Influence of Groundwater on Qinghai-Tibet Railway

Analysis of topography, climate and hydrology along Qinghai-Tibet railway and their influence on sand damage

Qinghai-Tibet Railway passes through an area with strong crustal movement, which is the regional unit with the strongest surface tectonic activity at present. There are a large number of folds and active fault zones, with broken rocks, loose soil, diverse landforms and serious diseases. At the same time, due to the high terrain and the influence of the alpine climate, the temperature difference is large, and the freeze-thaw weathering is strong, producing a large number of fine-grained materials such as cuttings, which provides a rich material source for sandstorm activities. There are wind-eroded gravel beaches similar to Gobi along the line, and large areas of extremely thick sediments are developed on the broken terrain. Especially in the river valleys and lakes where the railway passes through many water systems, there are various aeolian landforms composed of aeolian sand, which cause sand damage in wind and dry seasons. Limited to the construction and opening of the Qinghai-Tibet Railway in recent years, the natural environment along the railway and its influence on railway sand damage are not fully understood. Therefore, on the basis of predecessors' research, this paper investigates the topography, climate and hydrology along the Qinghai-Tibet Railway, and analyzes its types, distribution, characteristics and its influence on sand damage, in order to systematically understand the sand damage law of the Qinghai-Tibet Railway and provide basis for sand control.

1 materials and research methods

The data in this paper are obtained through field investigation and indoor analysis. In the field, combined with local meteorological data, the landform, temperature, precipitation, wind conditions, types, characteristics and distribution of rivers and lakes along the Qinghai-Tibet Railway were investigated. Indoor, mainly using Google Earth image interpretation and GIS processing, and consulting related literature, analyzing the impact of the above natural factors on railway sand damage.

2 investigation and analysis results

2. 1 terrain

Starting from Xining, the Qinghai-Tibet Railway has successively passed through the following main geomorphic units: Huangshui Valley, Sun Moon Mountain, Qinghai Lake, Guanjiao Mountain (Nanshan in Qinghai), Qaidam Basin, Kunlun Mountain, Chumar high plains, Kekexili Mountain, Xiushui River-Beilu River, Huofeng Mountain, Riaqiqiqu, Wuli Mountain and Basin, Tuotuo River, Kaixinling, Tongtianhe River, Buqu Valley and Hot Spring Basin. Except Sun Moon Mountain, Guanjiao Mountain, the northern slope of Kunlun Mountain, Kekexili Mountain, Huofeng Mountain, Kaixinling Mountain, Tanggula Mountain, Jiuzina Mountain, Nyainqentanglha Mountain and other steep terrain, the rest are mostly dome-shaped, with rounded and gentle slopes, basins and valleys generally spread in NWW-SEE direction, and the valleys are wide and shallow with gentle terrain. Therefore, except for the northern slope section of Kunlun Mountain, Yangbajing-Lhasa section belongs to a valley with steep slope, while the central sections such as Fenghuo Mountain, Kekexili Mountain, Kaixinling Mountain, Tanggula Mountain, Jiuzina Mountain and Nyainqentanglha Mountain have steep slopes, while the rest sections belong to high plains landform macroscopically, with ancient planation and flat and open terrain. Generally speaking, there are mountains and hills along the line, as well as high plains Basin between mountains. The lowest elevation of the whole line is 2220m (Xining Station) and the highest elevation is 5067 m (Tanggula Station). The section above 4000 m is 960km, accounting for 49% of the whole line, of which the frozen soil section is 550km, accounting for 28% of the whole line.

2.2 Climate

The Qinghai-Tibet Railway passes through high-altitude areas and lives inland, far from the ocean. Except the southeast monsoon to the east of Guanjiao Mountain, the southwest monsoon to the south of Nyainqentanglha Mountain and the inland arid climate of Qaidam Basin, other sections have unique cold, arid and semi-arid climate characteristics. Cold and cold, there is no summer all year round, the four seasons are not clear, and the climate is complex and changeable. In mountainous sections, with the increase of altitude, the climate presents a vertical zone.

