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Attributes for NHDPlus Version 2.1 Catchments and Modified Routing of Upstream Watersheds for the Conterminous United States: Topographic Wetness Index

Dates

Publication Date
Time Period
1995

Citation

Wieczorek, M.E., Jackson, S.E., and Schwarz, G.E., 2018, Select Attributes for NHDPlus Version 2.1 Reach Catchments and Modified Network Routed Upstream Watersheds for the Conterminous United States (ver. 4.0, August 2023): U.S. Geological Survey data release, https://doi.org/10.5066/F7765D7V.

Summary

This tabular data set represents average topgraphic wetness index compiled for two spatial components of the NHDPlus version 2 data suite (NHDPlusv2) for the conterminous United States; 1) individual reach catchments and 2) reach catchments accumulated upstream through the river network. This dataset can be linked to the NHDPlus version 2 data suite by the unique identifier COMID. The Topgraphic Wetness Index is a steady state index that’s used to predict areas susceptible to saturated land surfaces and areas that carry the potential to produce overland flow. The index is represented by ln (a/tan(beta)), where ln is the Napierian logarithm, a is the upslope area per unit contour length, and tan/(beta) is the slope gradient (Wolock [...]

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TWI_CONUS.zip 22.06 MB application/zip
56f97be4e4b0a6037df06b70_acc.parquet 16.01 MB application/octet-stream
56f97be4e4b0a6037df06b70_cat.parquet 15.88 MB application/octet-stream
56f97be4e4b0a6037df06b70_tot.parquet 16 MB application/octet-stream

Purpose

This data set was created by the U.S. Geological Survey's (USGS) National Water-Quality Assessment Project (NAWQA) which is part of the USGS National Water Quality Program (NWQP). This effort was undertaken to estimate the average topgraphic wetness index for NHDPlusV2 flowline catchments and upstream river networks to support statistical analysis, map display, and model parameterization.

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  • USGS Maryland, Delaware, and the District of Columbia Water Science Center

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