(3)The variation of road erosion rate can be divided into three stages during which the variation of erosion rate with rainfall process is great from the commence of soil erosion by runoff to 20 min,and from 40 min to the end of runoff erosion processes,and is relatively steady from 20 min to 40 min.

The results of runoff scouring experiments with a slope range of 3° -30° show that the average flow velocity increased with the discharge of flow and slope gradient and the formula is V=0.096S0.37Q0.13,the slope gradient has bigger effect on velocity than discharge.

According to the result of simulated runoff experiment in laboratory, the Effective Depth of Interaction (EDI) of runoff with soil mineral nitrogen is analyzed and the methods to confirm EDI of fertilization experiments and underutilization ones are proposed.

利用室内模拟降雨试验,初步探讨了径流与土壤矿质氮素的有效作用深度(Effective Depth of Interaction,EDI),对施肥和不施肥试验分别提出用拐点法和反推法确定EDI。

Discussion on the Effect of Comprehensive Harnessing and Prevention Measures of Soil and Water Loss──According to the Analysis of Runoff and Sediment Variations in Xishui River Watershed

Following the principles of runoff-collecting forestry and applying the forest structure investigation results, the authors developed a formula to calculate appropriate density for forests on the basis of different diameters at breast height (DBH).

This technique is used to construct a model of runoff transformation for fragments of the Volga basin.

Methods of the use of radar information in applied hydrology (in particular, for calculation of runoff probability) are developed.

The anthropogenic components of runoff dynamics from drained fields are calculated.

However, some components of the total runoff into the Arctic Ocean feature distinct and fairly complicated disturbances in the homogeneity of runoff variations.

In order to investigate the rule of soil erosion and sediment transportation in basins of the upper Yangtze river,the Lin stream,a tributary of the middle Jialing river,has been selected as a typical basin to be analysed and studied.Based on the data of rainfall,\runoff and sediment transportation obtained from site investigation,field test and observed from 1960 to 1991,equations for calculating the sediment amount and the maximum sediment discharge have been established respectively by using single-factor...

In order to investigate the rule of soil erosion and sediment transportation in basins of the upper Yangtze river,the Lin stream,a tributary of the middle Jialing river,has been selected as a typical basin to be analysed and studied.Based on the data of rainfall,\runoff and sediment transportation obtained from site investigation,field test and observed from 1960 to 1991,equations for calculating the sediment amount and the maximum sediment discharge have been established respectively by using single-factor correlation analysis and multi-factor regression analysis.With reference to the principle of the instantaneous unit hydrograph of runoff and on the basis of the linear hour-invariant system,the model of instantaneous unit hydrograph of sediment transportation has been established.The hydrograph of sediment discharge at the basin exit section can be obtained by means of convolution of the unit hydrographof sediment transportation and the net soil erosion of a time interval.The model has been verified by using data from other basins.

According to the theory of conceptural model of coupled simulation.the paper applies thecoupled model of runoff and sediment of a basin into the evaluation of water and sediment reduction benefits through soil conservation measures. First of all,It devides various measures intotype of water reduction (or type of storing water and retaining sediment) and type of vegetation.then use the model to evaluate separately the benefits of water and sediment reduction caused byusing the two kinds of measures and...

According to the theory of conceptural model of coupled simulation.the paper applies thecoupled model of runoff and sediment of a basin into the evaluation of water and sediment reduction benefits through soil conservation measures. First of all,It devides various measures intotype of water reduction (or type of storing water and retaining sediment) and type of vegetation.then use the model to evaluate separately the benefits of water and sediment reduction caused byusing the two kinds of measures and the total benefits of water and sediment reduction. It isshown through the evaluation of benefits of soil conservation measures used in Heifangou watershed that the method is rational and each result of separated evaluation tallies with the actual situation. Comparing the observed value with the calculated individual flood yield and sediment production modulus, the relative value of the total absolute error is 20. l% and 20. 4% respectively.

Based on statistical analysis of observed data of experiment of water and soil runoff plots at Xifeng soil andwater conservation station from 1964 to 1980,it is proved that there is a very close corelation(y=aH￣b)betweenindividual rain fall erosive modulus and depth of runoff,which is a power funetion,The unit individual runoff depth(KW)was as soil anti scour index which was used to evaluate the faetors affecting soil anti scourability.