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RBEROST Code and User Guide
Citation:
Chamberlin, C., N. Detenbeck, M. Ten Brink, A. Le, K. Munson, I. Morin, M. Marks, AND Y. Li. RBEROST Code and User Guide. U.S. Environmental Protection Agency, Washington, DC, 2022.
Impact/Purpose:
Excess loading of nutrients, especially nitrogen and phosphorus, can cause problems such as low dissolved oxygen or harmful algal blooms at multiple locations within a river basin. Stakeholders often need to meet annual nutrient loading targets at these multiple locations simultaneously. For examples, stakeholders may need to meet a loading target for nitrogen for an estuary at the base of the watershed as well as total phosphorus loading targets to protect lakes or reservoirs within the river network. This sub-product includes an application (computer code in R and RShiny), an associated user guide, and example input data files for the River Basin Export Reduction Optimization Support Tool (RBEROST). RBEROST is designed to help users identify the least cost set of management practices (including both types of practices and their levels of implementation) to meet their specified loading targets for nutrient loading at multiple points within a river basin. Management practices to be considered can include upgrades to wastewater treatment plants, agricultural conservation practices such as no-till or vegetated filter strips, stormwater best management practices including both traditional grey (detention ponds) and green infrastructure (e.g., rain garden) practices, and forested or grassed riparian buffers along streams. The optimal (least cost) solution is summarized for the user along with the spatial configuration of implementation and associated costs. Uncertainty in input data is used to generate an estimate of the likelihood of meeting each specified target, as well as uncertainty bounds around total associated costs.
Description:
The River Basin Export Reduction Optimization Support Tool (RBEROST) is a decision support tooldesigned to support integrated, regional, watershed planning. The tool is designed to help managers reducenutrient loading to targeted waterbodies for the least financial cost. This tool optimizes costs for meetingtargets for nutrient export at the annual scale and is designed to be used as a screening tool for largewatersheds (e.g., HUC 6 - HUC 8 scale). The tool is mathematically similar to the Watershed ManagementOptimization Support Tool, or WMOST (Detenbeck, ten Brink, et al., 2018; Detenbeck, Piscopo, et al.,2018). WMOST is built for optimization at the HUC10 or HUC12 scale and can be run on daily or monthlytimesteps. RBEROST was developed as a regional screening tool to overcome computational challenges withrunning WMOST at larger spatial scales. All RBEROST scripts are written in R 4.0.5. and may displayincompatibilities with other versions. Execution of the RBEROST application is recommended with RStudioversion 1.4.1106 and may display incompatibilities with other versions. Additional R packages may needto be installed by the user. The R code and instructions on how to execute the code necessary for theseinstallations are included in the documentation. RBEROST allows users to screen which locations and choices of Best Management Practices (BMPs) will meetannual loading targets for the least financial cost. There are three main steps within RBEROST including apreprocessing step, an interaction with an online server, and a postprocessing step. Additional work maybe necessary before beginning RBEROST to collect and format the necessary data. The preprocessing stepcombines medium-resolution National Hydrography Dataset Plus (NHDPlus v2; McKay et al. (2012)) reachlengths, NHDPlus v2 catchment-level annual nutrient loading, land use data, hydrologic soil group data,nitrogen (N) deposition data, user-defined loading targets, user-defined agricultural, urban, point source andriparian buffer BMPs, and data on BMP-specific costs and nutrient removal efficiencies. The preprocessingstep then uses this information to write three program files in A Mathematical Programming Language, orAMPL, including a model, data, and command file. There are two options available for the preprocessingstep, i.e., creating AMPL files with or without uncertainty information included. The AMPL files describe amodel that defines a cost-minimization optimization problem subject to meeting downstream annual loadingtargets. These files are then sent to a free online CPLEX server hosted by the Network-Enabled OptimizationSystem (NEOS; University of Wisconsin in Madison (2021)). CPLEX is a linear solver that will solve theoptimization problem defined by the user inputs of loading targets and selected BMPs for the least cost.Once the solution is optimized, the model outputs its decisions of which BMPs to implement, and whereto implement them. The final step of RBEROST is the postprocessing step. This step parses the outputfrom NEOS into a summary report describing which BMPs were implemented. It also provides csv files fordownload that describe the BMP choices on the NHDPlus v2 catchment-level scale. If the user chooses to runthe model with uncertainty, the postprocessor will provide information on the expected cost range, as well asthe likelihood of meeting each loading target. When run with uncertainty, the model can display multiplescenarios with increasing cost and likelihood for meeting targets.
URLs/Downloads:
https://github.com/USEPA/RBEROST
RBEROST Code and User Guide (PDF, 85 pp, 4786 KB, about PDF)