The characteristics of rainfall-runoff are important aspects of hydrological processes. In this study, rainfall-runoff processes and soil moisture dynamics at different soil depths and slope positions of grassland with two different row spacings (5 cm and 10 cm, respectively, referred to as R5 and R10) were analyzed, by means of a solution of rainfall simulation experiments. Bare land was also considered as a comparison. The results showed that the mechanism of runoff generation was mainly excess infiltration overland flow. The surface runoff amount of R5 plot was greater than that of R10, while the interflow amount of R10 was larger than that of R5 plot, although the differences of the subsurface runoff processes between plots R5 and R10 were little. The effects of rainfall intensity on the surface runoff were significant, but not obvious on the interflow and recession curve, which can be described as a simple exponential equation, with a fitting degree of up to 0.854–0.996. The response of soil moisture to rainfall and evapotranspiration was mainly in the 0–20 cm layer, and the response at the 40 cm layer to rainfall was slower and generally occurred after the rainfall stopped. The upper slope generally responded fastest to rainfall, and the foot of the slope was the slowest. The results presented here could provide insights into understanding the surface and subsurface runoff processes and soil moisture dynamics for grasslands in semi-arid regions.

To learn about the changing trend of water resources quantity in the Yangtze River Delta, make rational allocation of water resources, and prevent regional drought & flood risks, the spatial and temporal distribution characteristics of precipitation and drought & flood in the Yangtze River Delta were investigated. Sliding average method, standardized precipitation index method (SPI), and inverse distance weighted interpolation method (IDW) etc. were used to analyze the hydrologic characteristics of YRD based on the daily precipitation data from 15 national meteorological stations in the Yangtze River Delta during the period from 1960 to 2010. According to the result: (1) The Yangtze Delta exhibited a gradually increasing trend of annual precipitation, while the flood frequency has been higher than drought frequency over the past 51 years; (2) At the Yangtze Delta, the maximum mean precipitation was normally observed in June, the minimum mean precipitation in December, the highest flood frequency in April and July, and the highest drought frequency in March; (3) The precipitation gradually increased from north to south at the Yangtze Delta, spatially, the precipitation was more evenly distributed in the north than in the south; the flood prone area was larger than drought prone area at the Yangtze Delta with West Hangzhou, East Shaoxing and West Ningbo susceptible to both drought and flood.1