Broadly speaking, natural water bodies covering the earth's surface in liquid or solid form belong to surface water. It includes sea water, lake water, glacier water, river water and swamp water. Total reserves are 13.86× 108km3. Surface water in a narrow sense mainly includes river water, lake water, glacier water and swamp water; Atmospheric precipitation is considered as the recharge source of surface water. Usually, the dynamic water volume of surface water bodies, that is, river runoff, is the main evaluation object.

The average annual runoff of rivers in China is 27115×108m3, which is equivalent to an annual runoff depth of 284mm. The direct recharge of precipitation to surface runoff accounts for about 765,438+0% of the total runoff, 27% is replenished by groundwater after precipitation seeps into groundwater aquifer, and 2% is replenished by alpine glaciers and snow melt water.

According to the changes of average river runoff and rainfall in river basins for many years, China's surface water resources are divided into five regions (attached figure 5), namely, surface water resource-rich region, surface water resource-rich region, medium surface water resource-poor region, surface water resource-poor region and surface water resource-poor region.

Ⅰ. Areas with abundant surface water resources. This area includes the area where the Yangtze River flows. The Yangtze River Basin spans three major economic zones in China's east, middle and west, covering 19 provinces (autonomous regions and municipalities), with a huge economic aggregate, including Shanghai, Nanjing, Chongqing and Wuhan, and is the concentration place of advantageous industries such as basic raw materials, electromechanical industry and high technology in China. It is also the water source of South-to-North Water Transfer Project in China. The total basin area is 180× 104km2, accounting for 18.8% of China's land area, and the main stream of the Yangtze River is more than 6300km long. There are many tributaries, of which 9 have an annual average flow exceeding 1500 m3/s, 8 have a length exceeding 500km, and 437 have a drainage area exceeding 1000km2. There are many lakes in the Yangtze River basin, with a total area of 1.52× 104km2, which is about 1/5 of the total area of lakes in China. The Yangtze River is the most abundant river in China, with a total water resource of 96 16× 108m3, accounting for 36% of the total river runoff in China and 20 times that of the Yellow River. The Amazon River and the Congo River (Zaire River) are second only to the equatorial rainforest, ranking third in the world. Rainfall is the main precipitation in the basin. The annual average rainfall is about 1 100mm, and the spatial distribution trend of rainfall is increasing from northwest to southeast. The time distribution is mostly concentrated in May ~ 10, accounting for more than 70% ~ 90% of the whole year. Judging from the precipitation, about half of the runoff supply in Qinghai-Tibet region comes from snowmelt water and groundwater; Runoff recharge in southwest and central China mainly comes from precipitation.

There are many lakes in the Yangtze River basin, and the five freshwater lakes in China are all in the middle and lower reaches of the Yangtze River except Hongze Lake. Poyang Lake is the largest freshwater lake in China, located between Nanchang and Jiujiang in Jiangxi Province, with an area of 39 13km2 and an annual runoff depth of 891.6mm. There are five rivers in the territory: Ganjiang, Fuhe, Xinjiang, Raohe (Pojiang) and Xiushui, and the northern end is connected with the Yangtze River. The maximum depth of the lake is 16m, and the total volume is nearly 300× 108m3, which is equivalent to 1.6 times the volume of Dongting Lake. Because Poyang Lake is higher than the Yangtze River, it mainly plays the role of regulating and storing "five waters". Generally, the flood can be regulated in flood season 100× 108m3, and the water flowing into the Yangtze River in dry season can reach 200× 108m3. Whenever the discharge of the Yangtze River is minimum in1~ February, Poyang Lake can supplement the water quantity of the Yangtze River with the discharge of 400 ~ 500m3/s, which is very beneficial to the navigation of the Yangtze River in dry season.

Dongting Lake, the second largest freshwater lake in China, is located in the north of Hunan Province, with Xiangjiang River, Zishui River, Yuanjiang River and Lishui River flowing in the south, Songzi, Taiping, Ouchi and Diaoxian County (blocked in 1959) in the north, and the lake flows into the Yangtze River from Chenglingji 1995 in the east. Dongting Lake has always been the lake with the largest throughput in the Yangtze River. The flood storage of the Yangtze River through Dongting Lake can generally be reduced by about 30%, so it plays an important role in flood control and detention in the middle and lower reaches of the Yangtze River. Dongting Lake is divided into East Dongting Lake, South Dongting Lake, Muping Lake and Qili Lake due to the large amount of sediment in the "four mouths" and "four waters" of the Yangtze River and the large amount of reclamation in the lake area.

