 So, let's play with a hypothetical example of using Darcy's lobe. So let's say we had a situation like this where we have a clay bund sitting on top of an impermeable material, and on one side of the clay bund we have three metres of water, and on the other side we have one point five metres of water. You can see that the three metres of water will create a hydraulic gradient with the one point five metres of water. The water will want to flow through the clay bund. So the question we might want to ask is, what is the flow of water per metre of a bund? And to do that we can use Darcy's lobe. So Darcy's lobe is looking at the flow, and that's equal to the cross-sectional area of flow, multiplied by the permeability, multiplied by the hydraulic gradient. Well what we're trying to answer is the flow per metre squared of bund. So we can just divide the flow per area and write the equation like this. So the flow per area is equal to the permeability times the hydraulic gradient. Well the permeability is given in the question. It's equal to ten to the minus nine metres per second. The hydraulic gradient is the change in height of the bund, the change in height of the water level, over the flow length. So the change in height is three metres minus one point five, minus one point five, divided by the length of flow, which is the thickness of the bund at zero point five metres. So that's equal to three. So for every metre squared of a bankment, the flow is equal to three times ten to the minus nine metres cubed per second per metres squared of bund. This is a bit of an awkward number, so we could also write that as 95 litres per year. A little bit more manageable.