Salinity Province 72, Merino Tablelands

The large Merino Tablelands Salinity Province is underlain by Cretaceous age sandstone and mudstone rocks of the Otway Group, which are overlain by a deeply weathered regolith and clay soils. Groundwater flow through the deeper fractured rock forms an intermediate scale Groundwater Flow System (GFS) while the regolith provides local scale GFSs whereby brackish groundwater is conveyed to discharge zones along some depressions and drainage lines. Dryland salinity occurrences are predominantly found associated with these drainage lines and depressions, with a few ‘break-of-slope’ occurrences seen at the northern end of the province. Increased groundwater recharge post land clearing has exacerbated high watertables in parts of the province that are naturally prone to waterlogging.

Management options rely mainly on vegetation treatments to either intercept more recharge through improved perenniality in pastures, or attempt to intercept local groundwater flows around discharge areas by, for example, tree belts along drainage lines. Waterlogged and saline discharge areas need to be fenced to protect them from soil damage and erosion.