Geographical environment of the Three Gorges of the Yangtze River

Located in the hinterland of China, the Three Gorges of the Yangtze River is the general name of Qutang Gorge, Wuxia Gorge and X

Geographical environment of the Three Gorges of the Yangtze River

Located in the hinterland of China, the Three Gorges of the Yangtze River is the general name of Qutang Gorge, Wuxia Gorge and Xiling Gorge. It starts from Baidicheng, fengjie county, Chongqing in the west and ends at Nanjinguan, Yichang, Hubei in the east, crossing fengjie county, Wushan, Badong, Zigui and Yichang, Hubei, with a total length of193km. Also known as "Three Gorges".

There are three gorge areas from west to east: Qutang Gorge in Chongqing, Wuxia Gorge in Chongqing and Xiling Gorge in Hubei, hence the name Three Gorges. The two sides of the Three Gorges face each other in high mountains, with steep cliffs and peaks generally higher than the river 1000- 1500m. The narrowest part is less than 100 meter. The Three Gorges was formed because the crust in this area is rising and the Yangtze River water is strongly incised. The Three Gorges of the Yangtze River belongs to the subtropical monsoon climate zone. 200 1 year (in 2000, 65438+February ~ 200 1,1year), the climate in the Three Gorges reservoir area is generally dry and warm. The annual precipitation is generally less and the temperature is generally higher. Compared with normal years, the precipitation in the reservoir area is more in winter and less in spring, summer and autumn. The temperature changes greatly in a year. Compared with normal years, the temperature is higher in winter, autumn, early spring and midsummer, and lower in mid-spring, early summer and late summer. The average wind speed in the reservoir area is slightly less than normal, with little seasonal change. Table 3-1 Monitoring Results of Meteorological Elements at Stations in Three Gorges Reservoir Area in 20061Average Temperature (℃) Relative Humidity (%) Precipitation (mm) Evaporation (mm) Average Wind Speed (m/ S) Sunshine Hours (h) Foggy Days (d) Thunderstorm Days (d) Celebration/KLOC-0 40.71.6 654438438+0187.91.6126.8 46 26 Fuling18.7 79 831.9/kloc-. 290,000 status19.1.78 848.61.276.7 0.51.288.6 27 26 Fengjie1.7.0 72 969.31. 0 18 28 Wushan18.9 69 876.21797.51.71836.51434 Badong17.77/kloc. 1.8 1584.6 96 33 belongs to17.1.781.31337.165433. 17.7761182.21408.31.61487.8130 Yichang17.875844. The annual precipitation in kloc-0/2 34 204 reservoir area is 800 ~ 1300mm, which is 0.5% ~ 30% less than 65438+. From the regional distribution of precipitation, as in 2000, it has the characteristics of more in the central and eastern regions and less in the western regions. In terms of time distribution, this year's precipitation shows a bimodal distribution, with the peak values appearing in June and 10, respectively, and the precipitation is the largest in 10. The precipitation concentration period appears from April to August, but the precipitation is obviously less. The average precipitation in spring and summer in the reservoir area is 239 mm and 367 mm, respectively, which is less than 20% than normal. The average precipitation in autumn in the reservoir area is 235 mm, which is nearly 20% less than normal.

In 2006, the average temperature in the reservoir area was 18. 1℃, which was 0.5℃ higher than normal. The annual average temperature in the reservoir area is17.0 ~19.1℃, which is 0.4 ~ 1. 1℃ higher than normal. The annual average temperature in the west is higher than that in the east, and Wanzhou has the highest annual average temperature of 19. 1℃. The annual average temperature in Fengjie is the lowest, which is 17.0℃. The temperature distribution in the reservoir area in 200 1 year is characterized by high in winter, autumn, early spring and summer, and low in mid-spring, early summer and late summer. Water quality status

According to the national environmental quality standard for surface water for environmental protection (GHZB 1- 1999), the permanganate index, ammonia nitrogen, volatile phenol, etc. 13 were selected for single water quality evaluation.

Dry season: the water quality is good, with the water quality sections of Class I and II accounting for 87% of the total monitoring section and Class III accounting for 13% of the total monitoring section.

In the normal water period: the water quality is good, with Class II water quality sections accounting for 67% of the total monitoring sections in the reservoir area and Class III water quality sections accounting for 33% of the total monitoring sections.

In wet season: the water quality is acceptable, with the number of Class II water quality sections accounting for 40% of the total monitoring sections in the reservoir area, Class III water quality sections accounting for 46.7% of the total monitoring sections, and only 1 section is of Class IV water quality.

