a study on infiltration characteristics of soils at andhra ... · horton’s equation ... kh=...

International Journal of Environmental Research and Development.

ISSN 2249-3131 Volume 7, Number 1 (2017), pp. 29-44

© Research India Publications

http://www.ripublication.com

A Study on Infiltration Characteristics of Soils at

Andhra University Campus, Visakhapatnam

Sreejani TP1, Abhishek D2, Srinivasa Rao GVR3, Abbulu Y3

JRF, Dept. of Civil Engineering, Andhra University

M.Tech Student, Dept. of Civil Engineering, Andhra University

Professor, Dept. of Civil Engineering, Andhra University

Abstract

An attempt has been made in the present work to evaluate infiltration

characteristics of soils at Andhra University campus using a single and double

ring infiltrometer. Experimentation work is carried out at five different points

in the campus. The study is aimed at determining the constant infiltration rates

of those soils using both the infiltrometers and comparing it with the

infiltration rates obtained by Kostiakov, Philip’s, and Horton’s and Green-

Ampt infiltration models. The values of various constants of the models are

calculated by graphical approach. To get best fitting model for a particular soil

condition the results obtained from various infiltration models are compared

with observed field data and graphs are drawn with correlation coefficient and

standard error as tools. The results showed that infiltration rate is as high as

17.43 cm/h near Samatha Hostel and, the infiltration is rate as low as 1.46

cm/h at Assembly hall area.

Introduction

Water in excess of infiltration capacity of the soil will flow overland as surface run-

off once the minor undulations in the surface have been filled. Runoff occurs most

frequently on degraded soils depending on topography and rainfall intensity. (Eze

Bassey Eze3 et.al 2011) Water is driven into the porous soil by force of gravity and

capillary attraction.( Jagdale5 et.al 2012). Infiltration is the process flow of water into

the soil profile vertically through the soil surface. Infiltration is crucial in modeling of

surface runoff, and it is usually difficult to be evaluated or measured accurately.

(Ieke4 et.al 2013) Infiltration capacity varies in space and time due to soil

heterogeneities, meteorological characteristics, clogging processes and temperature

fluctuations, as well as other processes. (Balraj Singh2 et.al 2014) The Infiltration

process is governed by two major factors viz. gravity which is a natural phenomenon

30 Sreejani TP et,al

and capillary action which is the ability of liquid to flow in narrow spaces (Anjaneya

Prasad1 et.al 2015). The methods used for calculation of infiltration capacity are

Green Ampt Method, General hydraulic budget method, darcy’s law, horton’s

equation. (Shikha6 et.al 2015). In the present study, the constant infiltration rates of

different soils under different soil conditions are calculated by double ring

infiltrometer method, and compared with the calculated values from Horton’s,

Philip’s, Kostiakov’s and Green-Ampt infiltration models. Also, the assessment of the

suitability of different models for estimation of infiltration rate of particular soil under

particular soil condition was carried out with correlation coefficient and standard error

as a tools.

Study Area

The study area, Andhra University is located in Visakhapatnam, Andhra Pradesh. It

lies between latitude 17º43’5.38’’N and longitude 83º19’17.61’’E with an area of 460

acres and a varying elevation from 10 MSL to 62.5 MSL. The average annual rainfall

is 1050 mm and the mean annual temperature and humidity are 23.7ºC and 67 to 78%

respectively. The study area is divided into two campuses viz., South campus and

North campus. Five locations are selected in the University each one at NCC building,

Near CSE Department, Samatha Hostel in the North Campus, as well as Dispensary

and Assembly hall in the south campus.

Figure 1: Study Area - Andhra University Campus

A Study on Infiltration Characteristics of Soils at Andhra University … 31

Materials and Methods

Measurement of Infiltration Rates:

Double ring infiltrometer method is used for measurement of infiltration rates at all

the sites. In this two concentric rings were used with 25cm deep, and diameter of

30cm for inner ring and 60cm for outer ring. The rings were driven at about 15cm

deep in soil by using falling weight type hammer striking on a wooden plank placed

on top of ring uniformly without undue disturbance to soil surface. Inner ring is

driven first. Water was poured into the rings to maintain depth of 5 to 9 cm and the

observations were carried out in the inner ring with measuring scale and stop watch.

