Flowing through the capital, Cheonggye Stream served many important functions. However, flooding and sanitation caused major problems. During the rainy seasons, many houses became flootded, and sanitation problems led to contagious diseases that affected the city. The sewer of Cheonggye Stream often flowed backwards into overpopulated areas and the Cheonggye Stream area had the mortality rate in Seoul population. During the period of Daehan Jeguk, a solution was devised to cover Cheonggye Stream. In 1895, the government ordered the dismantling of Jongno road and use it for streetcars. Between 1958 and 1961, Cheonggye Stream was completely covered. Since that time, many stores have opened along the covered road and the volume of traffic has increased drastically. (http://www.lifeinkorea.com/travel2/travel.cfm
The development of the stream affected and displaced people ! This is their video. I got this from a man protesting on the street besides the Seoul City Hall.