In 200 1 year, the main pollution factors affecting the water quality of urban reach in reservoir area are still chemical oxygen consumption, permanganate index and ammonia nitrogen. Main pollution factors Water quality categories Main pollution factors in dry season, normal season and wet season Zhu Tuo ⅲ biochemical oxygen demand in the main urban area of Chongqing, Total mercury Ⅱ Ⅱ Huang Xi Ⅱ Wanglongmen Ⅱ Cuntan Ⅱ Huangcaoxia Ⅱ Huangcaoxia Ⅱ Changshou District of Chongqing Ⅱ Duckbill Ⅱ Ⅲ Chemical Oxygen Demand Meiqi Ⅱ Ⅲ Permanganate Index Ⅱ Ⅲ Chemical Oxygen Demand Ⅲ Red Sandstone Ⅱ Ⅲ Chemical Oxygen Demand Ⅲ Chemical Oxygen Demand Ⅲ Chemical Oxygen Demand Ⅲ Chemical Oxygen Demand Ⅲ Chemical Oxygen Demand Ⅲ Permanganate Index Ⅲ Chemical Oxygen Demand Ⅲ of Yunyang County Salt Wharf in Chongqing Chemical oxygen demand ⅲ chemical oxygen demand ⅲ chemical oxygen demand ⅲ chemical oxygen demand In dry season, wet season and normal season, the cross-sectional proportions of water quality reaching or better than Class III are 100.0%, 100.0% and 93.3% respectively, and the water quality is better than Class III. Comparison of annual variation of water quality in urban reach of Three Gorges reservoir area in dry season+0999 2000 2006 5438+0 1 999 2000 2006 5438+01999 2000 2006 5438+0 Total number of monitoring sections1. 161316151615151315. 38+0 1 15 14 is 81.281.210075.050.010068.8. During the flood season, the water quality declined and there was a certain degree of heavy metal pollution. The main over-standard item is total lead. The water quality of tributaries in the reservoir area is in good condition, and the annual water quality is Grade II.

Seasonal fluctuation

Judging from the quarterly water quality, the pollution in the third quarter (the main flood season of the Yangtze River) was more serious, especially the heavy metal lead in Cuntan, Qingxichang and Tuokou exceeded the standard, resulting in the quarterly water quality being Grade V. Name of regional section: water quality category and exceeding standard multiple in the first quarter, in the second quarter, In the third quarter and the whole year of the fourth quarter: Cuntan 235 (total lead 0.67) 22Qingxi Field 235 (total lead 0.63) 22Tuokou 225 (total lead 0.98) Ⅱ Ⅱ Ⅱ Ⅱ Guandukou Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ Ⅱ

200 1 clear water and muddy water samples were compared and analyzed. The results showed that the content of muddy water samples was significantly higher than that of clear water samples, especially the differences of seven items (permanganate index, phosphorus, mercury, arsenic, copper and cadmium). The change trend of each monitoring section shows that the concentration of monitoring factors in muddy water samples changes with the water period, while the content in clean water samples is low and stable, and the change is not obvious.

The permanganate index in the main stream of the Yangtze River is on the rise along the middle and lower reaches. The ratio of clear water and muddy water samples with permanganate index is basically stable, and the ratio of clear water and muddy water samples with total phosphorus is relatively large.

Compared with 2000, there was no obvious change in water quality in 200 1 year. The monitoring results show that the water quality of 200 1 Yangtze River is generally good, and the annual water quality of the section is Grade II and III.

Compared with the same period in 2000, the water quality of the main stream of the Yangtze River was good in the first and fourth quarters of 2000/KLOC-0, with no obvious change. In the second quarter, Qingxichang and Tuokou sections were classified as Class III and Class II, respectively, which was better than Class V water quality in 2000, and the water quality of other sections remained unchanged. In the third quarter, Cuntan, Qingxichang and Tuokou sections still reached Grade V water due to excessive heavy metals; Compared with the same period in 2000, the water quality of Linjiangmen section of Jialing River and Wulong section of Wujiang River in the reservoir area has not changed significantly. In 2000, 200 1, the name of the water quality comparison area in the Three Gorges reservoir area and the middle and lower reaches of the Three Gorges, the annual comparison of water quality categories in the first quarter, the second quarter, the third quarter and the fourth quarter, and 2000 5438+0 2000 2006 5438+0 2000 2000 438+0 2000 2006. Cuntan III II II II II III V II Qingxichang II V II II II II II II II II V II V II V II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II Ii II II II II II II II II II II II II II II II II II II II II II II, Padang Water Station II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II Ii II II II II II II II II II II II II II II II II II II II II II II II II II II II II II II 22222222 Hankou 22222255 5555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555 Five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five six five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five five