Obtaining Data:Sample Values

From Gsshawiki

Overland Parameters

TABLE 17.17 Adjustment for the Erodibility Factor (K)

For soils with high very fine sand content of greater than 15%
1. For soil textures coarser than loam (represented by the shaded area in the nomograph), subtract 5% from the percentage of verv fine sand and add the difference to the silt content. The 5% remaining very tine sand should be added to the % total sand"
2. For soil textures finer than loam (represented by the areas outside of the shaded area in the nomograph), subtract 10% from the % very fine sand and add the differenct to the silt content. The 10 % remaining very fine sand should be added to the % total sand.
3. Determine the K value from the nomograph using the corrected sand and silt contents

For soil conditions outside the ideal conditions used to develop the nomograph as follows:

If organic matter content is different from 2%, add the correction values provided in the following table

		Correction values when organic matter is
K value	0%	1%	2%	3%	4%

Greater than 0.40	+0.14	+0.07	0.00	-0.07	-0.14
0.20-0.40	+0.10	+0.05	0.00	-0.05	-0.10
Less than 0.20	+0.06	+0.03	0.00	-0.03	-0.06

if rock content greater than 15%. the following table is used to adjuSt the K values. Rock content is the amount of soil particles by volume greater than 2.0 mm.

	Correction values when rock content is about
K value	15-35%	35-60%	60-75%

0.10	+0.06	+0.05	+0.02
0.15	+0.10	+0.05	+0.02
0.17	+0.10	+0.05	+0.02
0.20	+0.10	+0.05	+0.02
0.24	+0.15	+0.10	+0.05
0.28	+0.15	+0.10	+0.05
0.32	+0.17	+0.10	+0.05
0.37	+0.20	+0.10	+0.05
0.43	+0.24	+0.15	+O.1O
0.49	+0 28	+0.15	+0.10
0.55	+0.32	+0.17	+0.10
0.64	+0.37	+0.20	+0.15

if soil structures are disturbed the following corrections are added to the K values.

Soil structure Corrections

Very fine granular -0.09

Fine granular -0.06

Moderate or coarse granular -0.03
K corrections for permeability are provided as follows:

Soil characteristics Corrections

Compact soil or pH greater than 9.0 + 0.03

Many medium or coarse pores -0.03

Source: From Goldman et al. (1986).

TABLE 17.18 Cropping Management Factor (C) Values for Various Types of Cover
Type of cover	C	Reduction, %
None (fallow ground)	1.00	0
Native Vegetation (undisturbed)	0.01	99
Temporary Seedings (90% stand)—after 60 days	0.10	90
90% cover, annual grasses, no mulch
Wood liber mulch, 0.75 ton/acre, with seed	0.50	50
Ryegrass (perennial type)	0.05	95
Ryegrass (annulus)	0.10	90
Millet or Sudan Grass	0.05	95
Small Grain	0.05	95
Permanent Seedings (90% stand)
First 60 days	0.40	60
60 to 365 days	0.05	95
After 365 days	0.01	99
Sod (laid immediately)	0.01	99
Mulch (rate of application in tons/ac)
Hay at 0.5 ton/ac	0.25	75
Hay at 1.0 ton/ac	0.13	87
Hay at 1.5 tons/ac	0.07	93
Hay at 2.0 tons/ac	0.02	98
Small Grain Straw at 2.00 tons/ac	0.02	98
Straw at 1.5 tons/ac, tacked down (for slopes up to 2:1)	0.20	80
Straw at 4.0 tons/ac, tacked down (for slopes up to 2:1)	0.05	95
Wood Chips at 6.0 tons/ac	0.06	94
Wood Cellulose at 1.75 tons/ac	0.10	90
Fiberglass at 0.5 ton/ac	0.05	95
Asphalt Emulsion (1250 gal/ac)	0.02	98
Excelsior mat, jute (for slopes up to 2:1)	0.30	70

Unit conversion: 1 ton/ac = 2.267 t/ha. Sources: From Wanielista, 1978 and Goldman et ai. (1986).