Taihu Lake is located in the south of the Yangtze River Delta, between Jiangsu and Zhejiang provinces, with a lake area of 2460km2, a volume of nearly 50× 108m3, and a surface water resource of118.8×108m3. Taihu Lake is formed by poor drainage in depressions and the expansion of river water in alluvial plains.

Chaohu Lake is the fifth largest freshwater lake in China, located in the middle of Anhui, between the Yangtze River and Huaihe River. It covers an area of 780 square kilometers. The surrounding rivers radiate into Chaohu Lake, enter Yuxi River and enter the Yangtze River through the southern hukou of Chaohu City. From 1950s to 1970s, due to siltation and human reclamation, the coastline of estuary delta and beach land along the lake was pushed to the lake area. According to the interpretation of aerial photos, during the 25 years from 1955 to 1979, the total reclamation area of Hangbu estuary delta has reached 62km2.

Ⅱ. Areas with abundant surface water resources. The main scope is the southwest basin and the Pearl River basin. The southwest river is located in the southwest border of China, which is a part of Qinghai-Tibet Plateau and Yunnan-Guizhou Plateau. 85. There are seven major water systems in the range of14×104km2, namely, western Tibet River, southern Tibet River (including southern Tibet inland river), Yarlung Zangbo River, western Yunnan River, Nujiang River, Lancang River and Yuanjiang River. Except for some inland rivers with different areas scattered in southern Tibet, other rivers flow out of Xinjiang, Tibet, Yunnan and Guangxi respectively. The annual average rainfall of rivers in southwest China is 9 186× 108m3, which is equivalent to the rainfall depth of 1088mm. In 2005, the surface water resources of southwest rivers were 5562.0× 108m3, equivalent to the annual runoff depth of 658.9mm, of which the basin area in western Tibet was 5.734× 104km2, and the total water resources were about 20. 1× 108m3. The basin area in southern Tibet is about 15.5778× 104km2, and the total water resources are about 1952× 108m3. The Yarlung Zangbo River originates from the Gemayengzong Glacier at the northern foot of the Himalayas in southwest Tibet, with a drainage area of 24.048× 104km2, a river length of 2057km and an average annual runoff of 1654× 108m3. Most rivers in western Yunnan belong to the Irrawaddy River system, with a drainage area of 2.1172×104km2 and total water resources of about 314.5x0/08m3. The main stream of the Nujiang River is about 1659km long, with a drainage area of 13.5984× 104km2 and an average annual runoff of 688.9× 108m3. The Nujiang River in Yunnan Province is about 62 1km long, with a natural drop of 1 123m and an average river gradient of 0. 18 1%. Watershed area 12.483× 104km2, annual average flow1840m3/s. ..

The Pearl River is a big river in the south of China, which flows through Yunnan, Guizhou, Guangxi, Guangdong, Hunan, Jiangxi and other provinces (regions) and the northeast of the Socialist Republic of Viet Nam, with a drainage area of 45.369× 104km2, including 44.2 1× 104km2 in China. The annual runoff of the basin is 34 12× 108m3, of which the annual average runoff of Xijiang River is 2670× 108m3, accounting for about 80% of the whole basin, Beijiang River is 475× 108m3 and Dongjiang River is 272× 108m3. The distribution of the Pearl River runoff is extremely uneven during the year. The flood season from April to September accounts for about 80% of the total annual runoff, and it exceeds 50% in June, July and August. The Pearl River is rich in water resources, with a per capita water resource of 4700m3, which is equivalent to 1.7 times of the national average, but it varies greatly from year to year and is unevenly distributed in time and space. The Pearl River Basin is located in the subtropical zone, and the Tropic of Cancer runs through the middle of the basin, with a mild and rainy climate. The annual average temperature is between 14℃ and 22℃, and the annual average rainfall is 1200 ~ 2200mm. The distribution of rainfall decreased obviously from east to west, and the distribution of rainfall was uneven during the year, with great regional differences and great interannual changes.

