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This article examines the dynamics of Singaraja’s urban morphology as a case of a coastal city in Southeast Asia that has been transformed by the intervention of colonial power, postcolonial discourse and global contemporary development trends. Depart from the critic to urban morphology approach that is dominated by the Global North, this article utilized multidisciplinary framework that combining historical morphology, the production of space, spatial hybridity and the role of the nation in the construction of spatial symbolic. The main finding shows that the urban form is never neutral but a result of power accumulation, identity politics, and the restructuration of regional connectivity network. This study calls for a more contextual, historical, and critical morphological approach to reading cities in the Global South.

Over recent years, many coastal engineering projects have employed the use of soft solutions as these are generally less environmentally damaging than hard solutions. However, in some cases, local conditions hinder the use of soft solutions, meaning that hard solutions have to be adopted or, sometimes, a combination of hard and soft measures is seen as optimal. This research reviews the use of hard coastal structures on the foreshore (groynes, breakwaters and jetties) and onshore (seawalls and dikes). The purpose, functioning and local conditions for which these structures are most suitable are outlined. A description is provided on the negative effects that these structures may have on morphological, hydrodynamic and ecological conditions. To reduce or mitigate these negative impacts, or to create new ecosystem services, the following nature-based adaptations are proposed and discussed: (1) applying soft solutions complementary to hard solutions, (2) mitigating morphological and hydrodynamic changes and (3) ecologically enhancing hard coastal structures. The selection and also the success of these potential adaptations are highly dependent on local conditions, such as hydrodynamic forcing, spatial requirements and socioeconomic factors. The overview provided in this paper aims to offer an interdisciplinary understanding, by giving general guidance on which type of solution is suitable for given characteristics, taking into consideration all aspects that are key for environmentally sensitive coastal designs. Overall, this study aims to provide guidance at the interdisciplinary design stage of nature-based coastal defence structures.

Changes in coastal morphology have broad consequences for the sustainability of coastal communities, structures and ecosystems. Although coasts are monitored locally in many places, understanding long-term changes at a global scale remains a challenge. Here we present a global and consistent evaluation of coastal morphodynamics over 32 years (1984–2015) based on satellite observations. Land losses and gains were estimated from the changes in water presence along more than 2 million virtual transects. We find that the overall surface of eroded land is about 28,000 km 2 , twice the surface of gained land, and that often the extent of erosion and accretion is in the order of km. Anthropogenic factors clearly emerge as the dominant driver of change, both as planned exploitation of coastal resources, such as building coastal structures, and as unforeseen side effects of human activities, for example the installment of dams, irrigation systems and structures that modify the flux of sediments, or the clearing of coastal ecosystems, such as mangrove forests. Another important driver is the occurrence of natural disasters such as tsunamis and extreme storms. The observed global trend in coastal erosion could be enhanced by Sea Level Rise and more frequent extreme events under a changing climate.

River deltas rank among the most economically and ecologically valuable environments on Earth. Even in the absence of sea-level rise, deltas are increasingly vulnerable to coastal hazards as declining sediment supply and climate change alter their sediment budget, affecting delta morphology and possibly leading to erosion 1 – 3 . However, the relationship between deltaic sediment budgets, oceanographic forces of waves and tides, and delta morphology has remained poorly quantified. Here we show how the morphology of about 11,000 coastal deltas worldwide, ranging from small bayhead deltas to mega-deltas, has been affected by river damming and deforestation. We introduce a model that shows that present-day delta morphology varies across a continuum between wave (about 80 per cent), tide (around 10 per cent) and river (about 10 per cent) dominance, but that most large deltas are tide- and river-dominated. Over the past 30 years, despite sea-level rise, deltas globally have experienced a net land gain of 54 ± 12 square kilometres per year (2 standard deviations), with the largest 1 per cent of deltas being responsible for 30 per cent of all net land area gains. Humans are a considerable driver of these net land gains—25 per cent of delta growth can be attributed to deforestation-induced increases in fluvial sediment supply. Yet for nearly 1,000 deltas, river damming 4 has resulted in a severe (more than 50 per cent) reduction in anthropogenic sediment flux, forcing a collective loss of 12 ± 3.5 square kilometres per year (2 standard deviations) of deltaic land. Not all deltas lose land in response to river damming: deltas transitioning towards tide dominance are currently gaining land, probably through channel infilling. With expected accelerated sea-level rise 5 , however, recent land gains are unlikely to be sustained throughout the twenty-first century. Understanding the redistribution of sediments by waves and tides will be critical for successfully predicting human-driven change to deltas, both locally and globally. A global study of river deltas shows a net increase in delta area by about 54 km 2  yr −1 over the past 30 years, in part due to deforestation-induced sediment delivery increase.

