billion cubic meters in glacial ice storage. The region contains 81% of Tibet's lakes, covering a total area of over . There are 11 lakes with an area of over and 121 lakes with an area of more than . Notable lakes include Namtso, spanning Nagqu's Baingoin County and neighboring Lhasa prefecture-level city's Damxung County with a surface area of , and Siling Lake (Qilin) spanning Baingoin and Xainza counties, which at is the second largest saltwater lake in the northern Tibetan Plateau. Dorsoidong Co and Chibzhang Co, over northwest of Nagqu Town covered a lake area of as of 2018. The principal rivers of Nagqu are the Dangqu, Zhajia Zangbo, Jiagang Zangbu, Suoqu, Xiaqu, Benqu, Ba Qingqu, and Yiqu with hundreds more throughout the region. Purugangri Glacier is located about from Naqu town within Qiangtang Nature Reserve, at 6,000 to 6,800 metres above sea level. Covering an area of , it has been confirmed to be the world's third largest. Nagqu is affected by monsoon climate, plate geology movements, and complex terrain and other disaster-causing factors, it is a natural disaster-prone, contiguous and frequent region. The annual average temperature is , while the coldest temperatures can reach minus . Overall it classifies as a dry-winter subarctic climate (Dwc) bordering on a cold semi-arid climate (BSk), with relatively warm, humid summers and long, bitterly cold, dry, windy winters. The differences between day and night are severe. It is not uncommon to have nights with temperatures below freezing after days with temperatures of or days with temperatures above freezing in winter after night temperatures of . The annual sunshine hours are more than 2,886 hours. Nagqu city had an average annual rainfall of between 1956 and 2010. The southeastern part of the prefecture is wetter, with annual precipitation exceeding . while the northwestern part is dryest with an average annual rainfall below . The effects of global warming increasingly pose a problem in the region, with record highs in 2019. Administrative divisions The Naqu City People's Government administrative headquarters is located at No. 3, Zhejiang West Road in the main town. It has 89 townships, 25 towns, and 1283 villages under its jurisdiction. Economy By 2009, 55 different minerals had been discovered in the region, with the largest mineral reserves being iron, chromium, gold, antimony, lead, zinc, copper, boron, lithium, rock salt and gypsum. There are significant reserves of oil, natural