5.2 Mangroves

  • This topic has 9 replies, 6 voices, and was last updated 1 week, 4 days ago by Jean Aquinde.
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  • #7678
    Rowena Kite
    Participant

      Hello,

      What are the dimensions of the coastline of Saibai? How deep is the water immediately off the island, and the depth of the water where they are currently planted?

      Thanks in advance!

      #7703
      Sai Rupa Dev
      Keymaster

        Hi Rowena,

        Saibai’s coastline stretches approximately 15kms. The depth of water immediately off the island varies with tidal changes, rainfall patterns, time of the year etc. But Saibai is in shallow waters and depth could be less than 10 mts at low tide and more than 30 mts at high tide. It is difficult to ascertain the plantation depth of the coastal mangroves, but my guess estimate would be between 7 mts to 25 mts.

        Cheers,
        Sai

        #8002
        Andrew McGlashan
        Participant

          To whom it may concern,

          We are completing ENEG11007 at CQU. We have chosen to investigate Design Area 5.2, coastal erosion protection on Saibai Island, for our project. Considering the broad scope identified in the EWB Challenge Brief, we would like to ask if you could provide some more clarity about the specific scope of this design area.
          We have taken into consideration the considerably slow growth of mangroves and would like some more details so that we can refine our project scope, schedule and risk assessment.

          To refine these areas, is there further details you can provide around:

          -Is the mangrove growth or erosion a seasonal issue?
          -What local resources are already available on Saibai Island?

          -What current community engagement strategies are available on the Island?

          -Does the community need a permanent or temporary solution (for example, an artificial reef to wait for mangrove growth)?

          -Are there any time restrictions to establish mangroves or stop erosion?

          -What current controls or measures are currently in place or available?

          -What is the extent or area of erosion/mangrove restoration?

          -What’s at risk? Industry, housing, foreshore or other?

          -Are we correct in assuming that it is preferable to produce a low-maintenance solution, that the community can monitor?

          -What are the safety and risks of erosion/mangrove loss (environmental, personal, industry)?

          -What industries are active on the island? It would be great to have some understanding of the context. What happens on the island, population, jobs, etc?

          -Is the desired objective or result just erosion control, or does the community have other desired benefits in mind?

          Thanks! Your clarification is appreciated,

          Online Group 2.

          #8014
          Jean Aquinde
          Keymaster

            Hi Andrew and the rest of the Online Group 2,

            It’s really good to see that you’ve developed these research questions with your team. As you comb through the resources provided on the EWB Challenge website, you’ll realise how these are addressed in different ways.

            Here are some of the specific resources that might help your team move forward:

            > Torres Strait 2021 State of Environment Report Card – will provide a bigger picture of the current state of mangroves protection in the Torres Strait environment where Saibai Island is part of

            > Report on Inundation Management on Saibai, Boigu and Iama Islands and Saibai Island Maps on Coastal Hazard and Flood Areas – will help you assess the safety and risks of erosion/mangrove loss and will give you some insights on current controls or measures that are currently in place.

            > TSRA’s Land and Sea Strategy 2016-2036 – will give you an idea of the long-term goals and government’s management directions in dealing with mangrove protection in the Torres Strait

            > Mangrove Makeover, featured in ABC’s Gardening Australia, will provide insights into mangrove cultivation and might inspire you to learn how mangrove restoration efforts can work at a community level.

            > EWB Challenge FAQs will provide practical tips and strategies for approaching the community’s perspective on your design proposal with limited information and the different scales on which you can implement your solutions. This resource will help you feel prepared and confident in your approach.

            These are all available on our Saibai Island Resources page and in our Additional Readings at the end of the Design Area 5 – Climate change adaptation brief.

            It is also essential to get to know the key stakeholder, the Torres Strait Island Regional Council (TSIRC), its role and function, and the limitations of its authority. In the Introduction to Local Government in the Torres Strait, we also featured the Torres Strait Regional Authority (TSRA), which operates at a regional level and complements the TSIRC.

            I hope this helps. I wish you all the best with your project!

