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StreamStats

Washington StreamStats Application Information

General Information

Project area general description

The state of Washington

Are any areas excluded?

The Columbia, Snake, Okanogan, Kettle, and Pend Oreille River mainstems.

Types of flow statistics available

Peak flows

ArcGIS version used for processing

Originally 9.1, with some updates using 9.2 and 9.3

Was TopoGrid used to process DEMs?

No.

DEM and derivatives projection (general description)

Albers Equal Area for conterminous US, horizontal datum NAD83,  vertical datum NAVD 88; same as NHDPlus Version 1. See http://www.horizon-systems.com/NHDPlus/NHDPlusV1_documentation.php for details.

DEM and derivatives (fdr, fac, etc.) resolution

 30 m

DEM source

NHDPlus V1 (NED 2004) http://www.horizon-systems.com/NHDPlus/NHDPlusV1_data.php

Hydrography source

NHDPlus V1 (1:100,000 NHD snapshot) http://www.horizon-systems.com/NHDPlus/NHDPlusV1_data.php

Hydrologic unit "walls" source

not used

Gage basin boundaries source

not used

Interactive map snapping tolerance

2 cells

Basin characteristics computed using continuous parameter grids (CPGs)

ELEV, CANOPY_PCT, PRECIP

Basin Characteristics Methods and Sources

Name

Description

Computation method

Data Source

Variable in report WRIR 97-4277

DRNAREA

Area that drains to a point on a stream, in square miles

polygon area

delineated watershed

A

ELEV

Mean Basin Elevation in feet

area-weighted mean

30-m DEM, NHDPlus elev_cm grid http://www.horizon-systems.com/NHDPlus

E

ELEVMAX

Maximum Basin Elevation in feet

maximum

30-m DEM, NHDPlus elev_cm grid http://www.horizon-systems.com/NHDPlus

not used

ELEVMIN

Minimum Basin Elevation in feet

minimum

30-m DEM, NHDPlus elev_cm grid http://www.horizon-systems.com/NHDPlus

not used

CANOPY_PCT

Area-weighted forest canopy, in percent, computed from NLCD 2001 canopy dataset

area-weighted mean

30 -meter, percent CANOPY grid http://www.epa.gov/mrlc/nlcd-2001.html

F

PRECIP

Mean annual precipitation, in inches

area-weighted mean

500 meter resolution grid created from:U.S. Weather Bureau, 1965, State of Washington, mean annual precipitation, 1930-1957: Portland, Oreg., Soil Conservation Service, map M-4430, 1 sheet, [no scale]
for areas within Washington State and  1km resolution grid from:  http://www.daymet.org/  data for areas outside Washington State 

P

RELIEF

Relief (maximum - minimum elevation), in feet

ELEVMAX - ELEVMIN

30-m DEM, NHDPlus elev_cm grid http://www.horizon-systems.com/NHDPlus

not used

SLPPCT

Mean basin slope in percent

area-weighted mean

slope of 30-m DEM, computed from NHDPlus elev_cm  grid http://www.horizon-systems.com/NHDPlus/

not used

SLPPCT30

Percent of area with slope greater than 30 percent

percent of area where slope is greater than 30%

computed from mean basin slope grid

not used

SLPPCT30N

Percent of area with slope greater than 30 percent and facing North

percent of area where slope is greater than 30% and the aspect is ge 315 or le 45

computed from mean basin slope grid

not used

The Washington StreamStats introductory page here has additional information regarding the application, including links to reports, cooperators, and other explanatory information.