NSI Hydrography Network for SSN Analysis

SSN analyses can be based on any digital hydrography network but these require topological reconditioning with the STARS ArcGIS toolkit to meet the compatibility requirements before conducting a spatial analysis. The reconditioning process may be time consuming and requires considerable GIS skills, so the NSI network was developed to expedite SSN analysis by reconditioning the NHD-Plus Version 2 medium resolution (1:100,000-scale) hydrography layer for all streams in the contiguous United States using the STARS toolkit. Use of NHD-Plus to create the NSI network also enables users to tap into large databases of reach descriptors developed for NHD-Plus that serve as useful predictor variables in spatial analyses. The NSI network is fully back-compatible with the original NHD-Plus layer after completion of a SSN analysis.

Shapefiles of the NSI network are available here for download by NHD production units; as are shapefiles of prediction points that can be used to make predictions at unsampled locations and map the results of SSN analyses. Each shapefile has specific metadata, but for general metadata see the General Flowline Metadata document or the Prediction Points Metadata document. A comprehensive description of the technical procedures applied to the NHD-Plus hydrography layer, as well as additional steps that are required to prepare datasets for SSN analysis are described in the NSI User Guide.

Related Presentation: The NSI Network: Modifying NHDPlus to Facilitate SSN Analysis

Stream line and prediction point shapefiles

Citation to use: Nagel, D., S. Wollrab, S. Parkes-Payne, E. Peterson, D. Isaak, and J. Ver Hoef. 2017. National Stream Internet hydrography datasets for spatial-stream-network (SSN) analysis. Rocky Mountain Research Station, U.S. Forest Service Data Archive, Fort Collins, CO. DOI: pending.

Processing Unit (NHD Plus V2)	Stream Line and Prediction Point Shapefiles (zip format)
01 Northeast	Flowline_NE01_NSI.shp PredictionPoints_NE01_NSI.shp
02 Mid Atlantic	Flowline_MA02_NSI.shp PredictionPoints_MA02_NSI.shp
03N South Atlantic North	Flowline_SA03N_NSI.shp PredictionPoints_SA03N_NSI.shp
03S South Atlantic South	Flowline_SA03S_NSI.shp PredictionPoints_SA03S_NSI.shp
03W South Atlantic West	Flowline_SA03W_NSI.shp PredictionPoints_SA03W_NSI.shp
04 Great Lakes	Flowline_GL04_NSI.shp PredictionPoints_GL04_NSI.shp
05 Ohio	Flowline_MS05_NSI.shp PredictionPoints_MS05_NSI.shp
06 Tennessee	Flowline06_NSI.shp PredictionPoints06_NSI.shp
07 Upper Mississippi	Flowline_MS07_NSI.shp PredictionPoints_MS07_NSI.shp
08 Lower Mississippi	Flowline_MS08_NSI.shp PredictionPoints_MS08_NSI.shp
09 Souris-Red-Rainy	Flowline09_NSI.shp PredictionPoints09_NSI.shp
10U Upper Missouri	Flowline_MS10u_NSI.shp PredictionPoints_MS10u_NSI.shp
10L Lower Missouri	Flowline_MS10L_NSI.shp PredictionPoints_MS10L_NSI.shp
11 Ark-Red-White	Flowline_MS11_NSI.shp PredictionPoints_MS11_NSI.shp
12 Texas	Flowline_TX12_NSI.shp PredictionPoints_TX12_NSI.shp
13 Rio Grande	Flowline_RG13_NSI.shp PredictionPoints_RG13_NSI.shp
14 Upper Colorado	Flowline_CO14_NSI.shp PredictionPoints_CO14_NSI.shp
15 Lower Colorado	Flowline_CO15_NSI.shp PredictionPoints_CO15_NSI.shp
16 Great Basin	Flowline_GB16_NSI.shp PredictionPoints_GB16_NSI.shp
17 Pacific Northwest	Flowline_PN17_NSI.shp PredictionPoints_PN17_NSI.shp
18 California	Flowline_CA18_NSI.shp PredictionPoints_CA18_NSI.shp