Modification of uncertainty analysis in adapted material flow analysis: Case study of nitrogen flows in the Day-Nhue River Basin, Vietnam

Abstract Nitrogen flows impacted by human activities in the Day-Nhue River Basin in northern Vietnam have been modeled using adapted material flow analysis (MFA). This study introduces a modified uncertainty analysis procedure and its importance in MFA. We generated a probability distribution using a Monte Carlo simulation, calculated the nitrogen budget for each process and then evaluated the plausibility under three different criterion sets. The third criterion, with one standard deviation of the budget value as the confidence interval and 68% as the confidence level, could be applied to effectively identify hidden uncertainties in the MFA system. Sensitivity analysis was conducted for revising parameters, followed by the reassessment of the model structure by revising equations or flow regime, if necessary. The number of processes that passed the plausibility test increased from five to nine after reassessment of model uncertainty with a greater model quality. The application of the uncertainty analysis approach to this case study revealed that the reassessment of equations in the aquaculture process largely changed the results for nitrogen flows to environments. The significant differences were identified as increased nitrogen load to the atmosphere and to soil/groundwater (17% and 41%, respectively), and a 58% decrease in nitrogen load to surface water. Thus, modified uncertainty analysis was considered to be an important screening system for ensuring quality of MFA modeling.

[1]  Bengt Steen,et al.  On uncertainty and sensitivity of LCA-based priority setting , 1997 .

[2]  W. de Vries,et al.  Approaches and uncertainties in nutrient budgets: implications for nutrient management and environmental policies , 2003 .

[3]  Suthipong Sthiannopkao,et al.  Anthropogenic influence on surface water quality of the Nhue and Day sub-river systems in Vietnam , 2010, Environmental geochemistry and health.

[4]  Mark A. J. Huijbregts,et al.  Application of uncertainty and variability in LCA , 1998 .

[5]  Georges Vachaud,et al.  Experimental investigation and modelling approach of the impact of urban wastewater on a tropical river; a case study of the Nhue River, Hanoi, Viet Nam , 2007 .

[6]  Ernst Worrell,et al.  Analysis of the paper and wood flow in The Netherlands , 2000 .

[7]  M. B. Beck,et al.  Water quality modeling: A review of the analysis of uncertainty , 1987 .

[8]  P. Willems,et al.  Sensitivity and uncertainty analysis for river quality modelling , 2004 .

[9]  Paul H. Brunner,et al.  Regional Material Management and Environmental Protection , 1992 .

[10]  K. Buzás.  Nutrient Balances of the Danube basin: The role of uncertainties , 1999 .

[11]  Hung Nguyen-Viet,et al.  Assessing nutrient fluxes in a Vietnamese rural area despite limited and highly uncertain data , 2011 .

[12]  M. B. Beck,et al.  Understanding the metabolism of urban-rural ecosystems , 2012, Urban Ecosystems.

[13]  Trinh Anh Duc,et al.  Partition of heavy metals in a tropical river system impacted by municipal waste , 2013, Environmental Monitoring and Assessment.

[14]  Hans-Peter Bader,et al.  Modeling the contribution of point sources and non-point sources to Thachin River water pollution. , 2009, The Science of the total environment.

[15]  Hasan Belevi,et al.  An approach to optimise nutrient management in environmental sanitation systems despite limited data. , 2008, Journal of environmental management.

[16]  Georges Vachaud,et al.  Biochemical modeling of the Nhue River (Hanoi, Vietnam): Practical identifiability analysis and parameters estimation , 2006 .

[17]  Peter Reichert,et al.  On the usefulness of overparameterized ecological models , 1997 .

[18]  Filip J. R. Meysman,et al.  Quantification of sediment‐water interactions in a polluted tropical river through biogeochemical modeling , 2012 .

[19]  Hans-Peter Bader,et al.  Modeling non-point source pollution from rice farming in the Thachin River Basin , 2011 .

[20]  Hans-Peter Bader,et al.  Modeling the contribution of pig farming to pollution of the Thachin River , 2010 .

[21]  Viet Anh Nguyen,et al.  Optimising water and phosphorus management in the urban environmental sanitation system of Hanoi, Vietnam. , 2007, The Science of the total environment.

[22]  Anna Björklund,et al.  Survey of approaches to improve reliability in lca , 2002 .