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Nam O Resort Development, Da Nang, Vietnam Coastal Protection Study Ander Chow 05 September 2017 Study Site Wind Rose at Danang Airport Site Tidal Levels at Son Tra Tidal Level MHHW +0.3m ND MLHW +0.1m ND MHLW +0.0 m ND MLLW -0.4 m ND Bathymetry (seabed elevation) Site -10m -5m Typhoon Modelling Delft3D Model Domain Use of historical typhoon tracks 1986 to 2016 (30 Years) 40 Selected Typhoons to generate the storm surge and wave height near site Historical Typhoon Tracks hitting Vietnam Typhoon Wave Modelling Simulation of Wave Heights and Storm Surge during passage of Typhoon XangSane 2016 Wave Heights Storm Surge 10/1/2006 6:00 10/1/2006 12:00 10/1/2006 18:00 10/2/2006 0:00 10/1/2006 0:00 10/1/2006 6:00 10/1/2006 12:00 10/1/2006 18:00 10/2/2006 0:00 Hs (m) 10/1/2006 0:00 9/30/2006 18:00 9/29/2006 12:00 9/29/2006 18:00 9/30/2006 0:00 9/30/2006 6:00 9/30/2006 12:00 9/30/2006 18:00 9/30/2006 12:00 9/30/2006 6:00 9/30/2006 0:00 9/29/2006 18:00 9/29/2006 12:00 9/29/2006 6:00 9/29/2006 0:00 9/29/2006 6:00 9/29/2006 0:00 Site Seabed Level -9mCD Seabed Level -20mCD Hs (m) Wave Heights at Point M1 Typhoon Xangsane 2016 Typhoon Xangsane (200615) Wave Heights at Point Typhoon Wave Heights at M1 and Pt Year Typhoon ID 1986 1986 1987 1987 1988 1989 1989 1989 1989 1990 1990 1990 1993 1994 1995 1995 1995 1997 1999 2000 2001 2002 198619 198622 198709 198711 198829 198904 198910 198923 198926 199016 199018 199025 199312 199422 199516 199520 199521 199721 199921 200011 200110 200220 Typhoon Max Hs M1 Name (m) DOM 1.60 GEORGIA 3.49 BETTY 7.19 CARY 4.36 SKIP 2.37 CECIL 7.27 IRVING 2.56 ANGELA 5.52 DAN 3.45 BECKY 3.97 ED 6.84 MIKE 4.44 WINONA 2.52 JOEL 2.26 TED 2.53 ANGELA 3.33 ZACK 6.78 FRITZ 7.11 EVE 2.71 KAEMI 4.31 USAGI 1.30 MEKKHALA 2.45 Max Hs Pt9 (m) 0.94 2.56 3.72 2.77 1.48 3.74 1.42 3.04 2.13 2.04 3.67 2.90 1.42 1.28 1.52 2.43 3.57 3.70 1.92 3.02 0.44 1.10 Year Typhoon ID 2003 2005 2005 2006 2007 2008 2009 2010 2010 2011 2011 2012 2013 2013 2013 2013 2015 2016 200320 200516 200521 200615 200714 200816 200916 201002 201005 201118 201119 201223 201310 201321 201325 201330 201519 201615 Typhoon Name Max Hs M1 (m) Max Hs Pt9 (m) NEPARTAK VICENTE KAITAK XANGSANE LEKIMA MEKKHALA KETSANA CONSON MINDULLE HAITANG NALGAE SOTINH MANGKHUT WUTIP NARI HAIYAN VAMCO RAI 5.71 3.15 6.18 7.69 4.32 2.65 7.39 4.54 4.03 1.42 1.46 6.19 1.85 5.78 7.17 6.87 2.63 2.01 3.46 1.72 3.57 3.86 2.42 1.30 3.77 2.75 2.40 0.85 1.16 3.41 1.10 3.37 3.71 3.68 1.86 1.49 Significant Wave Height Hs (m) Extreme Wave Heights near Site (Pt 9) Return Period (Year) Wave Height Hs (m) Wave Period Tp (s) 2.73 13.0 3.59 15.5 10 3.93 16.5 50 4.34 17.7 100 4.42 18.0 Modelled Max Hs = 3.86m at 2016 Typhoon Xangsane NOAA Global Wave Climate Simulation NOAA WaveWatch3 Model Simulated 3hourly wave data from Feb 2005 to May 2017 Max Hs = 7.1m, Mean Hs = 1.2m Net wave energy direction = 67°Az Site Wave Rose US National Oceanic Atmospheric Administration Wave Climate near Site M1 Max Hs = 5.4 m Mean Hs = 0.7 m Net wave energy direction 65°Az Pt Max Hs = 3.2 m Mean Hs = 0.4 m Net wave energy direction 55°Az NOAA Max Hs = 7.1m Mean Hs = 1.2m Net wave energy direction 67°Az M1 10 When waves approach shoreline, its direction tends to align with the seabed bathymetry contour 17 Undermining of a seawall built on a high energy coastline (CCD 1997) 18 Summary Wave heights near the site can reach m (at m depth contour) during typhoon events The beach normal almost aligns with the net wave energy direction; this implies significant cross-shore sediment transport during typhoon