The Victorian government's Wimmera Southern Mallee subregion is part of the Grampians region in western Victoria. It includes most of what is considered the Wimmera, and part of the southern Mallee region. The subregion is based on the social catchment of Horsham, its main settlement.

The Wimmera River, an inland intermittent river of the Wimmera catchment, is located in the Grampians and Wimmera regions of the Australian state of Victoria. Rising in the Pyrenees, on the northern slopes of the Great Dividing Range, the Wimmera River flows generally north by west and drains into Lake Hindmarsh and Lake Albacutya, a series of ephemeral lakes that, whilst they do not directly empty into a defined watercourse, form part of the Murray River catchment of the Murray-Darling basin.