TABLE 17.19 Cropping Management Factor (C) for General Land Use
General land use	C
Crop Land	0.08
Pasture Land	0.01
Forest Land	0.005
Urban Land	0.01
Other	1.00

Source: Wanielista (1978).

TABLE 17.22 Erosion Control Practice Factors for Construction Sites
Surface condition	P
Compacted and smooth	1.3
Trackwalked along contour¹	1.2
Trackwalked up and down slope²	0.9
Punched straw	0.9
Rough, irregular cut	0.9
Loose to 12-in (30-cm) depth	0.8

¹Tread marks oriented up and down slope
²Tread marks oriented parallel to contours.
Source: From Goldman et al. (1986)

Overland Roughness Table
Land Use or Cover	Recommended n-Value	Range
Concrete or asphalt	0.011^a	0.01-0.013^a
Developed/industrial	0.0137^b	-
Bare sand	0.01^a	0.010-0.016^a
Graveled surface	0.02^a	0.012-0.03^a
Bare clay-loam (eroded)	0.02^a	0.012-0.033^a
Gullied land	-	0.320-0.357^c
Bare field - no residue	0.05^a	0.006-0.16^a
Range (natural)	0.13^a	0.01-0.32^a
Range (clipped)	0.10^a	0.02-0.24^a
Grass and pasture	-	0.05-0.15^a
Pasture	-	0.235-271^c
Clover	-	0.08-0.25^a
Small grain	-	0.1 -0.4^a
Row crops	-	0.07-0.2^a
Cotton/soy	-	0.246-0.261^c
Grass (bluegrass sod)	0.45^a	0.39-0.63^a
Short grass prairie	0.15^a	0.10-0.203
Dense grass	0.24^a	0.17-0.30^a
Bermuda grass	0.41^a	0.30-0.48^a
Forest	0.192^b	0.184-198^c
Sparely vegetated	0.150^b	-

^aEngman (1986), ^bDowner, ^cSenarath et al (2000)

Wetland Parameters

Stream Parameters

Table 12.2.1 Variation of Manning's Roughness Coefficients n with Bed Type
Bed characteristics	Reference Manning's roughness coefficient n
Sand:
Plane bed	0.011-0.020
Ripple bed	0.018-0.035
Dune bed	0.020-0.035
Standing waves	0.014-0.025
Antidunes	0.015-0.035
Gravel and cobbles:	0.020-0.030
Boulder	"Roughness varies greatly. Usually roughness increases with decreasing flow depth, n can reach 0.1"
Vegetation	"Roughness varies greatly with the changes of density, height, flexibility of vegetation, and the relative ratio between flow depth and vegetative elements"
"Bermuda, Kentucky, Buffalo grasses"	Flow depth more than 5 times vegetation height n between 0.03 and 0.06
"Bermuda, Kentucky, Buffalo grasses"	Flow depth the same or less than that of vegetation height. 0.01-0.2
Extremely dense vegetation	"Vegetation height above flow depth, n can exceed 1"
Natural sandy streams:
Clean and straight	0.025-0.04
Winding and some weeds	0.03-0.05
Mountain streams with boulders	0.04-0.1
align="center" \| Floodplains:
Short grass	0.02-0.04
High grass	0.03-0.05
Dense willow, brush, etc.	0.05-0.20

