Team #22362 Page 9of 29 Water, Water, Everywhere Summary A feasible and cost-efficient water strategy need determining for Chinese projected water needs in 2025. Firstly ， China was divided into seven zones to focus on the water-scarce regions. Prediction model was built after adding up the statistical data, namely performing multivariate regression on regional water consumption and GDP, water demand, irrigation, then the function about the three and time was fitted by MATLAB. After obtaining the function of water consumption and time, the supply-demand balance was analyzed. It was found that the water-scarce zones are zone B,C,F and G， and the water shortage in 2025 ，316.42 10 m ，229.65 10 m ，281.85 10 m . To solve the water crisis，four models-storage、mobilization、 desalination、and sewage treatment were established. In desalination and sewage treatment model, processing costs and environmental effects were calculated quantitatively. In the storage model, storage capacity of underground reservoirs was acquired by idealizing the aquifer. While in mobilization model, the various diversion routes were linear programmed by means of LINGO, four routes were found to have the lowest cost- AB、CD、FD、CE. And sensitivity analysis was done. The priority of the above measures is assessed by AHP, which showed the mobilization is optimal, followed by desalination. Then in that order the measures are combined to make up water. For the Internal water allocation, freshwater optimal allocation model is built to maximum the economic benefits. Then The final best water strategy is as follows: For C zone, CD、CE two routes need building with the total costs 72.78 billion yuan. For F zone, FD with the costs 5.43 billion yuan and 100 desalinators in Shandong, Tianjin need building. For B,F zones, those measures cant completely work out, extras such as agricultural drip irrigation technology which can reduce the water demands should be adopted. Contents 1.Introduction.2 2. Analysis of This Freshwater Problem in China.2 3. General Assumptions.3 4. Symbols and Definitions.4 5. Mathematical Models.4 5.1 Prediction model.4 5.2 Water storage model .10 5.3 Mobilization model.12 5.4 Seawater desalination model.14 5.5 Sewage treatment model.19 5.6 AHP model.22 5.7 Model for intra-regional optimal allocation of water24 6 The non-technical position paper.25 7. Examination.27 8. Evaluation.27 8.1 Strengths.27 8.2 Weaknesses.28 9. Improvement.28 10.References.29 1. Introduction China is a seriously droughty and water-scarce country. The total freshwater resources of China is 2.8 trillion cubic meters, accounting for 6% of the worlds freshwater resources, second only to Brazil, Russia and Canada, ranked fourth in the world. However, water resource per capita in China is only 2,300 cubic meters, which is only 1/4 of the world average, and China is one of the countries with the poorest water resources per capita in the global. Whats more, China has the most water consumption in the world. In 2002, its national freshwater usage amount has already reached 549.7 billion cubic meters, accounting for about 13% of the worlds annual usage amount, and it is about 1.2 times of freshwater supply-470 billion cubic meters the United States used in 1995. Since the 1970s, China has begun drying out, which is not an alarmist, but an objective fact. Since the 1980s, Chinas water shortage has already begun to spread from the local gradually to the whole country, and the situation is more and more serious, which has a serious impact on agriculture and the national economy. So it is necessary to build a mathematical model for determining an effective, feasible, and cost-efficient water strategy for 2013 to meet the projected water needs of China in 2025, and the best water strategy should be identified as soon as possible. 2. Analysis of This Freshwater Problem in China The requirements of the subject are to determine a feasible and effec