Downstream benefits vs upstream costs of land use change for water-yield and salt-load targets in the Macquarie Catchment, NSW

The net present value (NPV) of downstream economic benefits of changes inwater-yield (W) and salt-load (S) of mean annual river flow received by a lowercatchment from an upper catchment are described as a 3-dimensional (NPV,W, S)surface, where dNPV/dW > 0 and dNPV/d(S/W)