The unprecedented floods of 2010 in Pakistan highlighted the necessity of a well-calibrated hydrological model of the Indus upper catchment for a comprehensive flood risk assessment. However, this modelling was an extremely challenging exercise because of the lack of hydrometeorological data, which are difficult to collect due to the geography of the catchment. In the study area (133,300 km2), there are 24 raingauges collecting sufficient daily data, which leads to an average area of Thiessen polygons well over (by 10 times) the WMO minimum density network requirements of 250 km2 for hilly area. The lack of local data for soil and aquifer poses another challenge. Despite those limitations, IFAS (Integrated Flood Analysis System) was run to conduct rainfall runoff analysis from the very upstream (in India and China) to Taunsa (midstream Indus in Pakistan).