1,181 research outputs found
Influence of irrigation water properties on furrow infiltration: Temperature effects
No full textFor surface irrigation, the rate and spatial
characteristics of infiltration processes influence crop
productivity, water use efficiency, and erosion potential
of stream flows. A change in infiltration rate alters
furrow stream flow velocity and shear, and hence
irrigation-induced erosion. Furrow irrigation models
may be improved if they can account for the influence of
water properties on these processes. Water temperature
may influence furrow infiltration by altering fluid
viscosity. We conducted laboratory soil column intake
(constant head), and field recirculating furrow
infiltrometer experiments, to determine whether
irrigation water temperature significantly altered
infiltration. The soil was Portneuf silt loam (coarse-silty,
mixed superactive, mesic, Durinodic Xeric Haplocalcids).
Soil column intake increased by 0.8 to 3.0 percent per
degree C. This increase was not significantly different
from that observed for furrows, 2.0 to 2.9% deg.-1. While
more field studies are needed, these data show that
diurnal and seasonal changes in irrigation water
temperature can significantly alter furrow infiltration
and stream flow. These effects may help explain observed
field-infiltration variability. Inclusion of temperature
algorithms in furrow irrigations models may increase
their predictive accuracy
Evaluating WEPP predicted on-field furrow irrigation erosion
No full textThe Water Erosion Prediction Project (WEPP) model
has the ability to predict erosion from furrow-irrigated
fields. A previous evaluation showed that WEPP-predicted
infiltration and soil loss correlated poorly with
field measurements. Our objective was to further
evaluate the WEPP model for furrow irrigation by
comparing on-field distribution of measured and
predicted infiltration, runoff and soil loss. We used data
from three fields with Portneuf silt loam (coarse-silty,
mixed, superactive, mesic Durinodic Xeric Haplocalcids)
near Kimberly, ID. Single-event WEPP simulations were
used so predicted erosion could be evaluated without the
effects of daily model adjustments to effective hydraulic
conductivity, critical shear and rill erodibility. Single-event
simulations showed that the model could only
adequately predict infiltration and runoff within a field
when effective hydraulic conductivity was calibrated for
each irrigation. However even with accurate furrow
flows, the WEPP model could not adequately predict
sediment detachment, transport, and deposition within a
field. Comparing measured and predicted on-field
distribution of soil loss indicated that transport capacity
was over-predicted by the model because deposition was
only predicted when detachment was greatly over-predicted.
More thorough investigation of the WEPP
model programming and more detailed furrow erosion
field data are needed to develop an accurate simulation
model for furrow irrigation erosion
Soil losses caused by chicory root and sugar beet harvesting in Belgium: importance and implications
No full textstatus: Publishe
Rocks and rills: the impact of rock fragments on soil loss by concentrated flow erosion in laboratory experiments
No full textstatus: Publishe
Hydraulic modeling of irrigation-induced furrow erosion
No full textIn the experimental Version 4.xx series, erosion
science is introduced into the surface-irrigation
simulation model, SRFR. The hydraulics of water flow in
furrows for individual irrigation events is predicted by
numerical solution of the unsteady equations of mass and
momentum conservation coupled to generally applicable
empirical equations describing infiltration and soil
roughness and to a known furrow configuration and
inflow hydrograph. Selection of appropriate field values
for the infiltration and roughness coefficients yields
infiltration distributions and surface flows (including
runoff) in reasonable agreement with measurements. The
erosion component consists in applying the simulated
hydraulic flow characteristics to site-specific empirical
determinations of soil erodibility, to general empirical
sediment-transport relations, and to general physically
based deposition theory to provide estimates of soil
erosion, flux, and deposition at various points along the
furrow as functions of time. Total soil loss off the field
and ultimate net erosion and deposition along the furrow
follow. At this initial stage of the investigations, a single
representative aggregate size is assumed adequate for the
analysis. Results are compared to measurements of
sediment concentrations in the furrow quarter points
and in the tailwater. For a given representative aggregate
size, the results are heavily dependent on the choice of
transport formula. The Laursen (1958), Yang (1973), and
Yalin (1963) formulas are programmed for investigation,
as are a variety of computational options. Preliminary
comparisons suggest the superiority of the Laursen
formulation, with the Yang and Yalin formulas
significantly over-predicting transport
Review of the thesis: “The activities of the Soviet police to combat crime and public protection in Western Siberia in 1925-1937” by D.E. Kuznetsov
No full textThe article analyses the thesis “The activities of the Soviet police to combat crime and protect public order in Western Siberia in 1925-1937” by D.E. Kuznetsov. The structure and logic of the construction of the work, the validity of the conclusions, the merits of the dissertation research and its controversial points are considered. Special attention is paid to the source of the dissertation. In conclusion, the author of the article summaries that the contents of D.E. Kuznetsov's facts, assessments and conclusions can be used to develop textbooks on the history of crime, the history of law enforcement bodies, the history of Russia
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