Calibration of the APEX Model to Simulate Management Practice Effects on Runoff, Sediment, and Phosphorus Loss

Bhandari, Ammar B.; Nelson, Nathan O.; Sweeney, Daniel W.; Baffaut, Claire; Lory, John A.; Senaviratne, Anomaa; Pierzynski, Gary M.; Janssen, K. A.; Barnes, Philip L.

doi:10.2134/jeq2016.07.0272

Cited by 25 publications

(26 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Better understanding of how management practices affect these parameters is desirable for more accuracy in the estimation of practice effectiveness. Bhandari et al (2017) arrived at a similar conclusion and recommended using calibration data that cover both practice and no-practice scenarios.…”

Section: Cross-validation Of Nb and Ub Modelsmentioning

confidence: 73%

“…The 23% and 30% reductions in runoff and TP, respectively, in the agroforestry watershed based on all March-November simulated daily values (table 8) were close to the total effect with the UB model (25% and 28%, respectively; table 7). On the other hand, the reductions estimated with the NB model (not shown) were farther apart (30% and 39%, respectively), which emphasizes the need for a model that performs well with and without the practice being evaluated (Bhandari et al, 2017). Discharge measurement methods with a flow-control structure but without periodic discharge checks typically yield measurement errors of 5% to 10% (Harmel et al, 2006).…”

Section: Buffer Effectiveness Using Simulated Paired Watershed Approachmentioning

confidence: 96%

See 1 more Smart Citation

Improved APEX Model Simulation of Buffer Water Quality Benefits at Field Scale

Senaviratne¹,

Baffaut²,

Lory³

et al. 2018

Transactions of the ASABE

Self Cite

View full text Add to dashboard Cite

Section: Cross-validation Of Nb and Ub Modelsmentioning

confidence: 73%

Section: Buffer Effectiveness Using Simulated Paired Watershed Approachmentioning

confidence: 96%

Improved APEX Model Simulation of Buffer Water Quality Benefits at Field Scale

Senaviratne¹,

Baffaut²,

Lory³

et al. 2018

Transactions of the ASABE

Self Cite

View full text Add to dashboard Cite

“…Calibration resulted in a reduced range of values for each indicator, as indicated by a smaller standard deviation, and increased the number of sites where PEC were met. Sites for which sediment r 2 and NSE did not meet the PEC were characterized by small sediment loads (average annualized load < 0.8 Mg ha −1 ; Bhandari et al, 2017; Nelson et al, 2017). …”

Section: Resultsmentioning

confidence: 99%

“…It potentially could be used to evaluate the runoff component of these indices, provided it is successfully tested on soils with different characteristics. Other papers in this special section include analyses of the calibrated parameterizations within and beyond the calibration conditions (Bhandari et al, 2017) and development of a regional parameterization that could provide acceptable performance (Nelson et al, 2017). …”

Section: Resultsmentioning

confidence: 99%

Multisite Evaluation of APEX for Water Quality: I. Best Professional Judgment Parameterization

et al. 2017

Self Cite

View full text Add to dashboard Cite

The Agricultural Policy Environmental eXtender (APEX) model is capable of estimating edge-of-field water, nutrient, and sediment transport and is used to assess the environmental impacts of management practices. The current practice is to fully calibrate the model for each site simulation, a task that requires resources and data not always available. The objective of this study was to compare model performance for flow, sediment, and phosphorus transport under two parameterization schemes: a best professional judgment (BPJ) parameterization based on readily available data and a fully calibrated parameterization based on site-specific soil, weather, event flow, and water quality data. The analysis was conducted using 12 datasets at four locations representing poorly drained soils and row-crop production under different tillage systems. Model performance was based on the Nash-Sutcliffe efficiency (NSE), the coefficient of determination (r 2 ) and the regression slope between simulated and measured annualized loads across all site years. Although the BPJ model performance for flow was acceptable (NSE = 0.7) at the annual time step, calibration improved it (NSE = 0.9). Acceptable simulation of sediment and total phosphorus transport (NSE = 0.5 and 0.9, respectively) was obtained only after full calibration at each site. Given the unacceptable performance of the BPJ approach, uncalibrated use of APEX for planning or management purposes may be misleading. Model calibration with water quality data prior to using APEX for simulating sediment and total phosphorus loss is essential. (P) and sediment loss from agricultural fields continues to degrade fresh water quality despite decades of efforts to understand loss processes and implement management practices to reduce nonpoint pollution (e.g., Sharpley et al., 1994Sharpley et al., , 2015Sims and Kleinman, 2005;Jarvie et al., 2013). Failure of conservation practices to produce expected improvements in water quality has renewed appreciation for the complexity of P movement within landscapes and to waterbodies Sharpley et al., 2013). Processbased watershed-and field-scale models offer the prospect of integrating knowledge to assess and quantify impacts of conservation and management practices.The P Index was developed in the mid-1990s to assess risk of P loss from agricultural land (Lemunyon and Gilbert, 1993) and is now an integral part of the NRCS 590 Nutrient Management Standard and other state and federal programs (Sharpley et al., 2003(Sharpley et al., , 2017. However, the diversity in P Index ratings and P management recommendations for similar conditions led and Osmond et al. (2006) to emphasize the need for science-based assessment and improvement of existing P Indices.Extensive testing of P Indices requires water quality data from field-scale watersheds from a broad range of soils and management scenarios with a sufficient number of monitoring years to estimate long-term average annual losses. Such extensive datasets are rare. Hence, computer models must ...