Ⅲ. Medium-sized surface water resources. The main scope is the southeast river basin, inland river basin and Liaohe River basin. The southeast of China has a watershed area of 24× 104km2, a river length of 6300km and an annual runoff of 2,557×108m3. The main rivers are Qiantang River, Minjiang River, Puyong River and other rivers in eastern Zhejiang, Jiaoou River and other rivers in southern Zhejiang, and rivers in Taiwan Province Province. 1993, with a total population of 65.07 million, accounting for 5.5% of the whole country; The gross domestic product (GDP) is 202.3 billion yuan, accounting for 7.5% of the whole country, of which the total industrial output value is 374.8 billion yuan.

The inland rivers in China mainly include Tarim River, Heihe River and Shiyang River. Tarim River is the largest inland river in China, with a total length of 2,437 kilometers. Tarim River Basin is the general name of the main stream of Tarim River 144 rivers, with a total area of 102× 104 km2. The average natural runoff of surface water in the basin for many years is 398.3× 108m3, which is mainly replenished by melting snow from glaciers. The non-repetitive groundwater resources are 30.7× 108m3, and the total water resources are 429× 108m3. Heihe River is one of the three inland rivers in Hexi Corridor of China, which originates from the northwest of Gansu Province and is formed by the rivers of Nanshan and Qilian Mountains between Zhangye and Jiuquan, with a total length of about 800km. There are 35 small tributaries in Heihe River Basin. The upper reaches include most parts of Qilian County in Qinghai Province and parts of Sunan County in Gansu Province. The middle reaches include Shandan, Minle, Zhangye, Linze and Gaotai counties (cities) in Gansu Province. The downstream areas include Jinta County of Gansu Province and parts of Ejina Banner of Inner Mongolia Autonomous Region. Shiyang River is 250 kilometers long. From east to west, the basin consists of eight rivers, including Dajing River, Gulang River, Huangyanghe River, Zamu River, Jinta River, Xiying River, Dongdahe River and Xidahe River, as well as numerous small ditches and rivers. The river is replenished by precipitation and melting water of snow and ice in mountainous areas, with a drainage area of 1. 1× 65438. The average annual precipitation in Shiyang River Basin is 222 mm, and the corridor area is only 150 mm ... The average total self-produced water resource for many years is 15.6× 108m3, and the net groundwater resource that is not duplicated with surface water is 1× 108m3, and the total self-produced water in the whole basin.

Liaohe River basin starts from Changbai Mountain, the second Songhua River and Yalu River in the east, reaches the southern end of Daxinganling and Inner Mongolia Plateau in the west, reaches Luanhe River, Daling River and Bohai Sea in the south, and reaches Songhua River basin in the north. The drainage area is 2 1.96× 104 km2, of which mountains account for 35.7%, hills for 23.5%, plains for 34.5% and sand dunes for 6.3%. The surface water resources per capita in Liaohe River Basin is 535m3, which is 1/4 of the national average.

The Liaohe River Basin is mainly composed of two water systems: ① the Liaohe River System, which is composed of the east and west Liaohe Rivers and the main stream of the Liaohe River. The water system enters the sea from Panjin, with a total length of1.394 km; (2) The Daliaohe River system consists of Taizi River, Hunhe River and Daliaohe River. The water system enters the sea from Yingkou, with a total length of 4 15.4km, and the Liaohe River Basin belongs to the temperate continental monsoon climate zone. Affected by geographical location, land and sea distribution and topography, the regional distribution of precipitation and runoff is very uneven. Declining from southeast to northwest, the southeast is a rainy center, and the annual precipitation is above 65,438 0,000 mm. The northwest is dry, windy and dusty, and the rain is scarce, only 380 ~ 000 mm The rainfall varies greatly from year to year, with little rain and snow in winter and spring, and concentrated rainfall in summer and autumn, especially in July and August, accounting for about 50% of the whole year. From the precipitation season, the precipitation in spring accounts for 1 1% ~ 16% of the whole year, which is prone to spring drought. Summer precipitation accounts for 60% ~ 70% of the annual precipitation, and heavy rains often occur, causing floods; Autumn precipitation accounts for 17% ~ 19% of the whole year, and autumn drought occurs frequently; The winter precipitation only accounts for 1% ~ 4% of the whole year.