The solar radiation along the Qinghai-Tibet Railway is strong and the sunshine time is long. Because of high altitude, low air pressure, thin air, low dust content and good transparency, solar radiation is absorbed, reflected and scattered in the atmosphere with little loss, so the intensity of solar radiation is far greater than that in other regions, ranking first in the country.

The Qinghai-Tibet Railway passes through the alpine region, with low average temperature, small annual variation and large daily variation.

The Qinghai-Tibet Railway is built in cold, arid and semi-arid areas, with less precipitation and uneven distribution in time and space. The annual precipitation in most areas along the line is 200-300mm, which varies greatly during the year, with uneven distribution and distinct wet and dry seasons. May-September is the rainy season, with the same season of rain and heat, with more convective precipitation, accounting for 90% of the whole year. It is the golden season of the climate along the railway, with less snowfall in dry season10-April. In terms of spatial distribution, Huangshui River Basin and Lhasa River Basin are less affected by the southeast monsoon and southwest monsoon respectively, with an annual precipitation of 300 mm Except for a few windward slopes in mountainous areas, the annual precipitation in most areas is less, especially in Qaidam Basin, where the annual precipitation is less than100 mm.

There are many windy days and strong winds along the Qinghai-Tibet Railway, which appear continuously for a long time. The annual average wind speed of most sections is 3-4, which exceeds the critical wind speed of sand blowing. A windy day refers to the day when the instantaneous wind speed is 8, and the total number of windy days in a year is the number of windy days in that year. The Qinghai-Tibet Railway is characterized by high and open terrain, drought and strong wind, especially in winter and the long dry and cold season of half a year, which is controlled by the westerly belt, mainly the westerly wind. At the same time, the Qaidam basin is affected by the cold front, and the wind is strong, which is the high value area of wind speed and gale days distribution in China. The number of windy days along the railway line is 50- 150d, with obvious seasonal variation, which is concentrated in winter and spring, synchronized with drought.10-May is the most, accounting for 75% of the number of windy days in the whole year, of which February-May accounts for half of the number of windy days in the whole year, especially in March, with more than two-thirds of windy days and less in summer and autumn. Strong winds are mainly concentrated in Wudaoliang-Amdo section. Among them, the number of windy days in Wudaoliang section is 135. 5d, extreme maximum wind speed; The number of windy days in Tuotuo reach is 167.8d, and the extreme maximum wind speed is 40.0m The number of windy days in Cuona Lake section is 148.8d, and the extreme maximum wind speed is 38.0m ..

In addition, due to strong convection, frequent lightning, active thunderstorms and more hail along the Qinghai-Tibet Railway. The annual average number of lightning is about 7600, accounting for 66.5% during the day, 33.5% at night, and the ratio of day to night is 2. 0, which is significantly higher than the lightning ratio of 1.2 in other parts of China. It mainly occurs from April to September, accounting for about 95% of the total lightning in the whole year. Especially, the annual average thunderstorm days along Amdo-Naqu section are about 80 days, accounting for 80 days from May to September. There are many hail days along the railway, ranking first in the country. Hail weather mainly occurs from June to September, accounting for about 80% of the annual hail days, of which Naqu is the most, with an average annual hail days of 35 days. Lightning, thunderstorm and hail threaten the safety of railway transportation.

The climate along the Qinghai-Tibet Railway belongs to five obvious types, namely, Xining-Guanjiaoshan section belongs to temperate continental semi-arid climate, Guanjiaoshan-Kunlun section belongs to temperate continental semi-arid climate, Kunlun-Tanggula section belongs to plateau cold region semi-arid climate, Tanggula-Nyainqentanglha section belongs to plateau sub-frigid zone semi-arid climate, and Nyainqentanglha-Lhasa section belongs to plateau temperate semi-arid climate.

