Abstract: According to the principles of soil water balance, Penman-Monteith function was adopted to calculate potential evapotranspiration. The daily soil available moisture was simulated, and the daily dynamic drought-monitoring index was put forward based on soil moisture (SM). With the comparison of the standardized precipitation index (SPI), relative moisture index (MI), and combined meteorological drought index (CI) recommended by the ‘meteorological drought levels of National Standards’ (GB/T 20481-2006), the applicability of the daily dynamic drought-monitoring index based on SM in Guangdong was evaluated, and the results showed that the drought season (from November to next April) based on SM lagged one month, compared to rain-less period (from October to next March). The SM index could describe the lag effect and gradual change characteristics of drought relative to the annual change of precipitation, and objectively reflect the seasonal distribution of drought frequency in Guangdong. The drought index based on SM automatically implied the time cumulative effect of precipitation-evaporation process, and thereby, could describe the start, development, and end of drought process in detail. In terms of progressive development, precipitation sensitivity, and integrity of drought course, the drought index based on SM was of good application value.

Key words: High efficient water use in agriculture, Water-saving agriculture