Located in the north of China, Songhua River Basin is the main tributary of Heilongjiang, with a basin area of 54.6× 104km2, a river length of 1729km and an average annual runoff of 777× 108m3. There are two sources: the Nenjiang River in the north originates from Xing 'an Mountains, and the second Songhua River in the south originates from Changbai Mountain. After the two rivers meet at Sancha River, they are called Songhua River. Songhua River has a huge water system, and its main tributaries are Nenjiang River, Second Songhua River, Lalin River, Ashe River, Hulan River, Mudanjiang River and Anbang River.

Ⅳ. Areas lacking in surface water resources. The main scope is the Yellow River Basin and Huaihe River Basin. The Yellow River originates at the northern foot of Bayan Kara on the Qinghai-Tibet Plateau, flows through Qinghai, Sichuan, Gansu, Ningxia, Inner Mongolia, Shanxi, Shaanxi, Henan and Shandong provinces, and flows into the Bohai Sea in Kenli County, Shandong Province, with a drainage area of 75.2× 104km2, a river length of 466mm and an annual runoff of 6/kloc-0 /×/kloc-0. The annual average temperature in the basin is -4℃ ~ 14℃, and the annual average precipitation is 478 mm. The precipitation in June ~1October accounts for 65% ~ 85% of the whole year, and the maximum rainstorm occurs in July ~ August. The measured annual runoff at Huayuankou Station in Henan Province is 470×1919 ~1974, which is 470× 108m3 if the upstream water volume is included.

The Yellow River basin is adjacent to the ocean in the east and inland in the west, with obvious differences in climate, precipitation, evaporation, light and heat resources and frost-free period. The climate of the basin can be roughly divided into arid, semi-arid and semi-humid climate, arid in the west and humid in the east. The average annual natural runoff of the whole river is 580× 108m3, accounting for only 2% of the national river runoff, and the per capita water volume in the basin is 593m3, accounting for 25% of the national per capita water volume. The outstanding feature of the Yellow River is "less water and more sediment, and water and sediment come from different sources".

Huaihe River basin is bounded by Niu Shan and Tongbai Mountain in Henan Province in the west, Yellow Sea in the east, Dabie Mountain, Jianghuai Hill, Toarey Yang Canal and Rutai Canal in the south, Yangtze River Basin in the north, Yellow River Basin in the south and Taishan Mountain in the north. The basin area is 26.9× 104km2, and the western, southwestern and northeastern parts of the basin are mountainous and hilly areas, accounting for about 1/3 of the total basin area. The rest are vast plains, accounting for about 2/3. The Huaihe River basin is bounded by the abandoned Yellow River and divided into two major water systems, namely Huaihe River and Yishu Sihe River, with the areas of 19× 104 km2 and 8× 104km2 respectively, and the Beijing-Hangzhou Grand Canal, Hu Aishu New River and Xu Honghe run through them. The total length of the Huaihe River is 1000km, and the annual runoff is 622× 108m3, of which the Huaihe River system is 453× 108m3, and the Yishu Sishui River system is 168× 108m3. The average shallow groundwater resource for many years is 353× 108m3. After deducting the repeated calculation between surface water and groundwater, the total water resource in Huaihe River Basin is 835× 108m3. The average annual precipitation is 883mm, including 9 10mm in Huaihe River System and 836mm in Yishu Sishui System. The precipitation in Dabie Mountain in the south is the largest, exceeding 1400mm, followed by Tongbai Mountain in the west, which is 1000 ~ 1200mm, and the precipitation in the north is the smallest, below 700 mm, with great annual variation, and the maximum annual precipitation is 3 ~ 4 times of the minimum annual precipitation. The annual distribution of precipitation is also extremely uneven, and the precipitation in flood season (June to September) accounts for 50% ~ 88% of the annual precipitation.

