Iain Hume

Mathematical Optimisation of Drainage and Economic Land Use for Target Water and Salt Yields

Land managers in upper catchments are being asked to make expensive changes in land use, such as by planting trees, to attain environmental service targets, including reduced salt loads in rivers, to meet needs of downstream towns, farms and natural habitats. End-of-valley targets for salt loads have sometimes been set without a quantitative model of cause and effect regarding impacts on water yields, economic efficiency or distribution of costs and benefits among stakeholders. This paper presents a method for calculating a ‘menu’ of technically feasible options for changes from current to future mean water yields and salt loads from upstream catchments having local groundwater flow systems, and the land-use changes to attain each of these options at minimum cost. It sets the economic stage for upstream landholders to negotiate with downstream parties future water-yield and salt-load targets, on the basis of what it will cost to supply these ecosystem services.

Upstream demand for water use by new tree plantations imposes externalities on downstream irrigated agriculture and wetlands

Large-scale tree plantations in high rainfall upstream areas can reduce fresh water inflows to river systems, thereby imposing external costs on downstream irrigation, stock and domestic water users and wetland interests. We take the novel approach of expressing all benefits and costs of establishing plantations in terms of

The ionic composition of the streams of the mid-Murrumbidgee River: implications for the management of downstream salinity.

per gigalitre (GL) of water removed annually from river flows, setting upstream demands on the same basis as downstream demands. For the Macquarie Valley, a New South Wales sub-catchment of Australia’s Murray-Darling Basin, we project changes in land and water use and changes in economic surpluses under two policy settings: without and with a policy requiring permanent water entitlements to be purchased from downstream parties, before plantation establishment. Without the policy, and given a high stumpage value for trees (

Price Discovery and Distribution of Water Rights Linking Upstream Tree Plantations to Downstream Water Markets: Experimental Results

70/m3), upstream gains in economic surplus projected from expanding plantations are

Distributional Consequences of Upstream Tree Plantations on Downstream Water Users in a Public-Private Benefit Framework

639 million; balanced against

Upstream-downstream benefit analysis of policy on water use by upstream tree plantations

233 million in economic losses by downstream irrigators and stock and domestic water users for a net gain of

Demand for Water Use by New Tree Plantations and Downstream Economic, Social and Environmental Interests

406 million, but 345 GL lower mean annual environmental flows. With the policy, smaller gains in upstream economic surplus from trees (

Using remote sensing to predict PI nitrogen uptake in rice

192 million), added to net downstream gains (

Developing conservation agricultural innovations and practice change: a model for future research, development, extension and training in a brave new world

138 million) from sale of water, result in gains of

Upstream-Downstream benefit analysis of policy on water use by upstream tree plantations.

330 million with no reduction in environmental flows. Sustaining the 345 GL flow for a