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Abstract
The net present value (NPV) of downstream economic benefits of changes in
water-yield (W) and salt-load (S) of mean annual river flow received by a lower
catchment from an upper catchment are described as a 3-dimensional (NPV,W, S)
surface, where dNPV/dW > 0 and dNPV/d(S/W) < 0. Upstream changes in land use (i.e.
forest clearing or forest establishment, which result in higher or lower water-yields,
respectively) are driven by economic consequences for land owners. This paper defines
conditions under which costs of strategic upstream land use changes could be exceeded by
compensations afforded by downstream benefits from altered water-yields and/or lower
salt loads. The paper presents methods, and preliminary calculations for an example river,
quantifying the scope for such combinations, and raising the question of institutional
designs to achieve mutually beneficial upstream and downstream outcomes. Examples
refer to the Macquarie River downstream of Dubbo, NSW, and Little River, an upstream
tributary.