ⅴ. Areas lacking in surface water resources. The main scope is the Haihe River Basin. Haihe river basin covers an area of 26.4× 104km2, with a river length of 1090km and an annual runoff of 228× 108m3. In 2005, the annual precipitation in Haihe River Basin was 487.0 mm, and the main tributaries were North Canal, Yongding River, Daqing River, Luanhe River, Ziya River and South Canal. Haihe river basin belongs to the continental monsoon climate zone, with an average annual precipitation of 548 mm, which is unevenly distributed during the year. The average precipitation in flood season (June-September) accounts for 75% ~ 85% of the whole year. Precipitation changes greatly every year. According to the resource statistics of 1956 ~ 1984, the average annual runoff of Haihe river basin is 264× 108m3. The runoff from June to September usually accounts for 70% ~ 80% of the whole year, and individual rivers reach 90%; Some rivers have spring flood and spring water recharge, and the runoff from June to September only accounts for 50% ~ 60% of the whole year. The characteristics of large annual variation and concentrated distribution of river runoff show that the possibility of flood in Haihe River basin in dry season is very small, and the possibility of flood in wet year is very high.

Second, the distribution of surface water quality in China

The natural water quality of rivers in China is generally good, but the salinity and total hardness are low. However, with the development of agriculture, river runoff pollution is becoming more and more serious. 1995, the Ministry of Water Resources conducted the second national water resources quality evaluation. According to the data of more than 800 water quality monitoring sections in China/kloc-0 and the National Environmental Quality Standard for Surface Water (GB 3838-88), the water quality of nearly 700 rivers with a length of about 10× 104km was evaluated. The results show that the length of comprehensive evaluation reaches in China is 986 14km, among which the lengths of water quality reaches of Class I, II and III are 6042km, 25773km and 20993km respectively, accounting for 6. 1%, 26. 1% and 2/kloc-0 respectively. The lengths of river sections with water quality of Grade IV, Grade V and Grade V are 27 17 1km, 8 163km and 10472km, respectively, accounting for 27.6%, 8.3% and 10.6% of the evaluated river sections. The length of the polluted river (that is, the sum of the lengths of rivers with water quality of Class IV, Class V and over Class V) is 45806km, accounting for 46.5% of the assessed river length. Compared with 1984, the length of polluted rivers in the comprehensive evaluation of river length in 10a has more than doubled. The regional distribution of river water resources quality is roughly as follows: the water quality in the upper reaches of rivers is better than that in the middle and lower reaches, and the water quality in cities and their lower reaches is generally poor; Generally speaking, the water quality of rivers in the south is better than that in the north, while the water quality in developed areas in the east, such as the surrounding areas of Beijing and Tianjin, the Yangtze River Delta and the Pearl River Delta, is worse than that in the central and western regions. From the comparative analysis of the first-class water resources, Taihu Lake, Haihe River and Huaihe River are the worst water quality areas in China, and the proportion of rivers with poor V class is at or near 50%, that is, nearly half of the rivers are seriously polluted and lose their use function; Both the Liaohe River Basin and the Songhua River Basin are affected by the poor natural water quality in the Heyuan reach and man-made pollution in the middle and lower reaches. The proportion of river length inferior to Grade V is 3 1.4% and 18.0% respectively, and the water quality is poor. The water quality of the Yellow River basin is acceptable; Except Tuojiang River and Jialing River, the water quality in the middle and upper reaches of the Yangtze River and the Pearl River Basin is in good condition. The southwest, northwest and southeast rivers have excellent water quality. From the distribution of river basins, the Huaihe River Basin, the Yellow River Basin, the Haihe River Basin and the Songliao River Basin are the most polluted, and the Taihu Lake area in the Yangtze River Basin is also very polluted.

Judging from the water quality evaluation, aerobic organic pollution is the main water pollution in China. Among the 9.55× 104km river length evaluated by aerobic organic pollution parameters in China, the polluted river length accounts for 33.8%, of which the seriously polluted river length (exceeding the class V) is 8305km, accounting for 8.7%. In all river basins, the aerobic organic pollution of Haihe River and Huaihe River is serious, and the length of polluted river exceeds 50% of the evaluated river length. Toxic and easy-to-accumulate substances are the second most polluted in China. Of the 9.2× 104km river length evaluated by this parameter, the polluted river length accounts for 3 1.6%, and the seriously polluted river length is 38 10km. The Yellow River, Songhua River, Liaohe River, Huaihe River and Haihe River basins in China are seriously polluted by toxic and easily accumulated substances.

