RESUMO
The study of short-term dynamics of soil moisture in the dry-hot valley area during rainfall process will help identify soil hydrological function. In this study, we analyzed the short-term responses of soil moisture to rainfall in Huajiang dry-hot valley of Guizhou, using in-situ monitoring method to yield high-frequency soil moisture monitoring data of different slope positions. The results showed that, during the whole monitoring period, soil moisture at each layer was at a moderate variation level (15.2%≤coefficient of variation CV≤29.7%), for both upper slope and middle slope. The fluctuation range of soil moisture of the upper slope (CV=21.1%) was greater than that of the middle slope (CV=19.1%), and that of the 0-5 cm soil layer (CV=26.2%) was greater than 20-40 cm layer (CV=16.5%). Compared with the middle slope, soil moisture of the upper slope had a faster response to rainfall. The supplement amount of rainfall was bigger and the supplement speed of rainfall was faster at the upper slope than that at the middle slope. The difference between the supplement speed and the depletion speed of soil moisture of the upper slope (2.3%·h-1) was greater than that of the middle slope (1.8%·h-1). With the increase of soil depth, the responses of soil moisture to rainfall in subsoil layer was earlier or synchronous with that in topsoil layer. When the supplement amount of soil moisture decreased and the supplement speed slowed down, the depletion speed slowed down. Compared with the middle slope, soil at the upper slope had greater water infiltration capacity and better water retention capacity. The responses of soil moisture to rainfall in dry-hot valley were influenced by micro-environment and microclimate, and the rapid recharge of dominant flow at rock-soil interface accelerated the response speed of subsoil moisture to rainfall, which made the slopes in this area easier to form mixed runoff generation mechanism.
Assuntos
Chuva , Solo , China , Hidrologia , Água , Movimentos da ÁguaRESUMO
Soil moisture influences plant growth and hydrological processes. Studying the response characteristics of soil moisture to winter rainfall under different vegetation types in humid karst areas is important for optimizing the restoration patterns in these areas. To this end, we monitored the soil moisture content of arable, grassland, shrub, and forest areas in the karst of Guanling County, Guizhou Province, China, at 10-min intervals. The rainfall threshold for the soil moisture response was the smallest in grassland areas. Under different vegetation types, the soil moisture increase tended to be maximized in light-rainfall events and minimized in medium-rainfall events. Moreover, the increase in soil moisture in the profile under the different vegetation types generally decreased with increasing soil depth during light and rainstorm events, but the opposite variation pattern was observed during moderate-rainfall events. In different rainfall events, the soil moisture recharge and soil moisture decrease were greatest in grassland areas. Among the vegetation types, shrubs maintained the highest mean soil moisture content in winter, with a higher recharge and a smaller decrease in soil moisture. This suggests that shrubs can better maintain their soil moisture content in winter than other vegetation types, which has implications for the selection of regional vegetation restoration patterns.
