COMPARISON OF ESTIMATED AND MEASURED HORIZONTAL Ksat VALUES

Abstract

Horizontal Ksat was estimated as one of eight classes according to guidelines based on soil morphology and then measured by a piezometer method in soils of the Ottawa area that differed widely in texture and structure. The Ksat class estimated by two observers was either the same as, or one class different from the measured class for 14 and 16 of 18 layers tested (average 83%). Measured horizontal Ksat exceeded vertical Ksat by a factor of 9 in some sandy layers with strata of relatively coarse material. Measured vertical Ksat exceeded horizontal Ksat by a factor of more than 3 in some layers having numerous more-or-less vertical earthworm channels. Horizontal Ksat of the layers measured ranged from 0.3 to 14 m∙day−1 and vertical Ksat values for those layers ranged from 0.1 to 27 m∙day−1. Guidelines for estimating horizontal Ksat were revised on the basis of results from this study to give more emphasis to stratification. The results support the view that adequate estimates of vertical and horizontal Ksat can be made rapidly from the observation of soil morphology if specific guidelines are followed. The guidelines are based on relationships between soil morphology and measured Ksat values. Key words: Horizontal Ksat, vertical Ksat, soil morphology