According to the comprehensive evaluation results of water quality of 50 major lakes, there are 1 lake with Class I water quality, accounting for 0.1%of the total area of lakes surveyed; 9 lakes with Class II water quality, accounting for 24.7%; Class III lakes 13, accounting for 23.6%; There are 7 lakes with Class IV water quality, accounting for 5.4%; 5 lakes with class V water quality, accounting for 26.6%; There are 15 lakes with water quality exceeding Grade V, accounting for 19.6%. That is to say, more than 75% of the lake water quality is polluted to varying degrees, and the main pollution is organic matter pollution (CODmn) and nonionic ammonia. In terms of geographical distribution, the organic pollution of lakes in southern cities and northeast plains and the salinization (high salinity) of lakes in arid areas in northwest China are more prominent. In the evaluation, the overall hydrochemical status of Poyang Lake, Dongting Lake, Taihu Lake, Hongze Lake and Chaohu Lake did not exceed Class III, but some areas along the lake were seriously polluted.

The Surface Water Pollution Zoning Map of China (Attached Figure 6) compares the surface water quality under the influence of human activities with the "background value" under natural conditions on the basis of the national surface water quality distribution map and the pollution status of major lakes in China. The degree of surface water pollution is divided into five areas, namely, light surface water pollution area, light surface water pollution area, moderate surface water pollution area, heavy surface water pollution area and heavy surface water pollution area.

Ⅰ. Areas with slight surface water pollution. There are few human activities, underdeveloped economy and slight surface water pollution in this area. The overall water quality of rivers in southwest China is good. Of the 9 rivers 16 sections, 87.5% are Class III water quality, 12.5% are Class V water quality, and there are no Class IV and V water quality sections. Only two sections in the Hekou county section of the Red River exceed the standard.

Ⅱ. Areas with slightly polluted surface water. The surface water pollution in this area is slight, mainly covering the inland river basin, the upper reaches of the Yangtze River and most parts of Guangdong. The inland water quality is generally good. Of the 7 rivers 19 section, 84.2% meet the requirements of Class III water quality, and 15.8% meet the requirements of Class IV and V. The main pollution indicators are permanganate index and petroleum.

Ⅲ. Moderately polluted areas of surface water. The main scope is the middle and lower reaches of the Yangtze River, the Pearl River basin, the southeast coastal rivers, the Yuanjiang-Honghe basin and the Songhua River basin. The low water quality of the Yangtze River system is high, and there is no obvious change. The main pollution indicators are petroleum, ammonia nitrogen and dissolved oxygen. Among the monitored 128 sections, there are 39 main stream monitoring sections. The main stream is dominated by Grade II water quality, and the proportions of Grade I, II, III and IV water quality are 2.6%, 7 1.8%, 20.5% and 5. 1% respectively. The water quality in the Pearl River Basin is generally good, and the main pollution indicators are dissolved oxygen and petroleum. Of the 49 monitoring sections, 73.5% are Grade I-III, 18.3% are Grade IV and V, and 8.2% are worse than Grade V.. The main pollution indicators of Songhua River Basin are permanganate index and petroleum. In the monitored 1 and 0 1 sections, the proportions of water quality from Class I to worse than Class V are 1.0%, 4.0%, 22.8%, 35.6%, 2 1.8% and14.8, respectively. Nenjiang River is Grade III water quality, Jilin section of Songhua River is Grade III water quality, and Heilongjiang section is Grade IV water quality. Among the 26 sections of the southeast 14 river, the section with Class III water quality accounts for 50.0%, the section with Class IV water quality accounts for 34.6%, and the section with inferior Class V water quality accounts for 15.4%, and there is no section with Class V water. The main pollution indicators are petroleum and dissolved oxygen, and the heavily polluted sections are concentrated in Qiantang River in Hangzhou and Yongjiang River in Ningbo. Among the 20 monitoring points in Taihu Lake, the proportions of water quality of Grade III, IV, V and worse than Grade V are 5%, 35%, 5% and 55% respectively. The main pollutants are total nitrogen and total phosphorus. The pollution of Wuli Lake and Meiliang Lake in the lake area is obviously heavier than that in the central, eastern and western coastal areas. Eutrophication evaluation shows that Taihu Lake is in a state of mild eutrophication. The permanganate index of Chaohu Lake reached the Class III water quality standard. However, due to the serious pollution of total nitrogen and total phosphorus, the water quality of 12 monitoring points in the lake was half of Class V and half of worse than Class V..