2.3 Hydrology

From Xining to Lhasa, the Qinghai-Tibet Railway passes through seven major water systems, namely, the Yellow River, Qinghai Lake, Qaidam Basin, Yangtze River, Zhajia Zangbo River, Nujiang River and Yarlung Zangbo River, among which six major river basins are Sun Moon Mountain, Guanjiao Mountain (Nanshan in Qinghai), Kunlun Mountain, Tanggula Mountain, Touer jiusan and Nyainqentanglha Mountain. The hydrological environment along the railway is influenced by geological structure, lithology, landform, climate, vegetation and other factors. Because of the existence of many rivers and permafrost, the burial and distribution of groundwater in permafrost regions are more complicated.

Numerous lakes are another important feature of the hydrological environment along the Qinghai-Tibet Railway. The larger lakes along the railway include Qinghai Lake in the northeast, Crook Lake near Delingha City, Tuosu Lake, Dabusong Lake near Golmud City, Cuona Lake near Amdo and Namco Lake near Dangxiong. According to the degree of mineralization, there are freshwater lakes and saltwater lakes along the line, and according to the causes, there are dammed lakes (such as Qingshui Lake, Salt Lake and Haiding Ruoer Lake). ), structural lakes (such as Yaxicuo in Tuotuo Valley) and hot melt lakes. In the vast areas along the railway, hot melt lakes and ponds are the main ones, accounting for more than 85% of the total. According to statistics, there are more than 600 hot-melt lakes and ponds in the range of * * * about 1 km on both sides of the Chumar River high plains Railway. The reason why many lakes exist is that the core of Qinghai-Tibet Plateau still retains the ancient planation plane, the erosion of the river source has not yet arrived, and the lake basin has not been cut by rivers.

In addition, swamps and wetlands are widely distributed along the Qinghai-Tibet Railway. In warm season, surface water flow or water in frozen soil layer is blocked during migration, and due to cold and weak evaporation, it gathers in low-lying areas to form wetlands. Generally, it grows on the edge of high plains, valley and alluvial fan with high groundwater level, with relatively flat terrain and poor surface water discharge. It has various shapes, such as ellipse, circle, strip or irregular shape. According to its causes, it can be divided into six types: hot melt type, flood plain type, bedrock fissure water seepage type, structural fissure water seepage type, water accumulation type and alluvial fan edge seepage type. The swamp wetlands of Qinghai-Tibet Railway are mainly distributed in Xidatan, Thawing Spring, high plains of Chuma River, Hoh Xil, Huofeng Mountain, Kaixinling, Buqu Valley, Hot Spring Basin, Tanggula Mountain Basin, Zhajia Zangbo Valley, Touerjiu Mountain Area, the middle and upper reaches of Naqu River and Lhasa River, and in the low-lying areas along the route, and most of them are filled and dug manually.

3 discussion

The influence of the topography along the Qinghai-Tibet Railway on sand hazards is as follows: many river valleys and lake basins where the railway passes are widely distributed in loose proluvial and rich in sand sources. Therefore, the sand damage is relatively concentrated, mainly distributed in the valleys and lake basins of Qaidam Basin (Xitieshan and Fushaliang), Hongliang River, Xiushui-Beilu River, Tuotuo River, Tongtianhe River, Zhajia Zangbo and Cuona Lake. The influence of climate on sand damage is as follows: the daily temperature difference is large, the positive and negative alternation time is long, and the freezing and thawing weathering is strong, which leads to loose and broken surface, weakened wind erosion resistance, enhanced erodibility and increased release of sand substances, providing material sources for sand damage; Less annual precipitation, uneven distribution, and scarce rain and snow in winter and spring provide favorable conditions for sand damage, especially in some areas of the Qaidam Basin, where the annual precipitation is less than 100mm and the sand damage is serious. There are many westerly winds in winter and spring, which are synchronized with drought, providing aerodynamic conditions for sand damage. The influence of hydrology on sand damage is as follows: in the summer half year, due to the erosion of running water, a large number of weathered rocks, sandy meadows and grassland debris are brought to river valleys and lake basins, forming river and lake sediments; In winter, rivers and lakes are in dry season, and the effect of running water is weakened. Most of the riverbeds and lakesides are exposed, and the sediments are loose and broken, which are blown to the railway by the wind. Especially in the section from Xitieshan to Lhasa, the railway runs generally north-south, the valley runs generally east-west, and the dominant wind direction is west wind. The direction of the river valley is consistent and the dominant wind direction is nearly perpendicular to the direction of the railway, which makes the sand flow accumulate when it is blocked, resulting in more serious sand damage on the west side of the railway than on the east side.