Table of Particle Classifications
	Size, mm		μm	Inches	Tyler	US. standard	Class

Boulders and cobbles:
	4000-2000			160-80			Very large boulders
	2000-1000			80-40			Large boulders
	1000-500			40-20			Medium boulders
	500-250			20-10			Small boulders
	250-130			10-5			Large cobbles
	130-64			5-2.5			Small cobbles
Gravel:
	64-32			2.5-1.3			Very coarse gravel
	32-16			1.3-0.6			Coarse gravel
	16-8			0.6-0.3	2 1/2		Medium gravel
	8-4			0.3-0.16	5	5	Fine gravel
	4-2			0.16-0.08	9	10	Very fine gravel
Sand:
	2-1	2.00-1.00	2000-1000		16	18	Very coarse sand
	1-11/2	1.00-0.50	1000-500		32	35	Coarse sand
	1/2-1/4	0.50-0.25	500-250		60	60	Medium sand
	1/4-1/8	0.25-0.125	250-125		115	120	Fine sand
	1/8-1/16	0.125-0.062	125-62		250	230	Very fine sand
Silt:
	1/16-1/32	0.062-0.031	62-31				Coarse silt
	1/32-1/64	0.031-0.016	31-16				Medium silt
	1/64-1/128	0.016-0.008	16-8				Fine silt
	1/128-1/256	0.008-0.004	8-4				Very fine silt
Clay:
	1/256-1/512	0.004-0.0020	4-2				Coarse clay
	1/512-1/1024	0.0020-0.0010	2-1				Medium clay
	1/1024-1/2048	0.0010-0.0005	1-0.5				Fine clay
	1/2048-1/4096	0.0005-0.00024	0.5-0.24				Very fine clay

Source: From Lane.⁷⁸

Culvert & Weir Parameters

Infiltration Parameters

RICHARDS_EQN_INFILTRATION_BROOKS Parameters
Table Name	# Values	Parameter	Units	Typical Range
RICHARDS_EQN_INFILTRATION_BROOKS 3 sets of values for each ID. one set of values per line for each soil layer	9x3	K_s	cm/hr	0.05 - 23.5
		e	none	0.4 - 0.55
		θ_r	none	0.01 -0.1
		θ_i	none	θ_r - e
		θ_wp	none	0.03 - 0.25
		d	cm	NA
		λ	none	0.1 - 0.4
		Ψ_b	cm	5.0 - 100.0
		Δz	cm	0.1 - 10.0

RICHARDS_EQN_INFILTRATION_HAVERCAMP Parameters
Table Name	# Values	Parameter	Units	Range
RICHARDS_EQN_INFILTRATION_HAVERCAMP 3 sets of values for each ID One set of values per line for each soil layer	11 x 3	K_s	cm/hr	0.05 - 23.5
		e	none	0.4 - 0.55
		θ_r	none	0.01 -0.1
		θ_i	none	θ_r - e
		θ_wp	none	0.03 - 0.25
		d_L	cm	NA
		α	none	fit to curve
		Β	none	fit to curve
		A	none	fit to curve
		B	none	fit to curve
		Δz	cm	0.1 - 10.0

