A Study on Water Resources Guarantee in Beijing City Based on Water Footprint Evaluation

A concept of water footprint was developed and elaborated in the present work in order to offer an indicator depicting water use with regard to consumption of people. The water footprint of a city is defined as the volume of water needed for the production of goods and services consumed by inhabitants in the city. The water footprint primarily contains industrial water, domestic water, agricultural water as well as environmental water. The domestic water, environmental water and the part of industrial entity water consumption are estimated by the entity water, which can be obtained from statistical data. The agricultural water and other virtual water consumption can be calculated by means of the footprint proposed by A.Y. Hoekstra and A. K. Chapagain in year 2002. Total volumes of water use in the agricultural sector are calculated on the basis of the total volume of crop productions and corresponding virtual water content, which can be calculated by the virtual water content of primary crops (m3/ton) by the total volume of yield. The methodology developed by the Food and Agriculture Organization of the United Nations (FAO) is adopted to calculate crop water requirements. To calculate the virtual water content of live animals (m3/ton), the results about Chinese live animals from A.Y. Hoekstra were utilized in this study. The developed concepts and methods were applied to calculate water footprint in Beijing. Results showed that the true water occupancy quantity was roughly 13.828×109 m3, which seems to be a more reliable quantity compared with the statistical data. Through analyzing the industrial structure and consumption pattern, it was found that grain and meat were two major products consuming water resources; meanwhile, planting and animal industries were major industries consuming water resources. Also, the water resources pressure index and different partial pressures were calculated, showing a value of 1.37 of the water resources pressure index and the partial pressures caused by industrial water, domestic water, agricultural product introduction water, eco-environment safeguard water, animal products and crop water of 0.082, 0.135, 0.570, 0.016, 0.350 and 0.213, respectively. The water resources imported by virtual water trades were estimated to be 5.978×109m3, and the external dependence degree was about around 0.43, which may be indicative of that native water resources cannot satisfy water demands and support sustainable development of economy and society. Furthermore, the authors analyzed the water footprint structure and water guarantee situations in Beijing. It was suggested that optimizing the water use structure, importing virtual water and the Water Transfer Project from the South to the North of China will be basic measures to ensure water supply in Beijing. The water footprint concept introduced in the study can be an effective and appropriate way to analyze water guarantee situations in future studies.