Application of deterministic distributed hydrological model for large catchment: a case study at Vu Gia Thu Bon catchment, Vietnam Ngoc Duong Vo and Philippe Gourbesville ABSTRACT In order to create a tool to help hydrologists and authorities to have good understanding about occurrences in stream flow regime together with its variation in the future under the impact of climate change in the Vu Gia Thu Bon catchment, a deterministic distributed hydrological model has been developed and constructed. This model covers the major processes in the hydrologic cycle including rainfall, evapotranspiration, overland flow, unsaturated flow, groundwater flow, channel flow, and their interactions. The model is calibrated and validated against the daily data recorded at seven stations during 1991–2000 and 2001–2010, respectively. The quality of results is demonstrated by Nash–Sutcliffe and correlation coefficients that reach 0.82 and 0.92, respectively, in discharge comparison. With water levels, the obtained coefficients are lower but the quality of results still remains high; Nash–Sutcliffe and correlation coefficients reach 0.77 and 0.89, respectively, in the upstream part of the catchment. This analysis demonstrates the performance of the deterministic distributed modeling approach in simulating hydrological processes one more time; it also confirms the usefulness of this model with ungauged catchments or large catchments. Additionally, this analysis proves the role of multi-calibration in increasing the accuracy of hydrological models for large catchments. Ngoc Duong Vo (corresponding author) Philippe Gourbesville Innovative City lab URE 005, Polytech Nice Sophia, Nice Sophia Antipolis University, Nice, France E-mail: duong.tltd.bk@gmail.com Ngoc Duong Vo Faculty of Water Resource Engineering, University of Science and Technology, The University of Da Nang, Vietnam Key words | deterministic hydrological modeling, long-term simulations, multi-calibration, sensitivity analysis, Vietnam, Vu Gia Thu Bon catchment INTRODUCTION Water is seen to be the premier constitutive factor of human beings. Thus, it always plays an important role in the develop- ment of human society (Gleick ; Watkins ). However, water distribution is not equal across time and space. These imbalances result in many negative impacts to human societies and activities. Annually, the natural disasters related to water issues, such as floods, droughts, and storms, produce significant severe damage, not only to property but also to human life ( Johnson et al. ; Guha-sapir et al. ). Furthermore, in recent years, under the impact of climate change, the consequences of catastrophic flood and drought events have been more frequent and serious (Vázquez et al. ). Gaining a deep knowledge of the hydro- logical factors and processes in a catchment is an essential objective for the hydrologist community in order to be able to transform disadvantages to advantages or to mitigate cata- strophic damage. Nowadays, with the development of mathematics and computer science, the simulation of the hydrological cycle for a catchment has become easier and more accurate (Blöschl & Sivapalan ). These improve- ments linked to modeling methods help hydrologists to gain more concrete and truthful insights about what happens in hydrological processes and support the decision-making pro- cess for reducing natural hazard impacts over the catchment. 885 © IWA Publishing 2016 Journal of Hydroinformatics | 18.5 | 2016 doi: 10.2166/hydro.2016.138 Downloaded from http://iwaponline.com/jh/article-pdf/18/5/885/390723/jh0180885.pdf by guest on 12 July 2022