Relative Sea-level Rise Research Articles

Sequence stratigraphy in fine-grained successions is often challenging with traditional datasets, and in such intervals, chemostratigraphy is increasingly used to facilitate interpretations. In this study, we present an example from mudstone units of the Horn River Group (Northwest Territories, Canada), which provide a local record of Middle to Late Devonian marine conditions. The dataset comprises geochemical composition data from X-ray fluorescence (XRF), mineralogical data from X-ray diffraction (XRD), wireline logs, total organic carbon (TOC) profiles, and lithological core and thin section descriptions. We first focus on a mudstone core with high-resolution thin-section and geochemical results, enabling the evaluation of chemostratigraphic signatures associated with surfaces and systems tracts in the Horn River Group. By employing chemostratigraphic proxies for terrigenous sediment supply and proportion of biogenic silica, sequence stratigraphic analysis is extended to three cores and five outcrops lacking extensive thin section coverage. Six complete transgressive–regressive (T–R) sequences are identified and correlated in the Horn River Group, comprising higher-resolution cycles in relative sea-level and sediment supply, which are superimposed on previously identified larger-scale sequences. The sequence stratigraphic framework presented illustrates the local balance between relative sea-level rise and sediment supply along the northwestern margin of Laurentia during the Eifelian to the Frasnian. Moreover, this study demonstrates the utility of integrating chemostratigraphic proxies with sedimentological results as a means of sequence stratigraphic interpretation and correlation in mudstone intervals.

Abstract Future sea level (SL) change in the Mediterranean Sea is one of the major climate hazards for populations living in coastal areas. In this study, we analyze projections of relative sea level (RSL) rise in the Mediterranean Sea until the end of the 21st century. For the first time, we provide a detailed characterization of regional patterns of future SL change using an ensemble of three multi-decadal SSP5-8.5 scenario simulations with high-resolution fully coupled regional climate system models (RCSMs) of the Med-CORDEX initiative and their driving global climate models (GCMs). At the basin-scale, RCSMs do not significantly modify the GCM-projected RSL changes by 2100, with a mean RSL change of 69 cm (60-93 cm, 17th-83rd percentiles) relative to 1995-2014. Among the RSL components, the sterodynamic (primarily driven by the global thermal expansion) and the surface mass balance drive the basin-scale RSL rise, with the latter being the largest source of uncertainty. We find that the RSL rise in the Mediterranean is expected to be 4-12% lower than the global mean due to differences in the surface mass contribution, and 6-15% lower than in the nearby Atlantic as a result of dynamic adjustments within the semi-enclosed basin. While dynamic SL drives the mean regional patterns, vertical land motion introduces the greatest local spatial variability along coasts, resulting in a projected local RSL rise by 2100 of -26 cm to +178 cm in GCMs and -39 cm to +170 cm in RCSMs. Furthermore, compared to GCMs, RCSMs incorporate local details that result in greater spatial variability, which is important to consider in risk assessments and adaptation planning.

