Combined processes of land-surface hydrology and hydroclimatology influence the response of a watershed to different hydroclimatic variables. In this paper, streamflow response of a watershed to hydrometeorological variables is investigated over a part of two tropical Indian rivers – Narmada and Mahanadi. The proposed HydroClimatic Conceptual Streamflow (HCCS) model is able to consider the time-varying basin characteristics and major hydrologic processes to model basin-scale streamflow using climate inputs at a daily scale. In addition, the proposed model is able to provide additional overall estimates of ground water recharge component and evapotranspiration component from the entire basin. Moreover, ability to consider the time-varying watershed characteristics and hydroclimatic inputs renders the proposed model usable for assessment of future streamflow variation. This application is also investigated for both the study basins. In general, the methodological approach of the proposed model can be applied to other tropical basins for daily streamflow modelling as well as future streamflow assessment.