[Qgis-user] How to calculate areas between contour lines (or isolines)

[Jaime Palalane]

Olás,

Q1: I created contour lines from a DEM and after that I converted them 
to vector lines. Now, for a basin (catchment) which is a polygon I need 
to calculate the basin area between specific contour lines ranges (e.g. 
300-400). How would appreciate an explanation how it could be done. 
Another possibility could be to calculate areas between certain contour 
rages direct from the DEM (my raster file) but I also do not know how to 
compute them from it.

Q2: Is it possible to define catchments which drains to a specific point 
in QGIS? I managed to create basins using the watershed command but I do 
not have too much control of the basins which are created and I failed 
to find how to define the basin draining to a specific section of the 
river I am studying.

Abraço,

Jaime