Influence of Middle Route Project on Environment and Land Use in Water Source Area

2.3. Impact of1Middle Line Project on Water Source Environment

2.3. 1. 1 is conducive to the development of large-scale agriculture.

The construction of South-to-North Water Transfer Project can directly and effectively improve the irrigation conditions in Nanyang City and increase the yield of crops per unit area. According to the preliminary estimation, after the completion of the relevant supporting water conservancy infrastructure in the Middle Route of South-to-North Water Transfer Project, the effective irrigation area in Nanyang City can reach 76%, basically alleviating the water shortage in agriculture in this city.

The Middle Route of South-to-North Water Transfer Project will provide a broad space for the ecological development of Nanyang City. The implementation of the middle route project of South-to-North Water Transfer Project is conducive to vigorously developing the industrial structure of eco-agriculture with high efficiency and characteristics based on ecological environment protection and focusing on the construction of pollution-free green industrial belts and the compound development of breeding industry.

2.3. 1.2 is beneficial to ecological environment protection and construction.

The middle route project of South-to-North Water Transfer Project will greatly improve the ecological environment of Nanyang City, and with the cooperation of some necessary supporting projects and measures, the whole area will be expected to restore its good natural ecological environment. The water ecological environment will be quickly and effectively restored. After the South-to-North Water Transfer Project, the rivers with reduced flow will be able to restore normal basic runoff and water level, the aquatic ecological environment on both sides will also be restored, the vitality of the river ecosystem will be enhanced, and the water-deficient reservoirs will be revived; Conducive to improving the local climate environment and increasing the rare lakes and mountains in Nanyang area; The normal recharge of groundwater and reasonable groundwater flow are conducive to improving the growth conditions of natural vegetation and the healthy development of artificial vegetation. The main canal of South-to-North Water Transfer Project with the length of 185 km will indirectly promote the better growth of natural vegetation and the development of biodiversity, and increase the balance and stability of the entire Nanyang ecosystem.

The South-to-North Water Transfer Project is conducive to the improvement of the artificial ecological environment in Nanyang City. The South-to-North Water Diversion Project can effectively restore the water demand of urban natural water bodies, thus improving the urban ecological environment conditions and meeting the growing requirements of people's living standards for the surrounding natural environment quality. The South-to-North Water Transfer Project will improve the water environment capacity of Nanyang as a whole, which is conducive to the improvement of the agricultural ecological environment in Nanyang.

2.3. 1.3 adverse effects

Nanyang is a natural barrier connecting northwest China and central China, an important gateway to prevent desertification, semi-desertification and sandstorm from invading the hinterland of central China eastward, and also a middle isolation zone between sulfur dioxide control areas in Xi 'an and northern Luoyang and acid rain control areas in Chongqing and southern Yichang. It is also the key implementation area of national natural forest protection, Yangtze River shelterbelt construction and the project of returning farmland to forest and grassland. The water source area is not only the key area of soil and water conservation in the middle and upper reaches of the Yangtze River, but also the key area of national ecological environment construction. From the development trend, with the excessive consumption of resources, the gradual increase of population and the gradual increase of industrial and mining enterprises in the reservoir area, there are the following outstanding problems to be solved urgently in the ecological environment.

(1) The ecological environment is fragile and the ability to resist natural disasters is limited: the upper reaches of Danjiangkou Reservoir involve Xichuan, Xixia, Neixiang and Dengzhou, with a total area of 639 1km2. Due to the unreasonable development and utilization of natural and human factors, the ecological environment around the reservoir area is poor. The distribution of forest resources is uneven, with more mountains in the north, west and southeast, and less in the middle, south and east; The structure of forest tree species is single, although the forest coverage rate is high, most of them are young, middle-aged and inefficient forests, with poor protection ability, decreased self-regulation ability and fragile ecosystem. Species resources are gradually decreasing, artificial logging and deforestation, serious water shortage in ecosystem, environmental pollution and so on. As a result, the number of animal (plant) species is obviously reduced, the distribution area is shrinking, and some rare species are on the verge of extinction.

