Why the Yangtze River floods frequently?
(1) The precipitation in the Yangtze River Basin is abundant and unevenly distributed, and 80% of the annual rainfall is concentrated in August-September. Coupled with the abnormal climate this year, the Yangtze River basin has experienced three consecutive large-scale heavy rainfall processes due to the "El Niñ o" and "La Nina" phenomena. Since the flood season this year, the rainstorm has covered a large area. At the same time, the rainstorm in the Yangtze River basin has moved from the middle and upper reaches to the middle and lower reaches this year, resulting in the superposition of floods and flood peaks in the main and tributaries, which is an important climatic factor causing floods.
(2) The Yangtze River is 6300 kilometers from its birthplace to its estuary. The source is gentle and vast, and the upper reaches are mountainous valleys and steep mountain landforms, young mountains, loose rock mass, fragile environment and unique terrain. Under the action of geological tectonic movement and gravity, it is a frequent area of earthquakes, landslides and mudslides, and it is also the area with the greatest soil erosion. The drop gradient of several major rivers in the upper reaches is between 144 ~ 485 m/ 100 km. Passing through the Three Gorges, the drop gradient of the middle and lower reaches of Yichang is only 2.8m/ 100km, and the drainage is not smooth. The famous Jingjiang River is located in this section. The flood with a large amount of sediment in the upper reaches flows down to the upper reaches, and the sediments in Jianghan Plain and lakes are all natural factors of the Yangtze River flood [1].
2. Blind reclamation, illegal construction, flood storage area is difficult to use.
There are many factors leading to the rise of flood level, among which the flood diversion and storage difference plays an important role. During the period of 1954, due to the low flood resistance of the middle and lower reaches of dikes, many dikes naturally burst. In order to reduce the flood level, it is used in many places except Jingjiang flood diversion project. The flood diversion volume of crevasse reaches 654.38+0023 billion m3, of which the ability to effectively reduce flood peak is about 70 billion m3. According to the flood inflow of 1998, if the water level of 1954 is to be maintained, the effective flood storage is about 40 billion m3. However, the total flood diversion breach of 1998 is only about
65.438+0 billion m3, of which the flood peak capacity can be effectively reduced by about 5 billion m3, thus reducing the flood diversion by about 35 billion m3, which is equivalent to reducing the flooded area by 467,000 hm2 (7 million mu). The state has planned dozens of flood storage areas, and made plans and arrangements for the production and life of people in flood storage and detention areas [2]. However, due to population growth and economic development, the flood diversion area has not only cultivated land, but also built permanent buildings and enterprise engineering facilities. If the flood is diverted as planned, it will suffer great losses. If the flood is not diverted according to the original plan and the water level is raised, the dike will bear the flood level exceeding the design standard and bear great risks. Considering that the flood ratio of 1998 is smaller than that of 1954, and the potential of military-civilian unity in fighting floods is great, the central authorities resolutely guard against it and strive to reduce the flood diversion losses caused by breaches. This is an extremely difficult decision, but it has been proved to be correct in practice.
Irrational land use led to floods.
Although there have been many floods in the Yangtze River basin in history, the current situation is that the frequency of floods has increased significantly in recent years. At the same time, compared with the historical floods in the Yangtze River, this year is at a medium level. However, the middle and lower reaches of the Yangtze River have always maintained a high water level, generally exceeding the warning water level, and the flood level in most areas has exceeded or approached the highest in history. This medium flow, high water level and catastrophe are closely related to population growth and unreasonable land use. ?
The misunderstanding of the population problem in the early days of the founding of the People's Republic of China led to population out of control. The population of China increased from less than 6,543.8+billion in the early Qing Dynasty to more than 300 million in the Qianlong period and reached 450 million in the War of Resistance against Japanese Aggression period. By 199 1, the population of the Yangtze River basin alone will reach 397 million. The total area of the Yangtze River basin only accounts for 18.8% of the total land area of China, but it has nurtured the population of13 of the whole country. Population pressure, economic growth and long-term one-sided emphasis on grain as the key link have led to blind deforestation, sloping land reclamation, lake reclamation, wetland degradation, grassland overload and unreasonable land use, resulting in changes in land cover pattern and serious consequences.
