2.3 Groundwater Resources

The national calculation area of shallow groundwater resources with a mineralization degree equal to or less than 2 g/L is 8.41 million km2 and the annual quantity of groundwater resources in 2015 was 779.70 billion m3,3.3% less than normal,in which plain area occupies 1.65 million km2 of calculation area and had 171.14 billion m3 of groundwater resources in 2015;mountainous and hilly area occupies 6.76 million km2 of calculation area and had 638.35 billion m3 of groundwater resources in 2015;and the overlap in the quantity of groundwater resources between the two types of areas in that year was 29.79 billion m3.See Table 5 for the quantity of groundwater resources in the Class I WRRs and Table 6 for that in the PARs in 2015.

The calculation area of plain shallow groundwater resources in the northern regions is 91% of the national total plain area and had 144.62 billion m3 of groundwater recharge in 2015,providing an important source for water supply in northern China.The total groundwater recharges in the plain areas of the northern regions in 2015 were:26.60 billion m3 in the Songhua;10.31 billion m3 in the Liaohe;15.60 billion m3 in the Haihe;15.03 billion m3 in the Yellow;29.20 billion m3 in the Huaihe;and 47.88 billion m3 in the Northwest Rivers.Of the total groundwater recharge in the plain areas of the northern regions,recharge by direct precipitation infiltration accounted for 50.2%,recharge by surface water infiltration 36.5%,recharge by piedmont lateral seepage 7.7%,and recharge by well irrigation 5.6%.Recharge by direct precipitation infiltration is the major source of groundwater resources in the Yellow-Huaihe-Haihe plain and Songhua-Liaohe plain,accounting for about 70% of total recharge;and recharge by surface water infiltration is the major source of groundwater resources in the Northwest Rivers plain,accounting for about 72% of total recharge.See Figure 6 for the composition of groundwater recharge in the plain areas of the Northern Six Regions in 2015.

Figure 6 Composition of groundwater recharge in northern plain Class I WRRs,2015