| The assessment indicator system of water-soil environmental effect has been established, which can be used to synthetically evaluate the influence degree to water-soil environment of water resources exploited by humanity, and examine its future development trend. Shiyanghe River Basin is a typical inland river basin, which was caused severe ecology problems by human over exploitation. It is a typical representative in whole dry land in Northwest of China.The paper takes the Shiyanghe River Basin as an example, analyses the regional water-soil environmental effect. Based on the analysis of the correlation of each factor of water-soil environment, the correspondent indicator is selected and the synthetic assessment indicator system starting from the connotation of the effect is worked out. The indicator system is a hierarchy system, and it is composed with one general aim, six guideline and thirty-two indicators. To reach the aim of reflecting entirely the degree of the effect, the general aim is decomposed with six aspects, which are water resource carrying capacity effect, surface water resource effect, groundwater resource effect, oasis and vegetation effect, soil salinification effect and land desertification effect. Water-soil environmental effect of water resources development is a complex system, it has fuzzy attribute, and can be synthetically evaluated by fuzzy comprehensive assessment. At the same time, the system is a poor information system with gray attribute, and it can be comparatively analyzed with gray relational assessment, which can make the assessment results more reliable and persuadable. By using the model, each county is evaluated. The Analytic Hierarchy Process was adopted, which supported by information entropy to decide the indicator weight. Some was discussed in the fuzzy synthetic assessment model, emphasizing on constructing the subordinate function and calculating the fuzzy matrix.In the paper, the degree of water-soil environmental effect is divided into five levels, namely, very strong, comparatively strong, middling, comparatively weak, very weak, which are represented by V, IV, III, II, I. The results indicate that the larger the value, the stronger the level of environmental negative effect. Based on the environmental status of the river basin in 1970, the upper reaches, middle and lower reaches in the river basin are evaluated, which are approximatively represented by the Gulang county, Liangzhou borough, Minqin county and Jinchang city. The good or bad degrees of the results are sorted to analyze the inner relation of water development between upper and lower reaches to set down some measures. The main conclusions are showed as follows:1. The Assessment Results in Counties of Shiyanghe River BasinThe assessment results of one grade is:(1) Water Resource Carrying Capacity Effect (P1). The order of assessment results is, Liangzhou < Gulang < Jinchang < Minqin.(2) Surface Water Resource Effect (P2). The order is, Liangzhou < Gulang < Jinchang < Minqin.(3) The Groundwater Effect (P3). Gulang < Liangzhou < Jinchang < Minqin.(4) Oasis and Vegetation Effect (P4). Liangzhou < Gulang < Jinchang < Minqin.(5) Soil Salinification Effect (P5). Gulang < Liangzhou < Jinchang < Minqin.(6) Land Desertification Effect (P6). Gulang < Jinchang < Liangzhou < Minqin. The synthetic assessment result of water-soil environmental effect is obtained after integrated considers analysis results hereinbefore. The order of the result is:Gulang (II~III) < Liangzhou (III) < Jinchang (III~IV) < Minqin (V)The conclusion shows that the environmental negative effect on water resources development is sharply increased from upper reaches to lower reaches, especially in Minqin county, the effect is up to very strong (V). It approximately matches case with practice, which reveals the feasibility of the thought of the models.2. The Dynamic Analyses of Water-Soil Environmental Effect in Minqin County(1) The Dynamic Analyses. The assessment results indicate that...
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