3. 1 Deforestation
Forests have great functions of water conservation and runoff regulation. The complex three-dimensional structure of forest can intercept precipitation layer by layer, which not only redistributes rainfall, but also weakens the kinetic energy of precipitation on ground erosion. According to the research, the annual average canopy interception of main forest ecosystems in China is 134 ~ 626mm, and the average canopy interception rate is 1 1.4% ~ 34.4%, with an average of 2 1.64%. The water holding capacity of forest litter is four times its own weight, and surface runoff is transformed into underground runoff with the help of good soil structure. In the rainy season, the peak flow can be weakened to some extent, and the arrival time of the peak can be delayed. In the dry season, the dry flow can be increased and the length of the dry season can be shortened. Moreover, the flood peaks in the forestless and Shaolin areas advance and retreat rapidly, which increases the threat of floods. Deforestation not only eliminates the nitrogen fixation of forests, but also increases the radiation absorption of the ground, raises the temperature of the ground and soil, promotes the decomposition and release of carbon in the soil, further exacerbates the "greenhouse effect" and causes global climate change. Rising temperature will lead to increased evaporation and precipitation. According to research, every time the temperature rises by 65438 0℃, the water vapor in the air will double, thus increasing the possibility of rainstorm disaster.
The water conservation function of forests is obviously different due to the stand status. Due to man-made destruction, the plantation is young, the growth rate is low, and the water storage and soil consolidation ability is poor. Taking Pinus massoniana as an example, the biological productivity of low-quality and low-efficiency Pinus massoniana stands is only 1/9 of that of excellent stands. Due to the good coverage of trees, shrubs, grass and dead cover, the rainfall intercepted by the biological layer in a rainfall is 6 ~ 10 times that of the inefficient stand. Because of the large non-capillary porosity, the maximum precipitation storage capacity of high-quality forest is about 4 times that of low-quality and low-efficiency forest. 20-year-old excellent stand intercepted 76.8 mm more precipitation in a rainstorm. The annual surface runoff per square kilometer of low-quality and low-efficiency secondary forest is 654.38+10,000 m3 more than that of superior forest. Accordingly, 654.38+ 1 100 million km2 of forest can store 654.38+ 1 100 million m3 of water.
The existing forest areas in China are mainly distributed in the northeast and southwest regions, which are just the middle and upper reaches of the two most severely flooded rivers. Due to long-term timber production, forest resources have been seriously damaged. The forest coverage rate in Heilongjiang decreased from 53.4% in 1949 to 35.55% in 1993. The recoverable area of over-mature forest decreased from 50% of 1948 to 13.3% of 1993. The stock dropped from 76.6% of 1948 to 20.6% of 1993; The forest quality has also decreased obviously, and the average volume per hectare has decreased from 1.99 m3 in the initial stage of development to 1.00 m3 now. The volume of precious Korean pine forest decreased by 85.4%, and that of broad-leaved forest decreased by 87.8%. Forests in southwest China, western Sichuan and northern Yunnan are distributed in alpine valleys, which are not only famous at home and abroad for their rich species composition, diverse ecosystem types and huge productivity, but also have important functions of water conservation and environmental protection. However, since the 1950s, the forests here have also experienced disasters. In particular, the construction of the third line, which started in the mid-1960s, further expanded and intensified the damage to natural forest areas, involving both the southwest forest area (the so-called Jinsha River forest area development campaign) and the Daxinganling forest area (the so-called Daxinganling forest area development campaign), which happened to be the source area of this year's flood. At that time, it was crazy to mobilize a lot of manpower and material resources from all over the country to concentrate on developing water conservation forests in the middle and upper reaches of large rivers, but at that time, it was carried out as a major decision of national construction. Compared with the 1950s, the area and volume of forests have decreased by more than 50%. Located in the upper reaches of the Yangtze River, the forest coverage rate of more than 50 counties in Sichuan Province is only 3% ~ 5%. For example, the annual wood consumption in Aba Prefecture is more than four times the annual growth. Some forestry bureaus have actually fallen into a situation where there is no forest to cut.