Readings were taken at regular time interval of 2, 5, 10, 15, 30, 60 min. till getting a

constant infiltration rate.

The experimental setup consists of:

Two rings having diameter 30cm and 60 cm respectively of height 25cm.

One ring having diameter 30cm and height 60cm.

A wooden log having 4 cm x 4 cm and 70 cm in length.

A hammer.

A spade to collect the remove the sample from site.

A measuring scale having 30 cm in length.

Stopwatch.

Equipment for writing records.

Sufficient amount of water for reading.

Infiltration Models

The following infiltration models are considered for finding best fitting model to

observed field infiltration rate data.

Horton’s Equation (1933) Horton expressed the decay of infiltration capacity with

time as an exponential decay given by

fp = fc + (f0 – fc) e–kht for 0 ≥ t ≤ tc ---- Eq 1

Where,

fp = infiltration capacity at any time t from the start of the rainfall.

f0= initial infiltration capacity when t = 0

fc = final steady state infiltration capacity occurring at t = tc. Also, fc is sometimes

known as constant rate or ultimate infiltration capacity.

Kh= Horton’s decay coefficient which depends upon soil characteristics and


Vegetation cover.

The difficulty of determining the variation of the three parameters f0, fc and Kh with

soil characteristics and antecedent moisture conditions preclude the general use of

Horton’s equation.

Philip’s Equation(1957) Philip’s two term model relates Fp (t) as

KtstFp 2/1

---- Eq 2

Where s = a function of soil suction potential and called as sorptivity.

K = Darcy’s hydraulic Conductivity.

Fp = Cumulative infiltration capacity

From the above equation infiltration capacity could be expressed as

Kstfp 2/1

2

1

---- Eq 3

3. Kostiakov Equation (1932) Kostiakov model expresses cumulative infiltration

capacity as

Fp= atb ---- Eq 4

Where,

Fp is Cumulative infiltration capacity

a and b are local parameters with a > 0 and 0 < b< 1.

The infiltration capacity would now be expressed as

fp= (ab) t(b-1) --- Eq 5

4. Green – Ampt Equation (1911) Green and Ampt proposed a model for infiltration

capacity based on Darcy’s law as

𝑓𝑝 = 𝐾 (1 + (𝜂𝑆𝑐/Fp)) ---- Eq 6

Where 𝜂 = Porosity of the soil.

Sc= Capillary suction at the wetting front and

K = Darcy’s Hydraulic Conductivity.

The above equation can be considered as, fp= m + (n/Fp)

Where m and n are Green – Ampt parameters of infiltration model.


Results and Discussion

The measured infiltration rates of soils in the field at five different locations in the

Andhra University are shown in table 1.

Table 1: Infiltration Rates (cm/hr) (Experimental Results)

TIME (Min) NCC

Building

CSE

DEPT.

SAMATHA

HOSTEL

DISPENSERY ASSEMBLY

HALL

2 25.2 9 109.2 23.1 6.22

4 18.3 8.7 90.84 22.5 5.21

6 9.9 8.4 87.3 19.8 4.57

8 8.4 8.1 76.5 18.3 4.16

10 7.8 7.8 74.64 16.02 3.96

15 6.84 6.72 71.04 15.9 2.92

20 5.64 6.36 65.4 15.72 2.74

25 4.92 6.12 65.2 15.6 2.46

30 4.68 6 60.36 15.34 2.43

35 4.2 5.64 58.68 15.04 2.25

40 4.08 5.6 56.52 14.7 2.12

50 3.96 4.8 54.72 14.64 1.7

60 3.6 4.4 54.6 14.4 1.46

70 3.42 3.8 53.28 12.64 1.46

85 3.32 2.72 50.52 12.32 -

100 2.96 2.69 46.58 11.88 -

115 2.84 2.6 41.92 11.32 -

130 2.8 2.36 37.26 10.92 -

145 2.68 2.24 33.48 10.32 -

160 2.68 2.2 30.17 9.72 -

190 - 2.06 26.98 8.76 -

220 - 2.06 22.72 7.8 -

250 - - 19.46 7.8 -

310 - - 17.43 - -


370 - - 17.43 - -

Constant

Infiltration

Rate

2.68

2.06

17.43

7.8

1.46

Table 2: Parametric values of different infiltration models.

