Scenario Of Mean Sea Level Rise Research Articles

Circulation and Stratification Changes in a Hypersaline Estuary Due to Mean Sea Level Rise

Hypersaline Hamelin Pool, with mean salinity >65, is located in Shark Bay, Western Australia. The high salinity has reduced its biodiversity, but it is home to a diverse assemblage of modern marine stromatolites. The limited exchange of water between Hamelin Pool and the rest of Shark Bay, due to the presence of the shallow Faure Sill together with high evaporation and low rainfall-runoff have resulted in a hypersaline environment. With climate-change-induced mean sea level rise (MSLR), hydrodynamic processes that maintain the hypersaline environment may be affected and are the focus of this paper. Oceanographic observations, together with hydrodynamic model results, were used to examine the hydrodynamic processes under present and future MSLR scenarios. A large attenuation in the tidal range, changes in the tidal characteristics, and current speeds together with a strong salinity gradient were observed across the Faure Sill under present-day conditions. Under an MSLR scenario of 1 m, the tidal amplitude decreased by up to 10% to the north, whilst to the south, the tidal range increased by up to 15%. Regions of strong vertical stratification were present on both sides of the Faure Sill. The simulations indicated that, under MSLR scenarios, these regions expanded in area and exhibited higher levels of vertical stratification. The salt flux across the Faure Sill was maintained as a diffusive process under MSLR scenarios.

National assessment of extreme sea-level driven inundation under rising sea levels

Episodic inundation from extreme sea-levels (ESLs) will have increasing social and economic impacts in response to relative sea level rise (RSLR). Despite the improved global understanding of ESL frequencies and magnitudes, detailed nationwide inundation maps are unavailable for many countries. This study quantifies New Zealand’s land area exposure to inundation from ESLs and RSLR by: (i) calculating ESL heights for nine annual recurrence intervals (ARI) between 2 and 1,000-years, (ii) converted into space-varying water surface grids, (iii) developing a composite topographical dataset comprised of Airborne Light Detection and Ranging (LIDAR) and bias corrected Shuttle Radar Topography Mission (SRTM), (iv) modifying topographical data to represent mitigation structures, and (v) executing a scalable static model to map land inundation areas for 0.1 m RSLR increments. This modular approach supports continuous integration of new models and data at resolutions appropriate for quantifying inundation hazard and risk trends. In response to 0.1 m–0.4 m RSLR expected in the New Zealand region from 2040 to 2070 under SSP5-8.5 global mean sea level rise scenarios, a rapid cumulative inundation area increase is observed for 10 and 100-year ESL ARIs at national and regional levels. The RSLR time independent maps developed here supports future investigations of ESL inundation hazards and risks for any prescribed RSLR heights or timeframes.

Coastal Flooding in the Balearic Islands During the Twenty-First Century Caused by Sea-Level Rise and Extreme Events

Sea-level rise induces a permanent loss of land with widespread ecological and economic impacts, most evident in urban and densely populated areas. Potential coastline retreat combined with waves and storm surges will result in more severe damages for coastal zones, especially over insular systems. In this paper, we quantify the effects of sea-level rise in terms of potential coastal flooding and potential beach erosion, along the coasts of the Balearic Islands (Western Mediterranean Sea), during the twenty-first century. We map projected flooded areas under two climate-change-driven mean sea-level rise scenarios (RCP4.5 and RCP8.5), together with the impact of an extreme event defined by the 100-year return level of joint storm surges and waves. We quantify shoreline retreat of sandy beaches forced by the sea-level rise (scenarios RCP4.5 and RCP8.5) and the continuous action of storm surges and waves (modeled by synthetic time series). We estimate touristic recreational services decrease of sandy beaches caused by the obtained shoreline retreat, in monetary terms. According to our calculations, permanent flooding by the end of our century will extend 7.8–27.7 km2 under the RCP4.5 scenario (mean sea-level rise between 32 and 80 cm by 2100), and up to 10.9–36.5 km2 under RCP8.5 (mean sea-level rise between 46 and 103 cm by 2100). Some beaches will lose more than 50% of their surface by the end of the century: 20–50% of them under RCP4.5 scenario and 25–60% under RCP8.5 one. Loss of touristic recreational services could represent a gross domestic product (GDP) loss up to 7.2% with respect to the 2019 GDP.

Saltwater Intrusion in the Upper Tagus Estuary during Droughts

Droughts reduce freshwater availability and have negative environmental, economic, and social impacts. In estuaries, the dynamics between the saltwater and the freshwater can be affected during droughts, which can impact several natural resources and economic sectors negatively. The Tagus estuary is one of the largest estuaries in Europe and supports diverse uses and activities that can be affected by the saltwater intrusion (e.g., agriculture). This study assesses the saltwater intrusion in the upper reaches of the Tagus estuary using a process-based model to explore different scenarios of freshwater discharge and sea level rise. For the river discharge and mean sea level rise scenarios analyzed, salinity can reach concentrations that are inadequate for irrigation when the mean Tagus river discharge is similar or lower than the ones observed during recent droughts (22–44 m3/s). Lower river discharges aggravate the consequences. Results also show that the salinity increases with the duration of the droughts. In contrast, the impact of a moderate sea level rise on salinity intrusion is modest when compared with the impact of low river discharges. These findings contribute to support the management of the agricultural activities in the upper Tagus estuary and the water resources in the Tagus river basin.

Assessing sea level-rise risks to coastal floodplains in the Kakadu Region, northern Australia, using a tidally driven hydrodynamic model

The low-lying coastal floodplains of the Kakadu Region in tropical northern Australia encompass World Heritage Kakadu National Park and are highly vulnerable to future sea level-rise (SLR) and extreme weather events, yet there are no modelling tools to assess potential impacts of saltwater inundation (SWI) on freshwater ecosystems and to evaluate future management options. A tidally driven hydrodynamic model was developed to simulate the frequency and extent of SWI in the Kakadu Region for the following four mean SLR scenarios: 0m (present-day, 2013); 0.14m (2030); 0.70m (2070); and 1.1m (2100). Simulations were undertaken at 60-m spatial resolution using October dry-season tides, and a digital elevation model (0.10-m vertical resolution) constructed from LiDAR point cloud data was used to resolve coastal and river-system terrains. Model outputs (maximum extent and frequency of SWI) were used to assess potential loss of freshwater floodplains for each scenario at a park-wide scale and for three case-study areas that differ in tidal influence. Results show little loss by 2030 (–3%), a possible threshold effect by 2070 (–42%) and ameliorating after 2100 (–65%). Although freshwater floodplains further from the coast showed least exposure to simulated SLR, indicating potential refuge areas, all floodplains on Kakadu will be exposed to SWI by 2132 (+117 years).