River Basin Export Reduction Optimization Support Tool; a tool to screen options for reducing nutrient loads while minimizing cost

摘要

Excess loading of nitrogen and phosphorus to river networks causes environmental harm,but reducing loads from large river basins is difficult and expensive. We developed a newtool, the River Basin Export Reduction Optimization Support Tool (RBEROST) to identifythe least-costcombinations of management practices that will reduce nutrient loadingto target levels in downstream and mid-networkwaterbodies. We demonstrate the utilityof the tool in a case study in the Upper Connecticut River Basin in New England,USA. The total project cost of optimized lowest-costplans ranged from $18.0 million to$41.0 million per year over 15 years depending on user specifications. Plans include bothpoint source and non-pointsource management practices, and most costs are associatedwith urban stormwater practices. Adding a 2 margin of safety to loading targetsimproved the estimated probability of success from 37.5 to 99. The large spatial scaleof RBEROST, and the consideration of both point and non-pointsource contributions ofnutrients, make it well suited as an initial screening tool in watershed planning.