Integrated Hydrologic-Economic Optimization Modeling for Watershed Evaluation of Agricultural BMPs and Policies

Oginskyy, Anatoliy
Journal Title
Journal ISSN
Volume Title
University of Guelph

This study develops and applies integrated hydrologic-economic optimization modeling for evaluating costs effectiveness of beneficial management practices (BMPs) in agricultural watersheds. The study has three components. Firstly, it defines agriculture as a social-natural system, formulates the system functions, and develops theoretical and empirical frameworks for integrated hydrologic-economic modeling for evaluating BMP cost effectiveness and optimal placement in agricultural watersheds. The integrated modeling contributes to advancing the methodology for watershed-based BMP assessment and improving our understanding on spatial tradeoffs of BMP costs and benefits. Secondly, the study develops a user friendly interface for the integrated modeling as an open-source Whitebox GIS plug-in. The interface facilitates the use of the complex integrated modeling for conducting watershed-based BMP assessment by scientists and conservation managers. Finally, the study empirically applies the integrated modeling to produce new information on the cost effectiveness of representative agricultural BMPs including zero tillage, optimium fertilizer application rates, and red clover as a cover crop in the Gully Creek watershed of southwestern Ontario. The simulation results show that zero tillage reduces the sediment and nitrogen loads by 45% and 43%, respectively, costing the farmers about 2% of the net return. Applying the practice to corn sown after soybeans appears to be profitable. Application of the optimum fertilizer application rates, red clover as a cover crop BMPs, and multiple BMPs are cost-effective in reducing sediment and nutrient loads. Simulation of optimal BMP allocations in the watershed produces several cost-effective BMP policies subject to environmental targets. It also shows that the magnitude of BMP cost depends on the number of available BMP alternatives. The functional relationships between BMP costs and water quality benefits depend on the type of pollutant and the level of environmental target. A piecewise function with steep, moderate, and flat regions better describes the relationships and produces the highest fit. This finding extends our understanding of the BMP cost benefit relationships which are considered to be generally monotonic.

Integrated modeling, BMPs, BMP cost, BMP effects, cost-benefit ratio, optimal BMP allocation, cost-benefit relations, total abatement cost, marginal abatement cost, BMP evaluation, social efficiency, cost efficiency, dynamic efficiency, BMP characterization, uncertainty, variability, evaluation criteria, conceptual model, empirical model, computer model, economic effects, hydrologic effects, integrated effects, model calibration, model validation, integrated assessment, conservation tillage, nutrient management, cover crop, BMP ranking, Pareto efficiency, Kaldor-Hicks efficiency, cost minimization, coupled system, holistic system, loose coupling, tight coupling, surface runoff, sediment yield, nitrogen load, phosphorus load, SWAT, Whitebox, model interface