2016年美国数学建模比赛（MCM/ICM） E题环境科学 Are we heading towards a thirsty planet? 人工精准翻译。

第二次参加建模，觉得建模太有趣了，用几天的时间，迅速学习新知识，并解决实际问题。

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Will the world run out of clean water? According to the United Nations, 1.6 billion people (one quarter of the world's population) experience water scarcity. Water use has been growing at twice the rate of population over the last century. Humans require water resources for industrial, agricultural, and residential purposes. There are two primary causes for water scarcity: physical scarcity and economic scarcity. Physical scarcity is where there is inadequate water in a region to meet demand. Economic scarcity is where water exists but poor management and lack of infrastructure limits the availability of clean water. Many scientists see this water scarcity problem becoming exacerbated with climate change and population increase. The fact that water use is increasing at twice the rate of population suggests that there is another cause of scarcity – is it increasing rates of personal consumption, or increasing rates of industrial consumption, or increasing pollution which depletes the supply of fresh water, or what? **

Is it possible to provide clean fresh water to all? The supply of water must take into account the physical availability of water (e.g., natural water source, technological advances such as desalination plants or rainwater harvesting techniques). Understanding water availability is an inherently interdisciplinary problem. One must not only understand the environmental constraints on water supply, but also how social factors influence availability and distribution of clean water. For example, lack of adequate sanitation can cause a decrease in water quality. Human population increase also places increased burden on the water supply within a region. When analyzing issues of water scarcity, the following types of questions must be considered. How have humans historically exacerbated or alleviated water scarcity? What are the geological, topographical, and ecological reasons for water scarcity, and how can we accurately predict future water availability? What is the potential for new or alternate sources of water (for example, desalinization plants, water harvesting techniques or undiscovered aquifers)? What are the demographic and health related problems tied to water scarcity?

Problem Statement

The International Clean water Movement (ICM) wants your team to help them solve the world’s water problems. Can you help improve access to clean, fresh water?

Task 1: Develop a model that provides a measure of the ability of a region to provide clean water to meet the needs of its population. You may need to consider the dynamic nature of the factors that affect both supply and demand in your modeling process.

Task 2: Using the UN water scarcity map (http://www.unep.org/dewa/vitalwater/jpg/0222- waterstress-overuse-EN.jpg) pick one country or region where water is either heavily or moderately overloaded. Explain why and how water is scarce in that region. Make sure to explain both the social and environmental drivers by addressing physical and/or economic scarcity.

Task 3: In your chosen region from Task 2, use your model from Task 1 to show what the water situation will be in 15 years. How does this situation impact the lives of citizens of this region? Be sure to incorporate the environmental drivers’ effects on the model components.

Task 4: For your chosen region, design an intervention plan taking all the drivers of water scarcity into account. Any intervention plan will inevitably impact the surrounding areas, as well

as the entire water ecosystem. Discuss this impact and the overall strengths and weaknesses of the plan in this larger context. How does your plan mitigate water scarcity?

Task 5: Use the intervention you designed in Task 4 and your model to project water availability into the future. Can your chosen region become less susceptible to water scarcity? Will water become a critical issue in the future? If so, when will this scarcity occur?

Task 6: Write a 20-page report (the one-page summary sheet does not count in the 20 pages) that explains your model, water scarcity in your region with no intervention, your intervention, and the effect of your intervention on your region’s and the surrounding area’s water availability. Be sure to detail the strengths and weaknesses of your model. The ICM will use your report to help with its mission to produce plans to provide access to clean water for all citizens of the world. Good luck in your modeling work!

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世界将来有一天会缺失水资源吗？根据UN的说法，1.6百万的人口正在经历水匮乏问题，这已将近世界四分之一的人口。相对于上个世纪而言，水资源的使用正以两倍于人口增长的速率递增。人类在工业、农业以及生活居住方面都需要用水。如今有两种类型的水资源匮乏起因：物理型以及经济型。物理型缺水是指这片区域没有足够的供水来满足需求。经济型缺水是指在这片区域中存在水资源，但是由于管理的乏力以及公共设施的缺失限制了净水资源的获取。随着气候的变化与人口的增长，许多科学家愈加觉得水匮乏问题正变得愈加严重。水资源的使用正以两倍于人口增长的速率增长的显示告诉我们，引起水资源的匮乏或许有另外的因素：会是个人使用的增长，还是工业使用的增长，甚至会是日益严重的污染情况锐减了净水资源的供应吗？抑或还会有其他的原因呢？

将净水资源提供给所有人是一个可行的将来吗？水资源的供给必须考虑水资源本身的物理获取（比如说是自然水资源还是科技获水）。我们需要知道水资源的获取在本质上是一个跨学科的问题。我们不止需要了解水资源供应的环境方面的限制，还需要了解社会因素是如何影响净水资源的获取与分配的。比如说，缺乏适当的卫生设施会使得水质的下降。在一个区域内，人口资源的上升也会加重水资源供给的负担。在分析水匮乏问题时，以下问题必须考虑在内：历史上，人类采取了什么措施加剧了亦或是减轻了水资源匮乏的问题？导致缺水的地质，地形和生态的原因是什么，以及我们如何能够准确地预测未来水的供应？新的或者是可替代水资源，他们潜力几何？和水资源匮乏相关的人口统计学问题以及健康问题有哪些？

Can you help improve access to clean,fresh water? 你能帮忙提升净水资源的获取吗？
Task 1：设计一个模型。这个模型提供的是一个测量一个地区能够供给净水资源的来满足人口需求的能力。在构造模型的步骤中，需要将影响供求关系的因素的动态性考虑进去。

Task2：http://www.unep.org/dewa/vitalwater/jpg/0222- waterstress-overuse-EN.jpg，在这里寻找一个heavily or moderately的城市，解释在该城市水资源是如何被污染的。确保从物理型以及经济型出发分析社会以及环境因素。

Task3：在你选择的这个城市，用task1模型展示水资源在15年后会呈现什么状态？这个状态将会如何影响该城市的居民生活？在模型的构件中确保要有环境驱使的因素存在。

Task4：为该城市设计一个干预措施，需要将影响水资源匮乏的所有诱因都囊括进来。任何干预计划都会不可避免地影响到周遭地区甚至是整个水生态。在这样一个更大的环境下来探讨这个影响的优劣何在。我们的计划将如何缓解水资源的匮乏？

Task5:使用你设计的干预计划以及模型来投射出未来水资源的获取情况。该城市会对水资源匮乏的问题变得不再那么敏感吗？水资源问题会变成未来一个至关重要的问题吗？如果会的话，那么这个匮乏问题会在什么时候出现呢？

Task6：写一篇20页左右的论文，包含模型是什么，没有干预计划下该城市的水资源匮乏情况，我们的干预计划，干预计划针对该城市以及周遭地区的水获取的影响。确保要将模型的优劣都具体写出来。