International Journal of Advancements in Research & Technology, Volume 3, Issue 6, June-2014
ISSN 2278-7763
101
Studies on spreading of splash material under simulated rainfall
V. N. BARAI
1*
, G. U. SATPUTE 2 , A. A. ATRE 3
------------------------------------------------------------------------------------------------------------------------------------------------1* &2
3
Department of SWCE, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola (M.S) India
Department of SWCE, Mahatma Phule Krishi Vidyapeeth, Rahuri, Dist.- Ahmednagar, (M .S.)India
1*
vnbarai@gmail.com
ABSTRACT
The present research work was undertaken during 2013 with six different rainfall
intensities and five different slopes under simulated rainfall. The importance of the soil erosion
problem and its impact on soil management and conservation led to the recent study, in which an
attempt has been made to quantify splash detachment for various combinations of land slopes
and rainfall intensities with the help of rainfall simulation system and modified Morgan’s splash
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cup. The clay loam soil was used to study the splash erosion. Uniformity coefficient of simulated
rainfall was above 70 per cent for all the six rainfall intensities viz. 7.75, 5.8, 4.23, 3.28, 2.04 and
1.07 cm h-1, which is acceptable. The directional splash soil loss rate (kg ha-1), i.e. upslope and
down slope were found increasing with increase in rainfall intensity and land slope. The rate of
increase in down slope splash was comparatively more than upslope. The highest soil splash i.e.
17898 kg ha-1 was observed for combination of 10 percent land slope and 7.75 cm h-1 rainfall
intensity in clay
loam soil. The results obtained showed that maximum average vertical
movement of splashed material was 89 cm in clay loam soil, for the combination of rainfall
intensity 7.75 cm h-1 and land slope 10 %. The maximum average horizontal movement of
splashed material was found 111.0 cm for the combination of rainfall intensity 7.75 cm h-1 and
land slope 10 %. The Splashed soil material was spread near about 111.0 cm in the down slope
direction and 75.5 cm in the upslope direction which highlights the need to modify the size of
splash cup to study the realistic soil movement during splash erosion.
Key words: Splash erosion, simulated rainfall, Morgan’s Splash cup, clay loam soil,
rainfall intensity
1*
Research Scholar,
2&3
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Associate Professor
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102
responsible for initiating water erosion,
since it is the first erosion to occur when an
1 INTRODUCTION
In recent
years
agriculture and
food
production have intensified the soil erosion
due to population increase and human activities transformation, so that about 75 billion
tons of soils are eroded from lands each year
(Bayramin et al. 2003).Water erosion is a
process by which soil aggregates and
primary particles are detached from the soil
matrix, transported down slope by raindrops
and flowing water, and deposited under
erosive rainfall event takes place ( Sempere
Torres et al., 1994; Though soil erosion is
usually associated primarily with surface
runoff, other studies have shown that under
certain
topographical
conditions,
soil
detachment is influenced more by raindrop
impact than by overland flow. Rose (1960)
observed that soil loss increases ten times
when water is applied as a spray in
comparison with the same application rate as
surface flow. Therefore, although surface
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certain energy-limiting conditions. Four
basic detachment and transport processes
have been identified, including detachment
by raindrops, detachment by flowing water,
transport by raindrops, and transport by
flowing water. Splash erosion is recognized
as the first stage in a soil erosion process
runoff is usually considered the major soil
moving agent, raindrop erosion also plays an
important role in not only detaching the soil
particles but also causing soil movement
even before the runoff starts (Quansah,
1981).
that results from the impact of rain drops.
One very effective approach to the study of
Soil particles are separated by rain drops and
soil erosion processes and the analysis of
are transmitted by runoff. Splash process
possible remedial strategies involves the use
can cause movement of soil particles, which
of rainfall simulator. Drop velocity is
show less cohesive forces (Wuddivira et al.
important in designing a rainfall simulator.
2009).
Drops from natural rainfall are at terminal
Splash erosion is a complex process
including the detachment of soil particles by
raindrops followed by splash transport of a
part of the detached particles. Splash is
Copyright © 2014 SciResPub.
velocity when they hit the soil surface
(Meyer and McCune, 1958). Therefore, a
rainfall simulator must create drops of
adequate size and velocity to simulate the
same condition, indicating the importance
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103
between an adequate and related fall
2 MATERIAL AND METHODS
distance and drop size distribution. Direct
The experimental set up consists of rainfall
relationship exists between drop diameter
simulation
and fall distance (Laws, 1941).The classical
splash cup and cover for protecting the cup
method for quantifying splash erosion relies
(Fig.1). A turbine nozzle is used for
on the use of splash cups, or small traps that
simulation of rainfall. The height of nozzle
collect
and
is kept 4.2 m from the ground surface. Lance
1978;
was connected to the PVC pipe. The details
soil
transported
particles
detached
by splash (Morgan,
system,
modified
Morgan’s
of nozzle are given as below. Version
Legout et al., 2005)
Standard: 61mm body with Ø1.0 mm with
The importance of the soil erosion problem
and its impact on soil management and
conservation led to the recent study, in
which an attempt has been made to study
combination of land slopes and rainfall
with
the
help
of
rainfall
simulation system and modified Morgan’s
splash cup. The present research work was
undertaken during 2013 in the Department
of
Soil
Engineering,
company Shree Parmeshwar Machine Tools
(PMT), Vavdi, Rajkot (Gujarat) with an
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splash detachment process for various
intensities
ball joint. Materials – brass, made by
and
Dr.
Water
Conservation
A.
College
S.
of
Agricultural Engineering, MPKV, Rahuri.
The following objectives selected for the
excellent micronization. A pressure gauge
having a dial diameter of 6 cm was mounted
on main supply line on a lance just near the
nozzle to monitor the water pressure. In the
present study, the pressure was varied from
0.2 to 2.8 kg cm-2 at an equal increment of
0.1 kg cm-2. Calculations for rainfall
intensity were based on amount of water
collected during each time interval. Rainfall
intensity was calculated for water pressure
range from 0.2 to 2.8 kg cm-2 at an
experiment viz. to study the effect of land
increment of 0.1 kg cm-2. The required water
slope on splash erosion, to study the
pressure at increment of 0.1 kg cm-2 was
movement of splashed material in vertical
and horizontal directions under different
rainfall intensities, to develop the device for
measurement of splash erosion and to
quantify the splash soil loss with developed
adjusted using flow regulating valve. The
total quantity of water received through the
nozzle at desired water pressure was
collected in plastic bucket for 2 minute
duration. This study was conducted with six
splash cup.
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104
rainfall intensities i.e. 7.75, 5.80, 4.23, 3.28,
catching tray. Muslin cloth was used to
2.04 and 1.07 cm h-1 for five different land
cover the catching tray. Two separate muslin
slopes i.e. 1, 3, 5, 7 and 10 %. The Clay
clothes were used for upslope and down
loam textured soil was used for the
slope
experiment. The uniformity coefficient of
covered over the floor of catching tray was
simulated rainfall was determined for all
removed by removing the semicircular G.I.
selected
using
wire frame, and washed with water in a
Christiansen
bucket to detach the soil particles. The
(1942). The raindrop size was determined
muslin cloth which was kept below and
by ‘flour pellet’ method (Hudson, 1964).
surrounding the splash cup at a distance
Modified
were
about 1.5 m on both sides from the centre of
fabricated by changing the diameter of
soil plot also removed and washed with
catching tray as 600 mm and keeping all
water in bucket. This water with splashed
rainfall
relationship
intensities
developed
Morgan’s
by
splash
cups
compartment.
The
muslin
cloth
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other dimensions same. The floor of the
soil is taken in sample bottles of 1000 and
catching tray was replaced with a wire mesh
1500 ml capacity and kept for 24 hours for
sheet covered with muslin cloth. This will
settlement of suspended soil particles. The
allow free drainage of the rainwater whilst
clear suspension was decanted off and
still allowing the collection of splashed
remaining sample with little water is stirred
particles. Two semicircular rings were made
thoroughly and filtered. Soil on filter paper
with G.I. wire to fix the muslin cloth over
was oven dried at 1050C for 24 h and
catching
easy
weighed. The upslope and down slope
replacement of muslin cloth. When set up on
weights combined are a measure of splash
a horizontal surface the apparatus will catch
detachment. Data may be expressed on a
all particles splashed from the soil in the
unit width per unit time or a unit area per
inner cylinder for distances less than the
unit time basis (Morgan, 1978).
tray
properly
and
for
radius of the catching tray (Fig.2).
