Modelling E. coli in the Waikato and Waipa River Catchments Development of a catchment-scale microbial model

TR 2018/62

Report: TR 2018/62

Author: Annette Semadeni-Davies, Sandy Elliott, Sharleen Yalden (National Institute of Water & Atmospheric Research Ltd (NIWA))

About this report

This report was commissioned by the Technical Leaders Group for the Healthy Rivers Wai Ora Project Report No. HR/TLG/2015-2016/2.6

The report presents the development of three models developed to provide input data to a farm cost model to evaluate the costs associated with mitigating farm practices to reduce E. coli loads.

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Modelling E. coli in the Waikato and Waipa River Catchments Development of a catchment-scale microbial model [PDF, 2.1 MB]

Contents
	Executive summary
1	Introduction
1.1	Preamble
1.2	E. coli
1.3	Scope
2	Methodology
2.1	Input data
2.1.1	Drainage network and monitoring stations
2.1.2	Catchment characteristics
2.1.3	Land use
2.1.4	Point sources and farm dairy effluent inputs
2.2	Calibration data
2.2.1	Annual median concentrations
2.2.2	Mean annual loads
	Rating curve method
	Ratio method
2.3	E. coli load models
2.3.1	Detailed load model
2.3.2	Calibration method
2.3.3	Coarse load model
2.4	Concentration model
2.4.1	Concentration estimated at unmonitored sites
2.4.2	Prediction of concentrations for future scenarios
3	Results
3.1	E. coli load models
3.1.1	Calibration
3.1.2	Detailed load model
3.1.3	Coarse load model
3.2	E. coli current concentration model
4	Model uncertainty
5	Recommendations for further work
6	Conclusions
	Acknowledgements
	References
	Appendix A - Mitigations for microbial load reduction
	Appendix B - Point sources
	Appendix C - Calibration data: Concentration
	Appendix D - Calibration data: Loads