PENENTUAN KONDUKTIVITAS HIDRAULIK TANAH TIDAH JENUH DENGAN TENSIOHIGROMETRI DAN PERBANDINGANNYA TERHADAP MODEL EMPIRIS MUALEM

Abstract

Study on soil water characteristics in unsaturated zone is challenging since most of field condition are in unsaturated condition. Developing such study is very cumbersome restricted by the lack of apparatus for measurement. The objective of this research was to develop a simple method in determination of unsaturated hydraulic conductivity (K ) using tensiohygrometry. Natural soil sample from loam to clay loam collected from field using ring sampler of ...cm u 3 in volume and 6 cm in height. Two gipsblock tensiometers and 1 hygrometer sensor inserted into soil sample through ring sampler’s wall. Soil water content and soil water tension data, ranging from saturated to dry, collected in every 4 hours. From accumulated data the unsaturated hydraulic conductivity were determined using method of Wind (1960). The result showed there were a tendency of decreasing hydraulic conductivity occur along increasing soil water tension with drying process for all soil sample. Hydraulic conductivity for loam varies from 2.10 -1 to 3.10 -6 cm.day -1 under water tension from 9.10 -1 to 9.10 4 hPa, and for clay loam varies from 3.10 -2 to 5.10 -6 cm.day -1 under water tension from 9.10 hPa. In relation to Mualem empirical model on unsaturated hydraulic conductivity, it was found the hydraulic conductivity determined with tensiohygrometry method tends to underestimated for loam sample, but overestimated for clay loam. However, with respect to all of its weaknesses in accuracy, the applied tensiohygrometry utilizing gipsblock tensiometer and capacitance sensor showed as a promising method in detecting unsaturated soil hydraulic conductivity in the laboratory. -1 -10 5