Effects of temporal resolution of river routing on hydrologic modeling and aquatic ecosystem health assessment with the SWAT model

Abstract Watershed models are widely used to study hydrological processes. Here, we investigated how the temporal resolution of river water routing within the Soil and Water Assessment Tool (SWAT) model can affect simulated riverine hydrological processes. We conducted numerical experiments in two watersheds in the Northeastern U.S. to execute the SWAT model's variable storage coefficient river routing method with six different time steps ranging from 1 min to 1 day for the period between 2001 and 2018. We found that simulated stream discharge largely stabilizes with different time steps, whereas the water storage and depth vary greatly. Those simulation results lead to a dramatic difference in the calculated Dendritic Connectivity Index (DCI), which is a widely used indicator for assessing aquatic ecosystem health. We recommend taking a time step that is shorter than 1 h, while recognizing that the appropriate time steps depend on actual watershed size and configuration.