Under the pressure of rapid urbanization, the development of urban land in Vietnam has invaded green lands and had a negative impact on their ecosystems and environments. The new urban development not only does not improve the demand for green urban space but makes the living environment worse. Studying the design seriously and putting forward solutions for green urban space is essential and urgent. Taking Da Nang as a case study, planning a network of multicenter urban green space would change ecological principles to create a sustainable urban ecosystem. This is based on a landscape metrics method to reveal the green space system characteristics and its spatial distribution, area, density, and shape. A set of shapes index including categories such as SHAPE, mean distance (m) between each cell (GYRATE) and mean Euclidean distance neighbour (ENN) was used to display the geometrical shape of patches and continuity. These indices stress the difference in spatial structure in various land-use types. This article draws upon ecological landscape theory to propose a green system of urban regions including green space wedges, greenways, corridors, greenbelts and green additions; these factors help to create a sustainable urban green space.

One of the most insoluble problems confronted by urban areas in developing countries is the shortage of open space; street space allows daily human activities, promotes social interaction, and is seen as a precondition for the sustainable development of the community. Although some seemingly public space is also built up in Vietnam, street space is often where resident’s go to perform activities. This research aims at studying behaviors of users in old street space and the interaction with existing physical settings; as an input to future renovation and the development of street space in a manner that respects the cultural and social context of the Vietnamese people. User’s behaviors in streets and physical characteristics of space were collected and processed in accordance with theories of behavior setting and proxemics using some methods including place-centered behavioral mapping (PcBM) and visual encounter surveys (VES). The analysis showed that three types of behavior, including (1) Type A where various frequent activities occurred, (2) Type B which discouraged most human activities, and (3) Type C where neither frequent nor infrequent behaviors can represent environmental behavior patterns in the old street spaces of Vietnam and for each of these types of patterns improvements have been proposed by organizing street and pavements layouts detailed in this paper. The proposed improvements are based on the relationship between human behaviors and properties of the street space to assist designers, administers, and authorities in renovating and developing better and more sustainable street space.

The shortage of open spaces in developing countries in Asia such as Vietnam has been a thorny question for urbanists. Due to a poor history of public spaces, people tend to use street spaces as open spaces and other functions that bring chaos and danger onto the streets. Although developed countries in the West have overcome the dangers of life on street spaces to some extent, Vietnam, with its low quality of life, retains its inherent street bustle. Street improvements have been carried out to enhance the quality of urban life. This research aims at comparing improved and unimproved street spaces in various aspects, including user behavior and the environment-behavior relationship within street spaces and their surroundings. The findings contribute to the future improvement of street spaces in Vietnam and other developing countries based on theories of Environment-Behavior Studies. Through this research, the street renovation and development idea can be processed in a distinctive manner that appreciates the cultural and social context instead of being derived from the arbitrary or intuitive ideas of designers. By using various observation methods such as centered behavioral mapping (PcBM) and visual encounter surveys (VES), and statistical analysis such as principal component analysis (PCA) and cluster analysis (CA), the findings show that a total of eight physical attributes need consideration during street renovations or development processes. Improved and unimproved street spaces share two attributes and differ in six attributes. Additionally, three environment-behavior patterns support the implications detailed in this paper. Finally, a suggestion for street space development and management is made to support related authorities and urbanists in future projects; it is hope that this research will contribute to creating more livable and sustainable street environments.

Flooding is one of the leading challenges faced by delta cities in the world. Flood risk management using flood control infrastructure (FCI) is a popular solution to prevent flood damage; however, this is receiving enormous criticism due to its negative impacts on urban ecosystems. Recently, there have been new approaches to flood risk management that gradually shifted the focus away from FCI, such as ecological infrastructure (EI) based approaches. However, the conventional thinking that cities cannot be safe without FCI seems an immutable one, especially in developing countries. This study firstly assessed human–river interaction in direct relation to FCI and outlined the limitations of FCI. Then, an urban ecology research model was used to conduct a case study in the Vietnamese Mekong Delta (VMD), in which the interaction between factors, including riverine urbanization, FCI formation dynamics, the changing hydrological regime, flood risk, and riverine ecosystem degradation were evaluated. Due to the dynamism and complexity of the interactions between humans and rivers at the VMD, this study attempts to demonstrate that building the ability to adapt to flood risks based on EI will have a crucial role in enhancing the sustainability of delta cities. Through a case study in My Tho City (MTC) a flood resilience management scenario for a riverine urban area along the Mekong River was developed to discuss the role of EI in flood risk reduction and the restoration of riverine native ecosystems. The findings from this study suggests that EI should be considered as an effective and indispensable design tool for the conservation of riparian ecological corridors and public open spaces—which is a major challenge for urban areas in the context of increasing climate change impacts in the VMD.

The improvement of street space, in both physical and non-physical aspects, has brought a new-look to the city but also raised some controversy. Undeveloped streets, despite their lower quality and fewer amenities, still prove to have a certain attraction to urban residents. This study explores users’ perceived usage of street space based on physical and non-physical attributes that help fill the knowledge gap in street design and development. The results show that higher-income individuals tend to gather and participate in activities on modern streets, while lower-income individuals have a tendency to use undeveloped streets. This result supports the hypothesis that differences in demography can lead to differences in environmental perceptions. These findings also provide empirical evidence of the irrationality of street improvement in Vietnam, which primarily focuses on physical factors but omits non-physical elements. The study also gives suggestions for street improvements and development in Vietnam, in particular, which can be applied in countries with similar socio-economic and cultural contexts.