ABSTRACT Sequence stratigraphy provides a framework for analysing sedimentary successions. It organizes multiscale cyclical units of genetically related rocks into a hierarchical chronostratigraphic framework. Within this framework, stacking patterns and stratigraphic surfaces serve as key sequence elements, reflecting the tectonic, climatic, and eustatic processes that drive sedimentary cyclicity. Building on this approach, the Xuankong Temple section in Hunyuan City, Shanxi Province, preserves a continuous Cambrian stratigraphic succession with distinct sequence boundaries and diverse depositional features influenced by relative sea-level fluctuations, yet it remains underexplored. This study investigates the succession with a focus on sedimentary facies, stacking patterns, and cyclicity. The Cambrian system at Xuankong Temple consists of Miaolingian and Furongian strata, including the Xuzhuang, Zhangxia, Gushan, Changshan, and Fengshan formations, which can be segmented into six 3rd order sequences (DS1 to DS6). The strata are primarily composed of calcareous mudstone in the lower part, followed by micritic limestone and are topped by oolitic grainstone banks and fossiliferous limestone. Ooids and fossiliferous limestone are restricted to the upper part of the Cambrian strata, which was overlain by calcareous mudstone belonging to the younger formation, representing the drowning unconformity. These confined deposits, associated with 3rd order sequences, resulted from a relative drop in sea level (forced regressive systems tract), challenge the conventional framework of sequence stratigraphy, which posits that sedimentation predominantly occurs during periods of relative sea level rise. The distinctive style of these regressive deposits aligns with Schlager’s sequence stratigraphic framework, which led to the development of a new ramp-type carbonate platform on the North China Platform (NCP). The model of facies superposition, Cambrian stratigraphic cyclicity, and updated chronostratigraphic scheme, together with the current depositional dynamics in the Xuankong Temple section, provide a reference for further research on regional correlations and the study of diverse biosedimentary fabrics on the NCP.

Marsh sill living shorelines are increasingly common nature-based features in coastal estuaries used to mitigate shoreline erosion and enhance coastal resilience. Evaluating the stability of these structures is crucial for shoreline design and coastal management strategies. Although several metrics have been developed to assess the stability of natural tidal marshes, their suitability for the created marshes of living shorelines is still unclear. This research compiles and analyzes data from 18 marsh sill living shorelines in Maryland, USA — nine with continuous sills and nine with segmented sills. We characterize their eco-geomorphic features and hydrodynamics with 15 metrics through both field sampling and remote sensing. Among the 15 metrics, six representative ones are selected to identify the major factors influencing potential marsh boundary degradation in marsh sill living shorelines. Our findings indicate that living shorelines with ponding at the marsh edge have a significantly higher Unvegetated/Vegetated Ratio (p < 0.05) and a lower sediment deposition rate (p < 0.1). Gap/Rock ratio and Relative Exposure Index contribute significantly to differences between living shorelines with and without ponding, explaining 5.46% and 4.41% of the variation, respectively (p < 0.05 for both). Functional marsh width, introduced here as a novel metric, shows a varying relationship with sediment deposition rate depending on whether the deposition rate exceeded or fell below the relative sea level rise. A marsh width of approximately 5–10 meters appears to optimize both cost-effectiveness and sediment accumulation. By integrating data across regional ecosystems, this study advances our understanding of potential degradation processes in living shorelines, offering valuable insights for shoreline design and post-construction maintenance.

Assessing the impacts of future relative sea level rise requires projections consistent with historical observations. However, existing projections often do not align with past data, complicating adaptation planning, impact assessments, and communication. We present a spatial Bayesian model that generates local projections at tide gauge sites from historical records. The model integrates tide gauges, GPS, and satellite altimetry with past and future constraints on mountain glaciers, polar ice sheets, thermal expansion, ocean circulation, land water storage, and glacial history. By separating unforced ocean variability from long-term trends, we provide posterior estimates of sea level change and vertical land motion. The inclusion of local constraints reduces uncertainty in near-term local projections while producing global median projections and uncertainty ranges similar to those in the Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change (IPCC). The model enables projections of local relative sea level rise for any given global temperature trajectory, illustrated with three IPCC AR6 Working Group III pathways.

Nest exposure to marine flooding and impacts on green turtle (Chelonia mydas) embryos under rapid sea level rise: The role of beach geomorphology and hydrodynamics.

