Studies on the improvement of Rainball simulator and effective experiments of soil erosion

K.Hosyamada和K.Kakita最新开发了一种“悬压喷雾式”降雨模拟器，给出了蓄水器压力、电磁阀开启和关闭时间、降雨强度、雨滴下落速度和雨滴直径之间的关系，并计算了每种情况下的降雨能量。对天然降雨侵蚀力因子R的计算结果表明，简便法计算结果与原始计算结果高度相关。给出了水滴冲击下土壤径向和角度分布的实验结果。通过对实验数据的统计分析，发现径向角度分布密度函数分别呈指数型函数-lt；Gamma和gt；型。T.Kusaka研究了土壤流失计算在实际农田中的应用，并将试验区的结果与实验室的结果进行了比较。其次，他得到了降雨量与地表径流的统计关系，并建立了估计方程。连续考察了无压降雨模拟器的性能，得到了降雨的局部分布和变化范围，并计算了降雨能量。翁长雄志指出，冲绳有一定强度的降雨具有较高的能量。此外，他还调查了冲绳的土壤性质(分级、结构等)和种植制度，总结了土壤灾害的实际情况和对策。Y.Shiotsuki利用10分钟的降雨数据，通过重新生成雨滴大小分布的方法计算了降雨能量。此外，他发现，集中降雨时的降雨能量是根据雨滴空间密度N_d的降雨能量计算公式外推得到的。

K.Hosoyamada and K.Kakita newly developed a rainfall simulator "hanging pressurized spray type" and showed the relations between a pressure of the reservolrs,open and close time of electro magnetic valves,rainfall intensity, falling velocity of raindrops and raindrop diameter.Next,they calculated the rainfall energy in each cases. On the erosivity factor R of natural rainfall,they showed that the results of calculation by convenient method were highly correlative to the ones by original calculation.T.Fujiwara et al. showed the experimental results of radial and angular distribution of soil splashed by a waterdrop impact.As a result of statistical analysis of the experimental data,it became clear that radial angular distribution density fuction was expressed by the exponential type function, <GAMMA>type respectively.T.Kusaka investigated the application of soil loss calculation for the actual field compairing the results at test plots with the ones at experimental laboratory.Next.he obtaind the relations between rainfall and surface runoff statistically and set up an estimate equation.N.Minami et al. Investigated the properties of the non-pressurized rainfall simulator consecutively and obtained the local distribution and the changing range of rainfall and calculated the rainfall energy.K.Onaga showed that rainfalls with certain intensity at Okinawa has high energy.Moreover he investigated the soil properties(grading,structgure etc.)and cropping systems,and summarized the actual conditions and the countermeasures for soil loass.Y.Shiotsuki calculated the rainfall energy by means of regenerating the distribution of raindrop size using the data of 10 minutes rainfall.Moreover he found out that the rainfall energy at a concentrated rainfall is gained by means of extrapolation of calculation equation of the rainfall energy based on space density N_d of raindrops.