Flood modeling is entirely dependent upon elevation measurements, and a hidden but crucial aspect of any elevation measurement is the datum on which it’s based. The datum defines the height of "zero." Once again I've asked my colleague at Intermap, Mike Wollersheim, to contribute his knowledge to the blog. When it comes to explaining what’s up with datums, he’s definitely up to the task.
If I told you that your city has an elevation of 3,400 feet, most people assume that I am referring to the height above mean sea level. What else are you going to measure your heights from? It seems obvious unless you really think about it. Then you start to ask questions like:
“If I am in the mountains 500 miles from the coast, how did anyone ever figure out what mean sea level is right here?”
