Modelling nutrient transport in Currency Creek, NSW with AnnAGNPS and PEST

Abstract The modelling package Annualized Agricultural Nonpoint Source Model (AnnAGNPS) was applied to the prediction of export of nitrogen and phosphorus from Currency Creek, a small experimental catchment within the Hawkesbury–Nepean drainage basin of the Sydney Region. The catchment is 255 ha in area and has experienced extensive soil erosion and losses of nutrients from intensive vegetable cultivation, irrigated dairy pasture and poultry farms. Simulations of nitrogen and phosphorus loads in the Currency Creek catchment were performed at various temporal scales and the degree of calibration was quantified by comparing the simulated data with the monitoring results. In addition, the model independent, nonlinear parameter estimation code PEST, was applied for sensitivity testing to determine and assess the relative importance of the key parameters of the model. Event flows were simulated satisfactorily with AnnAGNPS but only moderate accuracy was achieved for prediction of event-based nitrogen and phosphorus exports. The biggest deviations from the measured data were observed for daily simulations but trends in the generated nutrients matched observed data. Despite achieving good resemblance between measured and predicted phosphorus loads the model showed high level of sensitivity to assigned pH values for topsoil. Increase in pH by one unit resulted in up to 34% increase in model generated particulate phosphorus load.

[1]  J Foerster,et al.  Application of AGNPS to model nutrient generation rates under different farming management practices at the Gunnedah Research Centre catchment , 1995 .

[2]  William H. Press,et al.  Numerical recipes , 1990 .

[3]  R. Young,et al.  AGNPS: A nonpoint-source pollution model for evaluating agricultural watersheds , 1989 .

[4]  Michael J. Stewardson,et al.  Comparison of six rainfall-runoff modelling approaches , 1993 .

[5]  W. Chambers.  San Antonio, Texas , 1940 .

[6]  D. Bennett,et al.  Evaluating Nonpoint Pollution Policy Using a Tightly Coupled Spatial Decision Support System , 2001, Environmental management.

[7]  W. G. Knisel,et al.  CREAMS: a field scale model for Chemicals, Runoff, and Erosion from Agricultural Management Systems [USA] , 1980 .

[8]  Lawrence W. Martz,et al.  Advances in Automated Landscape Analysis , 1995 .

[9]  Donald Woodward,et al.  A user agency's view of hydrologic, soil erosion and water quality modelling , 1999 .

[10]  Robert A. Corbitt,et al.  Standard Handbook of Environmental Engineering , 1989 .

[11]  R. A. Young,et al.  Modeling Linked Watershed and Lake Processes for Water Quality Management Decisions , 1990 .

[12]  Anthony J. Jakeman,et al.  Performance of conceptual rainfall‐runoff models in low‐yielding ephemeral catchments , 1997 .

[13]  Ian D. Moore,et al.  Terrain analysis : integration into the agricultural nonpoint source (AGNPS) pollution model , 1991 .

[14]  R. T. Roberts,et al.  Urban Hydrology for Small Watersheds (TR-55 Rev.) , 1985 .

[15]  U. S. Tim,et al.  Evaluating Agricultural Nonpoint-Source Pollution Using Integrated Geographic Information Systems and Hydrologic/Water Quality Model , 1994 .

[16]  M. Dilshad,et al.  Evaluation of the USDA curve number method for agricultural catchments in the Australian semi-arid tropics , 1994 .

[17]  J. Nash,et al.  River flow forecasting through conceptual models part I — A discussion of principles☆ , 1970 .

[18]  Walter C. Boughton,et al.  A review of the USDA SCS curve number method , 1989 .

[19]  L. D. Norton,et al.  AN AGNPS-BASED RUNOFF AND SEDIMENT YIELD MODEL FOR Two SMALL WATERSHEDS IN GERMANY , 1999 .

[20]  Raghavan Srinivasan,et al.  Nonpoint Source (NPS) Pollution Modeling Using Models Integrated with Geographic Information Systems (GIS) , 1993 .