Sensitivity Analysis, Calibration, and Validations for a Multisite and Multivariable Swat Model

Abstract

The ability of a watershed model to mimic specified watershed processes is assessed through the calibration and validation process. The Soil and Water Assessment Tool (SWAT) watershed model was implemented in the Beaver Reservoir Watershed of Northwest Arkansas. The objectives were to: (1) provide detailed information on calibrating and applying a multisite and multivariable SWAT model; (2) conduct sensitivity analysis; and (3) perform calibration and validation at three different sites for flow, sediment, total phosphorus (TP), and nitrate‐nitrogen (NO3‐N) plus nitrite‐nitrogen (NO2‐N). Relative sensitivity analysis was conducted to identify parameters that most influenced predicted flow, sediment, and nutrient model outputs. A multi objective function was defined that consisted of optimizing three statistics: percent relative error (RE), Nash‐Sutcliffe Coefficient (RNS2), and coefficient of determination (R2). This function was used to successfully calibrate and validate a SWAT model of Beaver Reservoir Watershed at multi‐sites while considering multivariables. Calibration and validation of the model is a key factor in reducing uncertainty and increasing user confidence in its predictive abilities, which makes the application of the model effective. Information on calibration and validation of multisite, multivariable SWAT models has been provided to assist watershed modelers in developing their models to achieve watershed management goals.

Modelling hydrological processes in mesoscale lowland river basins with SWAT—capabilities and challenges

“…This parameter revealed a relatively low sensitivity in the Kielstau model set-up, in contrast to what was found by White & Chaubey (2005).…”

Improvement of SWAT2000 modelling to assess the impact of dams and sluices on streamflow in the Huai River basin of China

“…For those sites with observed data, good fits of Nash-Sutcliffe efficiency criterion (NSEC) (White and Chaubey, 2005;Wang et al, 2009) and RSO also mean good fits of RC; thus we set w 1 C w 2 D 1. The types of outlets and their corresponding data requirements and objectives are shown in Table II.…”

“…This process of calibration of SWAT, especially auto-calibrating algorithms, including the sensitivity analysis of parameters, has been the subject of many hydrological studies (Eckhardt and Arnold, 2001;Benaman et al, 2005;White and Chaubey, 2005;Cao et al, 2006;Bekele and Nicklow, 2007;Kannan et al, 2007). For example, Lenhart et al (2002) conducted a sensitivity analysis in SWAT whereby two approaches were considered as equivalent: one was to change the value of a given parameter by a fixed percentage of the initial value (Lenhart et al, 2002;White and Chaubey, 2005), and the other was to vary it by a fixed percentage of the valid parameter range (Lenhart et al, 2002). In both sensitivity analysis approaches, the greatest importance was attributed to soil parameters.…”

Regionalization of SWAT Model Parameters for Use in Ungauged Watersheds

“…Watersheds used in parameter regionalization were located in Arkansas. Datasets used in this study were developed based on previous modeling work conducted at the 8-digit hydrologic unit code (HUC) level [19] in seven Arkansas' priority watersheds [20][21][22].…”