events; however, the long-term net longshore sediment transport move the sands toward NW Look at the historical satellite images, no significant beach erosion is found The beaches at site seem to be at an equilibrium state This equilibrium could be affected when the beach system is disturbed The wave runup during extreme storm surge and typhoon events could reach the elevation +3mND, we suggest ‘no’ development at the beach area between low water level and wave runup level 19 Consequence of Beach Intrusion 20 Recommendation: All structures be located at the landside of wave run-up contour Approximate Contour Line of +3.0mND Club-House Possible encroachment on wave run-up zone Possible encroachment on wave run-up zone by club-house Landward Seaward Potential undermining the beach due to reflected wave Club-House Wave Run-up Level 100-year Sea Level Mean Sea Level -1 mND -2 -3 -4 Section -5 -6 50 100 150 200 metres 250 300 350 400 480 Landward Offshore Breakwater Seaward Wave Run-up Level Club-House 100-year Sea Level Mean Sea Level -1 mND -2 -3 -4 Section -5 -6 50 100 150 200 250 metres Note: Location of offshore breakwater to be confirmed in detailed design 300 350 400 480 Engineering Implications on Club-house Design Discrete piled foundation for clubhouse Design clubhouse slab for wave uplift pressure Avoid wall structure at the edge of clubhouse that would reflect wave and undermine beach Provide offshore wave attenuation structure such as offshore breakwater/submerged reef structure Note: Location of offshore breakwater to be confirmed in detailed design 100-y Water Level = +2.19 mND B Normal Water Level = +1.0 mND HB Underlayer BW BT Breakwater Dimension (for Southern Beach) Parameters Unit Value (appro.) Slope of armour structure (v:h) 1: Length m 100 HB m B m BW m 33 BT m 39 Cross-Section Area m^2 106 Mean Armour Dimension, Dn50 m 1.6 Mean Armour Weight, Wn50 tn 4.6 Crest Level mND +1.2 Toe Level mND -3.8 *The armour size and extent for underlayer and bedding layer is to be determined Design Conditions Parameters Unit Value (appro.) Significant Wave Height m 4.84 Design Water Level mND Distance from shoreline m 380 *The relocation of structure may be considered when more information is available (e.g sounding survey) Note: Design dimensions of offshore breakwater to be confirmed in detailed design Offshore breakwaters 28 Near River Mouth The NW corner is very dynamic, sediments are moving around in the river mouth area; and sediments at beaches tend to move tower NW The system seems to be stable when sediment supply from Cu De River is not disturbed However the sediment supply from Cu De River will decrease in future due to urban development The maintenance dredging activity in the northern port development may reduce the volume of sediments underlying in Da Nang Bay Suggest to build a breakwater with lookout to retain/anchor the NW corner of the site development 29 Western Edge Possible Lookout +3m fill END 31 ... Typhoons to generate the storm surge and wave height near site Historical Typhoon Tracks hitting Vietnam Typhoon Wave Modelling Simulation of Wave Heights and Storm Surge during passage of Typhoon... 199025 199312 199422 199516 199520 199521 199721 199921 200011 200110 200220 Typhoon Max Hs M1 Name (m) DOM 1.60 GEORGIA 3.49 BETTY 7.19 CARY 4.36 SKIP 2.37 CECIL 7.27 IRVING 2.56 ANGELA 5.52... 200816 200916 201002 201005 201118 201119 201223 201310 201321 201325 201330 201519 201615 Typhoon Name Max Hs M1 (m) Max Hs Pt9 (m) NEPARTAK VICENTE KAITAK XANGSANE LEKIMA MEKKHALA KETSANA CONSON
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