Merely from the aspect of nature, drought and drought disasters are two different scientific concepts. Drought, a climate phenomenon, usually means that the total amount of fresh water is not enough to meet the needs of people’s survival and economic development. Drought is generally a long-term natural disaster phenomenon, and a climate phenomenon that the air is dry and the soil is short of water because of the shortage of rain for a long time. But the drought disaster has different meaning, it is only one of the occasional natural disasters, and even occurs in the area where usually has abundant rainfall just and only because of a temporary climate anomaly. Drought and drought disaster both are the main natural disasters that human beings have been facing from ancient times to the present. Even today, as science and technology are so developed, the disastrous consequences of them are still quite serious. Especially, it is worth noting that with the development of human economy and population expansion, the supply of water resource has been increasingly challenged. All these also directly lead to the expansion of arid areas and the aggravation of drought. The trend of aridity has caught attention globally.
In China, drought can be devided into following types:
Meteorological drought. During the abnormal arid weather, lack of water can effect regional hydrology and even make it unbanlanced.
Agricultural drought. The climate change of lacking for rainfalls is severe enough to impact crop yield and ranch production.
Hydrological drought. It happens when the moisture content in river, reservoir, groudwater aquifer, lack and soil serves as less than annual average level in the same term.
Drought warning has two level which are demonsrated by Orange and Red:
Orange standard: the comprehensive meteorological drought index could reach severe drought (meteorological drought may happen for every 25 to 50 years) during the coming week, or there are more than 40% of the crop in a county (District) is arid.
Red standard: the comprehensive meteorological drought index could reach special drought (meteorological drought may happen ever more than 50 years) during the coming week, or there are more than 60% of the crop in a county (District) is arid.
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