Development of HydroClimatic Conceptual Streamflow (HCCS) model for tropical river basin Parag P. Bhagwat and Rajib Maity ABSTRACT 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. Parag P. Bhagwat Rajib Maity (corresponding author) Department of Civil Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, West Bengal, India E-mail: rajib@civil.iitkgp.ernet.in; rajibmaity@gmail.com Key words | climate, conceptual model, hydroclimatology, prediction, streamflow INTRODUCTION In the context of a changing climate, identification of stream- flow response to other hydroclimatological variables is a research challenge (Kumar & Maity ; Maity & Kashid ). Most of the existing approaches attempt to consider and conceptualize different hydrological processes. How- ever, time varying watershed characteristics are not considered. As a consequence, consistency (decadal to cli- matic scale) of the model performance is affected under a changing climate and changing watershed characteristics that are not accounted for. Here lies the importance of this study since recent observation of climate change has added a new dimension towards this overall research direction in hydrologic modelling. The question examined was, is it poss- ible to model watershed response as streamflow with the simultaneous consideration of changing climate and time varying watershed characteristics? As such, it was found that there is a need to develop a streamflow model having few parameters, which will be able to consider time varying watershed characteristics and climatic inputs, and provide better or at least comparable performance to existing approaches. Background and literature review A brief review (with respect to the huge amount of literature available) of existing approaches reveals that the hydrologi- cal models for streamflow estimation can be grouped into three broad categories viz: (a) physically based models, (b) conceptual models, and (c) artificial intelligence (AI)-based models. In physically based models, existing knowledge of all possible hydrological processes is represented through a set of mathematical equations. Examples of some popular physically based models include System Hydrologique Euro- pean (Abbott et al. a,b), Better Assessment Science Integrating point and Non-point Sources (EPA ), Soil and Water Assessment Tool (SWAT) (Eckhardt & Arnold ; Grizzetti et al. ), and Community Land Model (Lawrence et al. ). However, an inability for accurate 36 © IWA Publishing 2014 Journal of Water and Climate Change | 05.1 | 2014 doi: 10.2166/wcc.2013.015 Downloaded from http://iwaponline.com/jwcc/article-pdf/5/1/36/374963/36.pdf by guest on 29 November 2023