It refers to the decrease of soil water content due to
the lack of precipitation, rivers and other water resources
during the growing period of crops, and the water supply
for a certain growing stage of crops is less than its water
demand, then will affect the normal growth of crops and the
production and life of the masses. The affected area is
called drought area.
Dry damage refers to the phenomenon that the precipitation
is significantly reduced compared with the same period of
the year due to long sunshine without rain or little rain.
After the occurrence of drought, due to the limitation of
water source, basic water conservancy conditions or economic
conditions, necessary drought-resistant measures are not
taken in time, resulting in the reduction of farmland production
or the loss of industrial production in cities and towns. The
degree of drought is closely related to the precipitation in
the early stage, duration of drought, groundwater level, and
the types and varieties of crops and their growth periods.
Therefore, the specific indicators of drought vary from place
to place and from crop to crop. More than 30% of the reduction
in farmland production is called disaster area, of which more
than 80% is called no harvest.
Drought does not mean dry damage, drought can only become
a disaster if it causes losses. Desert is dry, but it will
not bring loss to people, drought here is not a disaster,
but a natural phenomenon.
Dry damage is one of the most widespread natural disasters
in the world, causing the greatest agricultural losses,
China is a big agricultural country, dry damage is the main
meteorological disaster affecting agricultural production in
China. According to statistics, annual dry damage losses in
China account for more than 15% of all natural disasters; 10
billion kg of grain is reduced annually due to dry damage.
In the past 50 years, with the development of economy and the
increase of population in China, coupled with the pollution of
water resources, the shortage of water resources has become
increasingly serious, against the background of global warming
and northern aridification, dry damage in China is on the rise,
with 77.4% of provinces and regions in China experiencing an increase.
Secondly, water resources are insufficient, for example, in north
China, over the past 30 years, because of the decreasing trend of
precipitation and the long-term over exploitation of groundwater, the
water level has been decreasing year by year, and some coastal cities
have seen the phenomenon of surface subsidence and seawater flooding.
All these have not only become the restrictive conditions for the
further development of many large and medium-sized cities, but also
seriously affect the development of industrial and agricultural production,
and even endanger the stability of the whole city. Long-term drought
will also lead to the deterioration of the ecological environment, such
as desertification, wind erosion and so on.