Water Resources of South Africa, 2012 Study (WR2012) Volume 6: Salmod: Salinity modelling of the Upper Vaal, Middle Vaal and Lower Vaal sub-Water management Areas (new Vaal Water Management Area) Water Resources of South Africa, 2012 Study (WR2012) Volume 6: Salmod: Salinity modelling of the Upper Vaal, Middle Vaal and Lower Vaal sub-Water management Areas (new Vaal Water Management Area) Posted in .