PLACE

HORTON’S

MODEL

fp=fc+(f0-

fc)e-k

ht

GREEN-

AMPT

MODEL

fp=m + n/Fp

KOSTIAKOV’S

MODEL

fp=(ab).t(b-1)

PHILIP’S

MODEL

fp=(1/2)s.t-1/2 +

K

K m n A b s K

NCC

building

2.0665 0.017 21.009 6.228 0.533 8.7724 1.0941

CSE

Department

1.4909 3.8246 2.3532 5.394 0.7784 3.4018 2.2873

Samatha

Hostel

0.7061 39.813 327.16 60.322 0.7859 35.798 26.658

Dispensary 0.6934 11.857 11.804 15.222 0.8548 6.158 9.3186

Assembly

Hall

3.2287 1.7384 1.1268 2.723 0.7186 2.212 0.7526

Table 3: Experimental Vs Calculated infiltration rates at NCC Building

Time (min)

Infiltration rate (cm/hr)

Experimental

value

Horton’s

model

Green-

Ampt

model

Kostiakov

model

Philip’s

model

2 25.2 23.7 25.03 30.6 25.14

4 18.3 22.3 14.51 13.5 18.1

6 9.9 21 11.82 10.8 14.97

8 8.4 19.77 10.22 9 13.11

10 7.8 18.64 9.07 8.1 11.85

15 6.84 16.11 7.29 6.84 9.87

20 5.64 14 6.26 5.88 8.69

25 4.92 12.2 5.58 5.28 7.89

30 4.68 10.7 5.06 4.8 7.3

35 4.2 9.43 4.67 4.44 6.84


40 4.08 8.36 4.34 4.2 6.47

50 3.96 6.7 3.83 3.78 5.9

60 3.6 5.53 3.46 3.48 5.48

70 3.42 4.7 3.16 3.18 5.16

85 3.32 3.88 2.81 2.96 4.78

100 2.96 3.4 2.56 2.72 4.49

115 2.84 3.11 2.36 2.52 4.26

130 2.8 2.94 2.19 2.32 4.08

145 2.68 2.83 2.05 2.24 3.91

160 2.68 2.77 1.93 2 3.78

Correlation

Coefficient

-

0.96

0.98

0.99

0.97

Standard

Error

-

2.0

1.09

0.89

1.32

Figure 2: Variation of experimental and calculated infiltration rates at NCC building

0

5

10

15

20

25

30

35

0 50 100 150 200Infi

ltra

tion R

ate

(cm

/hr)

Time, t (minutes)

Observed Infiltration rate (cm/hr)

Infiltration rate by Horton’s model (cm/hr)

Infiltration rate by Green-Ampt model (cm/hr)

Infiltration rate by Kostiakov model (cm/hr)

Infiltration rate by Philip’s model (cm/hr)


Table 4: Experimental Vs Calculated infiltration rates at CSE Department-AU

Time

(min)


