The definition of the distribution relates to the update of the dredger. You must specify the distribution of the material for a given fraction in %. This means that the total value must be 100%.
When the update of the dredger is included, the specified distribution is the inital distribution of material on the dredger. The actual distribution on the dredger, taken into account dredger material, is calculated during the simulation and this distribution is used for disposal of material and the related spill. The distribution for dredged material, the related spill and the material placed on the dredger, when update of the dredger is included, is the distribution in bed.
When update of the dredger is excluded, the specified distribution is used for the disposal of material (i.e. negative source) and the related spill.