The determination of the drainage factor as a criterion for the soils of the Indos Plains.

1968 ◽  
Vol 16 (1) ◽  
pp. 25-35
Author(s):  
W.C. Hulsbos
Keyword(s):  
Hydraulic Conductivity ◽  
Water Table ◽  
Additional Data ◽  
Design Criteria ◽  
Saline Groundwater ◽  
Horizontal Drainage ◽  
Limited Accuracy

Drainage factors (DF) were used as design criteria for comparing relative costs of horizontal and tubewell drainage of mainly medium-textured silty loams, especially in saline groundwater areas. DF calculated from recharge estimates were higher than those calculated from leaching requirements. For tubewell drainage (normally maintaining a water-table lower than is possible with horizontal drainage) DF from recharge estimates should serve as criteria for establishing the capacity of the installation. For calculating the required spacing for horizontal drainage, DF slightly higher than those derived from leaching requirements are desirable to take into account drainage or seepage from line sources. If wide spacings are calculated with relatively small DF, the reaction of the water-table halfway between the drains to intermittent recharge may be too slow, and a smaller spacing may be required. Because of limited accuracy of the DF, additional data on hydraulic conductivity of the soil are desirable. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Water Phase Inclination Theory for Hydraulic Conductivity Determination of Vadose Zones in Shallow Water Table Systems

2021 ◽  
Vol 54 (2B) ◽  
pp. 85-100
Author(s):  
Arkan Radi Ali
Keyword(s):  
Hydraulic Conductivity ◽  
Shallow Water ◽  
Linear Relationship ◽  
Water Table ◽  
Correlation Factor ◽  
Water Phase ◽  
Shallow Water Table ◽  
Allowable Limit ◽  
Undisturbed Soil

Water Phase Inclination is an innovative theory for hydraulic conductivity and determination of vadose zone overlying shallow water table systems. It was originated and analytically derived from Darcy's Law and based on some physio-mechanical properties of soil. Al-Musayab area of 176 Km2 at Mesopotamian region, mid-Iraq was undertaken as a case study. It consists of unconsolidated quaternary deposits and is usually finer-grained than the underlying pebbly sandstone with Mediterranean weather. The Experimental part was divided into field tests which include double ring infiltrometer tests, water table depth measurements and sampling of 32 undisturbed soil samples of surface layers scattered over the study area Whereas lab tests include; the falling and constant head permeability, grain size distribution (sieve and hydrometer analysis), soil specific gravity, direct shear tests and the measuring of Water Phase Inclinations. Angle \emptyset a glassy infiltration box is an experimental device that was manufactured to measure the Water Phase Inclination angle and aquifer simulation. It is found a generalized linear relationship between  and the angle of internal friction which is valid for   23.37 with correlation factor R² = 0.99 and both angles depend on soil texture. The k values estimated by WPI theory and that measured by traditional techniques offer a linear relationship with acceptable Root Mean Square Error equals 0.0642 < 0.1 the max allowable limit and correlation factor R² = 0.96, pointing out to the reliability and stability of the Water Phase Inclination results.

scholarly journals DETERMINATION OF HYDRAULIC CONDUCTIVITY BY THE AUGER HOLE METHOD

2018 ◽  
Vol 3 (1) ◽  
pp. 91
Author(s):  
Oswaldo Palma Lopes Sobrinho ◽  
Stephanie Soares Arriero ◽  
Gerlange Soares da Silva ◽  
Aline Bezerra de Sousa ◽  
Álvaro Itaúna Schalcher Pereira
Keyword(s):  
Hydraulic Conductivity ◽  
Water Table ◽  
Main Parameter ◽  
Saturated Hydraulic Conductivity ◽  
Agricultural Drainage ◽  
Empirical Formulas ◽  
Drainage Systems ◽  
Average Value ◽  
Drainage Capacity

The hydraulic conductivity of a soil is the main parameter that determines its drainage capacity. However, its determination is of great importance for sizing in agricultural drainage systems. To determine the hydraulic conductivity of the soil in the presence of water table through the Auger-Hole. The experiment was carried out at Embrapa Manioc and Fruticulture (EMBRAPA), located in the municipality of Cruz das Almas-BA. In order to estimate the hydraulic conductivity, several empirical formulas have been proposed, such as Ernst's, which is the model that most closely approximates the soil situation studied. The hydraulic conductivity values for the studied soil obtained by the Auger-Hole method ranged from 0.24821 to 0.28544 m day-1. With an average value for hydraulic conductivity of 0.266835 m day-¹, being considered slow. The soil under analysis is classified in slow saturated hydraulic conductivity. The Auger-Hole method proved to be practical, fast, safe and easy to handle.

Time and Latitude in South Africa

1972 ◽  
Vol 1 ◽  
pp. 27-38
Author(s):  
J. Hers
Keyword(s):  
South Africa ◽  
Cape Town ◽  
Astronomical Observations ◽  
Royal Observatory ◽  
The Republic ◽  
Astronomical Determination ◽  
Limited Accuracy ◽  
Better Than

In South Africa the modern outlook towards time may be said to have started in 1948. Both the two major observatories, The Royal Observatory in Cape Town and the Union Observatory (now known as the Republic Observatory) in Johannesburg had, of course, been involved in the astronomical determination of time almost from their inception, and the Johannesburg Observatory has been responsible for the official time of South Africa since 1908. However the pendulum clocks then in use could not be relied on to provide an accuracy better than about 1/10 second, which was of the same order as that of the astronomical observations. It is doubtful if much use was made of even this limited accuracy outside the two observatories, and although there may – occasionally have been a demand for more accurate time, it was certainly not voiced.

EFFECT OF SPATIAL VARIABILITY IN HYDRAULIC CONDUCTIVITY ON WATER TABLE DRAWDOWN

1997 ◽  
Vol 40 (2) ◽  
pp. 371-375
Author(s):  
S. O. Prasher ◽  
M. Singh ◽  
A. K. Maheshwari ◽  
R. S. Clemente
Keyword(s):  
Hydraulic Conductivity ◽  
Spatial Variability ◽  
Water Table
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