Analysis on Temporal Differences in Water Resources Security and Grain Security in China
中国水资源生态安全与粮食安全状态评价

Agricultural economic activities are important fields linking water resources security and grain safety. Quantitative evaluation of water resources security and grain safety is meaningful for understanding the ecological fragility of the water resources system. Based on analysis of conception, characteristics, and the relationship between water resources security and grain security, the authors conceptually divided the development process of security (safety) into three stages. It is stated that on the third stage, grain safety grows while environmental quality is improving. This is considered a sustainable stage and an ideal goal of social and economic development. In order to make a reasonable investigation, the authors developed an index system for assessing the security (safety). The index system of ecological security is a Pressure-State-Response (PSR) index consisting of a series of indexes in a hierarchical sequence for pressure, state, and response, respectively. The index system of grain safety was established within the same framework. Data at the national scale during the period 1997-2006 were obtained and analyzed. In terms of the requirement of the PSR index system, each index is standardized. Subsequently, values of pressure indexes, state indexes, and response indexes were calculated for water resources security and grain safety, respectively. Furthermore, the overall value of water resources was calculated by adding the values of each component involved in the Pressure-State-Response system. The values of water resources and grain safety were compared in detail. In the meanwhile, the coupling degree among pressure indexes, state indexes, and response indexes was compared for water resources security and grain safety, respectively. It was found that: 1) the level of grain safety rose stably but the water resources security showed a declining trend during the study period; 2) there was high coupling between state indexes and response indexes for grain safety. Hence, the level of grain safety kept growing under the condition of high pressure; 3) there existed high coupling between state indexes and pressure indexes for water resources security. After year 1998, pollution to water resources was aggravated. As a result, the quality of water resources became increasingly exacerbated. The coupling between response indexes and state indexes for water resources security was found to be generally low. Although the values of the response indexes grew significantly, the effect of human intervention was showed to be limited. To that end, more capital should be input into related areas and policy associated with alleviating environmental degradation should be adjusted in the future.