The CallisonRTKL planning and urban design team with Arcadis socioeconomic, water, environmental, and infrastructure teams developed a strategic urban waterfront assessment of the Red River in Hanoi, the capital of Vietnam. The team was asked by the City of Hanoi to assess two existing options for flood protection and urban redevelopment of the Red River, along with the creation of another new, more sustainable option, and to evaluate these options in terms of overall contribution to the city.
Due to the Red River water level drop controlled by the newly built reservoirs upstream, about 11,005 hectares (27,000 acres) of land can be reclaimed on both banks of the river in Hanoi and transformed into an urban development land bank. By maximizing land use value, the riverfront regeneration would attract investment and a diverse population, provide high-value jobs, and contribute to tax revenues and gross domestic product (GDP) of the city and the region. The design team provided a new flood control strategy to the riverfront area, while creating sustainable and resilient urban development along both sides of the Red River.
The three flood protection options are intended to protect the Hanoi riverfront urban areas from a 1-in-500-year flood. The CRTKL\Arcadis design team evaluated two previously proposed flood protection options: Option 1—an all-new conventional dike as close as possible to the current Red River water line, and Option 2—a combination of a new dike and improvement to existing dikes.
The design team proposed a third, more sustainable solution that has no dike, using instead a riverbank stabilization and riverfront urban park system that is designed for flooding. Unlike hard dikes, this recommended option results in a soft and flexible urban setting with a landscaped waterfront park design. During periods, water in riverside parks can rise and fall, and in the dry season, citizens can enjoy the attractive and spacious public and eco-friendly public riverfront spaces. A layer of resilient medium-density development blocks and various cultural, sports, and activity facilities also were proposed between the waterfront park and a new urban traffic corridor, addressing the problems of serious traffic congestion and lack of public open space in Hanoi.
Summarizing the results of the flood protection option comparison, the new proposed sustainable option performed the best and was more acceptable to the various government agencies: Option 3 had the lowest flood hazard risk and lowest risk to people and properties, while minimizing environmental impact, creating strong socioeconomic development potentials, maximizing land development opportunities, attracting investment, focusing on high-value jobs, creating additional tax revenues for the city, and increasing the contribution to the nation’s GDP. Investment in the Red River will become a cornerstone of Hanoi’s vision of becoming a world-class green and smart city by 2030.
A VISION FOR HANOI
The Vision for Hanoi is to be a world-class city by 2030. Investing, in the development of the Red River waterfront will be a catalyst to achieve that vision. Cities such as New York, Shanghai, London, Chicago, and Singapore have created significant development and distinctive destinations along their waterfront areas that support tourism and, has resulted in sustainable socioeconomic growth. To achieve the Vision for Hanoi, a number of strategies need to be employed.
The Heart of the City
The first strategy is make The Red River waterfront the heart of the city by implementing the Hanoi urban development framework from the 2030 Master Plan and the 2050 Vision. The riverfront development zones will then link to the entire city’s green network, connect the old city on the Right Bank with the new city on the Left Bank, offer an expansion to the city in a high-value location, and bring together the radiating development corridors into the heart of the city.
Smart and Resilient Urban Growth
The second strategy is to make urban growth smart and resilient. The city needs space to grow and to accommodate an increasing population. The Red River waterfront—and beyond—has the potential for development if this new city space is designed to be safe. This can be achieved by smart and resilient design of infrastructure, buildings, and open space that will create not only enjoyable places to live, work, play, and learn, but also a high-quality, world-class urban riverfront environment.
Competitive District Positioning
The third strategy is to competitively position the districts along both riverbanks to target specific types of development to take best advantage of the location along the river and within the city framework. Five zones are positioned differently: new eco-living communities in zones R1 and R5; a focus on leisure in zone R2; industry, education, and culture in R3; and mixed use urban development in zone R4. High-intensity land uses will link these diverse districts and communities with parks and preserved cultural heritage attractions. Multimodal riverfront transportation systems will support the Hanoi riverfrontr as a tourism destination with convenient accessibility.
Unlocking Socioeconomic Potential
The fourth strategy is to unlock the socioeconomic potential of the new riverfront by maximizing land development opportunities, maximizing property values, attracting investment and a diverse population, focusing on the creation of high-value permanent jobs, creating additional tax revenues for the city, and increasing contributions to the gross domestic product of the city, the region and the nation.
