University of Oulu

Makumbura RK, Gunathilake MB, Samarasinghe JT, Confesor R, Muttil N, Rathnayake U. Comparison of Calibration Approaches of the Soil and Water Assessment Tool (SWAT) Model in a Tropical Watershed. Hydrology. 2022; 9(10):183.

Comparison of calibration approaches of the Soil and Water Assessment Tool (SWAT) model in a tropical watershed

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Author: Makumbura, Randika K.1; Gunathilake, Miyuru B.2,3; Samarasinghe, Jayanga T.4;
Organizations: 1Department of Civil Engineering, Faculty of Engineering, Sri Lanka Institute of Information Technology, Malabe 10115, Sri Lanka
2Hydrology and Aquatic Environment, Environment and Natural Resources, Norwegian Institute of Bioeconomy and Research, 1433 Ås, Norway
3Water, Energy and Environmental Engineering Research Unit, Faculty of Technology, University of Oulu, FI-90014 Oulu, Finland
4Department of Earth Environmental and Resource Sciences, University of Texas, El Paso, TX 79968, USA
5Institute for Sustainable Industries & Livable Cities, Victoria University, P.O. Box 14428, Melbourne, VIC 8001, Australia
6College of Engineering and Science, Victoria University, P.O. Box 14428, Melbourne, VIC 8001, Australia
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 5.6 MB)
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Language: English
Published: Multidisciplinary Digital Publishing Institute, 2022
Publish Date: 2023-06-09


Hydrologic models are indispensable tools for water resource planning and management. Accurate model predictions are critical for better water resource development and management decisions. Single-site model calibration and calibrating a watershed model at the watershed outlet are commonly adopted strategies. In the present study, for the first time, a multi-site calibration for the Soil and Water Assessment Tool (SWAT) in the Kelani River Basin with a catchment area of about 2340 km² was carried out. The SWAT model was calibrated at five streamflow gauging stations, Deraniyagala, Kithulgala, Holombuwa, Glencourse, and Hanwella, with drainage areas of 183, 383, 155, 1463, and 1782 km², respectively, using three distinct calibration strategies. These strategies were, utilizing (1) data from downstream and (2) data from upstream, both categorized here as single-site calibration, and (3) data from downstream and upstream (multi-site calibration). Considering the performance of the model during the calibration period, which was examined using the statistical indices and NSE, the model performance at Holombuwa was upgraded from “good” to “very good” with the multi-site calibration technique. Simultaneously, the PBIAS at Hanwella and Kithulgala improved from “unsatisfactory” to “satisfactory” and “satisfactory” to “good” model performance, while the RSR improved from “good” to “very good” model performance at Deraniyagala, indicating the innovative multi-site calibration approach demonstrated a significant improvement in the results. Hence, this study will provide valuable insights for hydrological modelers to determine the most appropriate calibration strategy for their large-scale watersheds, considering the spatial variation of the watershed characteristics, thereby reducing the uncertainty in hydrologic predictions.

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Series: Hydrology
ISSN: 2306-5338
ISSN-E: 2306-5338
ISSN-L: 2306-5338
Volume: 9
Issue: 10
Article number: 183
DOI: 10.3390/hydrology9100183
Type of Publication: A1 Journal article – refereed
Field of Science: 212 Civil and construction engineering
Funding: This research was carried out under the Sri Lanka Institute of Information Technology (SLIIT) Research Grant of FGSR/RG/FE/2022/02.
Copyright information: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (