Imhoff cone determination of sediment in irrigation runoff

Sojka, R.E. and Carter, D.L. and Brown, M.J. (1992) Imhoff cone determination of sediment in irrigation runoff. Soil Science Society of America Journal. 56(3):884-890.

PDF 774.pdf Download (476kB)

Abstract

There is a need to rapidly quantify erosion from irrigated farmland.
The prevailing method consists of collecting runoff samples, then filtering,
drying, and weighing them to determine sediment concentration.
Labor cost and slow data availability prompted development of
a faster, less expensive technique. Sediment settling volume in a graduated
vessel was expected to correlate well with total mass of suspended
sediment. Eight soils varying in texture, mineralogy, and
organic-matter content were sampled, fragmented, and air dried. A
series of 1-L suspensions was prepared with sediment concentrations
from 1 to 30 g L-1. Samples were either hand shaken for 30 s or
mechanically blended for 60 s. Suspensions were decanted into graduated
Imhoff cones and allowed to settle for 0.5 h (1800 s). The series
was repeated three times for each soil. Settling volume was regressed
against sediment concentration (total sediment, g L-1 ). Field calibrations
for two soils were developed from furrow runoff samples. Laboratory
regressions had a mean r2 of 0.99. Field regressions of two
soils had r2 of 0.94 or higher. Cone design did not permit accurate
volume estimates of the first 1 mL, causing slopes and intercepts to
very among field regressions for sediment concentrations <1.0 g L-1.
These samples, however, represent negligible erosion, and therefore
have little value. Slope and intercept of field regressions corresponded
closely to 30-s-shaken laboratory regressions but different statistically
at P ≤ 0.05. The technique provided a rapid, inexpensive, and accurate
suspended-sediment determination in the field for concentrations
>1.0 g L-1. Several settling-volume predictions based on textural
components and organic-matter content had r2 > 0.60. Laboratory 30-
s hand-shaken calibrations may be adequate for diagnostic purposes,
but individual field calibrations should be performed for research
purposes

Item Type:	Article
NWISRL Publication Number:	0774
Subjects:	Irrigation > Furrow irrigation > Runoff losses > Sediment Mass Import - autoclassified (may be erroneous)
Depositing User:	Dan Stieneke
Date Deposited:	20 Nov 2010 21:53
Last Modified:	01 Dec 2016 22:45
Item ID:	579
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/579