12
1 Physical Settings and Water Challenges
821.81 km
3 . The mountainous area of the country included in the evaluation is
6,784,790 km
2 , with the average annual groundwater resources from that area at
677.02 km
3 , making up 81.6% of the total. The average annual baseflow amount
equals 655.77 km
3 , which represents 97.6% of groundwater resources in mountainous areas. A mountainous area of 3,552,077 km
2 is located in northern China
with average annual groundwater resources equal to 137.70 km
3 , of which the baseflow amount is 116.61 km
3 , making up 84.7% of the total in this area. Mountainous
regions of 3,232,713 km
2 are distributed in southern China, with average annual
groundwater resources of 539.33 km
3 , almost all of which reverts to baseflow.
The total plain area of the country involved in the groundwater evaluation is
1,666,320 km
2 . The average annual plain groundwater resources equal 176.51 km
3 ,
of which 102.46 km
3 are derived from precipitation.
The plain area in northern China involved in the groundwater assessment
is 1,505,873 km
2 . The corresponding average annual groundwater resources are
138.31 km
3 , making up 78.4% of the total plain groundwater resources, of which
73.22 km
3 are derived from precipitation.
The plain area in southern China involved in groundwater resource evaluation is
160,447 km
2 . The corresponding average annual groundwater resource is 38.20 km
3 ,
making up 21.6% of the total plains resources, of which 29.24 km
3 is derived from
precipitation.
1.2.3.3 Hydrological Budget
The long-term mean annual precipitation of the country is 6,177.5 km
3 , or 649.8 mm,
of which 33% forms river runoff, 54% goes to land surface evapotranspiration, and
13% seeps into supply groundwater. The land evaporation from surface water bodies,
plants and soils, and phreatic water evaporation is 55% of the precipitation. The
river runoff, consisting of surface runoff directly supplied by precipitation and baseflow formed by groundwater discharge from precipitation infiltration, is 44% of the
precipitation.
The values of the water budget elements and their relations are different for
different regions. In northern China, the total precipitation is 1,987.5 km
3 , equal
to 328.2 mm, of which 74% ends up in land evaporation, 15% forms surface runoff,
and 11% infiltrates into groundwater. In southern China, the total precipitation is
4,190.0 km
3 , or 1,214.4 mm, of which 45% ends up in land evaporation, 42% forms
surface runoff, and 13% infiltrates into groundwater.
1 Physical Settings and Water Challenges
821.81 km
3 . The mountainous area of the country included in the evaluation is
6,784,790 km
2 , with the average annual groundwater resources from that area at
677.02 km
3 , making up 81.6% of the total. The average annual baseflow amount
equals 655.77 km
3 , which represents 97.6% of groundwater resources in mountainous areas. A mountainous area of 3,552,077 km
2 is located in northern China
with average annual groundwater resources equal to 137.70 km
3 , of which the baseflow amount is 116.61 km
3 , making up 84.7% of the total in this area. Mountainous
regions of 3,232,713 km
2 are distributed in southern China, with average annual
groundwater resources of 539.33 km
3 , almost all of which reverts to baseflow.
The total plain area of the country involved in the groundwater evaluation is
1,666,320 km
2 . The average annual plain groundwater resources equal 176.51 km
3 ,
of which 102.46 km
3 are derived from precipitation.
The plain area in northern China involved in the groundwater assessment
is 1,505,873 km
2 . The corresponding average annual groundwater resources are
138.31 km
3 , making up 78.4% of the total plain groundwater resources, of which
73.22 km
3 are derived from precipitation.
The plain area in southern China involved in groundwater resource evaluation is
160,447 km
2 . The corresponding average annual groundwater resource is 38.20 km
3 ,
making up 21.6% of the total plains resources, of which 29.24 km
3 is derived from
precipitation.
1.2.3.3 Hydrological Budget
The long-term mean annual precipitation of the country is 6,177.5 km
3 , or 649.8 mm,
of which 33% forms river runoff, 54% goes to land surface evapotranspiration, and
13% seeps into supply groundwater. The land evaporation from surface water bodies,
plants and soils, and phreatic water evaporation is 55% of the precipitation. The
river runoff, consisting of surface runoff directly supplied by precipitation and baseflow formed by groundwater discharge from precipitation infiltration, is 44% of the
precipitation.
The values of the water budget elements and their relations are different for
different regions. In northern China, the total precipitation is 1,987.5 km
3 , equal
to 328.2 mm, of which 74% ends up in land evaporation, 15% forms surface runoff,
and 11% infiltrates into groundwater. In southern China, the total precipitation is
4,190.0 km
3 , or 1,214.4 mm, of which 45% ends up in land evaporation, 42% forms
surface runoff, and 13% infiltrates into groundwater.