This report details the results of an investigation carried out for Tamworth Regional Council (TRC) to upgrade the FPLAIN hydraulic mode! of the Peel River floodplain at Tamworth. The model covers the floodplains of the Peel and Cockburn Rivers from about 6 km upstream of their junction to the east of Tamworth continuing to a point about 2 km downstream of the junction of the Peel River and the Wallamore Anabranch. Timbumburi Creek is also modelled for a distance of 6 km upstream of the West Tamworth-Barraba Railway crossing. The FPLAIN mode! was developed for the Tamworth Floodplain Management Study (PPK, 1993) and has been upgraded in several later investigations. The latest version of the model, which had been developed to investigate the impacts on flooding patterns of the proposed extensions to the Westdale Sewage Treatment Plant (LACE, 2005) was used as the base model for the present investigation and was upgraded with additional survey of the floodplain.