中文摘要：

水土资源是人类生存和发展最基本的资源，各种人类社会、经济活动，都离不开对水资源、土地资源的利用，水土资源生态系统的安全程度，直接影响到区域社会经济的发展。因此，保护水土资源，保证水土资源合理、高效、可持续利用，是区域社会经济快速发展必不可少的前提条件。以西安市为例，在水资源、土地资源生态安全的概念、研究方法和目标的基础上，初步探讨了城市水土资源生态安全评价方法，按照自然、经济和社会3个系统层建立水土资源生态安全层次结构评价指标体系，使其能够从整体上反映城市水土资源生态安全的状况。运用层次分析法确定权重，综合评价法计算生态安全值，并将生态安全值划分为5个判别等级，以此来判定西安市水土资源生态安全状况。结果表明：西安市2000年～2005年生态安全值均在0．41-0.44之间，处于水土资源安全中警状态，水土资源生态系统受到较大的人为破坏和干扰，承载能力较低，土地退化较严重，水资源重度紧缺，生态问题突出。

英文摘要：

Land and water are the basic resources of human survival and development. Each social or economic activity and development is dependent on the use of water and land resources, with ecosystem security levels directly impacting regional social and economic development. Protecting water and land resources and making proper, efficient and continuous use of them is an essential prerequisite for promotion of rapid local social and economic development. So far most studies focus on the evaluation of land ecological security and their methods are well-developed, but they seldom include issues of water resource ecological security. This article takes Xi＇an as an example, based on the water and land resource ecological security concept and research. Using official data from 2001 to 2006, we first discuss the assessment methods for land and water ecological security and establish a hierarchical structure of ecological security evaluation index system from the three aspects of nature, economy and society. Then we use the method of AHP to determine weights and relevant mathematical models to calculate the ecological security of every evaluation index. We used the synthetic evaluation law to compile them in order to reflect integrated ecological security. The ecological security values were divided into five grades to estimate the state of land and water resource ecological security in Xi＇an. The results showed that the ecological security value of Xi＇an from 2000 to 2005 is between 0.41 and 0.44. The land and water resources security are in a police state, as the ecosystems of land and water resources have been seriously disturbed by human activity and have lower carrying capacity. The function of land was degraded, as according to the statistics from 2000 to 2005, the cultivated land of Xi＇an was reduced by 2.8 × 10^4 hm2 and grain yield also declined accordingly. Water resources are in severely short supply and often scarce, and between 2000 and 2005 the per capita water availability for Xi＇an was less than 500m3