Response characteristics of soil moisture to rainfall for a single grass type in an urban area

Urbanization significantly impacts hydrological processes and the water environment in the urban area. Research works on soil moisture are necessary to explore the hydrological characteristics under 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.