Penilaian keberaliran hidraulik untuk makroliang buatan melalui kaedah wooding dan penyelesaian songsang

Abstract

The present study was carried out to investigate artificial macropore as an alternative structural measure to reduce surface runoff. Disturbed soils were sampled to determine soil texture and conduct soil column experiment. Initial water content, saturated hydraulic conductivity, residual water content, dry bulk density, and organic matter contents were measured from undisturbed soil samples. Field infiltration was measured by using tension disc infiltrometer with three different pressure heads i.e. -5, -2, and 0 cm H2O. Wooding's solution was then used to estimate unsaturated hydraulic parameters. The result of Wooding’s solution was then used as initial estimates of optimized van Genuchten-Mualem hydraulic parameters by inverse solution using cumulative infiltration data. Soil column experiment, 20 cm in diameter and 20 cm in height, was carried out to investigate water flow in the soil with an artificial macropore for sandy clay loam and loam soil. HYDRUS 2D/3D was employed to design an artificial macropore and to simulate the water flow. Determination coefficients (R2) for cumulative infiltration from observation and simulation are found to be 0.98-0.99. In addition, R2 for drainage from observation and simulation are in the order of 0.99. Increasing macropore diameters (0, 5, 8 and 10 cm) for the both soil textures were found to increase total drainage and cumulative infiltration. Increasing macropore lengths (0, 10, 20 and 10 cm) for the both soil texture were found to increase total drainage and cumulative infiltration. Increasing initial water contents (12%, 20% and 25%) for the sandy clay loam and loam soil (15%, 20% and 25%) were found to increase total drainage but to decrease the cumulative infiltration. Artificial macropore in sandy clay loam and loam soil proved to infiltrate much water compared without macropore. The study on hydraulic conductivity using Wooding and inverse solutions succesfully revealed that an artificial macropore has the potential to be an alternative structural measure to reduce surface runoff.