There is an east-west Qinling Mountains on both sides of the Weihe River, and a Liupanshan barrier in the north. Weihe river basin can be divided into loess hilly and gully region in the west and Guanzhong plain region in the east.
Question 2: The causes of water shortage in Weihe Plain do not include insufficient precipitation and small river runoff. Runoff varies greatly with seasons. The economy is developed and there is plenty of water.
Question 3: What are the problems in Weihe River? Since liberation, especially since the reform and opening up, the comprehensive management of Weihe River has made remarkable achievements. First, local laws and regulations such as Regulations on the Prevention and Control of Water Pollution in Weihe River Basin of Shaanxi Province, Measures for the Management of Environmental Pollution Control Projects within a Time Limit in Shaanxi Province, and Regulations on the Prevention and Control of Water Pollution in Urban Water Supply Sources of Shaanxi Province have been promulgated, which have intensified the prevention and control of pollution in Weihe River and shut down a number of enterprises with hopeless governance and serious pollution; Second, grasping the main contradiction of water shortage, a number of water storage and diversion projects have been built, such as Baoji Gorge, Fengjiashan, Shitou River and Heihe Jinpen Reservoir Project. Third, with the support of the state, the flood control project in the lower reaches of Weihe River was implemented. Fourth, based on the construction of basic farmland and taking small watersheds as a unit, the unified planning of landscape farmland villages was implemented, and the ecological environment construction achieved remarkable results. However, there are still some serious problems that cannot be ignored in the comprehensive management of Weihe River.
1, the problem of water shortage is becoming more and more prominent.
The total water resources of Weihe River Basin in Shaanxi Province is 6.85 billion cubic meters, with a per capita of 380 cubic meters, which is equivalent to 1/8 of the national total, and the water resources are seriously insufficient. The average water resources per mu of cultivated land is 250 cubic meters, which is 1/6 of the national average, and it is a serious water shortage area. The annual runoff changes greatly during the year and is unevenly distributed. 50~70% of the annual runoff is concentrated in 7 ~ 10, so it is difficult to use it in the form of flood. The Weihe River has a large sediment concentration and is difficult to develop and utilize. Therefore, the lack of water in Weihe River is the biggest restrictive factor for our province's economic development, social progress and the implementation of the strategy of developing the western region.
2. The water quality has deteriorated and the pollution is serious.
With the development of economy and the increase of urban population, more and more industrial wastewater and domestic sewage are discharged into Weihe River, and the water pollution is getting worse year by year. According to the data of relevant departments, the amount of garbage and sewage accepted by the Weihe River in the 1980s was 465 million tons, and by 2000 it had increased to 620 million tons. Weihe River receives 78% of the province's industrial wastewater and 86% of domestic sewage every year. The main stream of Weihe River is more than 370 kilometers from Baoji to Tongguan, most of which are Grade V and Super Grade V water quality.
3. The runoff is sharply reduced and the ecological environment is deteriorating.
In 1950s and 1980s, the average annual runoff of Linjia Village in Weihe River was 21~ 2.3 billion cubic meters, and in 1990s it was1.700 million cubic meters, which was only 49.2% of the average in the previous 40 years, and only 400 million cubic meters in 1.997 and 2000. Due to the sharp drop of river runoff, the main stream of Weihe River is cut off in many places, which greatly reduces its own dilution and pollution capacity, aggravates the pollution degree of Weihe River, and reduces the sediment washing capacity of the river, resulting in serious sediment deposition in the downstream. Due to over-exploitation, the Weihe River Basin has become one of the areas with serious soil erosion on the Loess Plateau. The soil erosion area is 36,000 square kilometers, accounting for 65% of the total land area, especially in Weibei coal mining area, Xiaoqinling gold mining area and highway, railway and other engineering construction areas. Serious soil erosion not only aggravated the deterioration of ecological environment, but also brought greater harm to the lower reaches of Weihe River.
4. The downstream siltation is serious and floods are frequent.
Due to the high water level storage operation of Sanmenxia Reservoir for many years, the sediment deposition in Sanmenxia Reservoir in the east of Guanzhong is serious, and the riverbed in the lower reaches of Weihe River is raised by about 5 meters, forming a suspended river. The cross-section of the main channel is shrinking, the flood discharge capacity is sharply reduced, and the estuary is moving up, which leads to the Yellow River flowing back to the Weihe River, resulting in poor flood discharge in Nanshan, a tributary, and the drainage conditions of 3 million mu of cultivated land and low-lying and waterlogged areas such as Xi 'an and Dali in Erhua Channel area are completely lost, leading to disasters. The groundwater level in Sanmenxia reservoir area rises, causing salinization; The flood discharge capacity of rivers is reduced, and floods occur frequently, which has become one of the high-incidence areas of floods in China.
