Using Google Map to Determine the Soil Profile for Slope Stability

[ONENGINEER]

Can I use Google map for getting the slope profile for slope stability purposes. I looked at the slope during my site visit and looked steeper than what Google map produces. Wonder if it is a vision problem? Does anybody have experience and are they using Google maps to find the soil profile? Thank you.

 

[GeoPaveTraffic]

I would not use google map or google earth to determine the slope for analysis.

You might be able to use google to get an idea of the slope for some prelminary analysis, but I wouldn't recommend it.

Mike Lambert

 

[cvg]

you can purchase topo maps online relatively cheaply that will be more accurate than google

 

[Mccoy]

I did some direct observations, the result is that Google earth (same database as googlemaps I think) can be very often way off the beam (very wrong) as far as topographic detail is concerned.
It cannot be used for slope profiling or topographic levels of site tests.

Unless you are speaking of some professional upgrade I'm not aware of.

 

[BigH]

and be careful about topo maps in heavily forested regions where LIDAR would be much better

 

[msquared48]

With the presence of trees in a heavily forested area, Google Maps is very likely give you a topo reading that is higher than it should be. It will be reading the tops or nearly the tops of the trees as the topo.

Mike McCann
MMC Engineering

 

[Mccoy]

I've recently noticed errors in the official DTM of my area. Contour lines are not where they should be and when you have been several times on the site and then compare the maps the error becomes evident and unquestionable. I'm speaking of ground with no vegetation nor any other covers.
Levels may be wrong of a few meters in some points, may be right in others.
Barely passable for a wide area stability analysis, not a detailed one.

So let's imagine how accurate can Google maps be... trees or not trees.

Again, unless there is some particular settings I'm not aware of which makes available a detailed DTM grid and in this case I'd like to know about it.

 

[ONENGINEER]

Thank you for all the contributions. My question was answered well. I understood Lidar would be more accurate than Google Map. It would also be helpful to know the accuracy of using Lidar to derive soil profiles for slope stability analysis.

 

[cvg]

the accuracy of any type of aerial mapping is related to height of the instrument from the ground, number of data points taken, accuracy of the vertical and horizontal ground control survey, ortho-rectification, presence and thickness of vegetation canopy,etc. Google uses satellite data and unless you own the satellite, the high quality elevation data is way too expensive and the data files are massive. The government uses the high quality data and google uses the cheap stuff.

Ground survey, aerial photogrammetry or Lidar is recommended for most engineering purposes.

 

[FixedEarth]

It should be mentioned that slope stability is very sensitive to slope inclination much more than soil friction angle and cohesion. For that reason, we only take on a slope stability project once we are provided with a topographic plan of 2 ft contour lines.

http://www.soilstructure.com/