Sahabi ‘B’ Reef is one of several pinnacle reefs located in the southern part of the Ajdabiya Trough. The Sahabi 'B' Reef is vague for several reasons: only four wells have penetrated the reef, resulting in limited subsurface information; two wells were abandoned as dry wells, while the other two have produced from different oil pay zones, indicating strong lateral facies variation in and around the reef. Utilizing seismic and well data, the distinct depositional architecture of the carbonate Late Paleocene successions and their potential as petroleum reservoirs are examined. The study aims to explain why some wells in the Sahabi ‘B’ Reef complex are producing while others are not, and to identify facies changes that facilitate an understanding of their evolution over geological time. Four developments of the lithofacies in the Upper Sabil Carbonate have been distinguished from bottom to top: (1) open shallow marine packstone/grainstone, (2) bioclastic grainstone/packstone with tidal effect, (3) coral floatstone/boundstone, and (4) bio-lithoclastic talus. The Sahabi "B" Reef consists of two reefs (older and younger parts). During the Middle Eocene, the area generally dipped towards the location of the younger reef. A tilt is attributed to bending rather than faulting, causing minor saddles and humps between these two reefs. This could plausibly explain the presence of oil accumulation in the younger part of the Sahabi 'B' reef, while its absence is noted in the older part. The reef complex is seismically divided into major lateral facies, which vary in terms of deposition and age; these include: (1) older reef, (2) shoal, (3) younger reef, and (4) talus. During the Paleocene, Upper Sabil carbonates exhibited an aggrading build-up that kept pace with relative sea-level rise, marking the first Sahabi 'B' Reef formation. Subsidence and relative sea-level rise resulted in the backstepping of the second Sahabi 'B' Reef within the pre-existing topography. By the end of the Paleocene, this stage marks the conclusion of the Sahabi 'B' Reef complex, when the reef was drowned due to rapid sea-level rise, leading to a basin dominated by shale deposition.

The Aptian shallow-water carbonate platform of the Benassal Formation in eastern Spain (Maestrat Basin) contains facies dominated by scleractinian corals. Corals and coral reefs are widely used as environmental archives; however, the effects of their complex diagenetic evolution are a major factor impacting reliable reconstructions of the environments. This study addresses the environmental signatures (i.e. relative sea-level changes) and burial conditions that controlled the various diagenetic minerals present in the Aptian coral facies. A multiproxy approach including petrographic and geochemical evaluation reveals the diagenetic pathways, fluid compositions and timing accounting for the syn- to post-depositional history of this ancient coral facies. Cc1, which shows low Fe and Mn content and high Na content, precipitated within the primary porosity, alongside the replacement of coral skeletons, in a mixing zone dominated by marine waters. Cement Cc2, characterized by its higher Fe and Mn content and low Na values, precipitated in the mixing zone dominated by meteoric waters related to a relative sea-level drop. Cement Cc3, distinguished by low Fe and Mn content and high Na content, reflects a subsequent phase of increased marine influence, likely associated with a relative sea-level rise. Silica and isolated rhombohedral dolomite crystals formed concurrently in this mixing zone. During intermediate burial, saddle dolomite and cement Cc4 precipitated from high-temperature formation brines. Finally, during uplift, meteoric fluids caused the calcitization of previously formed dolomite rhombohedra.

Delta under pressure: A holistic assessment of morphodynamic change in the Indian Sundarbans from 1972 to 2025.

Abstract Globally, coastal forested wetlands are increasingly affected by relative sea level rise. However, the mechanisms underlying coastal wetland degradation remain unclear. Using the eddy covariance approach, we evaluated the long-term (i.e. 2009–2019) net ecosystem exchange (NEE), associated hydrology, and ecosystem structural changes in a forested wetland in North Carolina, USA. We quantified tree mortality in response to changes in hydrology. The ecosystem shifted from a net C sink (NEE = − 3.68 Mg C ha−1 yr−1) pre-2010 to a net C source (NEE = 0.87 Mg C ha−1yr−1–7.59 Mg C ha−1 yr−1) afterward. We ascribe the ecosystem C loss to increasing tree mortality (i.e. from 1.6% in 2009 to 45.8% in 2019), partly due to relative sea level rise (R 2 = 0.62). Tree mortality, and consequent shift of NEE, provide early warning signs of a transition in this ecosystem more than 20 km inland from the coast.

