Field Monitoring of Suction Distribution Due to Grass Cover

A field-monitoring program was conducted to investigate the suction induced by Axonopus Compres sus in sandy silt under tropical climate. Matric suction data were recorded twice per day from August to December 2015 , accounting for less than 10 periods of continuous d rying of longer than 5 days over 5 months of measurement. Th e highest suction occurred on 3-Sept with 12 days of drying duration. However, the grasses failed to retain the soil suction, which dropped to a minimum magnitude at al l depths after a rainfall event. This may due to the high infiltration rate of the dry soil after 12 days of drying. For comparison between Axonopus Compressus and Cynodon Dactylon, the data was obtained from two different sites. However, the rate of evapotranspiration for both st udies was assumed similar because of the similar hot and sunn y weather conditions in Malaysia and Hong Kong. The r esults from both studies showed similar suction profile during 6 days of the drying period with maximum difference of 10 kPa at 10 cm and 30 cm depths. This shows that these tw o grasses may produce similar suction profiles when monitored under similar conditions.

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