2.1 DETERMINATION OF SPLASH SOIL
LOSS
For estimating the splash soil loss, splashed
soil is collected separately from the up slope
and down slope compartments of the
Copyright © 2014 SciResPub.
2.2 DETERMINATION OF HORIZONTAL AND
VERTICAL MOVEMENT OF SPLASHED SOIL
PARTICLES
The modified Morgan’s splash cup was
installed on a soil plot by giving the desired
slope just below the sprinkling unit (nozzle).
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ISSN 2278-7763
105
Soil plot was covered by muslin cloth of
This study was undertaken to observe the
suitable size. Antecedent moisture content at
soil loss due to splash as influenced by
pre-wetted condition was selected. Pre-
rainfall intensity and land slope for bare soil
wetting was done by applying water through
condition
the drain for 24 h. The pre- wet soil was
Accordingly, modified Morgan’s splash cup
immersed in the inner hollow cylinder up to
with outer diameter 60 cm and partitioned
full depth. The six rainfall intensities viz.
into two compartments i.e. up slope and
7.75, 5.8, 4.23, 2.98, 2.01 and 1.07 cm/h
down slope was used to quantify directional
were selected to test the movement of
splash. This study was conducted at six
splashed particles with two replications.
rainfall intensities i.e. 7.75, 5.80, 4.23, 3.28,
Simulated
rainfall
2.04 and 1.07 cm h-1 and for five different
intensities was continued till the runoff takes
land slopes i.e. 1, 3, 5, 7 and 10 %. The Clay
place from the soil placed in the inner
loam textured soil was used for the
rainfall
at
various
under
simulated
rainfall.
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cylinder of length 11 cm. The splashed soil
experiment and height of rainfall simulator
particles from inner cylinder of modified
was kept constant. The suitability of
Morgan’s cup which marked the stains on
simulator is tested by determining the
muslin cloth. The range of horizontal
uniformity coefficients at different rainfall
movement of splashed soil particles was
intensities. The time of exposure was
measured by measuring tape .The vertical
maintained up to runoff generation from soil
splash
filled in inner cylinder. The splash soil loss
boards
arranged
adjoining
the
modified Morgan’s splash cup received the
for
splashed soil particles. The vertical distance
intensities and land slopes were observed in
was measured, where the soil particles
two replications and the results obtained are
strikes on the graduated marking of the
described below. The uniformity coefficient
splash board. The horizontal and vertical
of simulated rainfall under different rainfall
movements of splashed soil particles were
intensities was 71.80 to 89.75% for rainfall
observed
intensities 11.22 to 1.07 cm h-1, which are
under
selected
six
rainfall
different
combinations
of
rainfall
intensities. The details of vertical splash
more
board are shown in Fig. 3
(Esteves et al. 2000). It is observed that the
3 RESULTS AND DISCUSSION
Copyright © 2014 SciResPub.
than 70 % and hence acceptable
raindrop size increased with increasing
rainfall intensity. The rain drop size
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106
observed from 1.48 mm to 3.24 mm for the
slope + down slope) with increase in rainfall
range of rainfall intensities from 1.07 cm h-1
intensity for all given land slopes. Similar
to 7.75 cm h-1 respectively. For different
results have been obtained and reported by
combinations of rainfall intensities and land
Akurde (2009). Splash soil loss was not
slopes up to the runoff generation, the soil
found for the intensities 2.04 and 1.07cm h-1.
splash in both the direction i.e. up slope and
This conclusion confirmed the findings
down
reported by Hudson (1971).
slope
were
collected
separately
according to the procedure described under
From Table 2, it was observed that for all
material and methods. The collected soil
rainfall intensities down slope vertical
splash
movement increased with increasing slope
in
different
direction
is
then
-1
converted to splash soil loss rate in kg ha .
and up slope vertical movement decreased
The values thus obtained are given in Table
with increasing land slope. The observations
1.
were taken with selected rainfall intensities
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From Table 1, it is found that with
7.75, 5.80, 4.23, 3.28 and 1.07 cm h-1 for
increase in land slopes, splash soil loss rate
different land slope. The horizontal and
increased for all selected rainfall intensities
vertical movement of splashed soil particles
for the clay loam soil. The splash soil loss
in down slope and up slope directions were
rate increased from 7643 to 17898 kg ha-1 as
observed and tabulated in Tables 2 and
land slope increased from 1 to 10 % at 7.75
3.The horizontal spread of splashed soil
cm h-1 rainfall intensity in clay loam soil.
