Question: Why did China need to resettle people into municipality containing the Yubei District?

full_context: Document 1: Sichuan: In the middle of the 17th century, the peasant rebel leader Zhang Xianzhong (1606–1646) from Yan'an, Shanxi Province, nicknamed Yellow Tiger, led his peasant troop from north China to the south, and conquered Sichuan. Upon capturing it, he declared himself emperor of the Daxi Dynasty (大西王朝). In response to the resistance from local elites, he massacred a large native population. As a result of the massacre as well as years of turmoil during the Ming-Qing transition, the population of Sichuan fell sharply, requiring a massive resettlement of people from the neighboring Huguang Province (modern Hubei and Hunan) and other provinces during the Qing dynasty.
Document 2: Liangping Airport: Liangping Airport () , also called Wanzhou Liangping Airport, is a former dual-use military and civil airport, located west of Liangping (formerly called Liangshan) in Chongqing Municipality, China. It served the city of Wanxian (now Wanzhou District) from July 1988 until May 2003, when all civil flights were transferred to the new Wanzhou Wuqiao Airport.
Document 3: Sichuan: Sichuan consists of two geographically very distinct parts. The eastern part of the province is mostly within the fertile Sichuan basin (which is shared by Sichuan with Chongqing Municipality). The western Sichuan consists of the numerous mountain ranges forming the easternmost part of the Qinghai-Tibet Plateau, which are known generically as Hengduan Mountains. One of these ranges, Daxue Mountains, contains the highest point of the province Gongga Shan, at 7,556 metres (24,790 ft) above sea level.
Document 4: Sichuan: The Three Gorges Dam, the largest dam ever constructed, is being built on the Yangtze River in nearby Hubei province to control flooding in the Sichuan Basin, neighboring Yunnan province, and downstream. The plan is hailed by some as China's efforts to shift towards alternative energy sources and to further develop its industrial and commercial bases, but others have criticised it for its potentially harmful effects, such as massive resettlement of residents in the reservoir areas, loss of archeological sites, and ecological damages.
Document 5: Kunming Changshui International Airport: Kunming Changshui International Airport (IATA: KMG, ICAO: ZPPP) is the primary airport serving Kunming, the capital of Yunnan Province, China. The airport is located 24.5 km (15.2 mi) northeast of the city center in a graded mountainous area about 2,100 m (6,900 ft) above sea level. The airport opened at 08:00 (UTC+8) on June 28, 2012, replacing the old Kunming Wujiaba International Airport, which will be demolished. As a gateway to Southeast and South Asia, Changshui Airport is a hub for China Eastern Airlines, Kunming Airlines, Lucky Air, Sichuan Airlines and Ruili Airlines.
Document 6: Sichuan: Sichuan was China's most populous province before Chongqing became a directly-controlled municipality; it is currently the fourth most populous, after Guangdong, Shandong and Henan. As of 1832, Sichuan was the most populous of the 18 provinces in China, with an estimated population at that time of 21 million. It was the third most populous sub-national entity in the world, after Uttar Pradesh, India and the Russian Soviet Federative Socialist Republic until 1991, when the Soviet Union was dissolved. It is also one of the only six to ever reach 100 million people (Uttar Pradesh, Russian RSFSR, Maharashtra, Sichuan, Bihar and Punjab). It is currently 10th.
Document 7: Sichuan: The majority of the province's population is Han Chinese, who are found scattered throughout the region with the exception of the far western areas. Thus, significant minorities of Tibetan, Yi, Qiang and Nakhi people reside in the western portion that are impacted by inclement weather and natural disasters, environmentally fragile, and impoverished. Sichuan's capital of Chengdu is home to a large community of Tibetans, with 30,000 permanent Tibetan residents and up to 200,000 Tibetan floating population. The Eastern Lipo, included with either the Yi or the Lisu people, as well as the A-Hmao, also are among the ethnic groups of the provinces.
Document 8: Dazu District: Dazu District () is a district of Chongqing, China, bordering Sichuan province to the northwest. It is where the famous Dazu Rock Carvings, a UNESCO World Heritage Site, is located.
Document 9: Sichuan: From 1955 until 1997 Sichuan had been China's most populous province, hitting 100 million mark shortly after the 1982 census figure of 99,730,000. This changed in 1997 when the Sub-provincial city of Chongqing as well as the three surrounding prefectures of Fuling, Wanxian, and Qianjiang were split off into the new Chongqing Municipality. The new municipality was formed to spearhead China's effort to economically develop its western provinces, as well as to coordinate the resettlement of residents from the reservoir areas of the Three Gorges Dam project.
Document 10: Caiyuanba Bridge: The Caiyuanba Bridge is an arch bridge which crosses the Yangtze River in Chongqing, China. Completed in 2007, the arch spans ranking among the longest arch bridges in the world. The bridges carries 6 lanes of traffic and two track of Chongqing Rail Transit Line 3 between the Nan'an District south of the Yangtze River and the Yuzhong District to the north.
Document 11: Yuan dynasty: The Central Region, consisting of present-day Hebei, Shandong, Shanxi, the south-eastern part of present-day Inner Mongolia and the Henan areas to the north of the Yellow River, was considered the most important region of the dynasty and directly governed by the Central Secretariat (or Zhongshu Sheng) at Khanbaliq (modern Beijing); similarly, another top-level administrative department called the Bureau of Buddhist and Tibetan Affairs (or Xuanzheng Yuan) held administrative rule over the whole of modern-day Tibet and a part of Sichuan, Qinghai and Kashmir.
Document 12: Sichuan: In the 20th century, as Beijing, Shanghai, Nanjing, and Wuhan had all been occupied by the Japanese during the Second Sino-Japanese War, the capital of the Republic of China had been temporary relocated to Chongqing, then a major city in Sichuan. An enduring legacy of this move is that nearby inland provinces, such as Shaanxi, Gansu, and Guizhou, which previously never had modern Western-style universities, began to be developed in this regard. The difficulty of accessing the region overland from the eastern part of China and the foggy climate hindering the accuracy of Japanese bombing of the Sichuan Basin, made the region the stronghold of Chiang Kai-Shek's Kuomintang government during 1938-45, and led to the Bombing of Chongqing.
Document 13: Changshou Yangtze River Bridge: The Changshou Yangtze River Bridge is a cable-stayed bridge over the Yangtze River in the Changshou District of Chongqing, China.
Document 14: Northeast (Vietnam): The northern part junction with Vietnam-China border are the plateau (highland) turns from west to east are: Bắc Hà, Quản Bạ, Đồng Văn. Two first plateau has an average elevation of 1000-1200m. Đồng Văn Plateau is 1600m. River and stream flowing through the plateau created a long and deep canyons. There are also some small plain, which is Thất Khê, Lạng Sơn, Lộc Bình, Cao Bằng.
Document 15: Yubei District: Yubei District (), literally means "the north of Yu (the abbreviation for Chongqing)", is a district of Chongqing municipality, bordering Sichuan province to the north. Lianglu, which is a town administered by Yubei District, is where the Chongqing Jiangbei International Airport is located.
ground_truth: the Three Gorges Dam project.
sub_queries: Yubei District >> located in the administrative territorial entity Answer: Chongqing
Why did China need to resettle people into Chongqing ? Answer: the Three Gorges Dam project.