Potential for Return on Investment in Rehabilitation-Oriented Blue Carbon Projects: Accounting Methodologies and Project Strategies

Opportunities to boost climate change mitigation and adaptation (CCMA) and sustainable conservation financing may lie in enhancing blue carbon sequestration, particularly in developing nations where coastal ecosystems are extensive and international carbon markets offer comparatively attractive payments for environmental stewardship. While blue carbon is receiving increased global attention, few credit-generating projects are operational, due to low credit-buyer incentives with uncertainty in creditable emissions reductions and high project costs. Little empirical guidance exists for practitioners to quantify return-on-investment (ROI) and viability of potential projects, particularly for rehabilitation where multiple implementation options exist with diverse associated costs. We map and model drivers of mangrove natural regeneration (NR) using remote sensing (high-resolution satellite imagery segmentation and time-series modeling), and subsequent carbon sequestration using field- and literature-derived data, across abandoned aquaculture ponds in the Philippines. Using project-specific cost data, we then assess ROI for a hypothetical rehabilitation-focused mangrove blue carbon project at a 9.68 ha abandoned pond over a 10-year timeframe, under varied rehabilitation scenarios [NR vs. assisted natural regeneration (ANR) with planting], potential emissions reduction accreditation methodologies, carbon prices and discount rates. NR was faster in lower-lying ponds with lower tidal exposure (greater pond dike retention). Forecasted carbon sequestration was 3.7- to 5.2-fold and areal “greenbelt” regeneration 2.5- to 3.4-fold greater in our case study under ANR than NR. Variability in modeled sequestration rates drove high uncertainty and credit deductions in NR strategies. ROI with biomass-only accreditation was low and negative under NR and ANR, respectively. ROI was greater under ANR with inclusion of biomass and autochthonous soil carbon; however, neither strategy was highly profitable at current voluntary market carbon prices. ANR was the only scenario that fulfilled coastal protection greenbelt potential, with full mangrove cover within 10 years. Our findings highlight the benefits of ANR and soils inclusion in rehabilitation-oriented blue carbon projects, to maximize carbon sequestration and greenbelt enhancement (thus enhance pricing with potential bundled credits), and minimize forecasting uncertainty and credit-buyers’ perceived risk. An ANR rehabilitation strategy in low-lying, sea-facing abandoned ponds with low biophysical intervention costs may represent large blue carbon CCMA opportunities in regions with high aquaculture abandonment.

Incorporating historical information to improve extreme sea level estimates

Extreme value analysis seeks to assign probabilities to events which deviate significantly from the mean and is thus widely employed in disciplines dealing with natural hazards. In terms of extreme sea levels (ESLs), these probabilities help to define coastal flood risk which guides the design of coastal protection measures. While tide gauge and other systematic records are typically used to estimate ESLs, combining systematic data with historical information has been shown to reduce uncertainties and better represent statistical outliers. This paper introduces a new method for the incorporation of historical information in extreme value analysis which outperforms other commonly used approaches. Monte-Carlo Simulations are used to evaluate a posterior distribution of historical and systematic ESLs based on the prior distribution of systematic data. This approach is applied at the German town of Travemünde, providing larger ESL estimates compared to those determined using systematic data only. We highlight a potential to underestimate ESLs at Travemünde when historical information is disregarded, due to a period of relatively low ESL activity for the duration of the systematic record.

Gabion as a coastal protection structure: a case study in Panjang Island Indonesia

Panjang Island is a small island in Jepara, Indonesia which is very vulnerable to coastal damage due to crashing waves. Therefore, presence of coastal protection structure is essentially important. Gabion structure was constructed to protect this coastal area. Considering the age, the existing gabion structure needed assessment and analysis to ensure its performance in term of protecting the coastal area. This study aimed at assessing and analyzing the performance of the existing gabion structure. Data of the study were collected through observing the condition of the structure. Assessment was carried out by scaling 1 (minor) to 5 (severe damage). Results of the analysis showed that the value of stability to overturning was 3.96, while the stability to shearing was 2.07, the structure stability was in safe category. Soil pressure under the structure in σ max. was 0.39 kg/cm2, while σ min was 0.16 kg/cm2, which means safe. The condition of gabion as a coastal protection structure in section 1 was partially damaged with a moderate level of damage, in section 2, the damage was revealed to be a minor level of damage, while in section 3, the damage was in a minor level of damage.

