LiDAR provides detailed (1 to 50 or more measurements per m2) accurate (+/- 10cm vertical +/-20cm horizontal) digital elevation measurements.
 
This kind of data can be obtained even under heavy forest cover.
 
This data can be used in …
Estimate documents
Scoping studies
Proposal documents (3-D fly through)
Engineered plans
“As built” confirmation
 
Rate of change maps …
coastline erosion
tailing dam change
urbanization
illegal miners

Digital elevation data can then be processed to develop a number of maps that are very useful.  For example some municipalities have bylaws that state only ground less than 3:1 slopes can be developed on.  Topo data can be manipulated into slope maps … areas >3:1 vs areas <3:1 slope