Purpose The Vietnamese Mekong Delta (VMD), a vital agricultural region supporting millions, faces severe environmental threats from interacting anthropogenic pressures and climate change, profoundly altering its hydrology. A comprehensive, quantitative understanding of recent water level changes is lacking. This study aims to identify and quantify changes in annual flood peaks and key tidal water level characteristics (1980–2024), analyzing the combined drivers. Design/methodology/approach This paper analyzed long-term (1980–2024) daily/hourly water level records from strategic hydrometric stations. Time series analysis, including low-pass filtering and Mann–Kendall/Sen’s slope tests, identified significant changes in annual flood peaks, mean water levels (MWLs) and tidal range (TR). Findings Analysis reveals significant upstream flood peak decline (especially post-2010s, linked to hydropower). MWL decreased upstream post-2000 but rose substantially mid-delta/coastally, amplified beyond regional relative sea level rise by local factors. Most stations show marked lower low water decreases alongside significant TR increases, indicating enhanced tidal propagation and amplification, more pronounced along the Tien River than the Hau River. Originality/value This paper offers a quantitative, spatiotemporal assessment connecting flood and tidal regime changes to the interplay of multiple drivers during accelerating environmental change. It highlights escalating risks—reduced freshwater availability, increased tidal inundation, heightened salinity intrusion—providing crucial insights for developing robust water resource management and climate adaptation strategies essential for the VMD’s sustainability.

Understanding the current Vertical Land Motion (VLM), including subsidence or uplift, is the basis for projecting Relative Sea Level Rise (RLSR) and estimating related risks. However, in Shanghai, the impacts of the spatiotemporal change of VLM are little known. The purpose of this study was to quantify the impact of VLM on RSLR and investigate the spatiotemporal evolution characteristics of VLM through tide gauge records, satellite altimetry observations, and Interferometric Synthetic Aperture Radar (InSAR) measurements. The calculations indicated that the RSLR (5.67±0.58 mm/year) from 1969 to 2019 was approximately twice the SLR trend (2.44±0.28 mm/year) from 1993 to 2019. The VLM, especially subsidence, is the main driver of RSLR. Moreover, spatial and temporal patterns of VLM are highly uneven and nonlinear. These results reveal that VLM is the main driver of RSLR. Unfortunately, previous studies have mostly underestimated or overlooked the impact of VLM on the risks of RSLR and subsequent coastal flooding. Thus, prevention strategies for controlling VLM are warranted to minimize the negative impact related to the RSLR. Our research provides a theoretical basis for urban disaster prevention in Shanghai and the planning of coastal cities worldwide.

The possibility of collecting new archaeological elements useful in reconstructing the dynamics of population, production and commercial activities in the Bronze Age at the edge of the central-southern Venice Lagoon was provided between 2023 and 2024 thanks to an intervention of rescue archaeology planned during some water restoration works in the Giare–Mira area. Three small excavations revealed, approximately one meter below the current surface and covered by alluvial sediments, a rather complex palimpsest dated to the late Recent and the early Final Bronze Age. Three large circular pits containing exclusively purified grey/blue clay and very rare inclusions of vegetable fibres, and many large, fired clay vessels’ bases, walls and rims clustered in concentrated assemblages and random deposits point to potential on-site production. Two pyro-technological structures, one characterised by a sub-circular combustion chamber and a long inlet channel/praefurnium, and the second one with a sub-rectangular shape with arched niches along its southern side, complete the exceptional context here discovered. To analyse the relationship between the site and the natural sedimentary succession and to evaluate the possible extension of this site, three electrical resistivity tomography (ERT) and low-frequency electromagnetic (FDEM) measurements were collected. Several manual core drillings associated with remote sensing integrated the geophysical data in the analysis of the geomorphological evolution of this area, clearly related to different phases of fluvial activity, in a framework of continuous relative sea level rise. The typology and chronology of the archaeological structures and materials, currently undergoing further analyses, support the interpretation of the site as a late Recent/early Final Bronze Age productive site. Geophysical and geomorphological data provide information on the palaeoenvironmental setting, suggesting that the site was located on a fine-grained, stable alluvial plain at a distance of a few kilometres from the lagoon shore to the south-east and the course of the Brenta River to the north. The archaeological site was buried by fine-grained floodplain deposits attributed to the Brenta River. The good preservation of the archaeological structures buried by fluvial sediments suggests that the site was abandoned soon before sedimentation started.