The overall project goals for the Red River development are:
- To move Hanoi towards a more sustainable and resilient future.
- To protect Hanoi from a 500-year flood while improving the overall urban environment in the Red River valley.
- To balance international best practices for flood protection and urban development with a comprehensive understanding of local conditions.
- And, perhaps most important, to be a cornerstone for socioeconomic growth in the city.
CHALLENGES AND COMPLEXITIES
The assessment of the three flood protection options uncovered a set of challenges and complexities that were beyond the scope and schedule of the initial study to fully resolve. But identification of these challenges and complexities also led to the identification of opportunities for further analysis. The options were assessed on the basis of overall performance and contributions to Hanoi City from the perspectives of flood protection, flood hazard, flood risk, environmental issues, development potential, riverfront urban character, cost, and socioeconomic benefit.
Flood Protection Comparison
Flood protection is the most significant opportunity to compare the options, since all options share the design intent of providing 1-in-500-year flood protection for the city of Hanoi:
- Option 1 is a utilitarian strategy of constructing new dikes for an 1-in-500-year flood protection, originally proposed by another international consultant team and later modified by a local team to build close to the river edge, but violating a new Vietnam Law on the Dikes, which prohibits the construction of any new dikes.
- Option 2 is a conventional strategy. It involves upgrading the three existing back dikes and constructing new dikes to provide 1-in-500-year flood protection and was proposed by a local planning institute. This option also violates the Vietnam Law on the Dikes.
- Option 3 is a sustainable strategy. It is an integrated strategy of riverbank stabilization and riverfront floodplains. Proposed by Arcadis and CallisonRTKL, this strategy aims to improve the existing dikes and create a floodable riverfront park system while providing a high flood warning level for 1-in-500-year flood protection purpose. As no new dikes will be built, this option complies with the Vietnam Law on the Dikes.
From a flood protection perspective, Option 3 was recommended for further study.
The options propose different cross-sections for providing flood protection:
Option 1’s hard-edged high dike and adjacent river roadway create a smaller, tighter river section, constraining the flow of water, and producing higher water levels. This option proposes hard-edged revetments on both riverbanks along the new dike. There is minimal provision for open space and landscape along the river. The roadway adjacent to the dike cuts off urban pedestrian access to the water. The aggressive reduction of the Red River cross section in the study area will increase the frequency of flooding events raising up the 1 -in-500 years water level, and increase the risk of economic losses due to flooding damage, and not be deemed to be safe.
Option 2’s eco-friendly dike with the riverfront road atop is lower in height than option 1, and creates a wider river section and intermediate water levels. This option proposes revetments on both banks of the river of eco-friendly and hard edges, depending on differing conditions along the river. The eco-friendly revetments will be planted for a green appearance. The roadway on the new dike, however, cuts off access to the water.
Option 3 has the lowest riverbanks, widest river profile, and lowest water levels and proposes the inclusion of a pedestrian waterfront promenade along the river, as well as new roadway setting back into the second layer of waterfront development blocks. This option proposes floodable parks and plazas, and a green pedestrian promenade along the waterfront areas — and a hard-edge where necessary—to address the particular conditions of the river.
From a cross-section performance standpoint, Option 3 was recommended.
Flood Risk and Hazard Comparison
Making room for the water is the key principle of flood protection. The options were assessed on the flood hazard at Flood Warning Class 2 when the water level equals +10.5 meters, and based on the probability of inundation at a particular location along the river and the return period of higher water levels. A typical portion of the river was examined, being the narrowest point of the river and subject to the highest peak water discharge. The water levels for each return period varied among the different options. Option 1 will see a 1-in-year or more flooding at +12m and 85 percent of the riverfront will be flooded. In Option 2, flooding will occur once in Seventy-five years and 75 percent of the riverfront area will be inundated. In Option 3, flood will occur once in 500 years or less frequent with 50 percent of the riverfront area will be inundated. Option 1 fails to meet the design intent of an 1-in-500-year flood event protection with dikes at the proposed +15 meter height. Option 2 functions better than Option 1, but not as well as Option 3.