In a word, the problem of Weihe River is very serious. If decisive measures are not taken and comprehensive management is carried out, it will seriously affect the sustainable development and stability of Guanzhong area and even our province's economy and society.
Question 4: Why is the Weihe Plain rich in groundwater resources? Reason: The central plain area is a graben with abundant groundwater resources.
Question 5: The present situation of Weihe River in Shaanxi 1. Present situation of sewage discharge.
Weihe River, which runs through Guanzhong area, has become a sewage river in Guanzhong area, and a large number of untreated industrial wastewater and domestic sewage are discharged directly, which makes Weihe River suffer greatly. The monitoring data in 2007 showed that Weihe River water was not only impossible to be used as drinking water source, but also seriously threatened as agricultural irrigation water, and aquatic organisms such as fish in the main stream basically disappeared. Weihe River not only basically lost its original function, but also affected the water quality of the Yellow River. See table 1 for the statistical results of sewage outlets and sewage discharge in Guanzhong area.
Table 1 Statistical Table of Sewage Outlet and Pollution Discharge in Guanzhong Area of Weihe River Basin
2. Non-point source pollution
Regional non-point source pollution is mainly related to rainfall-runoff process, land use, vegetation and human activities. The water pollution of Weihe River system mainly comes from point source pollution, that is, a large number of urban industrial and domestic sewage discharges. Because there is no detailed investigation and monitoring of river non-point source pollution, only the main influencing factors that can produce non-point source pollution are analyzed here.
(1) is closely related to soil erosion in this area. After years of treatment, the annual sediment yield is 55.29 million t, accounting for 7.4% of the whole province, and the average erosion modulus for many years is 998t/km2.
(2) Compared with the soil background value, the average contents of organic matter, total nitrogen, available nitrogen, available phosphorus and available potassium in the surface soil of Weihe River Basin are 65438 0.65, 438 0%, 0.08%, 49PPM, 7.4PPM and 65438±0.55 ppm, respectively, which are slightly higher than the provincial average.
(3) It is related to the use of pesticides and fertilizers. According to statistics, the total annual consumption of pesticides in Weihe River Basin is 4728t, with an average consumption of 0.279kg per mu, which is higher than the average consumption of 8 1.2% in the whole province. The total annual consumption of chemical fertilizer is 3410.5 million t, with an average consumption per mu of10.28 kg, which is 70.2% higher than that of the whole province. The average pesticide consumption per mu in Xi is 0.348 kg, followed by Weinan, Xianyang, Baoji and Tongchuan.
(4) It is related to air pollution and acid rain. According to the monitoring, the annual average value of SO2 in seven cities and counties in Weihe River Basin 1995 is 0.085mg/m3, and the daily average value ranges from 0.003 ~ 1. 130, and the over-standard rate is 14. 1%. Only Tongchuan, which exceeds the national second-class standard, appears in winter; During the period of 1995, the pH value of precipitation in Guanzhong area was between 4.35 and 9.35, and the total amount of acid rain collected in the whole year accounted for 2.75% of the total collected water, and acid rain samples accounted for 2.0% of the total rainfall. Acid rain only occurs in Xi and Weinan in Guanzhong.
(5) Related to the utilization of land resources. The unreasonable utilization of land resources such as steep slope reclamation, decreased forest coverage rate and intensified human activities will increase the load of non-point source pollution. At present, the main problems existing in the utilization of land resources in Weihe River Basin are: the total area of forest land and grassland is declining sharply. Due to the decrease of cultivated land, the cultivated land in Guanzhong area is more than 25 degrees 124.94hm2, accounting for 5.8% of the cultivated land area, of which the cultivated land in Baoji area accounts for 17. 1%, and the cultivated land in steep slope accounts for 25% of the water quality of Weihe River system.
