Thanks for uploading this tool, referring to the richard.m function I however struggle when trying to calculate the flow. I try this on the left side, so to speak the surface where the flow should correspond to the predefined value, as we have a constant flux BC. I multiply the pressure gradient at the boundary (obtained by difference quotients) with the local value of hydr. conductivity, but the result differs from the BC value. Do you have any idea why this is so? Am I making a mistake somehow?