The Allocation of Nutrient Load Reduction across a Watershed: Assessing Delivery Coefficients as an Implementation Tool
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Delivery coefficients have long been used in economic analysis of policies that seek to address environmental problems like water pollution (Montgomery, 1972). However, the derivation and validity of delivery coefficients have not been examined carefully by empirical analyses. In this study, we derived estimates of delivery coefficients and then evaluated them as a bridge between complex biophysical models and economic policies. Specifically, delivery coefficients were first derived for the effects of nitrogen application reduction based on the simulation results of a watershed based model, the Soil and Water Assessment Tool (SWAT). Nutrient load reduction responsibilities were then allocated to subwatersheds based on the delivery coefficients using four different allocation principles. We found that the allocations based on delivery coefficients achieved results that differed from the water quality goals by only a few percentage points in general. Moreover, our results indicated that potential cost savings, measured in percentages, outweighed the deviation from water quality goals.