Field_SWAT: A tool for mapping SWAT output to field boundaries

The Soil and Water Assessment Tool (SWAT) hydrological/water quality model divides a watershed into hydrological response units (HRUs) based on unique land cover, soil type, and slope. HRUs are a set of discontinuous land masses that are spatially located in the watershed but their responses are not tied to any particular field. Field_SWAT, a simple graphical user interface (GUI)-driven tool, was developed to map SWAT simulations from the HRU layer to a user-defined field boundaries layer. This stand-alone tool ingests spatial and nonspatial SWAT outputs and helps in visualizing them at the field scale using four different aggregation methods. The tool was applied for mapping the SWAT model's annual runoff and sediment outputs from 218 HRUs to 89 individual field boundaries in an agriculturally dominated watershed in Northeast Arkansas. The area-weighted spatial aggregation method resulted in a most suitable mapping between HRU and field outputs. This research demonstrates that Field_SWAT could potentially be a useful tool for field-scale targeting of conservation practices and communicating model outputs to watershed managers and interested stakeholders.

► We have developed a graphical user interface driven tool, Field_SWAT, to map HRU output from SWAT model to user-defined field boundaries.
► We examined mean, mode, geometric mean, and area-weighted aggregation methods for mapping the output.
► We found that area-weighted aggregation method resulted in most suitable mapping between HRU and field outputs.
► We feel that this tool will improve communicating model output to watershed managers and interested stakeholders.