Option 3 has the overall lowest flood risk and hazard at Flood Warning Class 2, and was recommended for further study.
Environmental Impact Comparison
In Option 3, more riverfront green open space will be created, compared to Option 1 and Option 2, for people to access during dry seasons in the future. This also helps to solve the current problem of the lacking green parks in Hanoi city center. In preliminary Environmental Impact Assessment comparing the three options, Option 3 yielded the highest score when considering land use, water resources, social environment, ecology and biodiversity, air, noise, and vibration as well as risks and hazards.
Option 3 performs the best among the three options from an environmental impact perspective and was recommended for further study.
Urban Image Comparison
The urban image of these options matters to the city’s aspiration of becoming a world-class city by 2030. Option 1 is clearly utilitarian and a common construction solution without people-friendly considerations. The riverfront will not be an attractive destination as a result. The riverfront will be cut off from the rest of the city by the proposed riverfront roadway. Option 2, while similar to Option 1, offers a more eco-friendly planted revetment that in time will “ green up”. But also, it is practical and conventional in appearance, but does not take the most advantages of the riverfront image potential. Option 3, however, makes the riverfront an eco-friendly park system with the pedestrian promenade and activities connecting the people of Hanoi to the riverfront.
From a visual character perspective, Option 3 was recommended for further study since it offers a sustainable, smart, and resilient urban image.
Potential Developable Land Comparison
All options attempted to maximize the amount of new developable land while retaining the maximum amount of existing development and population. Density factors, land use programs, and preservation of cultural heritage were identical among the three options—with Option 1 at the highest for most development land and projected gross floor area, Option 2 the least, and Option 3 at a moderate level. Option 3 also aims at reducing the need for landfill.
Option 3 was recommended for further study because it offers a moderate amount of development potential.
In terms of cost, Arcadis prepared an order-of-magnitude estimate for the overall project cost for each option. This high-level cost comparison for the three options is made for the following: project cost, which includes the construction of new dikes, auxiliary dikes/renovated old back dikes, riverbank improvement, and construction of the new development land area. Projections for Option 1 is the most at US$16.5 billion; Option 2 costs the least at US$10.6 billion; and Option 3 is moderate at US$13 billion. In addition, the cost of option 1 as currently proposed does not reflect the added cost of the additional flood protection measures needed to make option 1 a low-hazard, low-risk solution.
On the basis of this preliminary cost analysis, Option 3 was recommended for further study.
Finally, the options were analyzed for socioeconomic benefit potential of riverfront development. Option 1 projects an estimated GDP contribution over 15-20 years of $30.6 billion USD, the creation of 150,000 permanent new jobs, a target investment value of $23.7 billion USD, and a 1.29 low risk return on investment. Option 2 projects a $20.7 billion USD GDP contribution, 110,000 permanent new jobs, a target investment value of $16.3 billion USD and a 1.27 return on investment. Option 3 projects an estimate GDP contribution of $25.0 billion USD over 15-20 years, 130,000new jobs, $20.2 billion USD in target investment value, and a comparable 1.24 return on investment.
Although Option 1 has the highest socioeconomic performance, it fails to meet the basic flood protection level. Option 2 is the lowest in terms of performance. Option 3 is moderate in socioeconomic performance and meets flood protection parameter. Option 3 from a socioeconomic perspective was recommended for further study.
Choosing the Middle Ground
In conclusion, Option1, while having the most development area potential and highest estimated economic benefits, has a utilitarian image, the highest cost, and the lowest environmental rating, the highest flood hazard and flood risk, and, significantly fails to achieve the 1-in-500-year protection design intent.
Option 2, while having a low development potential, the lowest economic benefit, and a conventional image, also the lowest cost, has a moderate environmental rating, and poses a lower flood hazard and flood risk than Option 1.
Option 3 has moderate development potential, economic benefit, and cost. In addition, it has a very positive “green” sustainable image, the highest environmental rating, and the lowest flood hazard and flood risk from a flood protection standpoint.
Therefore, the sustainable Option 3 was recommended to be the starting point of further study and analysis. This is a sustainable approach to unlock socioeconomic opportunities for the Red River and the City of Hanoi.