Operations:
- Slope: DEM Layer.tif=[QGIS/Raster Based Terrain Analysis]=>slope.tif=>[r.in.gdal]=>slope
- Grid: [QGIS/Vector/Research Tools/Vector Grid]=>grid.shp=[v.in.ogr]=>grid=>[v.to.rast]=>grid
- Crossing Grid and Slope: grid*slope=[r.average]=>gridSlope=[r.to.vect]=>gridSlope=[v.out.ogr]=>gridSlope.shp