3.2 Unreasonable development and utilization of wetlands and lakes (drainage, reclamation and land reclamation)
Wetlands include lakes, swamps, peatlands, coastal areas, mangroves and coral reefs. Wetlands and lakes are the "sinks" and reservoirs of incoming water in river basins, which undertake the functions of storing and discharging river water, maintaining water balance in river basins, degrading pollutants and providing tourism resources, and are known as "kidney of the earth". For example, the saturated water-holding capacity of grass roots and peat bottoms in freshwater herbaceous marshes can reach 84.5% ~ 97.0%, and the total water-holding capacity of marshes in Sanjiang Plain alone can reach 3.4 billion m3. In addition, wetlands can provide various resources; High biodiversity; Regulating climate and purifying environment play an important role in protecting biodiversity and maintaining ecological balance. At present, the international community attaches great importance to the protection and rational development and utilization of wetlands, and put forward the International Convention on Wetlands (Ramsar) in 197 1. The Convention is the first intergovernmental international convention for the protection of natural resources in the world. At present, more than 100 countries have joined this convention. The wetland area in China is about.
25 million hm2, accounting for 2.6% of the land area (the world average is 6%), has been completely degraded. At present, unreasonable reclamation in the middle reaches of the Yangtze River has a history of nearly a thousand years. Humans have been reclaiming land along rivers and lakes, and the 500km stretch from Zhicheng to Wuhan has been basically reclaimed, greatly reducing the flood storage capacity. According to the survey and incomplete statistics, more than/3 lakes13 have been reclaimed since the founding of the People's Republic of China, and the total area of reclamation is more than10.3 million km2, and more than10.3 million lakes have died as a result of reclamation. Reclamation reduces the storage capacity of lakes by more than 500m3, which is equivalent to 1.65 and 438+0 times of the annual runoff of Huaihe River, 1.3 times of the total storage capacity of five freshwater lakes and 5.8 times of the storage capacity of the Three Gorges under construction. The decrease of lake area and storage capacity directly leads to insufficient water storage in rivers. So the water level of the same flow is higher than before. There are five large reservoirs in Hunan Province with serious siltation, and the siltation amount is1.1.400 million m3, which is equivalent to scrapping a large reservoir. There are 2 10 medium-sized reservoirs, of which 35 are seriously silted. Dongting Lake is the only good water storage lake in China, with an area of 6000km2 in 1825, only 4350km2 in 1949, and only 26,965,438+in 14 1978. n bsp55.2%。 The water capacity of the lake decreased from129.3 billion m3 in 949 to 1978.
654.38+07.4 billion m3, down 40.6% [3 ~ 5]; Due to sediment deposition, the bottom of the lake increases by an average of 3.6cm per year; At present, the beach area has reached 6.5438+0.2 million hm2, and it is expanding at the rate of 666.7hm2 every year. Under the combined action of reclamation and siltation, the lost storage capacity of Dongting Lake accounts for1/5 of its total storage capacity; Compared with 1937, the water level in Chenglingji, the exit of Dongting Lake, is about 2m higher. At the same water level, the flood volume decreased by 25,000m3/s, which increased the potential threat of flood. In particular, lake siltation is harmful to the middle and lower reaches and harmful to the middle and upper reaches. For example, 82% of the sediment in Dongting Lake comes from the middle and upper reaches of the Yangtze River, while the backwater sediment only accounts for 18% of the sediment deposited in the lake.
