DIMENSIONAL ANALYSIS TO ESTIMATE THE UNSATURATED HYDRAULIC CONDUCTIVITY OF A SANDY LOAM SOIL IN THE AGRICULTURAL FIELD

Al-Dosary, Naji Mordi Naji; Aboukarima, Abd El Wahed Mohamed; Marazky, Mohamed Said El

doi:10.1590/1809-4430-Eng.Agric.v42n3e20220015/2022

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Scientific Paper • Eng. agríc. (Online) 42 (3) • 2022 • https://doi.org/10.1590/1809-4430-Eng.Agric.v42n3e20220015/2022 copy

DIMENSIONAL ANALYSIS TO ESTIMATE THE UNSATURATED HYDRAULIC CONDUCTIVITY OF A SANDY LOAM SOIL IN THE AGRICULTURAL FIELD

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

Hydraulic conductivity in unsaturated soil controls water movement and measuring it in agricultural fields is a challenging task requiring time-consuming, costly, and skilled experimentation. This study was conducted to reduce the cost of experimentation through the development of an estimation model. The developed model is based on dimensional analysis to determine the value of hydraulic conductivity of unsaturated soil as it relates to soil moisture content, irrigation water electrical conductivity, and suction rate (pressure head). Data points were acquired from measurements of cumulative infiltration in the field, using a mini disc infiltrometer. The developed model gave a mean discrepancy ratio of 1.10 (the acceptable range is 0.5–2.0) and a mean percentage of relative errors of 9.96%. These values indicate that the dimensional analysis model is reliable for the prediction of sandy loam soil’s unsaturated hydraulic conductivity.

KEYWORDS
Electrical conductivity; infiltration rate; mini disc infiltrometer; soil density; water management

Water samples	(meq L⁻¹)						ECw	pH
Water samples	Ca	Mg	Na	HCO₃	Cl	SO₄	(dSm⁻¹)	(-)
W1	6.61	6.48	6.30	2.40	11.97	5.10	4.72	6.83
W2	4.77	2.56	5.74	2.09	5.89	4.09	1.32	7.15
W3	11.62	7.09	10.20	8.00	17.95	8.50	1.77	7.33
W4	10.02	4.46	11.10	4.40	13.96	7.30	3.02	7.40
W5	10.42	3.42	11.33	3.69	9.49	8.14	1.56	7.70
W6	11.41	4.65	13.58	3.98	11.49	14.20	2.38	7.75
W7	14.34	11.28	20.56	5.33	15.47	22.00	3.89	8.00
W8	20.87	10.78	23.56	3.20	19.48	27.04	2.60	8.20
Mean	11.26	6.34	12.79	4.14	13.21	12.05	2.66	7.55
Minimum	4.77	2.56	5.74	2.09	5.89	4.09	1.32	6.83
Maximum	20.87	11.28	23.56	8.00	19.48	27.04	4.72	8.20

Variables	Symbol	Unit	Dimensions
Dependent Variable
The field unsaturated soil hydraulic conductivity	KU	ms⁻¹	M⁰LT⁻¹
Independent Variables
Water electrical conductivity	ECw	Sm⁻¹	M⁰L⁰T
Suction rate	SR	m	M⁰LT⁰
Soil bulk density	BD	kgm⁻³	ML⁻³T⁰
Soil moisture content	MC	%	M⁰L⁰T⁰

Data points	ECw (dSm⁻¹)	MC (decimal)	BD (kgm⁻³)	Suction rate (cm)	KU (mh⁻¹)	Z (dSm⁻¹.cm⁻¹)
1	1.32	0.10927	1.52	5	0.0092	0.02885
2	1.56	0.10677	1.65	5	0.0095	0.03331
3	1.77	0.10049	1.60	5	0.0098	0.03557
4	1.32	0.11066	1.55	4	0.0145	0.03652
5	1.56	0.10292	1.55	4	0.0223	0.04014
6	1.77	0.10537	1.55	4	0.0233	0.04663
7	1.32	0.11057	1.58	3	0.0246	0.04865
8	1.56	0.10399	1.58	3	0.0252	0.05408
9	2.38	0.10339	1.57	3	0.0306	0.08202
10	1.32	0.12805	1.68	2	0.0271	0.08451
11	2.6	0.10302	1.44	3	0.0276	0.08928
12	1.56	0.12293	1.53	2	0.0284	0.09589
13	1.77	0.11946	1.59	2	0.0331	0.10572
14	2.6	0.11534	1.48	2	0.0339	0.14994
15	1.32	0.13042	1.63	1	0.0398	0.17216
16	1.56	0.11831	1.64	1	0.0454	0.18456
17	1.77	0.13648	1.68	1	0.0481	0.24156
18	2.38	0.10538	1.64	1	0.0552	0.25080
19	2.6	0.11411	1.47	1	0.0599	0.29669
20	3.02	0.12293	1.63	1	0.0647	0.37126
21	3.89	0.11961	1.58	1	0.0675	0.46527

Data points	Discrepancy ratio	Relative errors (%)
1	1.99	98.51
2	1.97	96.86
3	1.96	95.77
4	1.32	32.33
5	0.88	-11.66
6	0.89	-11.36
7	0.85	-15.02
8	0.86	-14.13
9	0.83	-16.62
10	0.95	-4.77
11	0.96	-4.12
12	0.96	-3.52
13	0.87	-13.30
14	1.03	2.78
15	0.95	-4.88
16	0.87	-12.77
17	0.98	-1.52
18	0.88	-11.87
19	0.92	-8.19
20	1.01	0.83
21	1.16	15.84
Mean	1.10	9.96

Associação Brasileira de Engenharia Agrícola SBEA - Associação Brasileira de Engenharia Agrícola, Departamento de Engenharia e Ciências Exatas FCAV/UNESP, Prof. Paulo Donato Castellane, km 5, 14884.900 | Jaboticabal - SP, Tel./Fax: +55 16 3209 7619 - Jaboticabal - SP - Brazil
E-mail: revistasbea@sbea.org.br

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[1] * Corresponding author. Department of Agricultural Engineering, College of Food and Agriculture Sciences, King Saud University, Riyadh, Saudi Arabia. E-mail: nalsawiyan@ksu.edu.sa