Experimental

value

Horton’s

model

Green-

Ampt

model

Kostiakov

model

Philip’s

model

2 9 8.66 11.66 11.4 11.6

4 8.7 8.34 7.81 8.1 8.87

6 8.4 8.04 6.53 7.2 7.67

8 8.1 7.75 5.9 6.9 6.95

10 7.8 7.47 5.51 6.6 6.45

15 6.72 6.84 5.03 5.88 5.69

20 6.36 6.28 4.77 5.52 5.23

25 6.12 5.78 4.61 5.28 4.92

30 6 5.35 4.5 5.04 4.69

35 5.64 4.97 4.42 4.8 4.51

40 5.6 4.63 4.36 4.56 4.37

50 4.8 4.06 4.27 4.5 4.15

60 4.4 3.62 4.22 4.32 4

70 3.8 3.28 4.18 4.08 3.86

85 2.72 2.89 4.14 3.96 3.72

100 2.69 2.64 4.12 3.84 3.6

115 2.6 2.46 4.09 3.68 3.52

130 2.36 2.33 4.08 3.56 3.44

145 2.24 2.24 4.06 3.48 3.38

160 2.2 2.19 4.05 3.4 3.33

190 2.06 2.12 4.03 3.32 3.24

220 2.06 2.08 4.01 3.2 3.18

Correlation

Coefficient

-

0.99

0.73

0.99

0.88

Standard

Error

-

0.32

1.17

0.27

0.98


Figure 3: Variation of experimental and calculated infiltration rates at CSE

Department-AU

Table 5: Experimental Vs Calculated infiltration rates at Samatha Hostel-AU

Time

(min)


Experimental

value

Horton’s

model

Green-

Ampt

model

Kostiakov

model

Philip’s

model

2 109.2 107.7 129.69 124.8 124.7

4 90.84 104.98 88.86 90.3 95.98

6 87.3 102.94 73.96 81 83.26

8 76.5 100.95 66.78 75 75.67

10 74.64 99 62.19 71.4 70.5

15 71.04 94.35 55.74 66.36 62.45

20 65.4 89.95 52.4 61.8 57.66

25 65.2 85.81 50.23 58.56 54.38

30 60.36 81.9 48.78 56.04 51.97

0

5

10

15

20

25

30

35

0 50 100 150 200

Infi

ltra

tion R

ate

(cm

/hr)

Time, t (minutes)

Observed Infiltration rate (cm/hr)Infiltration rate by Horton’s model (cm/hr)Infiltration rate by Green-Ampt model (cm/hr)Infiltration rate by Kostiakov model (cm/hr)Infiltration rate by Philip’s model (cm/hr)


35 58.68 78.22 47.73 54 50.09

40 56.52 74.74 46.92 52.44 48.58

50 54.72 68.38 45.74 50.46 46.26

60 54.6 62.73 44.9 48.36 44.55

70 53.28 57.7 44.29 46.62 43.23

85 50.52 51.18 43.63 44.88 41.7

100 46.58 45.7 43.17 43.24 40.52

115 41.92 41.15 42.84 41.88 39.58

130 37.26 37.3 42.6 40.68 38.82

145 33.48 34.1 42.42 39.72 38.17

160 30.17 31.3 42.27 38.84 37.62

190 26.98 27.24 42.04 37.72 36.71

220 22.72 24.32 41.88 36.46 36

250 19.46 22.27 41.76 35.42 35.42

310 17.43 19.82 41.58 34.1 34.53

370 17.43 18.6 41.43 32.73 33.86

Correlation

Coefficient

-

0.97

0.82

0.99

0.91

Standard

Error

-

7.33

11.11

2.94

9


Figure 4: Variation of experimental and calculated infiltration rates at Samatha

Hostel-AU

Table 6: Experimental Vs Calculated infiltration rates at Dispensary-AU

Time

(min)


Experiment

al value

Horton’

s model

Green-

Ampt

model

Kostiak

ov

model

Philip’s

model

2 23.1 22.75 27.18 24.9 26.18

4 22.5 22.41 19.62 24.1 21.24

6 19.8 22.07 17.27 18.9 19.05

8 18.3 21.74 16.08 17.4 17.75

10 16.02 21.43 15.41 17.1 16.86

15 15.9 20.66 14.39 16.44 15.47

20 15.72 19.94 13.83 15.48 14.65

25 15.6 19.26 13.48 15.12 14.09

30 15.34 18.61 13.23 14.52 13.67

35 15.04 18.01 13.06 14.28 13.35

40 14.7 17.43 12.92 13.92 13.09

50 14.64 16.38 12.73 13.56 12.69

0

20

40

60

80

100

120

140

0 50 100 150 200 250 300 350 400Infi

ltra

tion R

ate

(cm

/hr)

Time, t (minutes)