3.3 unreasonable farming slogan, one-sided emphasis on food as the key link
The Chuanjiang Valley in the upper reaches of the Yangtze River is an ancient agricultural area with a large population, and the agricultural population accounts for about 85.6% of the total population. Under the huge population pressure, the reclamation rate in this area is very high. For example, the mountains in western Sichuan are high and steep, and there is little arable land, so farmers should open up wasteland on both sides of the river. About 70% of the cultivated land in the upper reaches of the Yangtze River is cultivated along the slope, and there are no soil and water conservation measures, especially the steep slope greater than 25. The dry land in the whole region is about 2.64 million hectares, accounting for 53.8% of the cultivated land, almost all of which are sloping cultivated land. Dry land with a slope of more than 25 in Jinsha River, Yalong River and Minjiang River accounts for 34%, and Yalong River reaches 45.6%. Located in Ebian County and Jinkouhe District in the middle reaches of Dadu River, 70% ~ 90% of the cultivated land area is 25. According to the survey in Chongqing, sloping farmland is very common, with sloping farmland larger than 25 accounting for 13.7% of the total cultivated land area, and sloping farmland with 5 ~ 25 accounting for 840,000 hm2, which together account for 89% of the total cultivated land area. According to the investigation in Shaanxi Province, Hanjiang River and Jialing River are the main tributaries of the Yangtze River, and their transit lengths in Shaanxi are 654km and 244km respectively. The basin covers an area of nearly 80,000 square kilometers. In the basin, the sloping farmland in Ankang area accounts for about 70% of the total cultivated land area. More than 35 "listed land" accounts for 23% of the total cultivated land area; The reclamation of steep slopes in zhenba county in Hanzhong area is serious, with sloping farmland larger than 25 accounting for 63. 1%, sloping farmland larger than 30 accounting for 4 1.3%, and sloping farmland with cracks above 45 accounting for 19.7%, which is far beyond the allowable range of natural conditions. Excessive reclamation is often accompanied by the reduction of forest land, and steep slope reclamation leads to serious soil erosion. As we all know, soil erosion increases with the increase of slope. When the slope is greater than 20, the erosion modulus reaches 5000 ~ 6000 t per hectare. According to the calculation of soil erosion under different land use conditions in the Three Gorges reservoir area, the annual erosion of woodland, shrub, grassland and agricultural land accounts for 6%, 1 1%, 23% and 60% respectively, and the contribution rate of sediment entering the river accounts for 6%, 12% and 35% respectively.
46% (5) Large-scale reclamation in the middle reaches of the Yangtze River has a history of nearly a thousand years, and the 250km section from Zhicheng to Hankou has been basically reclaimed, greatly reducing the flood discharge capacity [5].
In 1950s, the area of soil erosion in the upper reaches of the Yangtze River was 299,500 km2, and now it has reached 393,000 km2, accounting for 39. 1% of the basin area. The upper reaches of the Yangtze River transport 680 million tons of sediment annually to the middle and lower reaches, most of which are deposited in Jingjiang reach and Dongting Lake. At present, the area of soil erosion in the whole basin is 5510.8 million km2, accounting for 36.2% of the total land area, with an average annual soil erosion of 2.4 billion tons. Every year, millions of hectares of land are degraded and even bare rocks are formed. Shi Jisen and Zhang ⑥ pointed out that the area of soil erosion was 363,800 km2 in the 1950s and 739,400 km2 in the early 1980s, and that the riverbed of the Yangtze River rose at a rate of 65438±0cm every year. Due to unreasonable development, the area of soil erosion in Hunan Province increased from 1. 1.000 km2 in 1950s to 47,200 km2 in 1990s. Red deserts have formed in some places, and the sediment flowing into Dongting Lake from Hunan, Guizhou, Yuanshui and Lishui increased by 34.4% in the 1980s compared with the 1990s. The research shows that the sediment in the Yangtze River mainly comes from Jialing River basin, Tuojiang River basin, Wujiang River basin and Jinsha River basin. According to the determination of Yichang station, the average annual sediment discharge for many years is 530 million t, and the main material of soil erosion comes from cultivated land, accounting for 60% ~ 78% of the sediment discharge into the river. Because a large amount of sediment carried by the Yangtze River is deposited in the Yangtze River estuary, the Beiyuan waterway in the Yangtze River estuary is almost blocked, and the flood discharge capacity is greatly reduced.
According to investigation and statistics, the average annual erosion in the upper reaches of the Yangtze River is 6.5438+0 million km2.
