphs presenting week series and can be found in Annex B. Figure 3-1 shows an example from 24/06/2013 till 30/06/2013 at the jetty of Lillo. Time series show recorded current velocity, direction, temperature, salinity, suspended sediment concentration (SSC) and water height. 30 Figure 3-1: Time series of measured velocity (magnitude and direction), temperature, salinity and suspended sediment concentration (SSC) at the jetty in Lillo, from 24/06/2013 till 30/06/2013. The given water level was calculated from data made available by Flanders Hydraulics Research.

31 The salinity is calculated from the recorded temperature, water depth and conductivity using the Practical Salinity Scale or PSS-78 (Unesco, 1983). A correlation was made in an earlier project (related to the nearby Deurganck dock) between the recorded turbidity and SSC extracted from water samples. The water samples were taken in the River Scheldt nearby Deurganckdok (IMDC, 2012). The recorded water level at Liefkenshoek was provided by Flanders Hydraulics Research of the Flemish government ( Waterbouwkundig Laboratorium in Dutch) and was recalculated to a water level above bottom by subtracting the average bottom level of mtaw (Table 1-1). 31

3.2 PONTOON AT STEENPLEIN Current measurement datasets have been visualised in graphs presenting week series and are presented in two types of graphs: - contour plots showing the water level and

32 3.2 PONTOON AT STEENPLEIN Current measurement datasets have been visualised in graphs presenting week series and are presented in two types of graphs: - contour plots showing the water level and vertical profiles of recorded current velocity and direction through the water column including the depth averaged current velocity. An example from the period 24/06/ /06/2013 can be seen in Figure line plots showing average current velocities and directions in the lower and upper 20% of the water column, as well as over the entire water column. Figure 3-3 gives an example from the period 24/06/ /06/2013. The water level was also recorded by the ADCP instrument and is presented in the graphs as well. The results of the full time period can be found in Annex C. 32 Figure 3-2: Time series of measured current magnitude (top) and direction (bottom) along depth, at the pontoon Steenplein, from24/06/2013 till 30/06/2013.

33 33 Figure 3-3: Time series of measured current magnitude (top) and direction (bottom), averaged over the full depth, and averaged over the upper (80-100%) and lower 20% (0-20%) of the water column, from24/06/2013 till 30/06/2013.

34 3.3 BRIDGE AT TEMSE The measurements at the bridge at Temse are processed similarly as those at the jetty of Lillo. The current measurement datasets have been visualised in graphs presenting week series and can be found in Annex D. Figure 3-4 shows an example from 02/09/2013 till 08/09/2013 at the bridge at Temse. Time series show recorded current velocity, direction, temperature, salinity, suspended sediment concentration (SSC) and water height. 34 Figure 3-4: Time series of measured velocity (magnitude and direction), temperature, salinity and suspended sediment concentration (SSC) at the bridge at Temse, from 02/09/2013 till 08/09/2013. The given water level was calculated from data made available by Flanders Hydraulics Research.

35 As with the measurements at the jetty of Lillo, the salinity is calculated from the recorded temperature, water depth and conductivity using the Practical Salinity Scale or PSS-78 (Unesco, 1983). Out of necessity, the same correlation between the recorded turbidity and SSC, extracted from water samples, was used, based on previous measurements at the Deurganckdok (IMDC, 2012). The recorded water level at Temse was provided by Flanders Hydraulics Research of the Flemish government ( Waterbouwkundig Laboratorium in Dutch) and was recalculated to a water level above bottom by subtracting the average bottom level of mtaw (Table 1-3). 35

36 4 DISCUSSION OF RESULTS In this chapter, a short discussion of the results is given for each location, without attempting to explain differences in different measurements in detail. 4.1 MEASUREMENT RESULTS JETTY AT LILLO The RCM-9 measuring device was installed on a buoy 2.7 m below the surface. Current velocity at this depth only rarely exceeded 1 m/s. This is lower than the measurement results mentioned in 1.2, but those measurements were taken during a through tide measurement campaign, along a cross section over the entire Scheldt width, and at a location further upstream, where the Scheldt has a more straight alignment. Lillo is located at an inner bend, which is a possible explanation for the lower velocities. 4.2 MEASUREMENT RESULTS PONTOON AT STEENPLEIN As expected, from the time series it can be deducted that peak current velocities during raising tide are found in the upper 20% of the water column, as here the current is experiencing the least resistance in its flow. However, the time series graphs also show that peak values for current velocity during falling tide are the averaged velocities over the entire water column. This means the highest current velocities occur in the middle of the water column (between 20% and 80% of depth). Possibly this is due to the presence of the pontoon with a draft of about 1 m, located (only) a few tens of meters upstream of the measurement location during falling tide. 36 No noticeable flows towards the quay wall could be detected. 4.3 MEASUREMENT RESULTS BRIDGE AT TEMSE Similar to the set-up near the jetty at Lillo, the RCM-9 measuring device was installed on a buoy, except the depth below surface was 1.1 m. During the measurement period at the bridge of Temse maximum current velocities at this depth vary between m/s. This velocities are intermediate between the measurement results obtained by Flanders Hydraulics Research (WL, 2005) and the results deducted by the 2D depth averaged model, as described in 1.4. A possible explanation for the difference in measurement results, could be that the measurements of Flanders Hydraulics Research took place on the upstream side of the bridge. Moreover, the new bridge was not yet constructed.

37 5 REFERENCE LIST Afdeling Kust Vlaamse Hydrografie (2012). Getijtafels (in Dutch). IVA Maritieme Dienstverlening en Kust, Brussel. Depotnr. D/2012/3241/222. Aqua Vision (2009). Varende ADCP metingen Schelde 2009 Locatie Liefkenshoek (in Dutch). Commissioned by Flanders Hydraulics Research. AV_DOC_ IMDC (2011). Getijdenenergie op de Zeeschelde dossier Interreg: Haalbaarheidsstudie (in Dutch). Final report. Study commissioned by Waterwegen en Zeekanaal NV, Department Sea Scheldt. I/RA/11372/11.071/TGO. IMDC (2012). Evaluatie van externe effecten op aanslibbing in het Deurganckdok: Report 2.12: Calibration of mobile and stationary instruments on 16 March Final report. Study commissioned by afdeling Maritieme Toegang Departement Mobiliteit en Openbare Werken. I/RA/11354/10.113/MBO. IMDC (2013). Getijdenenergie: Mogelijke locaties vrijestromingsturbines (in Dutch). I/NO/11407/12.262/TGO. Unesco (1983). Algorithms for computation of fundamental properties of seawater, UNESCO Technical Papers in Marine Science, 44. UNESCO, France. WL (2005). Brug over de Zeeschelde te Temse/Bornem Hydraulische en nautische studie van het voorontwerp (in Dutch). Flanders Hydraulics Research (Waterbouwkundig Laboratorium). MOD

38 Annex A Measuring Equipment 38

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43 Annex B Time series at Jetty of Lillo (RCM-9) 43

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49 Annex C Time series at Pontoon Steenplein (ADCP) 49

50 C.1 Contour plots 50

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53 C.2 Line plots 53

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58 Annex D Time series at bridge at Temse (RCM-9) 58

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Notices to Mariners. OSTEND august 15th 2013 NR. 17

Notices to Mariners. OSTEND august 15th 2013 NR. 17 Notices to Mariners + OSTEND august 15th 2013 NR. 17 1 BELGIUM >17/263 CANCELLED NOTICES NtM nr. Cancelled Charts 2011-25/294 (T) Approach Western Scheldt - Scheur - Obstacle 2013-11/172 (T) Port of Antwerp