Evapotranspiration Parameters

Table A.l: Albedos of shortwave radiation for assorted types of vegetation/land-cover types^a
Ground Cover	Albedo
Snow	see Figures A.l and A.2
Fresh snow	0.75-0.95^b, 0.70-0.95^c, 0.80-0.95^d, 0.95^e
Fresh snow (low density)	0.85^f
Fresh snow (high density)	0.65^f
Fresh dry snow	0.80-0.95^g
Pure white snow	0.60-0.70^g
Polluted snow	0.40-0.50^g
Snow several days old	0.40-0.70^b, 0.70^c, 0.42-0.70^d, 0.40^e
Clean old snow	0.55^f
Dirty old snow	0.45^f
Clean glacier ice	0.35^f
Dirty glacier ice	0.25^f
Glacier	0.20-0.40^e
Dark soil	0.05-0.15^b, 0.05-0.15^g
Dry clay or gray soil	0.20-0.35^b, 0.20-0.35^g
Dark organic soils	O.10^f
Dry black soil	0.14ⁱ
Moist black soil	0.08ⁱ
Dry gray soils	0.25-0.30ⁱ
Moist gray soils	0.10-0.20^g, 0.10-0.12ⁱ
Dry blue loam	0.23ⁱ
Moist blue loam	0.16ⁱ
Desert loam	0.29-0.31ⁱ
Clay	0.20^f
Dry clay soils	0.20-0.35^d
Dry light sand	0.25-0.45^b
Dry, light sandy soils	0.25-0.45^g
Dry, sandy soils	0.25-0.45^d
Light sandy soils	0.35^f
Dry sand dune	0.35-0.45^b, 0.37^c
Wet sand dune	0.20-0.30^b, 0.24^c
Dry light sand, high sun	0.35^f
Dry light sand, low sun	0.60^f
Wet gray sand	0.10^f
Dry gray sand	0.20^f
Wet white sand	0.25^f
Dry white sand	0.35^f
Yellow sand	0.35^f
White sand	0.34-40ⁱ
River sand	0.43ⁱ
Bright, fine sand	0.37ⁱ
Rock	0.12-0.15ⁱ
Peat soils	0.05-0.15^d
Dry black coal spoil, high sun	0.05^f
Dry concrete	0.17-0.27^b, 0.10-0.35^e
Road black top	0.05-0.10^b
Ground Cover	Albedo
Asphalt	0.05-0.20^e
Tar and gravel	0.08-0.18^e
Densely urbanized areas	0.15-0.25ⁱ
Urban area	0.10-0.27 with an average of 0.15^e
Long grass (1.0 m)	0.16^e
Short grass (2 cm)	0.26^e
Wet dead grass	0.20^f
Dry dead grass	0.30^f
High, dense grass	0.18-0.20ⁱ
Green grass	0.26ⁱ
Grass dried in sun	0.19ⁱ
Typical fields	0.20^f
Dry steppe	0.25^f, 0.20-0.30^g
Tundra and heather	0.15^f
Tundra	0.18-0.25^e, 0.15-0.20^g
Heather	0.10ⁱ
Meadows	0.15-0.25^g
Cereal and tobacco crops	0.25^f
Cotton, potatoes and tomato crops	0.20^f
Cotton	0.20-0.22ⁱ
Cotton plantations	0.20-0.25^g
Potatoes	0.19ⁱ
Potato plantations	0.15-0.25^g
Lettuce	0.22ⁱ
Beets	0.18ⁱ
Sugar cane	0.15^f
Orchards	0.15-0.20^e
Agricultural crops	0.18-0.25^e, 0.20-0.30^d
Rice field	0.12ⁱ
Rye and wheat fields	0.10-0.25^g
Spring wheat	0.10-0.25ⁱ
Winter wheat	0.16-0.23ⁱ
Winter rye	0.18-0.23ⁱ
Deciduous forests - bare of leaves	0.15^e
Deciduous forests - leaved	0.20^e
Deciduous forests	0.15-0.20^g
Deciduous forests - bare with snow on the ground	0.20^d
Mixed hardwoods in leaf	0.18^f
Rain forest	0.15^f
Eucalyptus	0.20^f
Forest - pine, fir, oak	0.10-0.18^c
Forest - coniferous forests	0.10-0.15^g, 0.10-0.15^d
Forest - red pine forests	0.10^f
Tops of oak	0.18ⁱ
Tops of pine	0.14ⁱ
Tops of fir	0.10ⁱ
Water	-0.0139 + 0.0467 tan Z, 1 ≥ A ≥ 0.03^h
Water	see Figure A.3

NOTE:- ^aThe smaller value is for high zenith angles; larger value for low zenith angles.
From ^b Sellers (1965); ^c Munn (1966); ^d Rosenberg (1974); ^e Oke (1973); ^f Lee (1978); ^g de Jong (1973); ^h Atwater and Ball (1981); and, ⁱ Eagleson (1970).

Table A.2: Typical Extinction of Insolation by Grass (adapted from Eagleson. 1970)
Height of Grass (cm)	K_t
100	0.18
50	0.18
10	0.68

Source: Data from O.G. Sutton, "Micrometeorology," McGraw-Hill, New York, 1953.

