2.2 Surface Water Resources
Quantity of surface water resources refers to the annual renewed quantity of surface water in rivers，lakes and glaciers，i.e.，annual quantity of natural river runoff formed by local precipitation.The quantity of surface water resources in China was 2，837.33 billion m3in 2012，equivalent to 299.6 mm in depth，which was 6.2%more than normal and 27.6%more than that in 2011.
Among WRRs，the quantity of surface water resources in Northern Six Regions in 2012 was 463.78 billion m3，equivalent to 76.6 mm in depth，which was 5.9%more than normal and 15.3%more than that in 201 1；and that in Southern Four Regions was 2，373.55 billion m3，equivalent to 695.4 mm in depth，which was 6.3%more than normal and 30.4%more than that in 2011.Among the 10 Class Ⅰ WRRs，except that the Songhua River had an annual quantity of surface water resources close to normal，and the Huaihe River and Southwest Rivers had 22.8%and 9.0%less than normal，respectively，the others all had an annual quantity more than normal，in which the Liaohe River and Southeast Rivers had an annual quantity 46.9%and 37.8%more than normal，respectively.Compared with 2011，except that the Huaihe River and Southwest Rivers saw 18.7%and 2.4%decrease in the annual quantity of surface water resources，all the other Class Ⅰ WRRs had an increased annual quantity in 2012，in which Southeast Rivers，the Liaohe River and the Haihe River experienced increases of 93.7%，80.5%and 73.0%，respectively.See Table 3 and Figure 6 forthe 2012 annual natural runoff and comparison with 2011 and normal in Class Ⅰ WRR.
Table 3 Natural runoff and comparison with 2011 and normal in Class Ⅰ WRR，2012
Figure 6 Natural runoff and comparison with normal in Class Ⅰ WRR，2012
Note：The Yangtze includes the Taihu Lake Basin.
Among the PARs，eastern China had 646.02 billion m3 of surface water resources，which was equivalent to 606.1 mm in depth and 24.6%more than normal；Central China had 688.31 billion m3，equivalent to 412.6 mm and 9.1%more than normal；and western China had 1，503.0 billion m3，equivalent to 223.2 mm and 1.2%less than normal.Among the 31 PARs，17 had a quantity of surface water resources more than normal，in which Tianjin，Liaoning and Zhejiang had a quantity 149.2%，62.8%and 51.6%more than normal，respectively；and 13 had a quantity less than normal，in which Henan，Shanxi，Yunnan and Hubei had a quantity 43.2%，24.0%，23.5%and 22.1%less than normal，respectively.Gansu had a quantity of surface water resource close to normal.Table 4 and Figure 7 show the 2012 natural runoff and comparison with 2011 and normal in PAR.
In 2012，the total quantity of water flowed into the territory of China was 20.45 billion m3.The total quantity of water flowed out of border of China was 532.02 billion m3.And 107.13 billion m3 flowed into boundary rivers.
In the whole country，the total quantity of water flowed into the sea in 2012 was 1，829.42 billion m3，or 609.88 billion m3 more than that in 2011，in which 32.24 billion m3 was from the Liaohe River，11.89 billion m3 from the Haihe River，27.69 billion m3 from the Yellow River，33.25 billion m3 from the Huaihe River，1，021.4 billion m3 from the Yangtze River，255.25 billion m3 from Southeast Rivers，and 447.7 billion m3 from the Pearl River.Water flowing into the sea accounted for 50%，54%，42%and 64%each for the quantity of local surface water resources in the Haihe River，the Liaohe River，the Yellow River and the Huaihe River，that also have more than 85%each in the Pearl River，the Yangtze River and Southeast Rivers.
Table 4 Natural runoff and comparison with 2011 and normal in PAR，2012
Figure 7 Natural runoff and comparison with normal in PAR，2012