Abstract:Tree soils, one of them is soil developed from Quaternary red clay, one is from granite and purple soil, were studied by permeameter. There are major types of soil, which were severely eroded in southern China. By stuy the relations between time and total measures of water permeating into soil, between time and permeability velocity, between permeability velocity and total water measures of permeation were established. The relation equations for 10 experimental plots were made and the properties of permeability of each soil were discussed.

Abstract:In order to process data of direct runoff and water infiltration through soil from field tesrs, curve-fitting techniques were used. By progressin gestablished equations express mutual relations between rainning time and funoff coefficient, between the time and infiltration capacity, between the time and infiltration velocity, respectively. Selected one from two groups of equations achieve optimum fitting effect and was used as mathematical model in practice.

Abstract:We collected 21 soil samples from different foresr soil in Chang Bai Mountain and built a mathematical model on infiltration coefficient of forest soil under saturation with theory(1) of quantification. Results are following.1.The mathematical model about infilfration coefficient of forest soil under satyration is drawn;2.First factor, which affects the infiltration is the interaction between soil texture and soil unit weight.According to the importance of other factors, we hace soil texture, unit weight, root quantity in soil and interaction retween the last two;3.Theory(1) of quantification could be used easily with higher pricision for estimating infiltration ofefficient of froest soil under saturation.