Abstract: The differential LDA system has been used to investigate the statistical characteristics of the turbulent boundary layer flow over a transitional rough flat plate.The characteristical quantities,such as turbulent intensity,third order moment,fourth order moment,probahilitv distrihution,auto-correlation and power spectrum,have been obtained.The experimental results expressed that the turbulent boundary layer car.be divided into subregions in the vertical direction according to the sign of higher order momentum,and the limits of divisions have been given.Meanwhile,it was found that the turbulent boundary layer flow tends to be homogeneous and isotropic owing to the roughness of the flat plate,i.e.,the distribution of probability density is close to Gussian distribution.
Abstract: on the basis of a simplified version of Einstein's total sediment transport model,analytical solution of Einstein total load function is rigorously derived,which has the following expressions:
The present solution has been verified by comparison of numerical results.Due to its simplificity,this solution can be widely applied to practical engineerings,especially to computation of river-bed deformations.
Abstract: The annual sea level of each long-term tidal station along the Chinese coast is analysed.The result shows that it has the feature of synchronistic rising and lowering.Its changing periods of 5,11 and 19 years are obtained by using the method of variance analysis. The comparison method of 11 years is used because the long-term tidal stations along the coast lack the observed tidal data with the record length of more than 38 years.The rising speed of 1.6±0.3 mm per year for the mean sea level along the coast in recent years(over 30 years) is obtained based on the data analysis of 13 selected benchmark tidal stations with a selected time interval close to the difference average of mean sea level of 11 years. This result agrees well with that of most researchers at home and abroad,and the method of analysis is easy to use.
Abstract: The connections of atmospheric circulation and runoff for the upper Yangtze River with the variation of Antarctic sea-ice extent are discussed by using correlation analysis in this paper.The processes associated with these connections are also analysed.It follows from the analysis that the variation of Antarctic sea-ice extent can change the intensity of zonal circulation in south Indian Ocean and affect the SST(sea surface temperature) at equatorial west Indian Ocean,and further,affect the 500hPa height distribution over the region between India and Burma.It also shows that there are some connections between the Antarctic sea-ice extent in Feb.to Mar.and runoff for the upper Yangtze River in Aug.to Sep.,which could be useful for revealing the physical background that affects the variation of runoff for the upper Yangtze River.
Abstract: Design flood estimation is one of the most difficult problems in Engineering Hydrology.Little progress has been made in the extrapolation of flood frequency curve by mathematics as yet. However,the latest studies reported in this paper show that the flood record can be expanded over thousands years by using the palaeoflood information,thus increasing the accuracy of estimating the flood events `Pith rare frequencies greatly.Also,the new developments in the estimation of the probable maximum precipitation/flood(PMP/PMF) are addressed.
Abstract: An auto/cross covariance approach for parameter estimation of the discrete linear transfer function model is a new method.The daily rainfall and runoff data series on four catchments are chosen to examine the new method(4 years rainfall and runoff data series for calibration periods and 2 years for the verification periods).The comparison between the results from the new method and coven. licnal ordinary least squares method shows that the accuracy of the new method is better than those of the conventional least squares method and the latter is a special case of the former.
Abstract: A improved by Schaake J.G.nonlinear monthly water balance model which describes the physical process of runoff yield is used to study the impact of climate change on runoff.The simulated results and their analyses are presented in this paper.
Abstract: According to the variation law of rice evapotranspiration,a linear regression method and a three-times smoothing method with exponential weight cocfficicnts are proposed for forecasting the rice evapotranspiration of different growing seasons respectively in this paper.The analysis of three real-world caamples shows that the two methods work well.Meanwhile; the proposed methods might be useful for forecasting the evapotranspiration of other crops.
Abstract: The depth-area relations of 24-hour-storms with a given order of magnitude in Hebei Province of Chian are analysed. The result shows that the relations of the area-averaged vary with area,and some storms parameters have been given.
Abstract: Recent torrential rain researches and its applications in China are breifly reveiwed. Since "August 1975 sever flash flood" occurred in Central China,new acheivements and progresses on torrential rain researches are comprehensively studied by the theoretical and experimental works,the satellite and radar analyses,the mesoscale and climatological studies,the atmo-physical parameters and diagnostic analyses,the formation and triggering mechanisms of heavy rains etc.