| Recently, the opinion of taking the rainwater as the total water resources has been accept gradually, but it is difficult if we want to apply this viewpoint to conduct our practice because the rainwater theory is still imperfect. In order to enrich and promote the rainwater theory, this research work, regarding the rainwater as the total water resources, applying the methods of theoretic analysis, experiment study and systemic engineering, established preliminarily the systemic theory of rainwater resourcfulization in watershed. The author analyzes and assesses the situation of water supply and requirement in watersheds applying this theory. A model of rainwater resources network utilization is put forward aiming to satisfy the water demand with least investment. Some important and significative conclusions followed.Based on the research results of rainwater utilization, the author puts forward the concepts of theoretic potential, available potential and practical potential taking the rainwater as the water resources in watershed. Introducing the parameter of X R which means the ability of measure to control and use rainwater, methods of calculating the potential of rainwater resourcfulization are provided in this paper. According to the feathers of technology of rainwater utilization, three kinds of calculating methods for the parameter of X R are built corresponding to three different way of rainwater use, which including the way of rainwater use in original spot, piled, and in other place.In the light of calculating method of X R, the values of X R of different rainwater utilization measures such as the level terrace, artificial forestry land, artificial grassland, sloping bench terrace, dam are determined in the precipitation of different design frequency. At the same time, the effect of quality of measures and new soil additive PAM on the X R are discussed. The characteristic and performance of catchments materials including concrete, plastic film, compressed soil are studied in this paper, and new rainwater catchments materials HEC and AAM mixed with loss are proved to be excellent materials with the advantage of high catchments efficiency, low cost, and the credible performance.According to the features and composition of water requirement in watershed in the Loess Plateau, the author thinks that the water requirement in watershed is made up of three parts, living, production, and ecological water requirement. Based on the eleven watersheds with integrated controls in the Loess Plateau, the water demand quota and amount of different water requirement system is determined. The results showed that the ecological water requirement is 75.97% of the total water requirement, the production water requirement for foodstuff is 22.90%, and the living water requirement is only 1.3%. about 30 thousand m^ in average.By analyzing the supply and requirement of rainwater resources in watershed, the author finds there is a serious situation of water deficiency in Changwu experiment station which has the biggest populationdensity. In normal precipitation year (the design frequency is 50%), the shortage rate of water resources reaches 14.77%. But because the few population and the low proportion of arbor that consumes much water resources in Guyuan and Xigi experiment station, it can still maintain the balance of the supply and demand of water resources, and can get some remainder in dry year (the design frequency is 90%).Based on the study on the theoretic potential, available potential, practical potential of rainwater resourcfulization in watershed and water requirement, the author puts foreword the assessment methods which adopt some indexes such as WDmax, WDreal, WD to appraise the utilization situation of rainwater in watershed. The assessment result in eleven experiment watersheds shows that in normal precipitation year, the rainwater resources supplied by the integrated controlled watershed which has the various rainwater utilization measures in the Loess plateau can not only meet the demand of wat...
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