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Erosion model testing – are doing enough?
The document discusses the necessity of testing soil erosion models to ensure their reliability for decision-making in land management. It highlights that existing models often show poor accuracy and uncertainty in predicting erosion rates. The authors argue for continuous evaluation of these models to improve their effectiveness and stakeholder trust.
Erosion model testing – are doing enough?
- 1. Erosion model testing- are we doing enough? Pedro V. G. Batista1,2, Jess Davies2, Marx L. N. Silva1,2, John N. Quinton2 1Lavras Federal University, Brazil 2Lancaster University, United Kingdom 1
- 2. Can models helpto control soil erosion? What can soil erosion models tell us: • Where, when, and with which magnitude erosion occurs; • How land use management and control measurements affect erosion rates. Do we trust are models enough to substantiate decision making? How to establish such trust? 2
- 3. Models are meantto be tested 3 Observational data Model outputs Evaluation Decision making But are we testing our models?
- 4. How is modelevaluation associated to conceptual structures in soil erosion research? Scientometric term co-occurrence analysis with VOSviewer (van Eck & Waltman, 2010) 4 •WoS query: “soil erosion model*” 1 •Title and abstract information from 550 articles (1985-2018) 2 •15 occurrences threshold •106 terms mapped according to relatedness and association strength 3 Rainfall intensity Calibration Validation Impact
- 5. Network map andresearch front clusters 5 Cluster 1: distributed large scale modeling Cluster 2: scenario-based simulations Cluster 3: process description Cluster 4: model evaluation
- 6. Focus on outlet-basedcalibration and “validation” 6
- 7. Both models havebeen outlet-calibrated and predict similar sediment yields 7 SWAT SEDD Which one is more useful? Eduardo (2017) Batista et al. (2017)
- 8. Publication trend: largescale distributed, simulation-based modeling 8 Normalised average year of publication
- 9. 9 How accurate areerosion models?
- 10. Erosion models are uncertain Casestudy: • MMF/ GLUE • Brazilian plot data • Nearing (2000) rejection criteria • 106 realisations 10 Observed data Bare Maize Erosionrate(kg/m²)
- 11. Then are weso confident about the performance of soil erosion models that we do not need to test them anymore? 11 The scientific literature says NO: • Modeled erosion/deposition patterns/rates frequently compare poorly to independent estimates (Takken et al., 1999; Jetten et al., 2003; Evans & Brazier, 2005); • Un-calibrated models do not provide reliable estimates of sediment yield (Jetten et al., 1999; Van Rompaey et al. 2003; de Vente et al., 2013); • Models outputs are considerably uncertain (Quinton, 1997; Brazier et al., 2000; Van Rompaey & Govers, 2002).
- 12. Conclusion 12 • If soilerosion models are to influence matters of public interest they must be continuously evaluated. • Our co-occurrence analysis indicates that this is not the case. • Evaluating erosion models is inherently difficult, defining tests according to the purpose, structure, and scale of the application would benefit both modelers and stakeholders.
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