Explanation of Format

N-VALUES SITE CONTENT:

Barnes Book:

Barnes Site Descriptions

Explanation of the n-value field data page

Location map: the study reach is identified with a red box on the quadrangle map

Aerial photograph showing physiographic features of the study reach. Also, cross sections used in the n-value computations are displayed with identification numbers

Shape of the cross sections used in the n-value computation. Cross sections are identified with identification numbers

Gage Location. -- This section gives the location of the streamflow gage and hence the study reach.

Study Reach. -- This section gives more detailed description about the location of study reach. The approximate length of the study reach is given also.

Drainage Area. -- The drainage area above the streamflow gage, or above the downstream end of the study reach if no streamflow gage is available, is given here.

Gage Datum and Elevation of Reference Points. -- The elevation above NGVD1929 datum for zero readings of the streamflow gage, and other reference points used in field data collection are given. Other reference points include: tape-down points, staff gages, and wire weighted gages.

n-value Table. -- The n values, the date of data collection, discharge, and associated hydraulic parameters are listed in ascending order. (Note the n-value and hydraulic parameters are reach-wise averaged data).

Field photos with n-value marked on the photo. Photos are arranged from low flows to high flows.

(photo presentation continues)

Stage and Discharge Measurement. -- This section describes how water surface elevation (and therefore slope) and discharges are measured for the study reach.

Description of the Channel. -- Describes the (common) n-value factors that can identified in the field, using the following sequence:

A general assessment of the channel (natural, man-made, urban, etc)
Bed: roughness material (specify height, if possible)
Bank: roughness material (specify height, if possible)
Geometry: height, width, slope, shape, others
Channel Obstruction: algae, logs, debris, boulders, weirs, structures, and others
Geomorphic parameters: uniformness of cross sections, riffle-and-pool structures, straight or meandering, possible effect from upstream and downstream reaches.

Floods. -- Describe maximum floods recorded at the study site (a reference to the current study)

Key Words. -- The key words are arranged in [bed, bank, geometry, channel obstruction, and geomorphic parameters]. They can be used for Web search.

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Water Resources of Illinois: n-values Project

Explanation of the n-value field data page