material was about 111.0 cm in the down
Similar trend was observed for all rainfall
slope direction and 75.5 cm in the up slope
intensities with increase in land slope. The
direction, which is beyond the diameter of
maximum value of splash soil loss rates
modified Morgan’s splash cup.
were observed at 10 % land slope, whereas
4 CONCLUSION
minimum values were observed at 1 % land
The horizontal spread of splashed soil
slope for all selected rainfall intensities. It is
material was about 111.0 cm in the down slope
revealed from Table 1 with the increase in
direction and 89.0 cm in the up slope direction,
rainfall intensity, upslope and down slope
which is beyond the diameter of modified
splash soil loss rates increased for all
Morgan’s splash cup. In order to get realistic
selected land slopes viz., 1, 3, 5, 7 and 10 %;
values of splashed soil loss for detail studies on
thus increase in total splash soil loss rate (up
Copyright © 2014 SciResPub.
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International Journal of Advancements in Research & Technology, Volume 3, Issue 6, June-2014
ISSN 2278-7763
soil erosion processes the dimensions of splash
cup need to be increased.
REFERENCES
[1] Akurde AB (2009), “Effect of rainfall
intensity and land slope on splash
erosion under simulated rainfall”,
M. Tech. thesis (SWCE) submitted
to
Mahatma
Phule
Krishi
Vidyapeeth, Rahuri.
[2] Bayramin IO, Baskan D and Parlak M
(2003), “Soil erosion assessment
with CONA model: case study
Beypazri area”, Turk Journal of
Agriculture, 27: 105–116.
107
American Geophysics Union 22:709721.
[8] Legout C, Leguedois S., Malam-Issa O.
and Le Bissonnais Y. (2005),
“Splash
distance
and
size
distributions for various soils”,
Geoderma
[9] Meyer LD and McCune DL (1958),
“Rainfall simulation for runoff
plots”, J. Agric Eng. 39: 644-648.
[10] Morgan RPC (1978), “Field studies of
rain splash erosion”, Earth Surface
Processes. 3(3):295-299.
[11] Quansah C (1981), “The effect of soil
type, slope, rain intensity and their
interactions on splash detachment
and transport”, J. of Soil Sci. 32:
215-224.
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[3] Christiansen JE (1942), “Irrigation by
sprinkling”, Bulletin 670. Berkely
Cal.Univ. California Agricultural
Experiment Station.
[4] Eseteves M, Planchon O,Lapetite JM,
Silveral N. and Cadet, P (2000),
“The Emire large rainfall simulator:
design and field testing”, Earth Surf.
proc. Land. 25:681-690.
[5] Hudson NW (1964), “The Flour pellet
method for measuring size of
raindrops”, Research bulletin 4,
Dept. of Conservation, Salisbury,
Rhodes.
[6] Hudson NW (1971), “A textbook of Soil
Conservation”, B. T. Batsford
Limited. Pp. 50, 52, 58 - 60.
[12] Rose CW (1960), “Soil detachment
caused by rainfall”, Can. J. Soil
Science. 89: 28-34.
[13] Sempere Torres D, Porrà J M, Creutin,
J D (1994), “A general formulation
for raindrop size distribution”,
Journal of Applied Meteorology 33,
1494–1502.
[14] Wuddivira MN, Stone RJ, Ekwue EI
(2009), “Clay, organic matter and
wetting effects on splash detachment
and aggregate breakdown under
intense rainfall”, Soil Science Society
of American Journal, 73: 226–232
[7] Laws JO (1941), “Measurements of fall
velocity of water drops and
raindrops”,
Transactions
of
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108
TABLE 1
Directional splash soil loss rate (kg/ha) at different combinations of rainfall intensity and land slopes in
clay loam soil.