Present situation of water quality in Weihe River basin
1. Present situation of river water quality
(1) section selection
Six monitoring sections (Tuoshi, Linjiacun, Xianyang, Gengzhen, hua county and Tongguan Suspension Bridge) and eight monitoring sections (Heiyukou of Heihe River, Weikou of Fenghe River, Wang Du of Bahe River, Zhangjiashan of Jinghe River, Jingcun, Wuqi of Beiluo River, Jiaokou and Zhuangtou) were selected as evaluation sections, and the river length was controlled at 40.
(2) Evaluation index, evaluation standard and evaluation method.
According to 24 indexes in Table 1 of Environmental Quality Standard for Surface Water (GB3838- 2002).
(3) Evaluation results
Beiluohe River system: the length of the assessed river reaches is 54 1.4km, with an average annual water quality of 58.8% of the assessed river reaches, and the length of the river reaches with poor water quality of V accounts for 4 1.2% of the assessed river reaches. The main items exceeding the standard are ammonia nitrogen, biochemical oxygen demand and chemical oxygen demand.
Jinghe River System: The length of the assessed river reaches is 222.5km, with an average annual length of 72.6% of the assessed river reaches with Grade V water quality, and 27.4% with inferior Grade V water quality. Biochemical oxygen demand, chemical oxygen demand, etc.
Weihe river system: the total length of the main and tributaries is 524.7 kilometers, and the average annual river length of Grade I ~ III water quality accounts for 35.0% of the assessed river length; The length of rivers with Grade IV ~ V water quality accounts for 29.4% of the assessed river length; The length of the river reach with inferior grade V water quality accounts for the evaluated river reach ... >>
Question 6: The picture below shows the change map of a section of Weihe River near Xi 'an. Complete the following small questions. Question 1: The natural reasons for the continuous northward movement of the Weihe River in the picture may be as follows: ① Area problem 1:D Question 2:C Analysis: Question 1: The geological plate movement keeps raising the Qinling Mountains. According to calculation, the average annual increase of Qinling Mountains is about 0.12mm. At the same time, the subsidence of Weihe graben led to differential uplift movement in Guanzhong Plain. There are few tributaries on the north bank of Weihe River, and the water flow is slow, which has little squeezing effect on the main stream of Weihe River. However, many tributaries on the south bank of Weihe River come down from Qinling Mountain and form a huge momentum after merging, pushing the Weihe River water to the north bank. It is wrong to say that geostrophic deflection should move south; It is said that the Jinghe River carries more sand, and the lower reaches of the Weihe River should move south, which has no effect on the upper reaches. 4 errors; The south bank is not easy to be washed away because of its large particles. Correct answer, so the answer is D. Question 2: According to the picture, the south of Xi 'an is the historical capital Chang 'an, with many historical sites. In order to protect the ancient sites, the new area of Xi will not expand southward.
Question 7: Information about He Wei: Weihe River, also known as Weishui, is also called Weihe River, Weihe River or He Wei.
The total length of Weihe River is 8 18km, and the drainage area is 134300 km2. Tributaries such as Jinghe River and Luohe River in the upstream and north bank flow through the Loess Plateau, carrying a lot of sediment. The middle and lower reaches waterway, from Han Dynasty to Tang Dynasty, is the main waterway in Guanzhong. Shan Hai Jing. "Sea Middle East Classic": "Birds and mice in the Weihe River come out of the same cave mountain, and the river flows eastward into Huayin North." Li Daoyuan's Notes on Water Classics in the Northern Wei Dynasty: "Wei River originated in the northwest of Bird and Mouse Mountain, and isolated in the south of Tingnan Mountain, Wei Shou, shouyangshan, Shouyang County. There is Gaochengling in this county, with the city number Weiyuan City on it, and the Weihe River goes out. " Tang Zhangji's poem "Climbing the North Temple Building in Xianyang" says: "Wei River is straight from the west, and Qinshan is deep from the south."
The tributaries accepted by Weihe River are Hulu River, Jinghe River and Luohe River. The precipitation in Weihe River Basin is concentrated in summer, with heavy rainfall and serious soil erosion. Among them, the annual sediment discharge of Jinghe River is 296 million tons, which is the largest among tributaries. Guanzhong Plain is the earliest area of water conservancy development in China. In 246 BC, Zheng Guoqu was opened in Qin Dynasty, and the Jingjing River flowed into the Luohe River, with a total length of 1.25 km and an irrigation area of 2.8 million mu. Emperor Wu of the Han Dynasty opened another Baigong canal to introduce the water from Jinghe River into Weihe River. Here, at the northern foot of the Qinling Mountains, there is a canal to introduce the water from Chang 'an (now Xi 'an) into the Yellow River, which is both a waterway and beneficial to irrigation. After several generations of expansion, the middle and lower reaches of Weihe River are criss-crossed, and there are irrigation projects such as Jinghui Canal, Weihui Canal and Luohui Canal, which is a famous grain-producing area in history.
