SCALGO Live Documentation

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Analysis - Sea-Level Rise

Sea-level Rise enables you to analyze which parts of the terrain that are potentially flooded at a given water level. The flooded areas illustrated on the map are areas below your chosen water level that have a direct connection to the sea via at least one path beneath your chosen water level. Areas that are beneath the water level but protected by an elevated area and thereby separated from the sea are called protected areas. These will not be displayed as flooded unless there is a waterway around the elevated area or a hydrological correction like e.g., a culvert through the elevated area.

Figure 2.4.1 illustrates how the analysis works in SCALGO live.

The picture illustrates how sea-level rise works. By setting a higher water level (red line), the tool will inform you about the flooded regions, and those that are beneath the sea-level but are protected due to hills, levees etc. will not be marked as flooded.

How to use Sea-Level Rise?

When selecting Sea-level Rise, flooded areas are displayed on the map according to the selected water level. It can be selected under Analysis in the Dock.

Slider: Adjusting the sea level

The slider adjusts how much the sea level rises on the map. A water level at 0.0 cm shows the current sea level. When increasing the water level, the flooded areas are displayed in blue.

Point query: View when an area is flooded by the sea

You can assess, for any chosen point, how much the sea level needs to rise before the point gets flooded by the sea. Just choose point query and select any point on the map.

Profile tool: View the water depth in profile

If you want to view the effect of a chosen sea level you can use the profile tool. The terrain profile displays a straight line on the graph. This line illustrates your chosen water level and shows how much of the cross section is flooded.

The straight line on the graph shows your chosen water level at the drawn profile and illustrates the maximum flooded area (beneath the line) at the chosen location.

Styles: The colors

The flooded areas can be illustrated in both blue and purple. Read more about styles in general in the dock.

Download

If you want to download the flooded area, follow the guide under download on the toolbar page. By default, data is downloaded in raster format and includes entails on which sea level leads to flooding at every raster cell. Alternatively, you can download the data as a vector file, which displays the outline of different floods depending on one or several sea levels. The sea levels are chosen in the displayed menu when vector is selected.

Critical Points

Critical points visualizes the points in the terrain where intrusion can occur and lead to significant flooding in low-lying areas behind the critical point. It must be enabled by selecting Critical Points under Sea-Level Rise. Black dots are shown on the map, representing the critical points. The dots on the map is different in size. The smaller critical point, the higher the chosen water level exceeds the elevation of the critical point. When the chosen water level exceeds the critical point with more than one meter, the critical point will no longer be visible on the map.

What are critical points

A critical point is a point in the terrain that blocks seawater intrusion. It is called a critical point because it marks where seawater intrusion can occur on the terrain and lead to
significant flooding in low-lying areas behind the critical point. The critical points are visible until they are more than one meter beneath the chosen sea level. If the critical point is surrounded by blue, it is flooded, but by less than a meter. The illustration below shows how critical points works in SCALGO live.

The red marks display the critical points. At the current water level (blue), there are five critical points. When changing the water level using the slider, the critical points will change as well. With a higher water level (red line), two points are no longer critical, as the water level has surpassed the points and already flooded the low-lying area behind the points.

How to use critical points

Slider: Filtering critical points according to the size of the flooded area behind

When Critical Points is chosen in the dock, an additional slider called flooded area emerges. This slider lets you filter critical points according to the protected low-lying area behind the critical point. For example, if you set flooded area a 500 m2, you will only see the critical points where at least 500 m2 is flooded when the water level surpasses the critical point.

  1. Move the slider to determine the size of the low-lying area behind any critical point.
  2. Now only relevant critical points are displayed with a point.

The dots on the map are different in size. The smaller critical points are flooded points where the water level is less than one meter above the critical point. The smaller the critical point, the closer the water level is to one meter above the point. When the water level is more than one meter above the point, it will no longer be visible on the map, as it is no longer regarded as critical.

Point query: Get information about a critical point

The point query tool provides information about:

  1. The size of the area behind the critical point which is flooded
  2. The volume of water in the flooded area at the time when it first floods
  3. The sea level necessary to flood the critical point

Download: Get data on the critical points

Critical point can be downloaded as a vector file showing a point for each critical point and information about the elevation, where the point is flooded as well as the area and volume of the flooded area behind the critical point. If you want to know how to download, please read the download section under toolbar.

Show Subsurface

By default, we do not include subsurface structures in the analyses. Subsurface structures (e.g. underpasses and culverts) can be created in a workspace. In some countries, they are also included in the national analysis through a national set of hydrological corrections. If this is the case, SCALGO Live has a Show subsurface option in the dock.

When enabling 'show subsurface', you can see where water flows underneath the surface of the map. The example above shows that water flows under a bridge.

NOTE: relevant subsurface structures are always included in the computation. The option in this analysis only affects how the output is rendered, not whether the subsurface structures have an effect or not