I have two rasters, one depicts current water depth and the second depicts the original pond depth. I wish to calculate the volume of the region between the two.
-be gentle, I'm a noob.
Using Raster Calculator in QGIS calculate the difference between the rasters (current water depth - original pond depth) and multiply by raster pixel size squared , ie raster cell surface. If you do not know cell size, check the Metadata tab in the layer properties.
The Raster Calculator in the Raster menu allows you to perform calculations on the basis of existing raster pixel values
The resulting raster will have values of volume per cell. Calculate the sum of all pixels using Zonal statistics, see for example top answer in existing Question How to sum up pixel values in QGIS?