10.568 billion t, the average sediment discharge of Yichang station in the main stream of the Yangtze River for many years is 530 million t, and the sediment transport ratio is 0.33. Below Yichang Station, the average annual sediment discharge of Hankou Station is 430 million tons. The difference between Yichang and Hankou is mainly the siltation of Dongting Lake. According to the research, the average siltation of Dongting Lake for many years is as high as 98.4 million m3, of which 82% comes from the middle and upper reaches of the Yangtze River, while the siltation through the four rivers of Hunan, Guizhou, Yuan and Li only accounts for 18%.
Soil erosion not only causes siltation in the middle and lower reaches, but also reduces the water storage function of "soil reservoir" According to the historian's calculation, the area of the upper reaches of the Yangtze River is 6.5438+0.0000 km2. Based on the average soil thickness of 0.78m, the sum of the whole soil pores is 65.438+0.973 billion m3. With the intensification of soil erosion, the total storage capacity of soil reservoirs is seriously lost. The erosion modulus of the 352,000 km2 loss area in the upper reaches of the Yangtze River is as high as 4,200 t/km2 a under the condition of annual total erosion of 65.438+0.478 billion t, which is equivalent to erosion of 4.0mm soil layer every year, that is, the water storage capacity is reduced by 26.5438+0.97 billion m3 every 65.438+0 years. In addition, after the vegetation was destroyed, the soil was exposed, and raindrops directly hit the soil surface, which destroyed the soil structure and seriously hindered the infiltration of rainwater into the soil reservoir, thus aggravating the flood discharge [6].
Take flood control as an opportunity to restore and rebuild the ecosystem.
The fundamental reason for the imbalance of ecosystem in China is that there are too many people and too few people. Rebuilding the ecosystem must be combined with the adjustment of economic structure and improve the ecological environment with the development of economy. Adhere to the principle of overall planning, tackling both the symptoms and root causes, and comprehensive management.
4. 1 Overall planning and integrated management
Guided by the principle of sustainable development, take the river as a whole system, comprehensively consider nature, society and economy, break the division of departments, make overall arrangements, and carry out comprehensive management and macro-control; Establish a corresponding management and operation system to properly arrange people's production and life: in the past, river basin agencies managed rivers regardless of lakes, while local agencies managed lakes regardless of rivers. Agriculture, forestry and water conservancy departments are fragmented, with unclear responsibilities and chaotic management. Driven by local and departmental interests, short-term actions are taken and long-term planning is lacking. Land reclamation and deforestation in the upper reaches, increasing soil erosion, reclaiming land from lakes in the middle reaches, and large-scale construction not only reduce the storage capacity, but also make it difficult to make decisions at critical moments. In the future, it is necessary to change the management mechanism of compartmentalization, establish a unified and coordinated river basin management institution, and carry out macro-control and supervision on the decision-making of major ecological construction and water conservancy construction issues. At the same time, we should strengthen the scientific and democratic decision-making. ?
4.2 Vigorously carry out comprehensive management of small watersheds
Taking small watersheds as a unit, combining ecological environmental protection with economic development, carrying out three-dimensional layout and comprehensive development is a successful experience of mountain management in China and the main research content of landscape ecology. This practice should be strongly advocated and supported in the process of restoring and rebuilding mountain ecosystems in the future.
Popularize measures such as changing slope into ladder, hedgerow on slope and planting on cross slope; Farmland on steep slopes should be returned to forests; Prevent the Three Gorges migrants from causing new ecological damage; The simple practice of stopping the "backward migration" in the process of Three Gorges resettlement will aggravate the steep slope reclamation. For example, according to Chongqing's statistics, the Three Gorges immigrants have cultivated sloping land so far.
6700hm2, a little carelessness will bring new serious soil erosion. Therefore, the resettlement should be re-planned according to the Ecological Function Zoning of Three Gorges Reservoir Area.
