SWC help

Why am I getting a negative number error?

Farm dams usually have batter slopes of 3:1 (3 metres run for every metre of depth), which is used for the formula in this calculator. The formula used to calculate the surface area of the bottom of the dam will produce a negative number if both the slopes overlap and, therefore, an incorrect calculation.

How do I correct it?

Don’t guess. Check that the dimensions you’ve entered are correct and adjust the dimensions and depth accordingly; maybe even measure or step out the dam again.

Note also that the depth is often overestimated and might not be as deep as you think. There may also be sediment to consider, so subtract that from the depth to compensate. If your measurements reveal a steeper batter slope than the 3:1 this tool uses, then you may need to calculate the volume of your dam manually as per: https://agriculture.vic.gov.au/farm-management/water/farm-water-solutions/how-much-water-is-in-my-dam