| In gneiss area of Tai-hang mountain of Hebei Province, the rainfall of each year is small, and the allocation of rainfall is not equality, 80 percent of rainfall is in summer. This is the main reason of drought in this area, which makes the entironment fragiled. While drought has been become the most important factor which restrict the economy development in this area. In order to ameliorate the status of water shortage and improve the economy development of this area, the technique of rain harvesting and water conservation in gneiss area of Tai-hang mountain have been studied by the experiment of rain and the experiment of the investigation in the field. And we have got the following result:1. the technique of storing water in soil in gneiss area of Tai-hang mountain: The more water in soil before rain is, the less water capability of soil is , the time shorter of water flowing from soil is , the easier the water flows on the ground; The soil capability of reserving water of different soil thickness is terrace>acacia land>pine land>grass land, so the soil is more thick, the soil capacity which contains water is more large; The accumulated water that flows on the ground is remarkable related with the logarithms of rain time. The equation is W=a+blnt, the interrelated coefficient are all larger than 0.92. When the rainfall intensity is steady, the time longer of rainfall is, the thinner of slope soil is, the more water in slope soil before rain is, the easier the water flows on the ground.2. the regulation and the technique of rain harvesing on slope in gneiss area of Tai-hang mountain: The amount of the water that flows on the ground is remarkable related with the rainfall. And when the rainfall is larger than 17.6mm, the amount of flow is exponential increasing with the rainfall increase. The equation is y=a ebx, the interrelated coefficients are all larger than 0.95; When the rainfalls are close, the volume of the surface runoff increases with the intensity of rainfall and the volume of the surface runoff is remarkable related with the maximum rain intensities of 30 minutes; With the effect on rain harvesting acreage, the cover rate of the plants, the gradient, and the average soil thickness, the cover rate of the plants and the average soil thickness are the important factors which can affect the volume of rain harvesting. And the average soil thickness is the dominant factor. In order to get good result, we must choice the slope which the cover rate of the plants is low and the average soil thickness is thin, meanwhile increase the rain-harvesting acreage. According to this experiment, there are 100m2 of rain-harvesting acreage, then 3m3 rain harvesting pool will be builtcorrespondingly in gneiss area of Tai-hang mountain.3. the technique of water conservation in gneiss area of Tai-hang mountain: On the facet of water conservation measure, four sorts of water conservation measures can all improve the soil water content. The result of straw mulch is best, using water holding agent in soil and plastic mulch are better, stone mulch is worse. Four sorts of water conservation measures all improve the physical character of surface layer soil. They decrease soil bulk density, increase soil porosity and soil saturated water content. The result of straw mulch is best, plastic mulch is better. The movement of soil water in gneiss area of Tai-hang mountain has following regulation. With increasing of the soil deepness, the soil water content is decrease gradually. In summer, the change of soil water content is larger. After rain, the soil water content is higher, while no rain, the soil water content decreases faster relatively. In autumn, the soil water content begins to drop, but the drop range is small than summer. During continual drought, the soil water content of surface layer approaches to that of middle layer and under layer; Water conservation measures can increase chestnut's new branch remarkably, results difference among water conservation measures are not significant, meanwhile,...
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