Lake retention timeLake retention time (also called the residence time of lake water, or the water age or flushing time) is a calculated quantity expressing the mean time that water (or some dissolved substance) spends in a particular lake. At its simplest, this figure is the result of dividing the lake volume by the flow in or out of the lake. It roughly expresses the amount of time taken for a substance introduced into a lake to flow out of it again. The retention time is particularly important where downstream flooding or pollutants are concerned.
CenoteA cenote (pronsᵻˈnoʊti or sɛˈnoʊteɪ; seˈnote) is a natural pit, or sinkhole, resulting from the collapse of limestone bedrock that exposes groundwater. The term originated on the Yucatán Peninsula of Mexico, where cenotes were commonly used for water supplies by the ancient Maya, and occasionally for sacrificial offerings. The term derives from a word used by the lowland Yucatec Maya—tsʼonoʼot—to refer to any location with accessible groundwater.
GansuGansu (UKgæn'suː, USgɑːn-; alternately romanized as Kansu) is a province in Northwest China. Its capital and largest city is Lanzhou, in the southeast part of the province. The seventh-largest administrative district by area at , Gansu lies between the Tibetan and Loess plateaus and borders Mongolia (Govi-Altai Province), Inner Mongolia and Ningxia to the north, Xinjiang and Qinghai to the west, Sichuan to the south and Shaanxi to the east. The Yellow River passes through the southern part of the province.
Ferrous metallurgyFerrous metallurgy is the metallurgy of iron and its alloys. The earliest surviving prehistoric iron artifacts, from the 4th millennium BC in Egypt, were made from meteoritic iron-nickel. It is not known when or where the smelting of iron from ores began, but by the end of the 2nd millennium BC iron was being produced from iron ores in the region from Greece to India, and sub-Saharan Africa. The use of wrought iron (worked iron) was known by the 1st millennium BC, and its spread defined the Iron Age.
NamibThe Namib (ˈnɑːmɪb ; Namibe) is a coastal desert in Southern Africa. According to the broadest definition, the Namib stretches for more than along the Atlantic coasts of Angola, Namibia, and South Africa, extending southward from the Carunjamba River in Angola, through Namibia and to the Olifants River in Western Cape, South Africa. The Namib's northernmost portion, which extends from the Angola-Namibia border, is known as Moçâmedes Desert, while its southern portion approaches the neighboring Kalahari Desert.
Tibetan PlateauThe Tibetan Plateau (, also known as the Qinghai–Tibet Plateau or the Qing–Zang Plateau () or as the Himalayan Plateau in India, is a vast elevated plateau located at the intersection of Central, South and East Asia covering most of the Tibet Autonomous Region, most of Qinghai, western half of Sichuan, Southern Gansu provinces in Western China, southern Xinjiang, Bhutan, the Indian regions of Ladakh and Lahaul and Spiti (Himachal Pradesh) as well as Gilgit-Baltistan in Pakistan, northwestern Nepal, eastern
Geography of ChinaChina has great physical diversity. The eastern plains and southern coasts of the country consist of fertile lowlands and foothills. They are the location of most of China's agricultural output and human population. The southern areas of the country (south of the Yangtze River) consist of hilly and mountainous terrain. The west and north of the country are dominated by sunken basins (such as the Gobi and the Taklamakan), rolling plateaus, and towering massifs.
Inner MongoliaInner Mongolia, officially the Inner Mongolia Autonomous Region, is an autonomous region of the People's Republic of China. Its border includes most of the length of China's border with the country of Mongolia. Inner Mongolia also accounts for a small section of China's border with Russia (Zabaykalsky Krai). Its capital is Hohhot; other major cities include Baotou, Chifeng, Tongliao, and Ordos. The autonomous region was established in 1947, incorporating the areas of the former Republic of China provinces of Suiyuan, Chahar, Rehe, Liaobei, and Xing'an, along with the northern parts of Gansu and Ningxia.