Mangrove forests serve as critical ecological barriers in coastal zones and play a vital role in global blue carbon sequestration strategies. In recent decades, China’s mangrove ecosystems have experienced complex interactions between degradation and restoration under intense coastal urbanization and systematic conservation efforts. However, the long-term spatiotemporal patterns and driving mechanisms of mangrove ecosystem health changes remain insufficiently quantified. This study developed a multi-temporal analytical framework using Landsat imagery (1986–2021) to derive kernel normalized difference vegetation index (kNDVI) time series—an advanced phenological indicator with enhanced sensitivity to vegetation dynamics. We systematically characterized mangrove growth patterns along China’s southeastern coast through integrated Theil–Sen slope estimation, Mann–Kendall trend analysis, and Hurst exponent forecasting. A Deep Forest regression model was subsequently applied to quantify the relative contributions of environmental drivers (mean annual sea surface temperature, precipitation, air temperature, tropical cyclone frequency, and relative sea-level rise rate) and anthropogenic pressures (nighttime light index). The results showed the following: (1) a nationally significant improvement in mangrove vitality (p &lt; 0.05), with mean annual kNDVI increasing by 0.0072/yr during 1986–2021; (2) spatially divergent trajectories, with 58.68% of mangroves exhibiting significant improvement (p &lt; 0.05), which was 2.89 times higher than the proportion of degraded areas (15.10%); (3) Hurst persistence analysis (H = 0.896) indicating that 74.97% of the mangrove regions were likely to maintain their growth trends, while 15.07% of the coastal zones faced potential degradation risks; and (4) Deep Forest regression id the relative rate of sea-level rise (importance = 0.91) and anthropogenic (nighttime light index, importance = 0.81) as dominant drivers, surpassing climatic factors. This study provides the first national-scale, 30 m resolution assessment of mangrove growth dynamics using kNDVI, offering a scientific basis for adaptive management and blue carbon strategies in subtropical coastal ecosystems.

The region surrounding Gouda, in the middle of the Dutch Delta, is one of the lowest-lying areas in the Netherlands. The historic inner city is situated at the current high-water mark (Amsterdam Ordnance Datum, or NAP). In contrast, the surrounding landscape lies between two and six meters below that due to subsidence as a result of draining the land and making it available for urbanization and agriculture. The original factors that caused the land to subside are still at play here, while relative sea level rise adds to the problem by making these areas prone to flooding. In this region, accurate digital terrain models make an invaluable contribution to data-driven governance and decision-making. These models can illuminate how changing conditions affect heritage sites and the cultural landscape. We propose and evaluate a methodology for developing accurate terrain models from historical aerial photographs. The method provides high-density, high-precision data for the past half-century. This data can provide insight into the long-term effects of local interventions on local subsidence, making the method a valuable tool for developing risk inventories for proposed interventions.