Infiltration rate by Horton’s model (cm/hr)Infiltration rate by Green-Ampt model (cm/hr)Infiltration rate by Kostiakov model (cm/hr)



60 14.4 15.45 12.06 13.2 12.39

70 12.64 14.61 12.51 12.72 12.17

85 12.32 13.53 12.41 12.6 11.9

100 11.88 12.62 12.34 12.24 11.7

115 11.32 11.85 12.29 11.96 11.54

130 10.92 11.2 12.25 11.72 11.41

145 10.32 10.66 12.22 11.56 11.3

160 9.72 10.21 12.19 11.36 11.2

190 8.76 9.5 12.15 11.14 11.04

220 7.8 9 12.13 10.9 10.92

250 7.8 8.65 12.1 10.68 10.82

Correlati

on

Coefficie

nt

-

0.97

0.82

0.99

0.92

Standard

Error

-

1.14

1.92

0.53

1.47

Figure 5: Variation of experimental and calculated infiltration rates at Dispensary-

AU

0

5

10

15

20

25

30

0 50 100 150 200 250 300

Infi

ltra

tio

n R

ate

(cm

/hr)

Time, t (minutes)


Infiltration rate by Horton’s model (cm/hr)Infiltration rate by Green-Ampt model (cm/hr)Infiltration rate by Kostiakov model (cm/hr)



Table 6: Experimental Vs Calculated infiltration rates at Assembly Hall-AU

Time

(min)


Experiment

al value

Horton’

s model

Green-

Ampt

model

Kostiak

ov

model

Philip’s

model

2 6.22 5.73 7.1 6.9 6.83

4 5.21 5.29 4.67 4.5 5.05

6 4.57 4.9 3.84 3.9 4.26

8 4.16 4.55 3.41 3.6 3.79

10 3.96 4.23 3.13 3.3 3.47

15 2.92 3.58 2.81 3.12 2.97

20 2.74 3.08 2.62 2.76 2.67

25 2.46 2.69 2.49 2.52 2.47

30 2.43 2.39 2.4 2.4 2.32

35 2.25 2.18 2.34 2.28 2.2

40 2.12 2.01 2.28 2.22 2.11

50 1.7 1.78 2.22 2.16 1.96

60 1.46 1.64 2.17 2.04 1.86

70 1.46 1.57 2.14 1.92 1.78

Correlati

on

Coefficie

nt

-

0.97

0.92

0.99

0.98

Standard

Error

-

0.33

0.51

0.18

0.27


Figure 6: Variation of experimental and calculated infiltration rates at Assembly

Hall-AU

From the results it is found that the values of parameters of Infiltration models vary

from soil to soil and from place to place. Also the Correlation Coefficients and

Standard errors are different for the soils at different locations as calculated. From the

analysis it is found that for all regions selected in the study area, Kostiakov’s Model is

best fitting with high degree of Correlation Coefficient and Minimum standard Error.

The values of Correlation Coefficient and standard Error for soils at different

locations in the study area for Kostiakov’s model are 0.99 & 0.89 for soil at NCC

respectively, 0.99 & 0.24 for soil at CSE Department respectively, 0.99 & 2.94 for

soil at Samatha Hostel respectively, 0.99 & 0.53 for soil at Dispensary respectively,

0.99 & 0.18 for soil at Assembly Hall respectively. From the graphs drawn on

variation of infiltration rates, it is observed that, initially rates are higher and

decreased with time up to a steady state infiltration rate.

Conclusions

From the present study it was found that constant infiltration rates of selected five

locations of the study area i.e. at NCC, CSE Dept., Samatha Hostel, Dispensary and

Assembly hall are 2.68, 2.06, 17.43, 7.8 and 1.46 respectively. The values of

parameters of infiltration models vary from soil to soil and place to place. The values

of unknown parameters of Horton’s, Green-Ampt, Kostiakov’s and Philip’s model are

0

1

2

3

4

5

6

7

8

0 10 20 30 40 50 60 70 80

Infi

ltra

tion R

ate

(cm

/hr)

Time, t (minutes)


Infiltration rate by Horton’s model (cm/hr)

Infiltration rate by Green-Ampt model (cm/hr)

Infiltration rate by Kostiakov model (cm/hr)



shown in table 2. From the correlation coefficient and standard error calculations it

was found that for the soil and their conditions in the study area Kostiakov’s model is

best fitting with high degree of correlation coefficient and minimum standard error.