4.3 Returning farmland to forests and lakes in a planned and step-by-step manner.
It is imperative to return farmland to forests and lakes. The key to success lies in arranging the transfer of rural surplus labor force to service industry and processing industry to solve the problems of eating and living. In steep slopes with a slope greater than 25 degrees and areas with serious soil erosion, we must resolutely put an end to reclamation, and the reclaimed areas should return farmland to forests as soon as possible; In cultivated land with good soil and water conservation conditions, gentle slope and less potential threat of soil erosion, comprehensive planning of foresters and farmers and comprehensive management system of agriculture and forestry can be implemented; For the tidal flat that is still in a natural state, in order to exert its storage function and production benefit, blind reclamation should be strictly stopped, and the built polder areas vary from place to place. In principle, we will continue to retain polder areas with high terrain, good foundation of water conservancy facilities, high degree of development and utilization, and no obvious impact on flood storage and detention, and further heighten dikes and improve flood control standards; Decisive measures should be taken to adjust and transform those low-lying polder areas that hinder flood discharge and storage. It is necessary to adjust and transform non-flood storage reclamation into flood storage reclamation, build safety islands (platforms), safety buildings, and emergency transfer roads for materials and personnel. When the water level rises to a certain height and may continue to rise, the floodgate is opened for flood discharge or artificial blasting is used to divert the flood; For dikes with thin dikes and unsuitable water conservancy facilities, or dikes that have been surrounded by dikes, which are important spawning grounds for fish, it is necessary to "return farmland to fish" in a planned and step-by-step manner. The so-called "returning farmland to fish" does not mean to restore the completed polder to the natural water surface state before the completion of the polder, but to transform the original closed reclamation planting into semi-closed polder farming under the condition of making full use of the facilities in the completed polder [8].
4.4 Planting grass and raising livestock
In mountainous areas with heavy rainfall, high relative humidity, relatively insufficient sunshine, steep slopes above the upper forest limit, plateau areas where it is difficult to grow general crops, and dry-hot valley areas with little rainfall, grass irrigation should be developed, which can not only greatly improve biological productivity and develop animal husbandry, but also play a role in soil and water conservation, and is an important way to get rid of poverty in mountainous areas as soon as possible and make agriculture embark on sustainable development.
4.5 Strengthen forestry construction
Forests have great functions of water conservation and runoff regulation. The existing forest areas in China are mainly distributed in the northeast and southwest regions, which are just the middle and upper reaches of the two most severely flooded rivers. Due to long-term timber production, forest resources have been seriously damaged. Suggestion:
(1) Strengthening the management of natural forests Natural forests have high biodiversity and complex hierarchical structure, which is conducive to water conservation and soil and water conservation and can play an important role in maintaining ecological balance. They are precious wealth in China's natural resources. At present, there are not many protected areas, and there are no forests in many areas. Especially in the upper reaches of major rivers and areas on both sides of the river, it is necessary to clearly define water source protection areas and strengthen protection. Seriously implement the natural forest protection project, prohibit any form of logging within one year, and let the long-term damaged natural forests recuperate. During this period, it is necessary to formulate management methods and measures for natural forest ecosystems and gradually transition to scientific management of different types of ecosystems. It is suggested that a national-level permanent forest water conservation area should be established within the range of 10km on both sides of the main stream and tributaries of the upper reaches of the Yangtze River, and any form of main logging is prohibited. Some rainy centers in the middle reaches of the Yangtze River, such as the north of Nanling Mountain, Xuefeng Mountain, Wuling Mountain, Qinba Mountain, Daba Mountain, Tongbai Mountain, Tianmu Mountain, Wuyishan Mountain and Mufu Mountain, which have great influence on the hydrology of the Yangtze River, should vigorously develop soil and water conservation forests, so that the area of shelter forests in the middle and upper reaches will reach 50% ~ 70%; In the middle and lower reaches, the proportion of timber forest and economic forest can rarely increase, and the proportion of shelter forest should not be lower than that of woodland 1/3.
(2) It is an economic and effective measure to speed up the greening in mountainous areas to vigorously carry out closing hillsides to facilitate afforestation and transform secondary forests; Closing hillsides to facilitate afforestation should be based on sealing, and sealing, caressing and supplementing should be combined; For aerial seeding forests and newly planted forests in ecologically fragile areas, it is necessary to close mountains all the year round, prohibit human and animal damage, and give full play to protection benefits as soon as possible.