Because mangroves store greater amounts of carbon (C) per area than any other terrestrial ecosystem, conservation of mangrove forests on a global scale represents a potentially meaningful strategy for mitigating atmospheric greenhouse-gas (GHG) emissions. However, analyses of how coastal ecosystems influence the global C cycle also require the mapping of ecosystem area across the Earth’s surface to estimate C storage and flux (movement) in order to compare how different ecosystem types may mitigate GHG enrichment in the atmosphere. In this paper, we propose a new framework based on diverse coastal morphology (that is, different coastal environmental settings resulting from how rivers, tides, waves, and climate have shaped coastal landforms) to explain global variations in mangrove C storage, using soil organic carbon (SOC) as a model to more accurately determine mangrove contributions to global C dynamics. We present, to the best of our knowledge, the first global mangrove area estimate occupying distinct coastal environmental settings, comparing the role of terrigenous and carbonate settings as global “blue carbon” hotspots. C storage in deltaic settings has been overestimated, while SOC stocks in carbonate settings have been underestimated by up to 50%. We encourage the scientific community, which has largely focused on blue carbon estimates, to incorporate coastal environmental settings into their evaluations of C stocks, to obtain more robust estimates of global C stocks.

The brine‐seawater interface (BSI) is a unique type of groundwater‐seawater interface (GSI) characterized by the higher density of underground brine compared to seawater. This study focuses on characterizing the bay‐scale BSI morphology and identifying submarine‐groundwater discharge windows using a comprehensive in‐situ geophysical detection on the south bank of Laizhou Bay. Our findings reveal that the BSI forms an extensive mixing zone (15–20 km) without distinct contours between waters of varying salinities. The discharge windows for underground brine are located in nearshore areas with fine sand distribution and offshore pockmark areas. Hydraulic and salinity gradients drive the underground brine discharge through these windows. The aquitard window is the primary area for shallow and deep brine exchange, likely evolved from paleochannels, ancient tidal creeks, or ancient underwater barriers. These findings provide crucial modeling support for analyzing environmental evolution mechanisms and theoretical basis for planning the underground brine mining in similar coastal regions. Plain Language Summary This study investigates a unique interface where underground brine meets seawater, known as the brine‐seawater interface (BSI). Unlike regular groundwater‐seawater interfaces, the BSI features brine that is denser than seawater. The research focused on characterizing the BSI's morphology and identifying locations where brine discharges into the sea along the south bank of Laizhou Bay. By using advanced detection methods and analyzing samples, the study found that the BSI forms a broad mixing zone of about 15–20 km. There are no clear boundaries between water of different salinities within this zone. The study also identified specific areas near the shore with fine sand and offshore pockmarks where brine discharges occur. These areas are recognized by the presence of suspended fine sediment on the seabed. The movement of brine through these discharge areas is driven by differences in water pressure and salinity. The study suggests that ancient channels and barriers underwater play a significant role in these discharge processes. Understanding these dynamics can help us manage coastal environments and predict how changes in sea and land interactions may affect them. Key Points The bay‐scale brine‐seawater interface (BSI) is a long mixing zone with underground water salinity ranging from high to low from land to sea The nearshore seabed fine sand area and offshore pockmarked area are the main windows for underground brine discharge The BSI morphology and submarine groundwater discharge/exchange windows can be identified by comprehensive geophysical detection results

