The main objective of this viewer is to provide detailed information on the areas that could be affected by sea level rise, thus facilitating territorial planning, risk management and adaptation to climate change by the competent authorities and the public.

The viewer is aimed at territorial managers, urban planners, researchers and policy makers who need precise data for decision-making in coastal management and adaptation to climate change. It is also useful for citizens interested in knowing the potential impact of climate change on coastal areas.

The viewer covers the entire Catalan coast and shows the areas that could be permanently flooded in different sea level rise scenarios.

Data and techniques

To develop this viewer, high-resolution digital terrain models and scientific projections on sea level rise have been used to perform the hydrological modeling.

The viewer shows the permanent flooding generated solely by the rise in mean sea level for five climate scenarios (SSP1-1.9, SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5) and nine time horizons (year 2020, 2030, 2040, 2050, 2060, 2070, 2080, 2090 and 2100). The projection values ​​in the Barcelona node (id=1811), as of September 2023, come from NASA's Sea Level Projection Tool and have the IPCC Sixth Assessment Report as a reference report.

The model used is what is known as the bathtub approach. This method is based on considering a sea level higher than the current one and identifying the cells of the digital terrain model (DTM) that have a lower elevation. In this way, the surface flooded by the considered sea level is determined, a surface that would remain permanently under sea water.

Viewer

Full window viewer

Formats, visualizations and interactive features

The viewer offers the observation of rasters created on the fly:

• Surface flooded by sea level rise.
• Drafts.
• Permanent Flood Probability Map for Mean Sea Level Rise (MPIP).

Surface flooded by sea level rise and drafts 

The user can choose to visualize the permanent flood in two ways: as a flooded surface or as the water height or draft of the flooded surface. The first way allows the identification of the surface of the land that is expected to be permanently flooded for each sea level considered. The second allows you to observe the depth of the flood in relation to the surface of the land, from the Digital Terrain Model (DTM) of the ICGC with a regular mesh of 2x2 m, classified in the following intervals: less than 20 cm, between 20 and 50 cm, between 50 and 100 cm, between 100 and 150 cm, between 150 and 200 cm and greater than 200 cm.

The user can choose different sea levels divided into two groupss:

• Water level according to the projections of the rise in sea level that come from the Sea Level Projection Tool of NASA and have as a reference report the IPCC Sixth Assessment Report of the Intergovernmental Panel on Climate Change of the United Nations (IPCC).
• Water level without relation to any projection.

When a water level unrelated to a projection is chosen, the viewer will distinguish with different colors the surface flooded by the highest water level value according to the projection and the surface flooded between this value and the free water level value chosen.

The user can choose where to apply these values: in the Digital Terrain Model (MDT) of the ICGC with a regular 2x2 m mesh, based on LiDARCAT1 data 2008-2011, or in the Digital Terrain Model with buildings and rigid structures (MDTe) of the ICGC with a regular 1x1 m mesh, based on LiDAR data of the coast of 2017 and the LiDARCAT2 flight of 2016-2017, both with an estimated altimetric accuracy of 15 cm (mean square error).

For more information, see report RN-0011/2023, Update of the model and viewer of permanent flooding due to sea level rise (SIDL 2023).

Permanent Flood Probability Map due to Sea Level Rise (MPIP)

The MPIP determines the risk of vulnerable areas by combining all the SSP scenarios (Shared Socioeconomic Trajectories) and the time horizons considered. On the Digital Terrain Model with buildings and rigid structures (MDTe) of the ICGC with a regular mesh of 1x1 m, the number of times a cell is flooded is calculated taking into account the 45 possible combinations. This frequency (number of times it is flooded) is translated into a value of favorable cases/possible cases and a probability of flooding (%) which is expressed as a risk using a traffic light index.

The viewer is based on Svelte and is composed of:

• UI Material.
• MapBox GL JS.
• ContextMaps.
• Vector Tiles.

Available information and how is it linked to other tools or services?

The viewer offers the observation of rasters created on the fly:

• Surface flooded by sea level rise: For each value of increase in the average sea level, a binary cartography is obtained, flooded cell or non-flooded cell.
• Drafts: For each value of increase in the average sea level, in the event that this is higher than the cell elevation, the difference between the two values ​​is calculated. The calculated value is equivalent to the height of the water column in the cell, that is, the draft.
• Permanent Flood Probability Map due to Mean Sea Level Rise (MPIP): Determines the risk of vulnerable areas by combining all scenarios (Shared Socioeconomic Trajectories) and Time Horizons considered. The probability of permanent flooding due to mean sea level rise is shown for all climate scenarios (SSP1-1.9, SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5) and time scenarios (2020, 2030, 2040, 2050, 2060, 2070, 2080, 2090 and 2100).

Regarding the linking of the bathtub model to other tools or services, it uses the ICGC Digital Terrain Model (MDT) with a regular 2x2 m mesh, based on LiDARCAT1 2008-2011 data, and the ICGC Digital Terrain Model with buildings and rigid structures (MDTe) with a regular 1x1 m mesh, based on LiDAR data from the coast in 2017 and the LiDARCAT2 flight in 2016-2017. Therefore, if the models are updated, the viewer would need to be updated. Similarly, the MPIP calculations would need to be redone with new digital terrain models.