Modeled flow metrics for stream segments in the United States under historical conditions and projected climate change scenarios

These files represent modeled streamflow across the contiguous United States, for the historical period (1977–2006), and two projected future time periods, mid-century (2030–2059), and end-of-century (2070–2099), based on gridded simulations of daily total runoff. The flow regime is of fundamental importance in determining the physical and ecological characteristics of a river or stream, but actual flow measurements are only available for a small minority of stream segments, mostly on large rivers. Flows for all other streams must be extrapolated or modeled. Modeling is also necessary to estimate flow regimes under future climate conditions. These use RCP 8.5 projections of temperature and precipitation, downscaled to a 1/8 degree (approximately 12 kilometers) cell size, which are used as inputs to the Variable Infiltration Capacity (VIC) macroscale hydrologic model. For each stream segment in the National Hydrography Dataset Plus Version 2 (NHDPlusV2) in the contiguous U.S. we calculated hydrographs for the three time periods. From these we calculated summary flow metrics to describe flow regimes for each stream segment and each time period and joined these to the NHD stream segments for visualization and analysis. These results allow scientists and managers to easily compare historical and projected flow patterns, including monthly, seasonal, and annual flow, flood and drought events, and timing of peak and low flows. This data publication includes the following three geodatabases: 1) flow metrics for all time periods, NHD regions, and models, merged, projected, and cleaned, for the 5-model average results; 2) individual streamflow metric files for each time period, absolute change between them, and percent change between them, for the 5-model average results; and 3) individual streamflow metric files for each time period, absolute change between them, and percent change between them, for each of 5 climate models.
The purpose of this study was to model streamflow across the contiguous United States, for the historical period (1977–2006), and two projected future time periods, mid-century (2030–2059), and end-of-century (2070–2099), based on gridded simulations of daily total runoff.
This data publication is an update to the "Western U.S. stream flow metric dataset" (Wenger et al. 2010). In this update we expand the spatial extent of the analysis, use updated climate scenarios, and include additional climate metrics. For more methodological details, see Wenger et al. (2010). This data publication only includes the summarized data, due to the size of the unsummarized files. Additional data, described in \Supplements\Data_available_upon_request.pdf, may be available upon request.