Table A.3: Typical values of canopy resistance at noon
Type of Vegetation	Canopy Resistance at Noon (s/m)
Cotton field^a	~ 17
Coniferous forest (Spruce)^a	~ 100
Coniferous forest (Hemlock)^a	~ 150
Coniferous forest (Pine, March)^b	~ 140
Coniferous forest (Pine, June)^b	~ 120
Coniferous forest (Pine, September/October)^b	~ 123
Prairie grasslands (late July)^c	~ 100
Prairie grasslands (mid September)^c	-500
Irrigated short grass crop^d	-86
Unirrigated barley^d	-43

from ^aPielke (1984), ^bGash and Stewart (1975), ^cMonteith (1975) and ^dSceicz and Long (1969)

Table A.5: Sample values of vegetation height (Eagleson, 1970)
Vegetation/Forest Types	Sample Vegetation Height (cm)
Mown Grass	1.5-4.5
Alfalfa	20 - 40
Long Grass	60-70
Maize	90-300
Sugar Cane	100-400
Brush	135
Orange Orchard	350
Pine forest	500 - 2700
Deciduous forest	1700

NOTE: The vegetation heights listed in Table A.3 are sample values only. Those values may not be the representative, expected vegetation height-values of those vegetation/forest types.

TABLE D-2
Visible-Range Reflectance (albedo) of Various Forms of Water and Various Earth Materials
Surface	Conditions		Albedo, a
Clouds	Low overcast:	100 m thick	0.40
		200 m thick	0.50
		500 m thick	0.70
Liquid water	Smooth; solar angle:	60°	0.05
		30°	0.10
		20°	0.15
		10°	0.35
		5°	0.60
	Wavy; solar angle:	60°	0.10
Solid water	Fresh snow;	low density	0.85
		high density	0.65
	Old snow;	clean	0.55
		dirty	0.45
	Glacier ice;	clean	0.35
		dirty	0.25
Sand	Dry, light;	high sun	0.35
		low sun	0.60
	Gray;	wet	0.10
		dry	0.20
	White;	wet	0.25
		dry	0.35
Soil	Organic;	dark	0.10
	Clay		0.20
	Sandy;	light	0.30
Grass	Typical fields		0.20
	Dead;	wet	0.20
		dry	0.30
Tundra, heather			0.15
Crops	Cereals, tobacco		0.25
	Cotton, potato, tomato		0.20
	Sugar cane		0.15
Trees	Rain forest		0.15
	Eucalyptus		0.20
	Red pine forest		0.10
	Mixed hardwoods in leaf		0.18

Data from Lee (1980).

Groundwater Parameters

TABLE 12.1.2 Porosity and Specific Weight for Sediments
Classification and range mm	Fine sand 1/8-1/4 mm	Fine sand 1/4-1/2 mm	Medium sand 1/2-1 mm	Coarse sand 1-2 mm	Coarse sand 2-4 mm	Gravelly sand 4-8 mm	Fine gravel 8-16 mm	Medium gravel 16-32 mm	Coarse gravel 32-64 mm	Coarse gravel 64-128 mm	Coarse gravel and boulders 128-256 mm
Porosity, %	44	43	41	39	37.5	34.5	33	27	23	18	17
Specific weight kN/m³	14	15	15	16	16	17	18	19	20	22	22
Specific weight lb f/ft³	93	94	98	101	103	108	111	121	127	130	137

Table 6. Specific Storage (Anderson & Woessner, 1992).
Material	Specific storage (S_s)/(m)
Plastic Clay	2.0E-02 to 2.6E-03
Stiff Clay	2.6E-03 to 1.3E-03
Medium-hard clay	1.3E-03 to 9.2E-04
Loose sand	1.0E-03 to 4.9E-04
Dense sand	2.0E-04 to 1.3E-04
Dense sandy gravel	1.0E-04 to 4.9E-05
Rock, fissure, jointed	6.9E-05 to 3.3E-06
Rock, sound	Less than 3.3e-6