(3) Carry out mass afforestation and accelerate the construction of shelter forests and public welfare forests in the middle and upper reaches of the Yangtze River. In areas with poor soil conditions and difficult vegetation restoration, such as limestone mountainous areas, severely degraded red soil hills and areas with serious petrochemical desertification, it is necessary to increase investment and ensure vegetation restoration through artificial afforestation. Afforestation should combine arbor, shrub and grass; Combination of shelter forest and economic forest; Combination of closing hillsides for afforestation and closing hillsides for afforestation; Combination of biological measures and engineering measures ". Artificial afforestation prohibits the use of land preparation methods such as full reclamation and mountain refining; It is necessary to further optimize and consolidate the established Yangtze River shelterbelt system. The proportion of economic forests can be increased in places with thick soil layers and returning farmland to forests; Replanting hedgerows in economic forests with poor protection benefits to improve protection benefits; Afforestation tree species should choose trees with developed roots, lush foliage, strong germination, fast growth, long life and high economic value to create various mixed forests. You can also build multi-forest compound forests, such as protection-timber forest, protection-economic forest, protection-firewood forest, protection-special forest and so on. , so as to give full play to the multi-functional and multi-purpose characteristics of forests. Investigate the completed shelter forest, evaluate its management and ecological function, and put forward measures and plans for further management on this basis.
(4) Explore new management mechanisms and models. The original management organization and staffing should be streamlined, and the management function should be changed from cutting down trees to afforestation and forest management and protection; We should make proper arrangements for the workers, workers and the masses who have changed jobs, give way, organize surplus labor to diversify, and rationally develop all kinds of forest resources, especially non-wood resources; Contract low-quality and inefficient secondary forest management and afforestation in barren hills, implement various forms such as joint-stock system and contract system, establish flexible and diverse management systems, and enhance the vitality and development potential of forestry industry; At the same time, under the guidance of sustainable development, we will explore a new mode of combining green mountains and green rivers with enriching the people and strengthening the province.
(5) Increase investment and broaden financing channels. In addition to the resettlement expenses of workers in forest industry enterprises, the afforestation conditions in the upper reaches are difficult and the expenses are high, while the areas are poor and lack of financial support. Therefore, in addition to local financing and increased investment by the central government, financing channels should be broadened to attract foreign capital and funds from the mainland and coastal areas. In addition, it is necessary to establish a compensation mechanism for ecological public welfare forests, determine the compensation channels for public welfare forests, and compensate the beneficiaries according to the principle of whoever benefits.
(6) Strengthen the construction of legal system and raise the awareness of forest protection of the whole nation. Therefore, it is necessary to improve supporting laws and regulations, strengthen law enforcement and publicity, and raise the awareness of ecological environment protection of the whole nation. Change the position of forestry in national economic and social development from the organizational structure and management system, resolutely crack down on and completely block deforestation, strictly enforce the forest law, and carefully implement the "natural forest protection project" to ensure that the forests in the upper reaches of major rivers and along the Yangtze River will not be destroyed again.
(7) Vigorously develop grass and raise livestock. In mountainous areas with heavy rainfall, high humidity and steep slopes and plateau areas with high altitude, as well as sloping fields and dry-hot valleys unsuitable for afforestation, grass should be planted to develop animal husbandry, so as to greatly improve biological productivity, conserve water and soil, improve ecological environment, and make people in mountainous areas get rid of poverty and become rich as soon as possible and embark on the road of sustainable development.
4.6 Strengthen wetland protection and rational development and utilization.
It is suggested to find out the present situation and trend of wetland degradation as soon as possible, adjust and restore wetlands along rivers, floodplains, lakes and swamps, rationally allocate wetlands and increase different types of wetland nature reserves; Strict ecological evaluation should be carried out before development; Improve the scientific and technological content in wetland protection and development, seek the best mode of sustainable utilization of wetland resources, and give full play to the functions of wetland in peak shaving and flood storage and runoff regulation.
