120 cubic metres.
There are 3,170.0646 US gallons of water in 12 cubic meters.
12 cubic meters = 423.78 cubic feet.
12*15*0.1=18 18 cubic meters
12,000,000 cubic centimeters.
It will hold 216 cubic metres.
Volume = 1.25 x 2 x 3.14 x 12 = 94.2 cubic meters 94.2 cubic meters = 20724 gallons
A cubic metre is a unit of volume. A square metre is a unit of area. The two units are therefore incompatible.
4 m diameter x 12 m long = (Pi/4)*4*4*12 = 48*Pi cubic metres = 150.79645 cu.m. (Almost 150.8 tonnes of water).
While this will depend on the size of the wheelbarrow, an industrial wheelbarrow is about 1/12th of a cubic meter. 12 of them is one meter, 1,200 of them for 100 cubic meters.
1.4202 meters
See http://www.wolframalpha.com/input/?i=cylinder+diameter+12,+height+6
You need a third dimension to provide a cubic measurement.