Environment Protection Authority Consultancy report: Nutrient Load Modelling for the NPI Water Catchment Reporting 1999 This report was prepared in 1999 by consultants for the then Environment Protection Agency (EPA) and the views expressed do not necessarily reflect those of the EPA. The EPA cannot guarantee the accuracy of the report, and does not accept liability for any loss or damage incurred as a result of relying on its accuracy. Nutrient Load Modelling for the National Pollutant Inventory Water Catchment Reporting 1999 Technical Report June 2000 Acknowledgements Funding: Funding for this work was provided by Environment Australia (Commonwealth Government). In-kind contributions were provided by the Environment Protection Agency (a Division of the Department for Environment and Heritage, South Australia). Data for this project was obtained from the sources listed below: GIS Services, Sustainable Resources (Primary Industries and Resources South Australia) PlanningSA (Department of Transport, Urban Planning and the Arts) Resource Information (Department for Environment and Heritage) Australian Water Quality Centre (SAWater) Water Data Services This document was produced for the: Environment Protection Agency Department for Environment and Heritage Adelaide South Australia June 2000 Author: Doug McMurray Scientific Officer Department for Water Resources Adelaide South Australia NPI Project Manager (South Australia): Diane Kotrotsos Environment Protection Agency Adelaide South Australia Disclaimer In as far as this report contains recommendations on proposals for further action it must not be assumed from this report alone that they form part of any approved policy. © Environment Protection Agency, Department for Environment and Heritage, 2000. This document may be freely copied and used provided that the source is acknowledged. Contents SUMMARY ......................................................................................................................................... 1 OVERVIEW .................................................................................................................................................. 1 PRESENTATION OF RESULTS........................................................................................................................ 2 INTRODUCTION ................................................................................................................................ 3 OVERVIEW .................................................................................................................................................. 3 REPORT STRUCTURE ................................................................................................................................... 3 STUDY AREA .............................................................................................................................................. 4 THE NATIONAL POLLUTANT INVENTORY (NPI).......................................................................................... 4 NUTRIENTS ................................................................................................................................................. 5 NUTRIENT LOADS AND NUTRIENT EMISSIONS ............................................................................................ 5 CATCHMENT MANAGEMENT SUPPORT SYSTEM (CMSS)............................................................................ 7 REASONS FOR DEVELOPING THE GIS MODEL ............................................................................................. 7 NUTRIENT LOAD MODELLING ....................................................................................................... 9 INTRODUCTION ........................................................................................................................................... 9 LANDUSE DATA .......................................................................................................................................... 9 NUTRIENT GENERATION RATES................................................................................................................ 10 GIS MODEL - CONCEPTS .......................................................................................................................... 14 CALIBRATION ........................................................................................................................................... 15 Native Vegetation ............................................................................................................................. 15 Grazing, Rural Living ...................................................................................................................... 15 Urban ............................................................................................................................................... 16 Horticulture...................................................................................................................................... 16 Other Landuses ................................................................................................................................ 17 Second Iteration ............................................................................................................................... 17 RESULTS OF THE CALIBRATION STAGE ..................................................................................................... 17 RESULTS FOR NPI SUB-CATCHMENTS ...................................................................................................... 17 REGIONAL AREAS ..................................................................................................................................... 21 Iron Triangle Towns......................................................................................................................... 21 The Riverland Towns........................................................................................................................ 22 The South East Towns ...................................................................................................................... 22 MONITORING DATA ....................................................................................................................... 25 OVERVIEW ................................................................................................................................................ 25 COMPOSITE SAMPLING.............................................................................................................................. 25 SAMPLE SITES........................................................................................................................................... 26 ANALYSIS OF GRAB SAMPLING DATA (FOR FIRST CREEK) ....................................................................... 27 ANALYSIS OF COMPOSITE SAMPLING DATA (WITHOUT PUMPED FLOWS).................................................. 29 ADDITIONAL ANALYSIS OF SAMPLING DATA WITH PUMPED FLOWS ........................................................ 34 Nutrient Loads in Water Pumped from the River Murray................................................................ 34 Houlgrave (Onkaparinga River) ...................................................................................................... 35 Millbrook Intake (River Torrens) ..................................................................................................... 37 AWQC SAMPLING DATA.......................................................................................................................... 38 CLIMATE CORRECTION FACTOR................................................................................................................ 39 DISCUSSION ................................................................................................................................... 43 Results for Nutrient Loads derived from the Monitoring Data ........................................................ 43 Results for the Sub-Catchment Modelling ........................................................................................ 45 Nutrient Load Model and Calibration.............................................................................................. 45 Estimation of Errors......................................................................................................................... 46 Monitoring Data............................................................................................................................... 47 Monitoring Program ........................................................................................................................ 47 FURTHER WORK ............................................................................................................................ 49 CONCLUSIONS ............................................................................................................................... 51 REFERENCES ................................................................................................................................. 53 GLOSSARY ..................................................................................................................................... 55 Page ii Nutrient Load Modelling for the NPI List of Figures Figure T1 (Map of) The Study Area œ Adelaide Region South Australia 4a Figure N1 (Map of) Sub-Catchments Modelled for Nutrient Loads