Kostiakov’s Infiltration model parameters of soils of Andhra University region are

estimated. The unknown parameter ‘a’ ranged from 2.723 to 60.322 and another

parameter ‘b’ ranged from 0.533 to 0.855, where ‘a’ and ‘b’ are local parameters. The

estimated values are substituted into the model equation to obtain the specific

infiltration equations for the soils of the study area. The model equations estimated in

this study area at selected five locations are Fp = 6.228t0.533, Fp = 5.394t0.778, Fp =

60.322t0.786, Fp = 15.222t0.855 and Fp = 2.723t0.719 for soils near NCC, CSE Dept.,

Samatha Hostel, Dispensary and Assembly Hall Respectively, where ‘Fp’ is in cm/hr

and ‘t’ is in hours. The obtained infiltration equations could be used to estimate

infiltration data at any time‘t’ for the soil of this area. This research work seeks to

save time and cost of field measurement during soil water management and water

resources conservative practices in this area. Double-ring-Infiltrometer (DRI) is

frequently used to estimate infiltration because the procedure is rather straight

forward and the instrumentation is simple, but the measurements are time-consuming

and tedious. From the present study it is found that the soil condition affects the

infiltration rate. The factors affecting infiltration rates are soil moisture, type of soil

medium, permeability, vegetal cover, surface fines, soil compaction, water holding

capacity, depth of surface detention, temperature of water etc. From the graphs of

infiltration rates against time it is found that initially infiltration rates were high and

decreased with time up to constant infiltration rate. To increase the infiltration rates of

the area infiltration facilities such as Rain Gardens, Vegetated filter strips, Porous

Pavements, Infiltration Planters, Grass Swales, Infiltration ponds etc.. Should be

adopted based on site conditions and economy.

Acknowledgements

The authors acknowledge Department of Science and Technology (DST), New Delhi

and Andhra University, Visakhapatnam for sponsoring a Research project under

which the present work is carried out.

References

[1] Anjaneya Prasad M, Sundar Kumar P et.al., Determination of Infiltration

Parameter Estimation Rates in a Small Region in Andhra Pradesh,

International Journal of Earth Sciences and Engineering ISSN 0974-5904,

Vol. 08, No. 02, April, 2015, pp. 212-214.

[2] Balraj Singh, Parveen Sihag, Diwan Singh, Study of Infiltration

Characteristics of Locally soils, Journal of Civil Engineering and

Environmental Technology, Volume 1, Number 5; August, 2014 pp. 9 – 13


[3] Eze Bassey Eze, Devalsam Imoke Eni, Oko Comfort, Evaluation of the

Infiltration Capacity of Soils in Akpabuyo Local Government Area of Cross

River, Nigeria, Journal of Geography and Geology, Vol. 3, No. 1, September

2011

[4] Ieke Wulan Ayu, Sugeng Prijono, Assessment of Infiltration Rate under

Different Drylands Types in Unter-Iwes Subdistrict Sumbawa Besar,

Indonesia, Journal of Natural Sciences Research, Vol.3, No.10, 2013.

[5] Jagdale Satyawan Dagadu and P. T. Nimbalkar, Infiltration Studies of

Different Soils Under Different Soil Conditions and Comparison of Infiltration

Models with Field Data, International Journal of Advanced Engineering

Technology, Vol.III, Issue II, April-June, 2012, 154-157.

[6] Shikha P. Shah, Gandhi MH, Jain RK, Review on Experimental Study of

Influence of Soil Parameters on Infiltration Capacity, International Journal for

Innovative Research in Science & Technology, Volume 1, Issue 12, May

2015.

a study on infiltration characteristics of soils at andhra ... · horton’s equation ... kh=...

Documents