Ⅳ. Areas with serious surface water pollution. The main scope is the Yellow River Basin and Huaihe River Basin. The main pollution indexes of the Yellow River system are petroleum, ammonia nitrogen and five-day biochemical oxygen demand. In the monitored 185 section, 49.7% of the water bodies are inferior to Class V.. Among the 28 sections of the main stream, the proportion of I-V water quality is 3.6%, 7.0%, 35.6%, 32.0% and 7.6% respectively, and the inferior V water quality accounts for 14.2%. The water quality of the main stream is better than that of the tributaries. The compliance rate of 49 sections of Huaihe River is 665,438 0.2%, and the water quality is basically stable. The main pollution indicators are five-day biochemical oxygen demand, permanganate index and ammonia nitrogen. Among the 93 sections monitored, the water quality sections of Class II-III account for 16. 1%, the water quality sections of Class IV and V account for 39.8%, and the water quality sections of Class V account for 44. 1%. In the main stream 13 section, I-III section accounts for 38.5%, IV and V sections account for 46.2%, and the inferior V section accounts for 15.3% ... The first-class tributaries are dominated by IV and V water quality; The secondary and tertiary tributaries, provincial boundaries and rivers in Shandong are mainly inferior to Grade V water quality.

ⅴ. Areas with serious surface water pollution. The main scope is Haihe River Basin and Liaohe River Basin. The Liaohe River and Haihe River are seriously polluted, and the inferior V water bodies account for more than 60%. Haihe river system is heavily polluted, and the main pollution indicators are permanganate index, five-day biochemical oxygen demand and petroleum. Of the monitored 1 18 sections, the water quality section of Class III accounts for 14.4%, the water quality sections of Class IV and V account for 14.4%, and the water quality section of Class V is worse than 710.2%. The main pollution indexes of Liaohe River system are five-day biochemical oxygen demand, ammonia nitrogen and petroleum. There are 67 monitoring sections, of which 17.9% is Grade III water quality, 29.9% is Grade IV and V water quality, and 52.2% is worse than Grade V water quality.

The total discharge of industrial wastewater (excluding direct cooling water from thermal power plants) and urban domestic sewage in China is ***606× 108t. According to basin statistics, the Yangtze River is 207× 108t, the Pearl River is 136× 108t, and Songliao is 608t. Haihe river is 55× 108t, southeast river is 40× 108t, Yellow River is 27× 108t, inland river is 7× 108t, and southwest river is 6× 108t. Among them, industrial wastewater accounts for 67% and domestic sewage accounts for 33%. The annual wastewater discharge is above 20× 108t in Shanghai, Henan, Hunan, Liaoning, Shandong, Heilongjiang, Guangxi, Zhejiang, Hubei, Jiangsu and Guangdong, and there are 1 1 provinces (autonomous regions and municipalities).

Three, the national surface water supply safety map

According to the National Surface Water Resources Zoning Map and the National Surface Water Quality Map, the national surface water supply safety map is divided into four zones (attached Figure 7), and the zoning situation is as follows:

Ⅰ. Relative safe area for surface water supply. Surface water resources are abundant, but surface water pollution is slight, mainly covering Xinjiang, western Tibet, northwest Gansu, northwest Qinghai, Inner Mongolia and other places.

Ⅱ. Safe area for surface water supply. The surface water resources are moderate, slightly polluted or abundant, and moderately polluted, mainly covering southeastern Tibet, Sichuan, Yunnan, western Guangxi, Guizhou, Hunan, Hubei, Chongqing, Henan, northern Anhui, northern Jiangsu, Shaanxi, southeastern Gansu, Shanxi, Hebei, Shandong, Shanghai, Zhejiang, Liaoning, Jilin, Heilongjiang and other places.

Ⅲ. The surface water supply in the whole area is unsafe. Surface water resources are scarce and surface water pollution is serious, mainly covering eastern Guangxi, Guangdong, Fujian, Jiangxi, southern Anhui, southern Jiangsu, southern Zhejiang, Hainan and Taiwan Province provinces.

Ⅳ. Unsafe areas for surface water supply. Surface water resources are scarce and surface water pollution is serious, mainly covering Tianjin and the northeast of Beijing.