            Regards,
            Jean

            #8038
            Andrew McGlashan
            Participant

              Hi All,
              Thanks for your previous response. We have considered the sources and information provided from this response and have aligned it with our research. Upon doing this, we have pulled together some ideas to consider for Design Area 5.2, Coastal Erosion Protection on Saibai Island, and were wondering if we could receive some feedback on the feasibility of our ideas. Specifically, we are wondering if any of these have been trialled before? Whether a combination of these ideas might contribute to a solution? And what materials, machinery, or manpower is available on the island to support these projects?

              Project 1- Tetra Pots: A large, heavy, tetrapod-shaped biodegradable pot to plant the mangroves within to allow them to establish as the pot degrades. This solution utilises local materials in the construction of the pots by using a coral aggregate concrete mix including organic materials. Issues around this solution are the pots being so heavy, weighing approximately 1t, and from our research Saibai seems to only have the 1 tractor on the island to be utilised. Another disadvantage is that it requires a slower, more expensive process to construct, pour and allow the pot to cure before use, with limited moulds available and a large working area is required.

              Project 2 – Temporary Sea wall: Throughout the planting process, spoil earth materials from construction around the island could be utilised to construct a small sea wall around high current areas allowing mangroves to establish. The main issues identified for this solution are the area required for protection, the limited material available, and the high risk to the environment and cultural heritage sites.

              Project 3 – Coconut husk Wave Breaker: A floating coconut curtain or net which reduces the impact and power of current and waves. This product hangs down the required depth to reduce the waves and current enough to maintain the integrity of the mangrove seedlings. The issues presented with this solution include the size of the protected area required, the wave breaker being of insufficient length, and the integrity of the wave breaker after exposure to weather and strong currents effecting longevity.

              Project 4- Planting bag with natural fibre: Planting mangrove seedlings within a natural fibre bag to stabilise the soil while the plants establish. This solution may need to be used in low current areas or in conjunction with another project to ensure effectiveness. This can be made to out of a range of materials, including palm leaves, and can be made to a range of different sizes to suit species and application of mangroves. The area and amount of mangrove restoration required presents an issue given that several holes need to be excavated, as well as back fill for planting with minimal access to machinery. Another challenge is meeting the mass production needs of the fibre bags with limited resources and manpower on the Island.

              Project 5 – Stakes: By placing extended stakes several metres into the soil it assures that the mangrove seedlings are supported, and the plants cannot be washed away by the rapid currents. These stakes may be timber, steel, or any material available, and can be recycled for multiple seedlings. The number of stakes required to restore the mangroves, as well as the availability of manpower or machinery to drive the stakes into the ground as well as remove them once mangroves are established, present some surmountable challenges.

              Project 6 – Implementation of a mangrove Nursery: Growing mangroves on site within a protected area until they are established enough that they can be planted on the coast and exposed to these intense natural elements. Utilising an onsite nursery to develop the mangroves provides an economic boost for the island. However, the area required for the nursery, transportation, maintenance, and planting present some challenges.

              Project 7 – Bamboo/timber Break wall: Constructing a break wall out of bamboo or timber piles, driven into the soil surrounding the desired planting area, to reduce the impacts of the rapid currents and waves. The issues associated with this solution are the area required for protection, the number of posts required, as well as limited machines and manpower to drive and remove the posts.

              Any feedback or suggestions are appreciated,
              Thanks, Online Group 2

              #8086
              Jean Aquinde
              Keymaster

                You’re welcome, Andrew!

                Thanks for generously sharing your design ideas in this forum. Your team has put a lot of thought into identifying some pros and cons of each project idea, and I can see that you’re considering narrowing down your options with feasibility in mind. To help you with this, I suggest that you perform a design options matrix to make this selection process more systematic. Please look at our Previous Top Reports page, such as the Nursery for cultivating bush tucker, where the student team defined the design criteria and each group member provided rankings. Please make sure to check our recommended Design Considerations specific to Saibai Island.

