TITLE:
Estimation of Hydraulic Conductivity of Soils at a Watershed-Scale Using Porchet’s Method: Application in the Olezoa Waterhed, Yaounde, Cameroon
AUTHORS:
André Firmin Bon, Auguste Ombolo, Guillaume Ewodo Mboudou, Jules Rémy Ndam Ngoupayou, Georges Emmanuel Ekodeck
KEYWORDS:
Unsaturated Zone, Quartile Graphs, Hydraulic Conductivity, Olezoa
JOURNAL NAME:
International Journal of Geosciences,
Vol.7 No.3,
March
31,
2016
ABSTRACT: Contamination analysis of
the unsaturated zone requires information on the spatial variability of
hydraulic conductivity. Two types of hydraulic tests (variable and constant
charge) were identified to estimate the spatial variability of the hydraulic
conductivity of the surface portion of the unsaturated zone in the Olezoa
watershed. These tests were performed on 100 holes at depths ranging between 50
and 90 cm, spread throughout the watershed. The hydraulic conductivity values
obtained at 50 and 90 cm are close to the absolute value for each method.
However, they show a difference of 10-1 m/s between the two types of test
regardless of the depth of investigation. The representation of data in the
graph indicates a staircase quartile distribution for the variable charge test.
The test at constant charge, rather presents a log normal distribution which is
also supported by the Kolmogorov-Smirnov test. Hydraulic conductivities have a
random component and a spatial organization which results from soil and/or
morphological factors. This organization thus permits the distinction of zones
which could show high pollution risk.