3 replies to this topic

[daak9193]

How do i raise waterlevel in a river?

 

I have height and elevation data.

 

I would be bery thankfull for replies.

 

// Daniel

[Hans van der Maarel]

What software are you using?

[daak9193]

Arcmap 10.1

[Gretchen Peterson]

The two basic things you need to do are 1) isolate all cells that are less than or equal to the new water height and 2) isolate the resulting cells that are connected to the original water feature.Basically, you are finding areas of the DEM > sea level rise (or whatever flooding elevation you are working with), convert the result to polygons, then intersect with the original flood extent to get rid of those areas that are below the sea level rise elevation but that aren't connected (that are separated from it by a hill for example). You can also use a cost distance function to do the same thing.

 

However, it can get complex if the base level of the water is not a constant, as in this analysis I did for an entire section of a river that flows from the Colorado foothills down to the plains: Wetlands Analysis.

 

You can find a simple explanation of methods in Simulate a Flood, which is a rather old description of the process, but is still applicable in ArcGIS 10.1. There are also much more complex methodologies that can be enacted using stream cross section data and specialized flood modeling programs.

 

Along these lines, here's an interesting interactive sea level rise site.