International Journal of Scientific Research in Knowledge, 2(5), pp. 224-232, 2014 Available online at http://www.ijsrpub.com/ijsrk ISSN: 2322-4541; ©2014 IJSRPUB http://dx.doi.org/10.12983/ijsrk-2014-p0224-0232 224 Full Length Research Paper Scaling Approaches to Evaluating Spatial Variability of Saturated Hydraulic Conductivity and Cumulative Infiltration of an Acrisol Henry Oppong Tuffour 1, 2* , Mensah Bonsu 2 , Abdul Aziz Khalid 2 , Thomas Adjei-Gyapong 2 1 School of Agriculture and Bio-Resources Engineering, Anglican University College of Technology, Nkoranza Campus, Nkoranza, Ghana 2 Department of Crop and Soil Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana * Corresponding Author: hoppongtuffour@gmail.com; (+233) 208 542 308 Received 01 February 2014; Accepted 12 April 2014 Abstract. Spatial variability of soil properties has been frequently assessed using classical statistics and geostatistics. However, the scaling theory approach has also proven to be an effective method to describe the variation of soil hydraulic properties. The objective of this study was to evaluate the structure of spatial variability in soil hydraulic and hydrologic processes using scaling techniques in the Plantations Section of the Department of Crops and Soil Sciences, KNUST, Kumasi. Field infiltration studies were conducted using the single ring infiltrometer. Saturated hydraulic conductivity ( K s ) was determined in the laboratory by the falling head permeameter. The similar media theory approach was employed in the scaling of K s , while cumulative infiltration amount (I) was scaled using the linear variability theory. Scaling factors and parameters of the reference curves were computed directly from the parameters of individual soil hydraulic and hydrologic parameters and reference curves were obtained to represent K s and I in the field. Scaling factors ranged from 0.23 to 2.66 with a mean of 1.00 for K s , I and cumulative time. The composite K s and I for the study area calculated by using different, but related, scaling factors was successful, though the distribution and range of the parameters were highly variable. Keywords: Spatial variability, Scaling, Similar media, Linear variability, Reference curves, Saturated hydraulic conductivity, Cumulative infiltration amount 1. INTRODUCTION Studies in soil water movement are increasingly concerned with the spatial variation of soil physical properties. In many studies, spatial variation of the soil hydraulic properties is expressed by scaling factors. In conventional scaling, reference parameter curves and scaling factors are determined from minimization of residuals. Thus, the single objective of scaling, therefore, is to coalesce a set of functional relationships into a single curve using scaling factors that describe the set as a whole. Most studies have shown that scaling factors are lognormally distributed (Hopmans and Overmars, 1987; Clausnitzer et al., 1992; Hopmans and Kosugi, 1998). The definition of scaling factors comes from the work of Miller and Miller (1956). They introduced the similar media concept (Miller similitude) which is based upon assumptions concerning the microscopic geometric structure of porous media. Similar media differ only in the scale of their internal microscopic geometries and have therefore equal porosities. In principle, the similar media concept allows results, either experimental or computed, of soil water behaviour in one soil to be used to describe the behaviour in another by employing reduced variables defined in terms of appropriate microscopic characteristic lengths. The purpose of scaling is to simplify the description of statistical variation of soil hydraulic properties. By this simplification, the pattern of spatial variability is described by a set of scale factors relating the soil hydraulic properties at each location to a representative mean. 1.1. Scaling Theory According to Miller and Miller (1956), the fundamental concept underlying the system is that two soils or porous media M and M o are similar when scale factors exist which will transform the behaviour of one soil or porous medium to that of the other, i.e., the variables that describe the physical phenomena that occur within them, differ by a linear factor λ, called microscopic characteristic length, which relates their physical characteristics (Reichardt et al., 2003).