试题库在线考试题库-历年真题模拟试题及答案-考博英语在线试题测试中心-希赛网

中国水利水电科学研究院

A great earthquake measured at 8.0 Ms according to the China Seismological Bureau occurred at Wenchuan, 80 km northwest of Chengdu, the capital of Sichuan, with a depth of 19 km. Seismicity in the region is caused by the northward movement of the Indian Plate at a rate of 5 cm/year and its collision with the Eurasian Plate, resulting in the uplift of the Himalaya and the Qinghai-Tibetan plateau and associated earthquake activity. The Wenchuan Earthquake occurred as a result of motion of the Qinghai-Tibet plateau at Longmenshan Mountain along the Yingxiu-Qingchuan fault.The earthquake causes many mass movements: rockfalls, avalanches and landslides. Rockfall is the phenomenon of a few huge rocks falling from a cliff or steep slope. An avalanche is the collapse of a cliff and slope under the action of gravity. A landslide is the mass movement of rock and soil down a slope along one or several sliding beds under the action of gravity. Rockfall and avalanches have essentially the same motion mechanism. The landslides triggered by the Wenchuan earthquake created more than 200 quake lakes, 35 of which have been identified as dangerous. Massive amounts of water were pooling up behind these landslide dams, some of which might eventually fail under the action of dam-outburst flood flushing, potentially endangering the lives of thousands of people in the downstream reaches.The essential cause of the landslides is the riverbed incision. As the river cuts into the bed below the sliding surface, the sliding body loses the support of the sediment and rock at the toe of the sliding body and the sliding body slides along the slip surface into the river. If the river bed was not incised to the depth of the slip surface then the landslide would not occur. From the viewpoint of river training and management, some landslides might be prevented if the riverbed incision were controlled.There are two strategies to manage the quake lakes. The first strategy is to preserve the quake lakes. The strategy is applied if a landslide dam consists of a high percentage of large boulders. Once the flow over the landslide dam deposits begins, erosion-resistant boulders overlap and construct a step-pool system, which consume the flow energy and protect the dam from erosion. The second strategy is to remove the quake lakes by 1) removing all boulders in the spillway before a flood arrives; and 2) helping the flowing water to scour the spillway bed, if necessary, by explosion. Thus the water volume stored in the lake is released and thus the pool level is reduced to a minimum and the risk of dam failure flooding is minimized. The strategy is often applied to quake lakes where there is high population density in the downstream reaches.Humans are used to having everything under control in hydro-projects. The landslide dams are naturally formed structures and the spillway develops following natural laws. The compositions, structures and mechanisms of landslide dams are not well understood. Therefore, people are more willing to remove quake lakes.Answer the following questions:1. What is the cause of the Wenchuan Earthquake?2. What are the differences between avalanche and landslide?3. Why some quake lakes are dangerous?4. Under what conditions a quake lake may be preserved?5. How to remove a quake lake?6. What is the essential cause of landslides? Why?7. Why people are willing to remove quake lakes?

The Maori story is more picturesque than scientific explanation. Maori legends tell how the principal lakes were created by the chief Rakaihautu, Captain of Uruao, which he beached at Nelson, he then headed south by an inland route. Rakaihautu used his famous Ko or digging tool to dig out the biggest of the South Island lakes. Water itself is abrasive and wears down the land. Above Lake Dunstan, distinct terraces mark ancient levels of the Clutha River.When people came to these shores the stories evolved in new ways. We don’t know how the early Maori arrivals reacted to the profusion of rivers they found, nor how they coped with their propensity to change with little warning. But rivers, lakes and wetlands served as a larder for the earliest settlers. Freshwater fish added variety to their diet. Numerous native species existed, although some later became extinct because of competition from introduced species. Eels in particular are an important part of Maori lore. Different kinds of eel traps existed, each with a specific name, some of which are still in use today. The long-finned eel is New Zealand’s biggest fish and it is estimated it has been in our rivers for at least 80 million years. In autumn, adult eels set out on an incredible journey. Starting from their home stream, they arrive at the sea and swim 6500 km north into the Pacific Ocean to breed. The tiny larvae return to New Zealand, swept along on ocean currents. Near the coast they develop into tiny transparent “glass” eels about 60 mm long and head for estuaries. In late autumn they set our upstream, often negotiating waterfalls and rapids, to return to the rivers of their ancestors.Rivers were also an important means of voyaging for Maori. With no wheeled vehicles, no industries and more interest in establishing their dominion over other tribes than over the land, Maori lived largely within the confines of nature as they found it, though they resorted to rampant burning in their eternal search for food.

As one of the most ecologically sensitive region on the earth, the Qinghai-Tibet Plateau has a unique and vulnerable environment, which is readily affected by global climate change and socio-economic activity. The terrestrial ecosystem of the region is complex. There are 2,308 species of herbaceous plants. Grassland vegetation fixes a large amount of CO2 in the atmosphere, and the frozen earth has the potential to give off greenhouse gas as a result of its sensitivity to heat. In the past decades the grassland has experienced widespread degradation due to overgrazing, soil erosion, increasing rat population, and climate change. There are numerous national red list mammal species and many bird species in the region. The degradation of meadows threatens these species.Permafrost in the region is now clearly undergoing a warming trend. The average annual air temperature has risen by 0.4℃ since the 1970s, and the average soil temperature has risen by 0.5℃. The thickness of permafrost has been reduced by 5 m. Global warming may result in a series of cascading effects on terrestrial ecosystem processes in the permafrost region. These responses are critical to cold region ecosystems. Increasing evaporation has caused shrinkage of swampland and lakes.Resources development in the region also impacts upon the ecology. Overgrazing, harvest of herbaceous medicine, mineral exploitation and water diversion impair the terrestrial and aquatic ecology. The strategic government project that aims to solve water shortage problems in the Yellow River basin will divert water from the Tongtian, Yalong, and Dadu Rivers into the upper Yellow River. Integrated management is essential for sustainable development of the Plateau to reconcile ecological protection with sustainable use of land and water resources.

Directions: Write an article on “Which is a better source of news—Newspaper or TV?” write an article lo clarify your own points of view towards this issue. You should use your own ideas, knowledge or experience to generate support for your argument with examples. You should write no less than 200 words. Write your article on the Answer Sheet.

The spontaneous emergence of social cooperation—the emergence of a system vastly more complex, responsive and efficient than any government could organize—is not universally acknowledged or appreciated. It discomforts a certain political sensibility, the one that exaggerates the importance of government and the competence of the political class. Government is important in establishing the legal framework for markets to function. The most competent political class allows markets to work wonders that government cannot replicate. Hayek, a 1974 Nobel laureate in economics, said, “The curious task of economics is to demonstrate to men how little they really know about what they imagine they can design.” People, and especially political people, are rarely grateful to be taught their limits. That is why economics is called the dismal science.

2 / 66