Salt Marsh Restoration for the Provision of Multiple Ecosystem Services

Restoration of salt marsh is urgent, as these ecosystems provide natural coastal protection from sea-level rise impacts, contribute towards climate change mitigation, and provide multiple ecosystem services including supporting livelihoods. This study identified potential restoration sites for intervention where agricultural and degraded land could be returned to salt marsh at a national scale in South African estuaries. Overall, successful restoration of salt marsh in some estuaries will require addressing additional pressures such as freshwater inflow reduction and deterioration of water quality. Here, we present, a socio-ecological systems framework for salt marsh restoration that links salt marsh state and the well-being of people to guide meaningful and implementable management and restoration interventions. The framework is applied to a case study at the Swartkops Estuary where the primary restoration intervention intends to route stormwater run-off to abandoned salt works to re-create aquatic habitat for waterbirds, enhance carbon storage, and provide nutrient filtration. As the framework is generalized, while still allowing for site-specific pressures to be captured, there is potential for it to be applied at the national scale, with the largest degraded salt marsh areas set as priorities for such an initiative. It is estimated that ~1970 ha of salt marsh can be restored in this way, and this represents a 14% increase in the habitat cover for the country. Innovative approaches to restoring and improving condition are necessary for conserving salt marshes and the benefits they provide to society.

Flooding of Sandy Beaches in a Changing Climate. The Case of the Balearic Islands (NW Mediterranean)

The fate of the beaches around the world has paramount importance as they are one of the main assets for touristic activities and act as a natural barrier for coastal protection in front of marine storms. Climate change could put them at risk as sea levels rise and changes in the wave characteristics may dramatically modify their shape. In this work, a new methodology has been developed to determine the flooding of sandy beaches due to changes in sea level and waves. The methodology allows a cost-effective and yet accurate estimation of the wave runup for a wide range of beach equilibrium profiles and for different seagrass coverage. This, combined with regional projections of sea level and wave evolution, has allowed a quantification of the future total water level and coastline retreat for 869 beaches across the Balearic Islands for the next decades as a function of greenhouse gases emission scenario. The most pessimistic scenario (RCP8.5) at the end of the century yields an averaged percentage of flooded area of 66% under mean conditions which increases up to 86% under extreme conditions. Moreover, 72 of the 869 beaches of the region would permanently disappear while 314 would be completely flooded during storm episodes. Under a moderate scenario of emissions (RCP4.5), 37 beaches would permanently disappear while 254 would disappear only during storm episodes. In both cases, the average permanent loss of beach surface at the end of the century would be larger than 50%, rising over 80% during storm conditions. The results obtained for the Balearic Islands can be extrapolated to the rest of the Mediterranean as the beaches in all the regions have similar characteristics and will be affected by similar changes in sea level and wave climate. These projections indicate that adaptation plans for beach areas should be put in place as soon as possible.

Impact Of Seawall Development To The Sulawesi Fishermen Community In Pambusuang Village

A coastal protection structure mostly built to protect human from the detructive wind and wave energy. The various option of type and design has been invented in the development. This study investigates the impact of seawall development in Pambusuang Village, West Sulawesi. This study will examine the fishery activity change after the development of seawall. The benefit and disadvantages of the seawall structure to the community also as well as the community response to address the impact of seawall development will be explored in this study. A mix quantitave and qualitative approach is used in this study. A set of questionnare has been distributed and structured interview to selected infromant were also conducted. The study found that fishermen has changed their docking behavior due to the limited area to docking. Moreover, the respondent believes that seawall has properly function to halt erosion, protect their house and other infrastructure from the wave attack. The other issues is the disharmony between pro and contra seawall development, inundated river flow and damage of natural habitat. The response of the community to addressing some impact of the seawall development such as their adaptation to the sloping gate between the seawall, the use of traditional anti fouling painting and their suggestion to construct breakwater disattached from the shoreline. The findings above has been formed the basis of recommendations to have a participatory development approach and experience sharing between the parties in the community to adapt with the impact of seawall development.