Sea level rise (SLR) and increased urbanisation of coastal areas have exacerbated coastal flood threats, making them even more severe in important cultural sites. In this context, the role of hard coastal defences such as promenades and embankments needs to be carefully assessed. Here, a thorough investigation is conducted in Grado, one of the most significant coastal and historical towns in the Friuli Venezia Giulia region of Italy. Grado is located on a barrier island of the homonymous lagoon, the northernmost of the Adriatic Sea, and is prone to flooding from both the sea and the back lagoon. The mean and maximum sea levels from the historical dataset of Venice (1950–2023) were analysed using the Gumbel-type distribution, allowing for the identification of annual extremes based on their respective return periods (RPs). Grado and Trieste sea level datasets (1991–2023) were used to calibrate the statistics of the extremes and to calculate the local component (subsidence) of relative SLR. The research examined the occurrence of annual exceedance of the minimum threshold water level of 110 cm, indicating Grado’s initial notable marine ingression. The study includes a detailed analysis of flood impacts on the urban fabric, categorised into sectors based on the promenade elevation on the lagoon side, the most vulnerable to flooding. Inundated areas were obtained using a high-resolution digital terrain model through a GIS-based technique, assessing both the magnitude and exposure of the urban environment to flood risk due to storm surges, also considering relative SLR projections for 2050 and 2100. Currently, approximately 42% of Grado’s inhabited area is inundated with a sea level threshold value of 151 cm, which occurs during surge episodes with a 30-year RP. By 2100, with an optimistic forecast (SSP1-2.6) of local SLR of around +53 cm, the same threshold will be met with a surge of ca. 100 cm, which occurs once a year. Thus, extreme levels linked with more catastrophic events with current secular RPs will be achieved with a multi-year frequency, inundating more than 60% of the urbanized area. Grado, like Venice, exemplifies trends that may impact other coastal regions and historically significant towns of national importance. As a result, the generated simulations, as well as detailed analyses of urban sectors where coastal flooding may occur, are critical for medium- to long-term urban planning aimed at adopting proper adaptation measures.

The geomorphology, hydrodynamics, and ecological balance of blackish water lagoons are significantly shaped by environmental factors like wave action, tidal currents, longshore drift, and relative sea level rise. These factors also have a direct impact on the management and long-term sustainability of these lagoons. This study looks at shoreline dynamics and related environmental effects in the Chilika Lagoon in India as a representative case. Natural episodic events like waves, tides, currents, and global sea level rise are all responsible for the Chilika Lagoon's dynamic coastal environment's constant reshaping. This study specifically examines shoreline lateral displacement, recognising that volumetric sediment changes are not captured by this method. Because of the high-energy interactions between wave action, tidal currents, and longshore drift along the coastal front, lateral movement of the shoreline can result in either accretion or erosion. This study evaluates the shoreline configuration changes of Chilika Lagoon and surrounding coastal areas over a 42-year period using the Digital Shoreline Analysis System (DSAS) of the U.S. Geological Survey. The analysis shows that, with some notable exceptions in certain depositional zones like Palibandha, the western flank of the new mouth inlet, the section from the old mouth to Harchandi Temple, and the stretch from Pentukota to Konark beach, the majority of the region shows net erosional trends. Shoreline retreat can reach 40.29 meters in the northeastern lagoon sector, which is closest to the present new mouth and shows the highest rates of erosion. A secondary line of barrier bars is now visible due to the frontal barrier spit breaching, which is the cause of this erosion. At the Rushikulya River's mouth, a comparable erosional pattern is visible. However, with a maximum advancement of 11.69 meters, the western side of the new mouth inlet exhibits notable accretion. The dynamic behaviors of the lagoonal inlets affects these morphological changes, with longshore drift and wave energy concentration becoming more dominant due to the Rushikulya River's reduced sediment supply. The foreshores of the Chilika Sand Spits and the Puri township coast exhibit moderate shoreline changes. These are mostly caused by high water levels during the monsoon season and wave breakers created by seasonal winds. Coastal retreat and sediment loss have been made worse by the lack of notable post-event recovery after the effects of cyclones Phailin and Hudhud. Gornitz et al. (1994) developed the Coastal Vulnerability Index (CVI) method to measure coastal vulnerability. This method incorporates a number of factors, such as shoreline change rate, mean tidal range, mean wave height, slope, relative sea level rise, and coastal geomorphology. Relative sea level rise stands out as the most important factor influencing vulnerability among these. A relative sea level rise of roughly 0.77 mm/year is indicated by data from the Paradip station (NOAA-PSMSL, 2015). The study area's CVI values, which are based on these parameters, show notable spatial variability in coastal risk throughout the Chilika region, ranging from 2.64 (very low vulnerability) to 21.45 (high vulnerability).