show abstract

“…Baffaut et al (2017) found that an uncalibrated Agricultural Policy Environmental eXtender (APEX) model failed to adequately simulate edge‐of‐field P loss. However, it was found that, with calibration, the APEX model could simulate P loss resulting from different management practices at nearby locations with similar soils (Senaviratne et al, unpublished data, 2016; Bhandari et al, 2017). If APEX could be calibrated at a regional level, then it could be used to generate the required P‐loss estimates for P Index evaluation.…”

mentioning

confidence: 99%

Multisite Evaluation of APEX for Water Quality: II. Regional Parameterization

et al. 2017

Self Cite

View full text Add to dashboard Cite

Phosphorus (P) Index assessment requires independent estimates of long-term average annual P loss from fields, representing multiple climatic scenarios, management practices, and landscape positions. Because currently available measured data are insufficient to evaluate P Index performance, calibrated and validated process-based models have been proposed as tools to generate the required data. The objectives of this research were to develop a regional parameterization for the Agricultural Policy Environmental eXtender (APEX) model to estimate edgeof-field runoff, sediment, and P losses in restricted-layer soils of Missouri and Kansas and to assess the performance of this parameterization using monitoring data from multiple sites in this region. Five site-specific calibrated models (SSCM) from within the region were used to develop a regionally calibrated model (RCM), which was further calibrated and validated with measured data. Performance of the RCM was similar to that of the SSCMs for runoff simulation and had Nash-Sutcliffe efficiency (NSE) > 0.72 and absolute percent bias (|PBIAS|) < 18% for both calibration and validation. The RCM could not simulate sediment loss (NSE < 0, |PBIAS| > 90%) and was particularly ineffective at simulating sediment loss from locations with small sediment loads. The RCM had acceptable performance for simulation of total P loss (NSE > 0.74, |PBIAS| < 30%) but underperformed the SSCMs. Total P-loss estimates should be used with caution due to poor simulation of sediment loss. Although we did not attain our goal of a robust regional parameterization of APEX for estimating sediment and total P losses, runoff estimates with the RCM were acceptable for P Index evaluation. T he Phosphorus (P) Index was developed as a tool to assess the risk of P loss from agricultural fields. Although this tool has been used to encourage the adoption of conservation practices and develop nutrient management plans, excess P losses from agricultural fields and associated water quality degradation persist ( Jarvie et al., 2013;Sharpley et al., 2015;USEPA, 2016). Due to the lack of water quality improvement and the disparity among state P Indices (Osmond et al., 2006), it has been proposed that the P Indices undergo evaluation to ensure accuracy in P-loss risk assessment (Sharpley et al., 2012).A wide variety of methods have been used to assess P Indices (Nelson and Shober, 2012); however, the ideal assessment would include comparison of P Index results to independently obtained quantitative estimates of long-term average annual P loss across a wide range of soils, topography, and management practices . This type of quantitative independent assessment requires long-term average annual estimates of P loss because the P Index is a generalized assessment of the average risk of P loss across an extended period, as opposed to an assessment of P loss for a specific year or weather sequence. Because measured edge-of-field P-loss data are highly dependent on the weather patterns during the years of data col...

show abstract

Calibration of the APEX Model to Simulate Management Practice Effects on Runoff, Sediment, and Phosphorus Loss

Cited by 25 publications

References 29 publications

Improved APEX Model Simulation of Buffer Water Quality Benefits at Field Scale

Improved APEX Model Simulation of Buffer Water Quality Benefits at Field Scale

Multisite Evaluation of APEX for Water Quality: I. Best Professional Judgment Parameterization

Multisite Evaluation of APEX for Water Quality: II. Regional Parameterization

Contact Info

Product

Resources

About