Semarang City is one of the areas that were often affected by flooding, both tidal flooding and flooding due to river overflow. Factors that cause flooding such as land use, high rainfall, high urbanisation rate, and lack of drainage capacity cause flooding to occur frequently. This research aims to analyse past flood inundation models using the HEC-RAS 2D model with model validation using Landsat 7 ETM+ data and CHIRPS rainfall data. The results show that floods in 3 (three) events, namely 23 January 2014, 16 February 2017, and 30 April 2019 have different areas, namely 378.25 ha, 377.61 ha, and 310.53 ha. Flood validation using Landsat 7 ETM+ satellite imagery using the wetness index value on each event is 81, 84, and 82 per cent respectively so the flood model with wetness index has a high validation value. The variation of values in flood validation is caused by cloud disturbance and spatial resolution of DEM data of Semarang City.