Phân tích rủi ro bờ biển Nam Ô Đà Nẵng

Nam O Resort Development, Da Nang, Vietnam Flood Risk Study Interim Report Rev01 10 August 2017 Flood Risk Levels at Coastline DaNang Tide Table Mean Sea level +0 mND Month Jan Feb Mar April May June Jul Aug Sep Oct Nov Dec M HHWL 0.5 0.4 0.3 0.3 0.4 0.3 0.3 0.4 0.5 0.7 0.7 0.6 LLWL -0.5 -0.5 -0.5 -0.5 -0.6 -0.6 -0.7 -0.6 -0.4 -0.2 -0.3 -0.3 MHHW +0.3m ND MLHW +0.1m ND MHLW +0.0 m ND MLLW -0.4 m ND Study Site and Son Tra Station Site Son Tra Station Son Tra Station – Annual Maximum Water Level T (Years) 10 20 50 100 200 WL (mND) 1.01 1.22 1.35 1.48 1.65 1.78 1.90 35 years data Maximum: +1.70 m ND Measured Water Level (1980-2014) Maximum Water Level vs Storm Surge Peak storm surge occurs with high tide  Highest measured water level Maximum Water Level vs Storm Surge Peak storm surge occurs with low tide  JUST MISS JUST MISS Storm Surge Modelling  Use of historical typhoon tracks 1986 to 2016 (30 Years)  40 Selected Typhoons to generate the storm surge near site Historical Typhoon Tracks hitting Vietnam Simulated Wave Height during passage of Typhoon Haiyan 2013 Storm Surge near Site – Nam O T (years) 10 20 50 100 200 Storm Surge (m) 0.51 0.96 1.26 1.54 1.91 2.19 2.46 40 storms in 30 years Maximum Surge 2.04 m SonTra WL mND 1.01 1.22 1.35 1.48 1.65 1.78 1.90 Climate Change Impact to Central Vietnam • Based on Climate Change and Sea Level Rise in Vietnam, published by MONRE 2009 Dựa Báo cáo Biến đổi Khí hậu Nước biển dâng Việt Nam Bộ TNMT ban hành năm 2009 Scenario Kịch Medium emissions B2 Hiệu ứng thải trung bình B2 High emissions A1FI Hiệu ứng thải cao A1F1 Climate Zone Vùng khí hậu North Central Miền Trung South Central Miền Nam Sea Level Rise (cm) relative to 1990 Mực nước biển dâng so với năm 1990 2020 2050 12 30 12 33 Changes in Annual Rainfall (%) relative to 1990 Thay đổi Lượng mưa (%) so với năm 1990 2020 2050 1.5 4.0 0.7 1.7 Climate Change and Sea Level Rise in Vietnam, MONRE 2009 10 Báo cáo Biến đổi khí hậu Nước biển dâng Việt Nam Bộ TNMT ban hành năm 2009 Flood Risk Levels along Cu De River Cu De River Basin Basin Area: 413.7 Km2 Historical Flood Events Site 14 Year Flood Peak (m3/s) 2008 ~1,700 2009 ~ 4,600 2010 ~ 2,300 Source: Report on Hydrologic and Hydraulic Calculation of Cu De River Basin, Environment Research and Protection Centre of Da Nang University, 09/2012 2008 Flood Extent Q=1,700m3/s Site 15 Source: Report on Hydrologic and Hydraulic Calculation of Cu De River Basin, Environment Research and Protection Centre of Da Nang University, 09/2012 2009 Flood Extent Q=4,600 m3/s Site 16 Source: Report on Hydrologic and Hydraulic Calculation of Cu De River Basin, Environment Research and Protection Centre of Da Nang University, 09/2012 2010 Flood Extent Q=2,300 m3/s Site 17 Source: Report on Hydrologic and Hydraulic Calculation of Cu De River Basin, Environment Research and Protection Centre of Da Nang University, 09/2012 Cu De River and Cross-sections CuD e Pla n: With ou t_1 00 yr 9/0 8/2 01 +0 00 (-36 0) 5 Le ge nd WS P F Groun d Ba nk Sta E le v a tio n( m ) -2 -4 -6 Chainage 0+000 -8 Flow -1 0 20 40 60 80 10 00 12 00 