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We often have to deal with very large models covering hundreds of river miles. The terrain data associated with these models can be equally massive, which can cause memory/processor issues when trying to delineate inundation maps.
This post is not concerned with pre-processing our model geometry. Instead, we have a completed model with results we are happy with, and now we want to make inundation shapefiles. This is often necessary when completing dam breach analyses/flood analyses/etc.
There are typically two ways in which flood inundation shapefiles are created: (1) using HEC-GeoRAS and (2) RAS Mapper. Both methods can face uphill battles when terrain data begin to exceed 20-30 gigabytes, depending on performance characteristics of your computer. Below are some typical errors you may see when trying to create inundation shapefiles with RAS Mapper on very large terrain.
Figure 1: RAS Mapper Memory Error Messages
There IS a way to get around this using RAS Mapper. The first thing you’ll need to do is