Does the Temporal Resolution of Precipitation Input Influence the Simulated Hydrological Components Employing the SWAT Model?

Abstract

This study aimed to evaluate the influence of sub‐daily precipitation time steps on model performance and hydrological components by applying the Green and Ampt infiltration method using the Soil and Water Assessment Tool (SWAT). Precipitation was measured at a resolution of 0.1 mm and aggregated to 5‐, 15‐, 30‐, and 60‐min time steps. Daily discharge data over a 10‐year period were used to calibrate and validate the model. Following a global sensitivity analysis, relevant parameters were optimized through an automatic calibration procedure using SWAT‐CUP for each time step. Daily performance statistics were almost equal among all four time steps (NSE ≈ 0.47). Discharge mainly consisted of groundwater flow (55%) and tile flow (42%), in reasonable proportions for the investigated catchment. In conclusion, model outputs were almost identical, showing simulations responded nearly independently of the chosen precipitation time step. This held true for (1) the selection of sensitive parameters, (2) performance statistics, (3) the shape of the hydrographs, and (4) flow components. However, a scenario analysis revealed that the precipitation time step becomes important when saturated hydraulic conductivities are low and curve numbers are high. The study suggests that there is no need in using precipitation time steps <1 h for lowland catchments dominated by soils with a low surface runoff potential if daily flow values are being considered. Editor's note: This paper is part of the featured series on SWAT Applications for Emerging Hydrologic and Water Quality Challenges. See the February 2017 issue for the introduction and background to the series.

Evaluating the SWAT model to predict streamflow, nitrate loadings and crop yields in a small agricultural catchment

“…The positive PBIAS values indicate a slight underestimation of the measured discharge. Generally, the model performance was similar compared to other studies performed in the same catchment (Bauwe et al, , 2017.…”

“…1. Parameter selection: Based on previous simulation studies in the same area (Bauwe et al, , 2017 we selected 27 parameters for sensitivity analysis. We performed a global sensitivity analysis using SWAT-CUP (SWAT-CUP 2012, version 5.1.6.2, Abbaspour, 2014).…”

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“…into the effective hydraulic conductivity expression (Bauwe et al, 2017;Boithias et al, 2017;Jeong et al, 2010;Maharjan et al, 2013;Nearing et al, 1996;Neitsch et al, 2011). Flood propagation in channels was simulated using the Muskingum river routing method (Cunge, 1969;Overton, 1966) whose main expression is presented in Eq.…”

Featured Series Conclusion: SWAT Applications for Emerging Hydrologic and Water Quality Challenges

“…Similarly, Bauwe et al . () found that precipitation time step of < 1 h does not provide significant differences in SWAT output except for a scenario when the saturated hydraulic conductivity is low and the curve number is high.…”