Development of a hydrologic connectivity dataset for SWAT assessments in the U.S.

Authors: White, Michael; BEIGER, KATRIN - Texas Agrilife Research; Gambone, Marilyn; HANEY, LIZ - Texas Agrilife Research; Arnold, Jeffrey; GAO, JUNGANG - Texas Agrilife Research

Submitted to: Water
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/11/2017
Publication Date: 11/15/2017
Publication URL: http://handle.nal.usda.gov/10113/5863772
Citation: White, M.J., Beiger, K., Gambone, M.A., Haney, L., Arnold, J.G., Gao, J. 2017. Development of a hydrologic connectivity dataset for SWAT assessments in the U.S. Water. 9(892):1-10. https://doi.org/10.3390/w9110892.

Interpretive Summary: National water quality assessments are an important part of conservation policy. It is very difficult to manage the shear amount of data required to describe how water moves across each field, to a stream, then a river, and finally to the sea. In this research we described the development of a simplified representative channel approach to condense these data while still accounting for all the important processes that occur throughout the system. All these data are provided via the web for other researchers to evaluate and utilize.

Technical Abstract: Model based water quality assessments are as important informer of conservation and environmental policy in the US. The recently completed national scale Conservation Effects Assessment Project (CEAP) is being repeated using newer data, greater resolution, and enhanced models. National assessments are particularly difficult as models must operate with both a very large spatial extent (the contiguous US) while maintaining a level of granularity required to capture important small scale processes. In this research, we developed datasets to describe hydrologic connectivity at the USGS 12-digit Hydrologic Unit Code (HUC-12) level. Connectivity between 86,000 HUC-12’s as provided by the Watershed Boundary Dataset (WBD) was evaluated and corrected. We also detail a method to resolve the highly detailed National Hydrography Dataset (NHD) stream segments within each HUC-12 into vastly simplified representative channel scheme suitable for use in the recently developed Soil and Water Assessment Tool + (SWAT+) model. This representative channel approach strikes a balance between computational complexity and accurate representation of the hydrologic system. These data will be tested in the upcoming CEAP II national assessment. Until then all the WBD corrections and NHDPlus representative channel data is provided via the web for other researchers to evaluate and utilize.