Understanding salt marsh resilience under increasing sea levels can inform for management decisions. We compared temporal projections from various wetland process-based models and a geospatially derived metric (i.e., marsh lifespan) to understand key considerations and uncertainties about salt marsh resilience when using these products for decision-making. The influences of lidar topographic correction and marsh surface sediment accretion were explored across a suite of relative sea level rise (RSLR) projections to assess differences in the timing and amount of habitat change for each modeling approach. All models were run for a small coastal wetland site located in the Chesapeake Bay, Maryland, USA, to assess potential change in marsh habitat, and timing of marsh loss due to RSLR. All modeling results agreed that marsh longevity was threatened by RSLR but they varied in the time of predicted marsh submergence between the years 2070 and 2100 depending on the initial marsh surface elevation and accretion rates. Models with similar accretion rates predicted similar years until marsh submergence. Removing a positive elevation bias from lidar surveys in densely vegetated marsh areas for these models resulted in onset of submergence ~ 7 years earlier. Because there are many tradeoffs to each model type, end users need to evaluate management questions, overall goals, the amount of effort involved in model parameterization, and the amount of uncertainty in the model that they are willing to accept.

Urban flooding in low-lying coastal regions (LCRs) is intensifying due to climate change and sea-level rise; however, the complex interplay of hydrological, climatic, and anthropogenic drivers remains poorly understood. This study investigates the specific meteo-hydrological factors linking climate-induced changes and human activities to the urban flooding event in My Tho City, a vulnerable coastal city in Vietnam's Tien Giang Province, from February 9 to 12, 2024. Analyzing historical meteo-hydrological data (rainfall, monsoon winds, river discharge, and water levels), we examined the contributing factors. Our findings reveal that the flooding was predominantly driven by the combination of high astronomical tidal levels and significant water surges. These surges were amplified by northeast monsoon circulation. This situation was compounded by critically low Mekong River discharge during the dry season, which enhanced the inland penetration of tidal effects. Rainfall during the period was minimal and did not contribute significantly. We utilized a filtering technique to differentiate between astronomical tides and non-tidal surges in the water level data. These results provide empirical evidence demonstrating that climate-driven sea-level influences (manifesting as high tides and surges) and anthropogenic alterations to river flow governed the urban flooding dynamics. The study underscores the urgent need for integrated adaptation solutions addressing the complex land-ocean interactions, particularly in the context of climate change and relative sea-level rise.

ABSTRACT Internal structures of Neogene coquina limestones in northern Hawke's Bay include small- to large-scale cross-beds, which are interpreted as the foresets of subaqueous dunes produced by strong tidal currents flowing in constricted straits between elongated submarine ridges. Analysis of the stratigraphic architecture of the studied deposits reveals a tectonic origin for the development of barnacle- and mollusc-dominated heterozoan carbonate depositional systems. Late Miocene to Late Pliocene limestone sheets across the study area are characteristically floored by an angular unconformity indicating that the onset of carbonate production was preceded by the tilting and folding of the underlying strata. Conversely, limestones are sharply overlain by deep-water siliciclastics recording the submergence and termination of heterozoan carbonate production. Shallow-water carbonates formed and accumulated in a morphostructurally-controlled multiple-strait system that developped following regional tectonic deformation and uplift. As such, carbonate production is associated with relative sea level fall. These conditions brought the seabed to tidal influence where heterozoan organisms could flourish. By contrast, regional tectonic subsidence led to relative sea level rise and rapid seabed drop, resulting in termination of the multiple-strait system and shut down of carbonate factories.