14 00 St ati o n (m) C uD e Pla n: With ou t_1 00 yr 9/0 8/2 01 +1 10 (-25 0) 5 Le ge nd WS P F G roun d Ba nk Sta E le v a tio n( m ) -2 -4 Chainage 0+110 -6 -8 -1 0 20 40 60 80 10 00 St ati o n (m) C uD e Pla n: ) With _10 0yr 09 /08 /20 17 2) With_ 100 _4 60 09 /08 /2 017 3) Wi th_ 10 0_2 30 09 /0 8/2 01 B ri d ge 5 10 Le ge nd WS P F - Wi th _10 0_4 60 WS P F - Wi th _10 0_2 30 WS P F - Wi th _10 0yr Groun d Ba nk Sta Bridge E le v a tio n(m ) -5 Chainage 0+315 -1 -1 20 40 60 80 St ati o n (m) 18 10 00 12 00 14 00 Flood Risk Level Profile along Cu De River HECRAS Backwater Profile Computation Existing Condition Bridge Q=2300 m3/s Flow Flow WL=+2.52 mND Site 19 Flood Risk Level Profile along Cu De River HECRAS Backwater Profile Computation After Development Bridge Q=2300 m3/s Flow Flow WL=+2.52 mND Site 20 Flood Risk Level Profile along Cu De River Q=4600 m3/s Q=2300 m3/s Q=1700 m3/s Flow 21 WL=+2.52 mND Flood Risk Level Profile along Cu De River Q=4600 m3/s Is this profile possible? Q=2300 m3/s WL=+2.52 mND Q=1700 m3/s Flow 22 Flood Risk Levels  The flood flow from Cu De River will increase the flood risk level along the study site; the larger the flood flow the higher the flood risk level  With a moderate flood flow, say 2300m3/s in 2010, the flood risk level will be increased to +2.8mND at the site  If a flood flow of 4600m3/s in 2090 hits the study site at the same time with the 100year storm surge, the flood risk level could go to +4.4mND at the study site However, we consider that this case is unlikely to happen  Hence, we suggest that the 100-year Flood Risk Level near the river mouth will be around +2.8 mND, say +3.0 mND 23 Flood Risk Area under +3 mND 24 Site Formation Levels  Based on our flood risk level assessment, the minimum site formation level near the river mouth could be +3mND; however the inland area may be needed to be filled up to +4mND depending on the drainage strategy to be adopted in this area  It should also be noted that in the “Amended Comprehensive Master Plan 2030 of Danang City – A Vision to 2050”, the urban area along Cu De River shall be constructed with minimum ground level of +3.84m with frequency P= 2%  The final site formation levels at Nam O Resort will be determined probably in an iteration process with the evolving masterplan layout and drainage strategy to be adopted for the masterplan 25 Fill Volume Potential fill area up to +3mND Estimated fill volume: 209,000 m3 26 Potential fill area up to +4mND Estimated fill volume: 368,000 m3 Thanks ... flood risk level along the study site; the larger the flood flow the higher the flood risk level  With a moderate flood flow, say 2300m3/s in 2010, the flood risk level will be increased to... LLWL -0 .5 -0 .5 -0 .5 -0 .5 -0 .6 -0 .6 -0 .7 -0 .6 -0 .4 -0 .2 -0 .3 -0 .3 MHHW +0.3m ND MLHW +0.1m ND MHLW +0.0 m ND MLLW -0 .4 m ND Study Site and Son Tra Station Site Son Tra Station Son Tra Station – Annual... site  If a flood flow of 4600m3/s in 2090 hits the study site at the same time with the 100year storm surge, the flood risk level could go to +4.4mND at the study site However, we consider that