سد سه دهانه چين ( three gorge project )
خلاصه اي از مشخصات سد سه دهانه چين ( three gorge project )
منطقه سد حدود 27 مايل بالا دست از شهر ييچانگ و 38 کيلومتر پايين دست سد از جژويا که در سومين دهانه سد قرار مي گيرد .
اين پروژه ، بزرگترين پروژه هيدروالکتريک دنيا خواهد بود ، اين سد پهنايي برابر با پل گلدن گيت و ارتفاعي معادل دو برابر آن دارد . توانايي توليد 18 گيگا وات با استفاده از نيروي هيدروالکتريک را دارا مي باشد . اين ميزان برق معادل توليد برق حدود 18 راکتور هسته اي مي باشد .
پس از اتمام در سال 2009 سد سه دهانه بيش از يک مايل در عرض رودخانه يانگ تسه و حدود 600 فوت بلندتر از کف دره قرار مي گيرد . اين سد بزرگترين سد بتني دنيا خواهد بود در حالي که سد ايتايپو برزيل در رده دوم قرار مي گيرد .
براي ساخت سد حدود 1 ميليون نفربايد جابجا شوند. مخزن350مايلي سد معبد تاريخي، دهکده ها، مناطق تدفين، وتنگه تماشايي که همه ساله توريست ها براي ديدنش به چين مي آيند را زيرآب مي برد. همچنين محيط زيست شناسان در مورد ازميان بردن تعدادي از گونه ها و اقسام زيستي نادر مثل دلفين رودخانه يانگ تسه بحث مي کنند ، همينطورمخزن سد، ميليون ها تن از مواد آلاينده که توسط بزرگترين شهر صنعتي چين يعني چونگينگ توليد مي شود را در يک محل جمع ميکند .
پس از تکميل اين سد يک نهم از قدرت برق چين را تامين خواهد کرد، همچنين پس از تکميل سد، مخزن غول آساي آن از کره ماه قابل ديدن خواهد بود.
مهندسين اين سد چانچينگ ( کميته منبع آب ) و سرمايه گذاري و طراحي آن بر عهده موسسه ژانگنون و هودونگ است . حدود هزينه از17 تا 100 ميليارد دلار، ظرفيت ذخيره 1039 ترليون فوت مکعب . اهدف ساخت به ترتيب عبارتند از کنترل سيل، نيروي هيدروالکتريکی ،آ بياري و کشتيراني.
Is it safe for drinking? Can fish and other aquatic life thrive in streams and lakes that are affected by human activities? What is the water quality? To answer these questions, it is helpful to understand what "water quality" means, how it is determined, and the natural processes and human activities that affect water quality. 
Urban and industrial development, farming, mining, combustion of fossil fuels, stream-channel alteration, animal-feeding operations, and other human activities can change the quality of natural waters. As an example of the effects of human activities on water quality, consider nitrogen and phosphorus fertilizers that are applied to crops and lawns. These plant nutrients can be dissolved easily in rainwater or snowmelt runoff. Excess nutrients carried to streams and lakes encourage abundant growth of algae, which leads to low oxygen in the water and the possibility of fish kills. 
Some pesticides have not been used for 20 to 30 years, but they are still detected in fish and streambed sediment at levels that pose a potential risk to human health, aquatic life, and fish-eating wildlife. There are so many chemicals in use today that determining the risk to human health and aquatic life is a complex task. In addition, mixtures of chemicals typically are found in water, but health-based standards and guidelines have not been established for chemical mixtures. 
Acid rain is a uniquely human-related phenomenon. The burning of fossil fuels (coal and oil) by power-production companies and industries releases sulfur into the air that combines with oxygen to form sulfur dioxide (SO2). Exhausts from cars cause the formation of nitrogen oxides in the air. From these gases, airborne sulfuric acid (H2SO4) and nitric acid (HNO3) can be formed and be dissolved in the water vapor in the air. Although acid-rain gases may originate in urban areas, it is often carried for hundreds of miles in the atmosphere by winds into rural areas. That is why forests and lakes in the countryside can be harmed by acid rain that originates in cities.
The environment can generally adapt to a certain amount of acid rain. Often soil is slightly 
(due to naturally occurring limestone, which has a pH of greater than 7). Because bases counteract acids, these soils tend to balance out some of the acid rain's acidity. But in areas, such as some of the Rocky Mountains and parts of the northwestern and southeastern United States, where limestone does not naturally occur in the soil, acid rain can harm the environment.
Acidity in rain is measured by collecting samples of rain and measuring its pH. To find the distribution of rain acidity, weather conditions are monitored and rain samples are collected at sites all over the country. The areas of greatest acidity (lowest pH values) are located in the Northeastern United States. This pattern of high acidity is caused by the large number of cities, the dense population, and the concentration of power and industrial plants in the Northeast. In addition, the prevailing wind direction brings storms and pollution to the Northeast from the Midwest, and dust from the soil and rocks in the Northeastern United States is less likely to neutralize acidity in the rain.
When you hear or read in the media about the effects of acid rain, you are usually told about the lakes, fish, and trees in New England and Canada. However, we are becoming aware of an additional concern: many of our historic buildings and monuments are located in the areas of highest acidity. In Europe, where buildings are much older and pollution levels have been ten times greater than in the United States, there is a growing awareness that pollution and acid rain are accelerating the deterioration of buildings and monuments. 
By the way, no, you don't need to start wearing a rainhat.
اميدوارم كه لحظات خوبي در اين وبلاگ داشته باشيد. هدف از ایجاد این وبلاگ افزایش اطلاعات مهندسی و تشویق یادگیری زبان انگلیسی به عنوان لازمه عصر حاضر می باشد. بهترين راه يادگيري زبان خواندن متون لاتين مورد علاقه شما و تكرار است. زيرا زبان فرار بوده و اگر تكرار نشود از يادتان خواهد رفت.