(2) Serious soil erosion: serious soil erosion and deterioration of ecological environment in the river basin have brought serious crisis to the reservoir area. According to the survey, the area of soil erosion in the whole region is 3369.0 1km2, accounting for 53% of the total land area, and the average annual soil loss is 990× 104t. Serious soil erosion has caused serious siltation of reservoirs and rivers, cut-off of gullies and streams, difficulty in drinking water for people and livestock, declining fertility of cultivated land, frequent disasters, low and unstable grain yield, difficult restoration of surface vegetation and deterioration of ecological environment. Sediment deposition at the bottom of the reservoir reduces the effective storage capacity and water source regulation capacity. Due to the devastating destruction of vegetation in this area, the amount of soil erosion has increased year by year, which has endangered the service life of the first phase of Danjiangkou Dam. The upstream inflow decreases and the runoff becomes worse, which affects the water regulation. The sediment content is high in rainy season. According to relevant data, the current sediment deposition has reached 12× 108m3, and the sediment deposition depth in front of the dam has reached 15m, which has seriously affected the storage capacity and water storage capacity of the reservoir. At this rate of development, Danjiangkou Reservoir will become the second Sanmenxia Reservoir due to siltation in 60 years.

(3) The pollution problem is serious: there are no sewage treatment plants and domestic waste treatment plants in Xixia and Xichuan counties of Laoguan River, the main tributaries of Danjiangkou Reservoir. With the increase of urban population, the pollution of domestic sewage and domestic garbage will become more and more serious. Although the papermaking and chemical industry in Xichuan and Xixia counties of Laoguan River basin have reached the discharge standard, the water quality of Laoguan River has exceeded the water quality category of surface water environmental function zoning in some periods due to high operating cost, abnormal operation of environmental protection facilities and unreasonable industrial structure caused by a large number of small-scale mining in the upper reaches of Laoguan River. The unreasonable use of chemical fertilizers, pesticides and herbicides in agricultural production has further aggravated the water pollution trend of Danjiangkou Reservoir.

(4) The ecological environment along the main canal of the Middle Route of South-to-North Water Diversion Project can not be ignored: the total length of the main canal of South-to-North Water Diversion Project in Nanyang is 1.85km, and the Qiangangqiu area on the west side of Funiu Mountain is one of the famous rainstorm areas in China; The east side is relatively flat, with high land utilization rate and convenient transportation. It is the main producing area of grain, cotton and oil. However, due to drought and water shortage, the river runoff is reduced, the groundwater falling funnel is enlarged, the water quality is deteriorated, and the environmental pollution is serious.

(5) The legacy of the first-phase resettlement of Danjiangkou Reservoir has a great impact on the ecological environment of the reservoir area: the first-phase resettlement of Danjiangkou Reservoir began during the Great Leap Forward and the Cultural Revolution, and the whole resettlement work lacked scientific argumentation and long-term planning, and was basically carried out by administrative intervention, resulting in the situation of water forcing people to move, moving first and then settling down, and then blindly relying on it. In addition, the national investment is low, the resettlement standard is low, the production and living facilities such as water, electricity, roads and schools are not matched, and there are few basic fertile fields, which leads to unreasonable resettlement and great pressure on reservoir ecological environment protection.

2.3.2 Impact of the Mid-line Project on Land Use in the Water Source Area

According to estimates, the construction of the Middle Route of South-to-North Water Transfer Project will increase the submerged area of Nanyang by 144km2, including cultivated land1.31.8000 mu; The main canal passes through 26 townships in 6 counties (cities) of Nanyang City, covering a permanent area of 37,400 mu. Shelterbelt belts on both sides will occupy 55,600 mu of cultivated land. The reduction of land makes the contradiction between population and land shortage in Nanyang more prominent. The relocated population at the start of the project is 6,543,800+0,430, and about 60,000 people will be relocated after the relocation, totaling 203,000 people. Calculated by the average net population growth rate of 5‰, it is equivalent to the net growth of the newly added population in four years, which is equivalent to the reduction of cultivated land by 4% and the increase of more than 200,000 people. With the development of economy, the demand for non-agricultural land is also increasing, and the per capita cultivated land is decreasing. On the premise that population increase and land decrease are irreversible, the implementation of the South-to-North Water Transfer Project has undoubtedly greatly aggravated the contradiction between man and land in Nanyang.