Barcelona Field Studies Centre

Manning n  Surface-Water Field Techniques

Rock Creek Canal near Darby, Montana - n = 0.060 (Source: U.S.G.S Water Supply Paper 1849)
 

Site Description

Station name
Rock Creek Canal, near Darby, Montana
Station number
 12-2455
Gauge location
 Lat 46°04'40'', long 120°28'30'', in SW 1/4 sec. 28, T. 4 N., R. 21 W., on downstream side of footbridge, 0.25 mile downstream from diversion dam, 1.5 miles downstream from Como Lake, and 4 miles northwest of Darby. Section 1 is about 0.25 mile upstream from gauge.
Date of flood
 September 23rd, 1948
Gauge height
 3.34 ft at gauge; 15.33 ft at section 1
Peak discharge
 138 cfs
Computed roughness coefficient
 Manning n = 0.060
Description of channel
 Bed and bank consist of boulders ; d50 = 210 mm, d84 = 375 mm. 

 

Reach Properties

Section Area (sq ft) Top Width (ft.) Mean depth (ft) Hydraulic radius (ft) Mean velocity (ft per sec) Length (ft) between sections Fall (ft) between sections
1 30 26 1.15 1.07 4.60 ....... .....
2 31 25 1.24 1.19 4.45 45 1.25
3 39 24 1.62 1.56 3.54 50 1.36
4 30 25 1.20 1.25 4.60 50 1.02
5 32 25 1.28 1.28 4.31 50 .93
6 37 26 1.42 1.37 3.73 50 .78
7 32 24 1.33 1.28 4.31 50 .85

 

 

Plan Sketch and Cross Sections

Plan and cross sections, Rock Creek Canal near Darby, Montana.

Plan and cross sections, Rock Creek Canal near Darby, Montana.

 

Site Images


Downstream from above section 1, Rock Creek Canal near Darby, Montana
Photo 136: Downstream from above section 1, Rock Creek Canal near Darby, Montana.

Downstream from above section 1, Rock Creek Canal near Darby, Montana

Photo 137: Downstream from above section 1, Rock Creek Canal near Darby, Montana

 

Source: USGS with thanks