Components and Tidal Modulation of the Wave Field in a Semi-Enclosed Shallow Bay

The wave field in coastal bays is comprised of waves generated by far-off storms and waves generated locally by winds inside the bay and regionally outside the bay. The resultant wave field varies spatially and temporally and is expected to control morphologic features, such as beaches in estuaries and bays (BEBs). However, neither the wave field nor the role of waves in shaping BEBs have been well-studied, limiting the efficacy of coastal protection and restoration projects. Here we present observations of the wave field in Tomales Bay, a 20 km long, narrow, semi-enclosed embayment on the wave-dominated coast of Northern California (USA) with a tidal range of 2.5 m. We deployed pressure sensors in front of several beaches along the linear axis of the bay. Low-frequency waves (4 * 10^-2 * 2.5 * 10*^-1 Hz or 4 - 25 s period) dissipated within 4 km of the mouth, delineating the "outer bay" region, where remotely-generated swell and regionally-generated wind waves can dominate. The "inner bay" spectrum, further landward, is dominated by fetch-limited waves generated within the bay with frequency >= 2.5 < 10*-1 Hz. The energy of both ocean waves and locally-generated wind waves across all sites were modulated by the tide, owing to tidal changes in water depth and currents. Wave energies were typically low at low tide and high at high tide. Thus, in addition to fluctuations in winds and the presence of ocean waves, tides exert a strong control on the wave energy spectra at BEBs in mesotidal regions. In general, it is expected that events that can reshape beaches occur during high wind or swell events that occur at high-tide, when waves can reach the beaches with less attenuation. However, no such events were observed during our study and questions remain as to how rarely such wind-tide concurrences occur across the bay.

Sand Trapping Fences as a Nature-Based Solution for Coastal Protection: An International Review with a Focus on Installations in Germany

Sand trapping fences are a widely used nature-based solution to initiate dune toe growth along sandy shorelines for coastal protection. At present, the construction of sand trapping fences is based on empirical knowledge, since only a few scientific studies investigating their efficiency exist. However, the restoration and maintenance of beach-dune systems along the coast requires knowledge of the interaction between the beach-dune system and the sand trapping fences to provide guidance for coastal managers on how and where to install the fences. First, this review gives an overview of the typical aerodynamic and morphodynamic conditions around a single porous fence and the influence of various fence height and porosity values to understand the physical processes during dune establishment. Second, different approaches for evaluating the efficiency of sand trapping fences to trap sediment are described. This review then highlights significant differences between sand trapping fence configurations, nationally as well as internationally, regarding the arrangement, the materials used, and the height and porosity. In summary, it is crucial to enable an intensive exchange among the respective coastal authorities in order to create uniform or transferable guidelines taking local conditions into account, and thus work collaboratively on the idea of sand trapping fences as a nature-based solution in coastal areas worldwide.

Coastal dynamics of the Gulf of Kalamita (Western Crimea)

The performed research showed that since the first third of the 20th century until today the beach width at various sections of the Gulf of Kalamita has decreased two-to fourfold, and at some of them beaches have totally disappeared. The average coast erosion rate for the last 100 years has been 1.3 m/yr, with the maximum being 7.8 m/yr. These processes are accompanied with depletion of debris on the beach and underwater slope, erosion of bench deposits, and destruction of coastal structures. This is due to deficiency of beach-forming material resulted from intense economic management in the coastal area. Implementation of scientifically and technically sound coastal protection projects is essential to preserve the beaches of the Gulf of Kalamita.