Calibration and validation of SWAT model for estimating water balance and nitrogen losses in a small agricultural watershed in central Poland

Abstract

Soil and Water Assessment Tool (SWAT) ver. 2005 was applied to study water balance and nitrogen load pathways in a small agricultural watershed in the lowlands of central Poland. The natural flow regime of the Zgłowiączka River was strongly modified by human activity (deforestation and installation of a subsurface drainage system) to facilitate stable crop production. SWAT was calibrated for daily and monthly discharge and monthly nitrate nitrogen load. Model efficiency was tested using manual techniques (subjective) and evaluation statistics (objective). Values of Nash–Sutcliffe efficiency coefficient (NSE), coefficient of determination (R2) and percentage of bias for daily/monthly discharge simulations and monthly load indicated good or very good fit of simulated discharge and nitrate nitrogen load to the observed data set. Model precision and accuracy of fit was proved in validation. The calibrated and validated SWAT was used to assess water balance and nitrogen fluxes in the watershed. According to the results, the share of tile drainage in water yield is equal to 78%. The model analysis indicated the most significant pathway of NO3-N to surface waters in the study area, namely the tile drainage combined with lateral flow. Its share in total NO3-N load amounted to 89%. Identification of nitrogen fluxes in the watershed is crucial for decision makers in order to manage water resources and to implement the most effective measures to limit diffuse pollution from arable land to surface waters.

Geostatistical Resampling of LiDAR-Derived DEM in Wide Resolution Range for Modelling in SWAT: A Case Study of Zgłowiączka River (Poland)

“…The Zgłowi ączka River watershed has been previously modelled in order to support the implementation of the Framework Water Directive in Poland [34], the determination of the dislocation ways and the size of the nitrogen loads [35], and the influence of permanent grasslands on nitrogen loads [36]. The considerable anthropogenic transformation of the natural hydrological conditions of the Zgłowi ączka River watershed has caused many problems [35].…”

Hydrological Responses of Watershed to Historical and Future Land Use Land Cover Change Dynamics of Nashe Watershed, Ethiopia

“…The p-factor is a proportion of measured data bracketed by the 95PPU that ranges from 0 to 1, with 1 being the optimal result. The r-factor ranges between 0 to infinity, and it is the average thickness of the 95PPU band to the standard deviation of the corresponding measured data [44,[47][48][49]. Twenty-four years of flow data were used for the calibration and validation.…”

Impact of conservation tillage on nitrogen and phosphorus runoff losses in a potato crop system in Fuquene watershed, Colombia

“…However, the calibration can be further improved when continuous records of water quality parameters are available. Also, several calibration techniques have been developed for a physically based model like SWAT (Smarzyńska and Miatkowski, 2016;Me et al, 2015;Akhavan et al, 2010;Harmel et al, 2014;Arnold et al, 2012) and these could be suitable depending on the final goal of the modeling.…”