Land
slope
(%)
1
3
5
7
10
Direction of
splash soil
loss
Rainfall intensities (cm/h)
7.75
5.8
4.23
3.28
2.04
1.07
Up slope
1592
1338
1210
1083
_
_
Down slope
6051
2739
1465
1210
_
_
Total
Up slope
Down slope
Total
Up slope
Down slope
Total
Up slope
Down slope
Total
Up slope
Down slope
Total
7643
2611
6561
9172
3121
7771
10892
3885
8280
12166
6051
11847
17898
4140
1465
2866
4331
1847
3248
5096
2611
6242
8854
5248
7261
10510
2739
1338
1975
3376
1274
2803
4076
2994
3694
6688
2739
4459
7197
2293
1401
1656
3057
1656
2611
4268
2357
3121
5478
2675
3439
6115
_
_
_
_
_
_
_
_
_
_
_
_
-
_
_
_
_
_
_
_
_
_
_
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ISSN 2278-7763
R.I.
(cm/h)
7.75
5.8
4.23
3.28
2.04
1.07
V.M
(cm)
U.S
D.S
U.S
D.S
U.S
D.S
U.S
D.S
U.S
D.S
U.S
109
TABLE 2
Average vertical movement of splashed material for different land slope and rainfall intensities in clay loam soil
1 % slope
3 % slope
5 % slope
7 % slope
A.V.M
A.V.M
A.V.M
A.V.M
(cm)
(cm)
(cm)
(cm)
R1
R2
R1
R2
R1
R2
R1
R2
74
76
75
72
71
71.5
70
71
70.5
67
66
66.5
78
80
79
80
82
81
84
83
83.5
86
87
86.5
65
64
64.5
60
61
60.5
58
57
57.5
56
55
55.5
69
68
68.5
71
70
70.5
73
75
74
77
79
78
46
47
46.5
43
44
43.5
40
38
39
38
36
37
50
49
49.5
52
53
52.5
54
56
55
58
60
59
30
32
31
28
27
27.5
25
24
24.5
24
23
23.5
34
33
33.5
36
38
37
38
40
39
40
42
41
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
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10 % slope
R1
R2
60
59
88
90
55
53
78
79
36
35
60
62
26
24
42
45
_
_
_
_
_
_
D.S
_
_
_
_
_
_
_
_
_
_
_
_
_
_
Note: R.I = Rainfall intensity, V.M = Vertical movement, A.V.M = Average vertical movement, U.S = Up slope, D.S = Down slope
TABLE 3
Average horizontal movement of splashed material for different land slope and rainfall intensities in clay loam soil
1 % slope
3 % slope
5 % slope
7 % slope
10 % slope
R.I.
H.M
A.H.M
A.H.M
A.H.M
A.H.M
(cm/h)
(cm)
(cm)
(cm)
(cm)
(cm)
R1
R2
R1
R2
R1
R2
R1
R2
R1
R2
U.S
85
84
84.5
83
82
82.5
81
79
80
78
76
77
76
75
7.75
D.S
90
92
91
93
94
93.5
96
98
97
100
102
101
110
112
U.S
75
73
74
73
71
72
71
70
70.5
69
68
68.5
66
65
5.8
D.S
80
81
80.5
83
84
83.5
85
86
85.5
90
92
91
105
106
U.S
72
70
71
70
69
69.5
69
68
68.5
66
65
65.5
60
58
4.23
D.S
75
77
76
78
80
79
80
82
81
85
86
85.5
95
96
U.S
52
51
51.5
50
48
49
48
46
47
46
45
45.5
42
41
3.28
D.S
55
56
55.5
58
60
59
60
62
61
65
66
65.5
70
72
U.S
28
27
27.5
26
25
25.5
25
24
24.5
22
20
21
23
22
2.04
D.S
3O
32
31
32
34
33
33
35
34
34
36
35
36
38
U.S
_
_
_
_
_
_
_
_
_
_
_
_
_
1.07
D.S
_
_
_
_
_
_
_
_
_
_
_
_
_
_
Note: R.I = Rainfall intensity, H.M = Horizontal movement, A.H.M = Average horizontal movement, U.S = Up slope, D.S = Down slope
Copyright © 2014 SciResPub.
A.V.M
(cm)
59.5
89
54
78.5
35.5
61
25
43.5
_
_
_
_
A.H.M
(cm)
75.5
111
65.5
105.5
59
95.5
41.5
71
22.5
37
_
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Fig.1 Complete arrangement for quantification of splashed soil.
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Fig.2 Modified Morgan’s splash cup
with 1% slope after splash
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Fig.3 Vertical Splash board
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