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Yang Ju Introduction Method Results Sea Level Rise and Impact on Accessibility of North Wing of Yangtze Delta 0.60% 25.03% 41.45% 48.68% 54.17% 59.12% 0.00% 10.00% 20.00% 30.00% 40.00% 50.00% 60.00% 70.00% 0 2 4 6 8 10 12 Area of Eleation<=6m Area of Eleation<=5m Percentage of Area under Elevation x The Yangtze River Delta is a world-class urban cluster in east part of China. Being west to East China Sea, the North Wing of the Delta (in Jiangsu Province) is extremely vulnerable to sea level rise since 25.30% per- cent of its land is within 5 meters above the sea level. Storm surge is a major natural disaster for this region. In 1905, an extreme storm surge in Yangtze River Estuary killed 27,000 people in Shanghai. Considering the vulnerable topographic characteristics of the North Wing, in the future, storm surge combined with Sea Level Rise is likely to go further inland and inundate more area compared to 1905, leading to the damage no one can bear. In this future scenario, five central cities in the North Wing are of great importance, as they are the base to send out army and rescue team. Furthermore, this potential rescue mission rely on road network a lot. Thus, it’s important to identify the potential inundated area and change of accessibility of five central cities, in order to evaluate the se- curity level of this region in the future. Key method 1: Inundation mapping this study used the SLR inundation mapping method employed by NOAA (http://www.csc.noaa.gov/slr/viewer/assets/pdfs/Inunda- tion_Methods.pdf), including creation of inland tidal surface and iden- tify connected inundation surface. This method can remove some low-lying areas which not connects to a water body, for example, a basin surround by mountains. In this case, even if the basin is below the sea level, it’s not going to be inundated as the surrounding mountain cut off the water flow. Key method 2: Scenario analysis This study also stimulated different future scenarios. Yafeng Shi, et al. (2000) estimated height of storm surge under different frequency and SLR in 6 different tidal stations along the Yangtze delta. Based on the estimation, this study stimulated the inundated area under different storm surge to help understand the potential inundation risk of the North Wing. The result shows that under different scenarios, 53% to 59% of urban land will be inundated in the North Wing. The study future chose the scenarios with 2% frequency storm surge under 50cm SLR to stimulate the change of accessibility. The result shows that, after inundation, the percentage of accessible area with in 4 hours from 5 central cities dropps from 75.61% (no storm surge and SLR) to 26.51%, meaning large population would not get timely recuse after the disaster. 1. Understanding the impact of sea level rise in the North Wing of Yangtze River Delta. 2. Identify the quantity and location of inundated urban land. 3. Calculate the change of accessibility of five central cities, determine whether the rescue team from the central cities can timely access inundated area in the North Wing. Client: Flood Control Office, Jiangsu Province 1. The North Wing is highly vulnerable for storm surge and SLR. 2. After inundation, the accessibility of 5 central cities to the region will lost greatly, leaving great difficulties for rescue team to arrive timely. 3. To deal with the potential risk, sea walls with around 10m height above sea level should be built. Also, road bed of highways should be raised to prevent inunda- tion. Location of the North Wing in the Yang- tze River Delta A Bird Eye View of Yangtze Delta in ArcScene Work Flow Accessibility of 5 Major Cities in the North Wing under no Storm Surge and SLR Road network in the North Wing, 2007 (Source: Nanjing Institute of Geography, China Academy of Sciences) Remaining Road network in the North Wing after Storm Surge Change of Accessibility after Storm Surge Accessibility of 5 Major Cities in the North Wing under 2% Frequency Storm Surge and 50cm SLR 0.00% 10.00% 20.00% 30.00% 40.00% 50.00% 60.00% 70.00% 80.00% 0 - 0.5 0.5 - 1 1 - 1.5 1.5 - 2 2 - 2.5 2.5 - 3 3 - 3.5 3.5 - 4 <=4 no storm surge and SLR 2% frequency storm surge and 50cm SLR 0cm SLR Inundation Urban Land Inundation: 53% 2% Frequency Strom Surge 1% Frequency Strom Surge 20cm SLR Inundation: Urban Land Inundation: 54% 50cm SLR Inundation: Urban Land Inundation: 56% 0cm SLR Inundation Urban Land Inundation: 54% 20cm SLR Inundation: Urban Land Inundation: 56% 50cm SLR Inundation: Urban Land Inundation: 59% 0cm SLR 20cm SLR 50cm SLR 0cm SLR 20cm SLR 50cm SLR 2% Frequency Strom Surge 1% Frequency Strom Surge Frequency （ %） SLR( cm) Highest tide level (m) Xiao Yang Kou Da Yang Port Lu Chao Port Jin Shan Zui Zha Pu Gan Pu 2 0 9.8997 8.2997 6.7797 7.4597 8.5397 9.5597 20 10.0597 8.4797 6.9497 7.6297 8.7097 9.7197 50 10.3097 8.7397 7.1997 7.8797 8.9497 9.9397 1 0 10.3597 8.5097 6.9397 7.5897 8.7897 9.8697 20 10.4997 8.6897 7.1097 7.7597 8.9597 10.0297 50 10.7697 8.9497 7.3597 8.0197 9.1997 10.2497 Inland Tidal Surface Inundated Area Inundated Area Location of Tidal Stations Projection of Highest Tide Level Based on Different Frequency of Storm Surge and SLR (Yafeng Shi, et al., 2000) DEM Highest Tide Projection Road Network Inland Tidal Surface Inundated Land Un-Inundated Land Remaining Road Network Accessibility Raster Calculation IDW Interpolation Network Analysis Aim Reference Conclusion Shi Yafeng, et al (2000). Prediction and prevention of the impacts of sea level rise on the Yangtze River Delta and its adjacent areas. Science in China Series D: Earth Scienc- es, 43(4), pp 412-422. NOAA. Detailed Methodology for Mapping SLR Inundation. http://www.csc.noaa.gov- /slr/viewer/assets/pdfs/Inundation_Methods.pdf