TABLE 6-1 Representative Values of Parameters in Equations (6-11) and (6-12) Based on Analysis of 1845 Soils^a
Soil Texture	Φ	K_hsat (cm/s)	\|Ψ_s\| (cm)	b
Sand	0.395 (0.056)	1.76 x 10^-2	12.1 (14.3)	4.05 (1.78)
Loamy sand	0.410 (0.068)	1.56 x 10^-2	9.0 (12.4)	4.38 (1.47)
Sandy loam	0.435 (0.086)	3.47 x 10^-3	21.8 (31.0)	4.90 (1.75)
Silt loarn	0.485 (0.059)	7.20 x 10^-4	78.6 (51.2)	5.30 (1.96)
Loam	0.451 (0.078)	6.95 x 10^-4	47.8 (51.2)	5.39 (1.87)
Sandy clay loam	0.420 (0.059)	6.30 x 10^-4	29.9 (37.8)	7.12 (2.43)
Silty clay loam	0.477 (0.057)	1.70 x 10^-4	35.6 (37.8)	7.75 (2.77)
Clay loam	0.476 (0.053)	2.45 x 10^-4	63.0 (51.0)	8.52 (3.44)
Sandy clay	0.426 (0.057)	2.17 x 10^-4	15.3 (17.3)	10.4 (1.64)
Silty clay	0.492 (0.064)	1.03 x 10^-4	49.0 (62.1)	10.4 (4.45)
Clay	0.482 (0.050)	1.28 x 10^-4	40.5 (39.7)	11.4 (3.70)

^a Values in parentheses are standard deviations.
Data from Clapp and Hornberger (1978).

Table 7. Specific Yield (Fetter, 1994).
Material	Specific Yield (S_y)
Material	Min	Max	Average
Clay	0.00	0.05	0.02
Sandy clay	0.03	0.12	0.07
Silt	0.03	0.19	0.18
Fine sand	0.10	0.28	0.21
Medium sand	0.15	0.32	0.26
Coarse sand	0.20	0.35	0.27
Gravelly sand	0.20	0.35	0.25
Fine gravel	0.21	0.35	0.25
Medium gravel	0.13	0.26	0.23
Coarse gravel	0.12	0.26	0.22

Table 1. Rawls & Brakensiek soil parameter estimates.
(1) USDA Textural Classification	(2) Total Porosity	(3) Effective Porosity	(4) Residual Water Content	(5) Wilting Point Water Content	(6) Air Entry Pressure (cm)	(7) Pore Distrib. Index	(8) Sat. Hydr. Conduct. (cm/hr)	(9) G&A Capillary Head (cm)
Sand	0.437	0.417	0.020	0.033	7.26	0.694	23.56	4.95
Loamy sand	0.437	0.401	0.035	0.055	8.69	0.553	5.98	6.13
Sandy loam	0.453	0.412	0.041	0.095	14.66	0.378	2.18	11.01
Loam	0.463	0.434	0.027	0.117	11.15	0.252	1.32	8.89
Silt loam	0.501	0.486	0.015	0.133	20.79	0.234	0.68	16.68
Sandy clay loam	0.398	0.330	0.068	0.148	28.08	0.319	0.30	21.85
Clay loam	0.464	0.390	0.075	0.197	25.89	0.242	0.20	20.88
Silty clay loam	0.471	0.432	0.040	0.208	32.56	0.177	0.20	27.30
Sandy clay	0.430	0.321	0.109	0.23'9	29.17	0.223	0.12	23.90
Silty clay	0.479	0.423	0.056	0.250	34.19	0.150	0.10	29.22
Clay	0.475	0.385	0.090	0.272	37.30	0.165	0.06	31.63

