Preserve wetland and reduce the impact of urban development

Wetlands (willow ponds) have is a unique and poetic riverside landscape in the semi-arid Loess Plateau. Recognizing the importance of preserving this distinctive habitat and native flora and fauna along the Qingshui River, the willow ponds were kept with water supported from the Qingshui River.

 

This conservation effort becomes increasingly important as the existing landscape along the River continues to disappear. By using the existing drainage route as the main line for the flood canal, the impact of development is minimized. This approach reduces the need for soil displacement and lowers the risk of soil collapse, striking a balance between flood control and environmental preservation.

 

Furthermore, the design incorporates a soft grass area in the side slope of the canal as much as possible. This choice aims to enhance the aesthetic appeal and livability of the canal area. Additionally, the bottom of the canal is kept permeable,  to improve the overall quality of the canal as a living space.

 

By carefully considering these design elements, the project seeks to create a harmonious and sustainable flood canal system that not only manages water flow but also preserves and enhances the unique landscape of the semi-arid Loess Plateau.

1- With the increasing emphasis on the environment and growing awareness of ecological principles, the ecological design of flood canals is gaining greater acceptance among clients and the general public.

2- The open space available at the site allows for the design of various dimensions for different sections of the flood canal. Additionally, as the building or urban facility is situated at a considerable distance from the canal, it becomes easier for the government client to implement initial experimental details.

The characteristics of the site play a critical role in determining the approach to mitigate the environmental impacts of man-made facilities. The unique attributes of a site are the primary factors considered when deciding how best to minimize the negative effects on the environment.

Increase the flood mitigation capacity and resiliency

The design approach for the flood canal seems well-thought-out. Diverting water through a weir into two pathways based on rainfall intensity allows for adaptability during different flood conditions.

 

Below the 5-year flooding level, the water is directed along a branch line to a wetland area, serving as a means for natural purification and infiltration of the water.

 

For higher flood levels, the canal incorporates an overtopping mechanism at the diversion weir, diverting excess water to the river via a flood channel, for up to a 50-year return period.

 

Consideration of various flood levels (5-year, 30-year, and 50-year) is important for erosion control measures. Different design strategies, such as impervious concretion base for the 5-year flood, retaining walls along the slope for the 30-year flood, and pervious surface measures above that level due to low erosion risk, help meet the requirements of each flood level and velocity.

 

Overall, the design of the flood canal appears to account for ecological concerns, varying flood conditions, and the management of sedimentation and erosion.

1- The completion of flood modeling during the early stages has proven advantageous for the flood canal design.

 

2- The design of the flood canal received support from a diverse team of experts, including hydrology and hydraulics (H&H) engineers, geotechnical specialists, and landscape architects. The successful implementation of integrated solutions would not have been possible without effective teamwork and collaboration.

Coordinating different departments and designers are very important through this comprehensive design, to make sure the design meets the demands. 

Mitigation of human pressures on the park’s natural resources

Before 1990, the area around Bau Sau was under severe pressures from local communities in Dak Lua Commune. Local people often entered the park for harvesting timber, fishing, and hunting animals. Conflicts between locals and forest rangers occurred frequently and seriously (with death, and a ranger station was burnt in 1990).

After establishment, the park managers focused on law enforcement. Number of donor projects in this period helped improving local livelihoods through productive and effective farming, e.g. irrigation, increasing rice crops cultivation from twice to three times/year, high yielding maize. With consensus from local people, households living in the core zone were supported to relocate to the buffer zones. Forest protection contracts were signed with local households, forest protection teams were established in villages around the park. Illegal activities were sharply reduced. Relationship with local communities has been improved, pressures on natural resources has reduced, and the habitat quality has been enhanced.

Along with proactive habitat restoration measures, wild fauna populations recovered rapidly. In addition to the Siamese Crocodile population that was re-established in Bau Sau area, other populations of animals of conservation concerns such as Gaur, and Green Peafowl etc. are well maintained.

  • New protected area policies have helped solving many limitations in the previous period.
  • Appropriate conservation plans and strategies are in place.
  • There are sufficient resources (human, financial) provided through nationally and internationally funded projects.
  • Active participation of local communities in conservation work.
  • New awareness on biodiversity conservation regarding restoration of  wild native and threatened species.

The conservation achievements of Cat Tien National Park could have only be achieved when the participation of the community was mobilised. Good strategic plans and sufficient financial investment have helped local communities redirect livelihood activities to reduce pressures on natural resources, thereby creating conditions for the restoration and improvement of the park’s biodiversity values.

