Research On Mechanism Of Virtual Water Transformation And Virtual Water Regulation

Severe scarcity of water resources compelled people to continue exploring ways to alleviate water resources crisis. In 1993, Professor Allan put forward the concept of virtual water which provided new approach to solve water problems. There had been many researches in virtual water estimation, virtual water trade, virtual water strategy and water resources carrying capacity. Whereas researches in virtual water transport and transformation and driving mechanism was weak which was not consistent with the virtual water management and regulation and it was necessary to further debate. It was important to analyze characteristics of virtual water transformation and migration, driving factors and regulating principle. Cognition of virtual water flowing process in social economic activities and function of regulating water in regional water system was important for water policy formulation, water resources plan and water carrying capacity improvement.Traditional virtual water research emphasized on characteristics of regional virtual water trade with outside and its impact factors, however, virtual water flow among different industrial sectors and its influencing factor was rarely discussed, and agricultural and industrial virtual water trade had not been analyzed separately which made it difficult jto mater flow law of virtual water. Simulation of water carrying capacity was mainly entity water and green water, blue water and virtual water input-output was not introduced into water system, but it was essential to deal with water crisis in view of broad water. It was common to establish agricultural water demand in the future using irrigation quota without considering impact of climate change on it which could not reflect precisely or using water demand in different climate change model without considering applicability of models in specific regions, and the method listed above could not reflect theoretical blue water demand when precipitation was less than crops water demand. This dissertation studied on transformation and trade mechanism for virtual water and regulation, took Tangshan as an example, the main content of paper were as follows:Based on input-output table, statistics data, plan data and meteorological data, this paper, taking heavy industry city of Tangshan which was serious shortage of water resources as a case, studied composition and variation of virtual water, analyzed process and driving factors of virtual water transformation and trade, modeled water resources carrying capacity over the past 10 years as well as in the coming 15 years, discussed regional applicability of climate change models using input-output analysis, principal component analysis, grey relational analysis, index decomposition method and system dynamics. The main conclusions were as follows:1. Characteristics and driving mechanism of virtual water transformation and trade were Qualitative and quantitative analyzedIn order to explore characteristics of virtual water transformation and trade, this paper estimated transformation among different industrial sectors in Tangshan and trade volume between Tangshan and outside region by input-output model. Results showed that within Tangshan agriculture was net output sector and transported large number of virtual water to industry, construction and service sector. Virtual water trade was net output, output regions were foreign countries and output volume was decreasing which was favorable development direction.As far as transformation and trade of virtual water concerned, qualitative and quantative analysis were integrated to reveal characteristics and driving factors for transformation and trade of virtual water. Firstly, various indexes for virtual water transformation, virtual water trade in agriculture and industry were put forward respectively. Secondly, function of every index was determined by principal component analysis and gray relation analysis. Results showed that agriculture planting structure, cultivated land area, grain yield and agriculture water-using level were the decisive factors which impact virtual water transformation between agriculture and industry. Factors which impact agricultural virtual water trade were agriculture water-using level, arable land resource and population. Intensity effect made industry virtual water trade volume decrease and structure effect made it increase.2. Virtual water measures were discussed based on water resources carrying capacity modelIn this paper, water resources carrying capacity model was constructed in the respective of virtual water and the model was realized using Vensim. Agricultural water was analyzed from water and green water angle, virtual water output was introduced into total water demand system. The water resources carrying capacity model emphasized on the relationship among the affecting and restricting factors, explored the key controllable factors and the controllable factors were precipitation infiltration coefficient in the angle of green water, irrigation water use coefficient in the angle of blue water, industrial water consumption of ten thousand yuan in the angle of industrial virtual water and virtual water trade volume in the angle of water flow respectively. And response of water resources carrying capacity to different key controllable factors was further simulated.3. Future water carrying capacity was constructed under climate changeSensitive meteorological factors of blue water requirements for main grain crops such as wheat, corn, rice, vegetables, oil crops and cotton were analyzed based on partial correlation. On basis of sensitive meteorological factors, simulation precision of different climate change models was analyzed and the applicability of the model to different regions and different research objects was analyzed at the same time.Water resources carrying capacity model was built under background of climate change in in period of 2016-2030 and future water resources carrying capacity was predicted based on meteorological data, planning data and forecast data. The results showed that in order to ensure the steady and fast economic development goals, measures such as improving precipitation infiltration coefficient, increasing irrigation water use coefficient, reducing water consumption of ten thousand Yuan and cutting down virtual water output were effective to alleviate pressure of water resources shortage.