【正文】 torage coefficient, it can be calculated that the maximum regulation and storage capacity of underground reservoir as: ???????? = ??????? (6) Where: ???????? refers to the regulation and storage capacity of underground reservoirs(m3)。Team 22362 Page 10of 29 Water, Water, Everywhere Summary A feasible and costefficient water strategy need determining for Chinese projected water needs in 2025. Firstly ， China was divided into seven zones to focus on the waterscarce 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 supplydemand balance was analyzed. It was found that the waterscarce zones are zone B,C,F and G， and the water shortage in 2025 ， 10 m ， 10 m ， 10 m . To solve the water crisis，four modelsstorage、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 bined 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 billion yuan. For F zone, FD with the costs billion yuan and 100 desalinators in Shandong, Tianjin need building. For B,F zones, those measures can’t pletely work out, extras such as agricultural drip irrigation technology which can reduce the water demands should be adopted. Contents ..................................................................................2 2. Analysis of This Freshwater Problem in China..........................2 3. General Assumptions..................................................................3 4. Symbols and Definitions............................................................4 5. Mathematical Models.................................................................4 Prediction model.................................................................4 Water storage model ..........................................................10 Mobilization model............................................................12 Seawater desalination model…………………………......14 Sewage treatment model……………………………....…19 AHP model…………………………………………….....22 Model for intraregional optimal allocation of water……24 6 The nontechnical position paper...............................................25 7. Examination………………………………………………......27 8. Evaluation.................................................................................27 Strengths…………..……………………………………27 Weaknesses…………………………………………...…28 9. Improvement……………………………………………….....28 ................................................................................29 1. Introduction China is a seriously droughty and waterscarce country. The total freshwater resources of China is trillion cubic meters, accounting for 6% of the world39。 is storage coefficient of the underground waterbearing medium in reservoir storage layer, for the no pressure waterbearing body?? = ?? + ???, for the pressure waterbearing body?? = ???,where is gravity specific yield(dimensionless),??? is elastic storage coefficient(dimensionless)。 =2. yuan/m3 Abide by the principle of cost minimization, the determination of the water transfer schemes need linear programming to solve. Linear programming As the figure shows, in order to simplify the transfer process, take one big city in each zone as a centralized point to study their water mobilization. Those centralized point turn to be respectively: A:Xining(+) B: Hohhot() C: Chengdu() D: Wuhan(+) E: Guangzhou(+108) F: Beijing() G: Harbin() Figure 7: Mobilization model ①Point A、D、E are water supply points, B、C、F、G are waterpoor points. A+D+E= B+C+F= So A、D、E don’t have enough water to meet the quantity B、C、F demand. While the distance between G and water supply points is the farthest， and the costs is the largest, so it can be ignored to transfer the freshwater to G zone. ②.It can be seen that D zone must supply water to B or F（DC），in order to avoid the costs caused by route repeat, when E provides water to B、 F, it can provide water to D firstly，then to B、F. ③.Because A zone had less water supply， and the distance between A and F is father than DF, and the distance between A and C is closer than CD and CE, so the routine AF can be excluded. So the feasible water supply line includes AC、AB、DB、DF、DC、EC、ED、（ED+DB）、（ED+DF） It can be sought by measuring tape through Baidu map that ED=838 km，EC=1233km，DF=1056km，DB=1061km，AC=703km，AB=984 km，CD=992km. It has been assumed that the water supply amount from A to B、C is respectively: ??1??13，the water supply amount from D to B、 C、F is respectively:??4??4??46，from E to B、C、F is respectively??5??5??56. Transportation costs of the unit volume of water are a， the transportation costs are W. So the Decision objective: minW=(703??12+984??13 +992??43+1061??42+1056??46+123353+189 9??52+1894) (7)