1 Asia-Pacific Journal of Science and Technology: Volume: 28. Issue: 05. Article ID.: APST-28-05-18. Research Article Asia-Pacific Journal of Science and Technology https://www.tci-thaijo.org/index.php/APST/index Published by the Research and Graduate Studies Division, Khon Kaen University, Thailand Performance of SWAT hydrological model of partially-gauged Nambul River urbanized catchment in Manipur IHR, India Victoria Ningthoujam 1,* , Ngangbam Romeji 1 and Kangjam S. Singh 2 1 Department of Civil Engineering, National Institute of Technology Manipur (NIT Mn), Manipur, India 2 Krishi Vigyan Kendra-Chandel, Indian Council of Agricultural Research (ICAR), Manipur, India * Corresponding author: vningthoujam@nitmanipur.ac.in Received 24 April 2022 Revised 27 July 2022 Accepted 10 August 2022 Abstract Hydrological modelling of partially-gauged and ungauged catchments is vital for the better development of land and water management policies. The Nambul river catchment in Manipur, is partially gauged, so observed data is scarce. The objective of the study is to calibrate and validate the Soil and Water Assessment Tool (SWAT) model using remotely sensed surface soil moisture along with available streamflow data to improve the model's performance in simulating the hydrological functions as surface runoff, sediment yield, evapotranspiration, etc for a partially-gauged urbanized river catchment which is under stress. Using the Sequential Uncertainty Fitting, version 2 (SUFI-2) program built-in to SWAT-CUP, SWAT model was calibrated and validated on a monthly basis. Streamflow calibration is carried out with available measured data for the years 2000-2002 and validation for the year 2003. The soil moisture calibration period (2001-2011) and validation period (2012-2020) are also carried out sequentially. SWAT model calibration and validation using streamflow and surface soil moisture (ECMWF) showed good model performance with NSE of 0.65, 0.69, and 0.67, 0.71, and R 2 of 0.71, 0.74, and 0.70, 0.71, respectively. This study shows that remotely sensed satellite data can be used as one of the parameters and as an alternative to observed data for calibration and validation of the SWAT model of the Nambul river catchment. Further study, assessment, and management of the catchment can be aided by the study's contribution to hydrological modeling of ungauged or partially-gauged catchments where there is a scarcity of lack of routine observed hydrologic data. Keywords: Remotely sensed, SWAT-CUP, SUFI-2, Surface runoff, Evapotranspiration, Sediment yield, R 2 , Soil moisture, Nash-sutcliffe, p-factor, r-factor 1. Introduction Hydrological modeling of partially-gauged and ungauged catchments is vital for development of land and water management policies. The calibration of parameters is imperative for implementing any study on hydrologic models. The hydrological models applied for the prediction of hydrological parameters depend on the quality of the model calibration. The hydrological cycle changes spatially and temporally; therefore, calibration and validation are necessary. The model parameters were selected for calibration such that they responded to watershed hydrologic components, such as runoff, evapotranspiration (ET), sediment yield, and water yield. The model parameters were fixed such that the simulated and measured data were closely approximated during the calibration process. Calibration is a process in which the parameters are fixed after several iterations such that the simulated values are close to the measured ones. Calibration and validation help in better simulation of hydrologic processes. The preference for objective variables in the process of model calibration and the resulting values of the parameters used strongly affect the simulated surface and subsurface flow fluctuations in hydrological modeling [1,2]. Hydrological modeling primarily focuses on the nature of the water cycle. The reliable study of the main components of the water cycle for resolving problems both quantitatively and qualitatively in water resource projects is streamflow. However, owing to the lack of routine gauging of catchments, there is scarcity of data. In recent years, regionalization techniques using remotely sensed satellite data have been used for parameter