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Urbanization significantly impacts hydrological processes and the water environment in the urban area. Studies on soil moisture are necessary to explore the hydrological characteristics against the background of urbanization. A regional grassland with Bermudagrass in Yangzhou City, China, was adopted as the study area. An analysis of its response characteristics to rainfall infiltration was carried out for different rainfall events. The Penman–Monteith equation was used to estimate the hourly evapotranspiration (ET) of the soil layers at depths of 0–30 cm and 0–10 cm. The results indicate that the response time of the soil water content in the root layer (0–10 cm) decreases with the decrease of the soil water content in the topsoil. The rate of the increase of the soil water content increases as the rainfall intensity increases in the state of unsaturation. The soil water in the root layer provided more than 70% of the total ET. The Nash efficiency coefficient of the simulation results of the soil water content at different depths obtained using the Hydrus-1D model was more than 0.75. The rationality of the results for the different rainfall events and the infiltration depth were verified via numerical simulations using the Hydrus-1D model.

A regional grassland with Bermudagrass in Yangzhou City of China was adopted as the study location. Based on the analysis of the different rainfall events and soil water content data in the same periods, the response characteristics of infiltration to rainfall were revealed in a certain degree. The surface resistance parameters (rs) are calibrated according to the soil water content at the depths of a range for 0-30 cm and of the root layer (0-10 cm). Penman-Monteith (P-M) equation was adopted to estimated the hourly evapotranspiration (ET) over the Bermudagrass lawn of the soil layers for the depths of 0-30 cm (ET30) and 0-10 cm (ET10), respectively. Applicability of HYDRUS-1D model for simulating soil water content at different depths was validated. The results indicated that the infiltration depth generally varies with the rainfall event grade, and on the whole, the infiltration depth increases with the improvement of amount of rainfall; the response time for the soil water content in root layer is much shorter with the less soil water content in the topsoil (0-5.5 cm); the increase rate of soil water content raised with increasing of rainfall intensity in the state of unsaturation; ET10 accounts for about 78% of ET30, which demonstrates the water consumed by ET is mainly provided by the soil water in the root layer. the rationality of the results of different rainfall events and infiltration depth achieved by the analysis of the observed data were verified via numerical simulation using Hydrus-1D.