''It's absurd to have a centralised water bureaucracy for the basin operating out of Canberra it won't work,'' University of Adelaide economist Mike Young said.

''It is impossible for any single government agency, or federal minister, to be aware of environmental needs and opportunities for water efficiency right across the basin. We need a system that uses local knowledge, and to do that, we need a revolution in water management.''

Professor Young said the ''nervous language'' and ''confused communication'' of the Murray-Darling Basin Authority's controversial guide to its draft water plan were indicative of its lack of power.

''So much of what they were asked to do was outside their authority which is why you get such awful, convoluted expressions and nervous qualifications about things like water buybacks.''

Some ministerial decision-making responsibilities should be transferred to an expanded role for the chair of the authority, he said.

''The chair must be responsible for coordinating a whole-of-government response and developing the basin plan. Otherwise, reform will get bogged in bureaucracy, and the tedious business of negotiating departmental approvals and sign-offs.''

Professor Young said he was ''grilled about the numbers'' in relation to feasible levels of water cuts during his appearance yesterday before a federal inquiry in South Australia.

The six-month parliamentary inquiry, chaired by Independent MP Tony Windsor, is investigating the social and economic impacts of water cuts outlined in the authority's guide to its draft plan.