Field Capacity

Field Capacity
Texture Class	-1 SD	MEAN	+1 SD
Sand	0.018	0.091	0.164
Loamy Sand	0.060	0.125	0.190
Sandy Loam	0.126	0.207	0.288
Loam	0.195	0.270	0.345
Silt Loam	0.258	0.330	0.402
Sandy Clay Loam	0.186	0.255	0.324
Clay Loam	0.250	0.318	0.386
Silty Clay Loam	0.304	0.366	0.428
Sandy Clay	0.245	0.339	0.433
Silty Clay	0.332	0.387	0.442
Clay	0.326	0.396	0.466

From: Handbook of Hydrology, Maidment

which reproduces it from Rawls & Brakensiek, "prediction of soil water properties for hydrologic modeling", Watershed Management in the Eighties, ASCE

Specific Gravity

Table 2.4 Specific Gravity of Common Minerals
Mineral	Specific gravity, G_s

Quartz	2.65
Kaolinite	2.6
Illite	2.8
Montmorillonite	2.65-2.80
Halloysite	2.0-2.55
Potassium feldspar	2.57
Sodium and calcium feldspar	2.62-2.76
Chlorite	2.6-2.9
Biotite	2.8-3.2
Muscovite	2.76-3.1
Hornblende	3.0-3.47
Limonite	3.6-4.0
Olivine	3.27-3.7

Weirs

Table 48. Values of C in the Formula Q = CLH^3/2 for Models of Broad-crested Weirs with Rounded Upstream Corner
Name of Experimenter				Head in feet, H
Name of Experimenter				0.4	0.6	0.8	1.0	1.5	2.0	2.5	3.0	4.0	5.0
Bazin	0.33	2.62	2.46	2.93	2.97	2.98	3.01	3.04
Bazin	0.33	6.56	2.46	2.70	2.82	2.87	2.89	2.92
U.S. Deep Waterways	0.33	2.52	4.57		2.77	2.8	2.83	2.92	3	3.08	3.17	3.34	3.5
U.S. Deep Waterways	1.33	6.56	4.56			2.83	2.83	2.83	2.82	2.82	2.82	2.82	2.81

Table 49. Values of C in the Formula Q = CLH3/2 for Broad-Crested Weirs with Crests Inclined Slightly Downward
Slope of Crest	Length of weir in feet	Head in feet, H
Slope of Crest	Length of weir in feet	0.1	0.2	0.3	0.4	0.5	0.6	0.7
12 to 1	3.0	2.58	2.87	2.57	2.60	2.84	2.81	2.70
18 to 1	3.0	2.91	2.92	2.53	2.60	2.80	2.74	2.62
18 to 1	10.0	2.52	2.68	2.73	2.80	2.90	2.80	2.68

Table 50. Values of C in the Formula Q = CLH^3/2 for weirs of Triangular Cross Section with Vertical Upstream Face and Sloping Downstream Face
Slope of down- stream face	Height of weir in feet, P	Head in feet, H
Slope of down- stream face	Height of weir in feet, P	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9	1.0	1.2	1.5
Hor. Vert.
1 to 1	2.46	3.88	3.85	3.85	3.85	3.85	3.85	3.85	3.85	3.85	3.85	3.85
2 to 1	2.46	3.48	3.48	3.49	3.49	3.5	3.5	3.5	3.5	3.5	3.51	3.51
2 to 1	1.64	3.56	3.47	3.47	3.51	3.54	3.57	3.58	3.58	3.58	3.59	3.57
3 to 1	1.64		2.9	3.11	3.22	3.26	3.33	3.37	3.4	3.4	3.41	3.41
5 to 1	2.46		3.08	3.06	3.05	3.05	3.07	3.09	3.12	3.13	3.13	3.18
10 to 1	2.46		2.82	2.83	2.84	2.86	2.89	2.9	2.91	2.91	2.92	2.93

Obtaining Data:Sample Values

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