                At this stage, we are unable to consult with TSIRC, which among the list has been trialled before. However, during our scoping trip, we identified Project 6 —Implementation of a mangrove nursery, known as the Saibai Mekem Garden community project, as an ongoing project in Saibai Island. You can read more about this in our Design Area 5—Climate Change Adaptation design brief.

                I hope this helps!

                Regards,
                Jean

                • This reply was modified 1 month, 1 week ago by Jean Aquinde.
                #8118
                Henry Han
                Participant

                  Hello,

                  I am curious regarding to a previous response to an answer about the depth level and I am wondering if it is still the same and is the measurement mts or a typo.

                  Thank you for your response

                  #8131
                  Jean Aquinde
                  Keymaster

                    Hi Henry,

                    Unfortunately, we can’t verify that data unless a site fieldwork is conducted. This report on (2015) Mangrove and Freshwater Wetland Habitat Status of the Torres Strait Islands, Biodiversity, Biomass and Changing Condition of Wetlands is a great resource that discusses mangroves in Saibai Island and other Torres Strait Islands, which include data on tree heights.

                    I hope this helps!

                    Regards,
                    Jean

                    • This reply was modified 3 weeks, 3 days ago by Jean Aquinde.
                    #8143
                    Bryan Wells
                    Participant

                      Hi Jean,

                      Thank you for your responses thus far.

                      To assist in completing the assessment of our options we require a few specific pieces of information:

                      1. Is it possible to provide some specific space requirements for the project as we have approaches that are better suited to larger areas and approaches that are better suited to smaller scale projects.

                      2. Is there a culture, custom or practice of weaving from natural materials in the local community that could be utilized for the weaving of baskets and bags for coastal rehabilitation?

                      3. Is there capacity for initial harvesting of bamboo, poles for stakes, and leaves for weaving, and for the cultivation of bamboo for an ongoing supply for future projects and maintenance?

                      4. Is there capacity for coconut harvesting to be used in an environmental restoration project or are they harvested for commercial purposes?

                      5. Is there capacity for local labour to participate in the harvesting of bamboo, construction of bags and baskets from natural materials and the erection of support stakes or bamboo breakwater walls?

                      Thanks
                      Online Group 2

                      • This reply was modified 2 weeks, 6 days ago by Bryan Wells.
                      #8153
                      Jean Aquinde
                      Keymaster

                        Hi Bryan,

                        To answer your questions:

                        1. Is it possible to provide some specific space requirements for the project as we have approaches that are better suited to larger areas and approaches that are better suited to smaller-scale projects.

                        > In our EWB Challenge FAQs, we have advice on the different scales at which projects might be implemented and managed, allowing for variables and thinking about a modular approach. Please make sure to check that page.

                        2. Is there a culture, custom or practice of weaving from natural materials in the local community that could be utilized for the weaving of baskets and bags for coastal rehabilitation?

                        > Yes there is. While we haven’t covered that specifically in our scoping trip, I’m seeing recent online publications that weaving practices are alive in Torres Strait, such as on Erub island. Check: Keeping culture alive through weaving and Traditional coconut leaf weaving is celebrated in the signature exhibition at the Cairns Indigenous Art Fair.

                        3. Is there capacity for the initial harvesting of bamboo, poles for stakes, and leaves for weaving, and for the cultivation of bamboo for an ongoing supply for future projects and maintenance?

                        > From my initial research, I see more on coconut harvesting and rarely on bamboo harvesting. Check this 2017 article that talks about the coconut industry. Historically, some evidence suggests that traditional houses on Saibai Island have been built of local materials including palm fronds and bamboo on Saibai Island.

                        For Q3, Q4 and Q5, I suggest that these opportunities are best included in your Stakeholder Engagement Plan (SEP). The SEP is collaborative in nature and these are the things you can highlight when you intend to consult the key stakeholders such as TSIRC and the residents of Saibai Island in terms of the feasibility and likability of your design proposals.

                        I hope this helps!

                        Regards,
                        Jean

                        • This reply was modified 1 week, 4 days ago by Jean Aquinde.
                        • This reply was modified 1 week, 4 days ago by Jean Aquinde.
                        • This reply was modified 1 week, 4 days ago by Jean Aquinde.
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