Coastal responses to sea level rise (SLR) include inundation of wetlands, increased shoreline erosion, and increased flooding during storm events. Hydrodynamic parameters such as tidal ranges, tidal prisms, tidal asymmetries, increased flooding depths and inundation extents during storm events respond nonadditively to SLR. Coastal morphology continually adapts toward equilibrium as sea levels rise, inducing changes in the landscape. Marshes may struggle to keep pace with SLR and rely on sediment accumulation and the availability of suitable uplands for migration. Whether hydrodynamic, morphologic, or ecologic, the impacts of SLR are interrelated. To plan for changes under future sea levels, coastal managers need information and data regarding the potential effects of SLR to make informed decisions for managing human and natural communities. This review examines previous studies that have accounted for the dynamic, nonlinear responses of hydrodynamics, coastal morphology, and marsh ecology to SLR by implementing more complex approaches rather than the simplistic “bathtub” approach. These studies provide an improved understanding of the dynamic effects of SLR on coastal environments and contribute to an overall paradigm shift in how coastal scientists and engineers approach modeling the effects of SLR, transitioning away from implementing the “bathtub” approach. However, it is recommended that future studies implement a synergetic approach that integrates the dynamic interactions between physical and ecological environments to better predict the impacts of SLR on coastal systems. Key Points The dynamic effects of sea level rise (SLR) are interrelated SLR research efforts are moving beyond the “bathtub” approach Synergetic studies integrating dynamic systems under SLR are needed

Coastal wetlands fulfil important functions for biodiversity conservation and coastal protection, which are inextricably linked to typical morphological features like tidal channels. Channel network configurations in turn are shaped by bio-geomorphological feedbacks between vegetation, hydrodynamics and sediment transport. This study investigates the impact of two starkly different recruitment strategies between mangroves (fast/homogenous) and salt marshes (slow/patchy) on channel network properties. We first compare channel networks found in salt marshes and mangroves around the world and then demonstrate how observed channel patterns can be explained by vegetation establishment strategies using controlled experimental conditions. We find that salt marshes are dissected by more extensive channel networks and have shorter over-marsh flow paths than mangrove systems, while their branching patterns remain similar. This finding is supported by our laboratory experiments, which reveal that different recruitment strategies of mangroves and salt marshes hamper or facilitate channel development, respectively. Insights of our study are crucial to understand wetland resilience with rising sea-levels especially under climate-driven ecotone shifts. A comparison of salt marsh and mangrove channel networks around the world exhibited different network extents. This could be linked to differences in vegetation colonization strategies, with major implications on coastal development.

Coastal engineering models frequently represent vegetation as rigid cylinders to simulate the geometry of mangrove trees, including their roots, trunks, and canopies. However, mangrove geometry varies widely across different species, ages, geographic locations, and environmental conditions. Despite numerous studies on mangrove morphology, comprehensive data describing these geometric variations for accurate coastal protection models remain scarce. These geometric variations, particularly in root structures, play a crucial role in influencing functions such as flow modifications, sediment deposition, surface elevation changes, and wave reduction. Acknowledging the ecological complexities often neglected in engineering models, our meta-analysis examines the differences in mangrove geometry among genera and climatic zones. We systematically reviewed the literature to compile published values of mangrove geometry, detailing the height, diameter, and densities of roots, trunks, and canopies for 28 mangrove genera across four climatic regions (tropical, subtropical, semi-arid, and temperate). Our findings offer a valuable resource for coastal protection modellers aiming to improve the precision and reliability of mangrove-based defence models. Additionally, the dataset reveals gaps and biases in data collection for certain genera in specific climatic regions, suggesting areas for future research to address these deficiencies.

The city of Lhokseumawe in Aceh is mostly located on the coast and is vulnerable to annual tidal waves, causing coastal settlements to sink. The rising sea levels in Indonesia, as observed by the IPCC using the TOPEX/POSEIDEN satellite, have reached 7 mm/year. A study was conducted to assess the impact of tidal waves exacerbated by sea level rise on changes in coastal morphology over 25 and 50 years. The study utilized the Delft3D numerical simulation method with various input data such as Topographic Data, bathymetry, tides, discharge, sediment, and waves. The results of the Delft3D modeling showed that erosion is slightly greater in the 25 and 50-year scenarios, with an average minimum erosion of about 12 m and a maximum erosion and retreat of about 18 m. However, in the 50-year scenario, there were points along the coast where sedimentation occurred, leading to the advancement of the coastline by about 36 m. These dynamic morphological changes in the coastal area of Lhokseumawe highlight the need for a coastal protection plan to address this vulnerability.