The natural climate edits this paragraph
Weihe river basin belongs to continental climate, with an annual average temperature of 6 ~ 13℃ and annual precipitation of 500 ~ 800 mm, of which 60% is from June to September, with short-term rainstorm, little precipitation in winter and spring, and frequent droughts in spring and summer. Xianyang Station has an annual runoff of 5.4 billion cubic meters and an annual sediment discharge of 65.438+700 million tons. Water mainly comes from the right bank tributary, and sediment mainly comes from the left bank tributary.
Weihe River Basin is an arid and semi-arid area, with an annual average temperature of 6 ~ 14℃, an annual average precipitation of 450 ~ 700 mm, an annual evaporation of 0/000 ~ 2 000 mm and a frost-free period of 0/20 ~ 220 days. The average annual runoff is 65.438+002 billion cubic meters (654.38+0934 ~ 654.38+0970 series), and the annual variation is similar to precipitation. June ~ 10 is
3. Edit this human history
Weihe River Basin is the birthplace of Xuanyuan Huangdi and Shennong Yan Di, the ancestors of Chinese culture. Huangdi and Yan Di are considered as the ancestors of the Chinese nation. "Mandarin?" "Today" contains: "In the past, few people married F and gave birth to the Yellow Emperor and Yan Di. The Yellow Emperor Weihe River was made of pumping water, and Emperor Yan was made of Jiang Shui. Merits are different, so the Yellow Emperor is discipline, not ginger. The second emperor used teachers to help each other, and the reasons for their different virtues were also different. "This is the earliest historical data that we can see that records the birthplace of Emperor Yan and Huangdi.
According to historians' research, Jishui and Jiangshui are both in the Weihe River Basin, and Jiang Shui is in Baoji. Jishui is the Qishui River in Wugong County, central Guanzhong. Both rivers are tributaries of the Weihe River.
Therefore, in any case, Xuanyuan Huangdi and Shennong Yan Di are two tribal leaders with similar blood relationship that originated in the Weihe River Basin. Later, the two tribes launched the battle of Hanquan, and Huangdi defeated Yandi. These two tribes gradually merged into the Chinese nation, which was called the Ministry of * * * after the Han and Tang Dynasties. Yan Di and the Yellow Emperor are also the ancestors of China's culture and technology. It is said that they and their courtiers and descendants created almost all the important inventions in ancient times.
4 river basin geomorphology editing this paragraph
The Weihe River basin has a complex landform. The mountains include the northern slope of Qinling Mountain, Liupanshan Mountain and Longshan Mountain across Shaanxi and Gansu. The faulted basin includes the alluvial plain in Guanzhong and the loess plateau, and the loess plateau includes the plateau gullies and hilly gullies in Longdong, Ningnan and northern Shaanxi. Heyuan to Baoji Gorge exit is upstream, with a total length of 430 kilometers. The river channel is narrow, with alternating rivers and canyons, and the current is fast, with an average gradient of 1/260. Baoji Gorge-Xianyang Railway Bridge is located in the middle reaches, with a length of 177km. The river bed is wide and shallow, with many sandbars and scattered water flow. It is a wandering river bed, and the slope gradually decreases from 1/500 to 1500. Xianyang to Tongguan estuary is the downstream, 2 1 1 km long, which is below the north of hua county. The river twists and turns without any tributaries. Due to sediment deposition and backwater from Sanmenxia Reservoir of the Yellow River, the longitudinal slope of the river gradually changed from 1/5000 to 1/6000. Before the Sanmenxia Reservoir was built, the lower reaches of the Weihe River was a relatively stable river with nearly balanced sediment transport, and the elevation of the Weihe River entering the Yellow River (Tongguan elevation) was 323 meters (1000 cubic meters per second). After the completion of Sanmenxia Reservoir, due to the influence of backwater siltation, the highest elevation of Tongguan section of Weihe River reached 329 meters, which affected the siltation and elevation of the lower reaches of Weihe River and often caused floods, so ...