Effects of rainfall intensity and slope gradient on the application of vetiver grass mulch in soil and water conservation |
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| Authors: | Somchai DONJADEE Chaiyuth CHINNARASRI |
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| Institution: | 1. Dept. of Irrigation Engineering, Kasetsart Univ., Kampaeng Saen Campus, Nakorn Pathom 71340,Thailand
2. Water Resources Engineering & Management Research Center(WAREE), Dept. of Civil Engineering,King Mongkut's Univ. of Technology Thonburi. Bangkok 10140, Thailand |
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| Abstract: | The objective of this study is to investigate the effect of rainfall intensity and slope gradient on the performance of vetiver grass mulch(VGM) in soil and water conservation. The study involved field experiments on 2m × 10m plots with 2 slopes of 3% and 30%. Two rainfall intensities of 55 mm hr?1 and 140 mm hr?1 were selected with a 1 hr for 2 year to 500 year return period. A set of artificial rainfall simulators was constructed and calibrated as part of the research project. Six dry matter quantities of VGM were used in the study. The runoff volume per unit surface area decreased with an increase in the quantity of VGM. For the 3% land slope, they varied from 5.6 to 13.4 mm and from 22.8 to 46.1 mm for rainfall intensities of 55 and 140 mm hr?1, respectively. For the 30% land slope, they varied from 8.0 to 21.4 mm and from 29.4 to 59.6 mm for rainfall intensities of 55 and 140 mm hr?1, respectively. The average soil losses were 0.32–2.85 kg m?2 on the bare soil plots, and 0.07–1.80 kg m?2 on the VGM plots. The VGM showed good potential for reducing runoff by 31.5–68.4% and soil loss by 33.7–82.4%, compared with the case without VGM. The quantity of VGM equal to 0.75 kg m?2 presented the best performance in reducing runoff and soil loss. |
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| Keywords: | Conservation Rainfall Runoff Soil erosion Vegetation |
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