4.7 Establish eco-economic accounting system and eco-benefit compensation system.
In view of the long-term and overall situation of ecological engineering construction, support is given in finance, taxation and credit through policies and legislation. At present, the State Council has established a forest price system and a forest ecological benefit compensation system, and implemented the paid use of forest resources. According to the level of forest ecological benefits, it is not only conducive to improving the enthusiasm of operators, but also necessary to improve the ecological awareness of the whole people. Evaluating forests with brand-new ideas should be implemented as soon as possible. The system should also formulate practical regulations on grassland and wetland management in order to manage the whole land use system.
4.8 Conscientiously implement laws and policies, strengthen environmental education and raise environmental awareness.
Since liberation, China has formulated five environmental protection laws and regulations, eight resource protection laws, and promulgated a series of policies aimed at protecting the ecological environment. However, due to lax law enforcement, people's legal concept is indifferent, and incidents of destroying resources and environment occur frequently. Therefore, we must strengthen law enforcement, strengthen law enforcement supervision, and resolutely stop deforestation, steep slope land reclamation and unreasonable land use. At the same time, it is necessary to strengthen publicity and raise people's awareness of environmental protection and law.
4.9 Strengthen scientific research and application of new technologies.
Summarize and popularize existing scientific and technological achievements; Carry out scientific and technological demonstrations; Focusing on the scientific and technological problems that need to be solved urgently in resource protection and ecological engineering construction, especially the research on regional sustainable development, ecological system environmental protection function, small watershed comprehensive management mode, watershed management eco-economic evaluation, resource pricing, water conservation forest and soil and water conservation forest management technology, we will establish and improve the dynamic remote sensing system and basic geographic information of land use in the Yangtze River basin, establish corresponding databases and monitoring systems, organize long-term multi-disciplinary cooperation, and work together to study the flood formation mechanism of the Yangtze River and the water and land in flood formation.
refer to
1 Yang Yupo, etc. Study on Shelterbelt in the Upper Reaches of Yangtze River (Chuanjiang River). Beijing: Science Press, 1993.
2 Yang Meiqing. 1998 Analysis of the Yangtze River Flood: Natural and Man-made Disasters. Science and Technology Herald, 1998( 10)
3 Yu Xiaogan, Jiang Ruhu, Dou and so on. The water control strategy in the middle reaches of the Yangtze River should be re-examined. China Science Journal, 1998-08-26.
4 Yu Xiao, etc. Influence of reclamation of Poyang Lake on flood and its countermeasures. China Science Journal, 1998-09- 16.
5 Jia Quanxin. Why are there many floods in the Yangtze River? China Reform, 1998-08-06.
6 stone,,, etc. Calling "soil reservoir" is the fundamental strategy for flood control and disaster reduction. China Science Journal, 1998- 10-2.
Introduction to the first author
Li Wenhua, male, born in 1932, is a researcher of the Natural Resources Comprehensive Investigation Committee of China Academy of Sciences and an academician of China Academy of Engineering. His major is forest ecology, and he has been engaged in the research of nature conservation, agriculture and forestry and the ecosystem of Qinghai-Tibet Plateau for many years.
(1) Zhang Zhiqiang Wang Lixian. Hydrological and ecological effects of forest vegetation change. See: paper on the relationship between forest resources protection and ecological environment construction. 1998.
② Northeast Forestry University. Relationship between forest, environment and catastrophic flood. See: Seminar Paper on the Relationship between Forest Resources Protection and Ecological Environment Construction 45438+0998.
③ Zeng Siqi. 1reflection after the catastrophic flood in 998. Seminar paper on the relationship between forest resources protection and ecological environment construction. 1998
4 Shen Guofang. Deeply reflect and swear to be green. Seminar paper on the relationship between forest resources protection and ecological environment construction. 1998
⑤ He Qingtang, Yu. Water control lies in mountain management, and mountain management lies in forest development. Seminar paper on the relationship between forest resources protection and ecological environment construction 45438+0998
⑥ Shi Jisen and Zhang. Protect and develop forests, eliminate floods and ensure national social, economic and environmental security. See: paper of the seminar on the relationship between forest resources protection and ecological environment construction .45438+0998.