Reintroduction of a Siamese Crocodile population in Bau Sau lake, Cat Tien National Park

In 1998, site managers and scientists discussed the possibility of reintroducing a crocodile population at Bau Sau. This was because the lake was situated in the historical occupation range of the species, and at that time, the habitat quality had been improved and ready for a reintroduction program. Feasibility studies were carried out. The park also held discussions among experts, managers, and authorities at all levels to gain consensus on the program.

In 2000, with the support from international experts, purebred Siamese Crocodiles, which are believed to have provenance from Cat Tien area, were selected from a farm in Ho Chi Minh City, to training for restoring their natural behaviours. From 2001 to 2005, a total of 60 adults were released into Bau Sau. In September 2005, the first baby crocodiles were recorded.

Recent monitoring shows that the number of individuals is increasing, the distribution area is also expanding with records in some neighbouring lakes. As of 2019, monitoring data has recorded at least 286 individuals (including 228 juveniles). Up to now, it can be confirmed that freshwater crocodile populations have been successfully re-established in Cat Tien National Park. The number and structure of the recorded population ensures that this is a healthy and viable population.

  • Natural habitats of Crocodiles in Cat Tien National Park (Bau Sau and surrounding wetlands) are well protected and restored, prey populations are well maintained to facilitate the reintroduction.
  • Source of breeds in the crocodile farms meet requirements in terms of genetics and epidemiology.
  • There is enough scientific basis for a population reintroduction program.
  • Supports from governments and international community helped the National Park managers have enough determination in re-establishing a Siamese Crocodile population.

The success of re-establishment of a Siamese Crocodile population in Cat Tien National Park is the result of a joint effort of Vietnam and the international conservation community. This is a good lesson for future re-wilding efforts. Local political determination (local governments and site leaders) plays an important role in creating the necessary conditions for population re-establishment.

Important elements for this success include: i) available breeding stock for re-wilding, ii) safe habitats with sufficient prey sources, and iii) proper awareness on animal-human conflict for to ensure the compatible behaviours for long-term survival of the re-established population.

To date, the freshwater crocodile re-establishment programme at Bau Sau was recognized as the first successful crocodile reintroduction effort in the world, and it therefore can provide experience for other population re-establishment projects in future.

Cat Tien National Park
Reintroduction of a Siamese Crocodile population in Bau Sau lake, Cat Tien National Park
Mitigation of human pressures on the park’s natural resources
Commitment of producers to try non-lethal alternatives to coexist with wild carnivores

Producers must also have to commit not to kill predators and to be part of a more environmentally friendly production. A final key aspect is that the conservationist using this technique will have to invest a considerable amount of time between training the dog, selecting puppy candidates, constant monitoring and much more. If the social factors mentioned before are not taken into account and these commitments are not met, the success of the project would not be possible.

Commitment by participating herders not to kill wildcats.

Recording of depredation events before and after the LGD to provide evidence-based results.

Selected herders should not use poison or traps in the livestock grazing area. It's important that they have a good relationship with their neighbours, otherwise the protection dogs will be at risk. Producers must be accompanied by technicians and be trained to successfully complete the protection dog training. On rare occasions when the puppy starts work it may bite or kill livestock, this behaviour must be corrected immediately using non-aggressive techniques. Producers must sign a pledge not to kill wildcats, mainly those at risk. It’s advisable to work with NGOs, producer associations, government and others to cover costs and ensure sustainability in time.

 

Raising, training and care of future protector puppies and breeding females

Social factors are important in conflicts between humans and predators. Predation has direct economic costs related to loss of income and food, and indirect economic costs such as time spent avoiding predation. There are also underestimated non-economic costs, related to the sense of uncertainty, insecurity and general disruption to livelihoods caused by the unexpected loss of livestock, which strongly influence human-carnivore interactions. Livestock keepers who choose to join this programme must be prepared to make cultural and behavioural changes, including changing their cultural relationship with predators and dogs.  They must be committed to caring for and managing LGDs in a different way to how they normally interact with dogs. The herder must spend time with the dog in the first few months to ensure that it does not get lost, and must provide food and water on a daily basis.

Commitment of the producers to work with, care for and complete the training of the LGD.

Logistical and technical capacity to visit and train the herders during the first months after receiving the puppy. This should be done until the puppy is at least one year old. This is essential to ensure that the puppy does not develop undesirable behaviours.

Producers must be fully committed and convinced that they want to keep, train and care for a puppy and know what is required from them. LGD puppies must be accessible to low-income producers, who are most vulnerable to predation events.