4 conclusion

(1) The Qinghai-Tibet Railway has a high altitude, and the landforms it passes through are mainly valleys, basins and mountains, belonging to an arid and semi-arid climate zone. From Xining to Lhasa, it passes through seven river and lake systems: Yellow River, Qinghai Lake, Qaidam Basin, Yangtze River, Zhajia Zangbo, Nujiang River and Yarlung Zangbo River.

(2) There are abundant sand sources along the Qinghai-Tibet Railway, and the sand damage is mainly distributed in river valleys and lake basins in space, and concentrated in winter and spring in time. The sand damage on the west side of the railway is more serious than that on the east side.

& lt！ -

￥

5.9

Baidu library VIP limited time discount is now open, enjoy 600 million +VIP content.

Go get it now

Analysis of topography, climate and hydrology along Qinghai-Tibet railway and their influence on sand damage

Analysis of topography, climate and hydrology along Qinghai-Tibet railway and their influence on sand damage

Qinghai-Tibet Railway passes through an area with strong crustal movement, which is the regional unit with the strongest surface tectonic activity at present. There are a large number of folds and active fault zones, with broken rocks, loose soil, diverse landforms and serious diseases. At the same time, due to the high terrain and the influence of the alpine climate, the temperature difference is large, and the freeze-thaw weathering is strong, producing a large number of fine-grained materials such as cuttings, which provides a rich material source for sandstorm activities. There are wind-eroded gravel beaches similar to Gobi along the line, and large areas of extremely thick sediments are developed on the broken terrain. Especially in the river valleys and lakes where the railway passes through many water systems, there are various aeolian landforms composed of aeolian sand, which cause sand damage in wind and dry seasons. Limited to the construction and opening of the Qinghai-Tibet Railway in recent years, the natural environment along the railway and its influence on railway sand damage are not fully understood. Therefore, on the basis of predecessors' research, this paper investigates the topography, climate and hydrology along the Qinghai-Tibet Railway, and analyzes its types, distribution, characteristics and its influence on sand damage, in order to systematically understand the sand damage law of the Qinghai-Tibet Railway and provide basis for sand control.

1 materials and research methods

The data in this paper are obtained through field investigation and indoor analysis. In the field, combined with local meteorological data, the landform, temperature, precipitation, wind conditions, types, characteristics and distribution of rivers and lakes along the Qinghai-Tibet Railway were investigated. Indoor, mainly using Google Earth image interpretation and GIS processing, and consulting related literature, analyzing the impact of the above natural factors on railway sand damage.

2 investigation and analysis results

2. 1 terrain

Starting from Xining, the Qinghai-Tibet Railway has successively passed through the following main geomorphic units: Huangshui Valley, Sun Moon Mountain, Qinghai Lake, Guanjiao Mountain (Nanshan in Qinghai), Qaidam Basin, Kunlun Mountain, Chumar high plains, Kekexili Mountain, Xiushui River-Beilu River, Huofeng Mountain, Riaqiqiqu, Wuli Mountain and Basin, Tuotuo River, Kaixinling, Tongtianhe River, Buqu Valley and Hot Spring Basin. Except Sun Moon Mountain, Guanjiao Mountain, the northern slope of Kunlun Mountain, Kekexili Mountain, Huofeng Mountain, Kaixinling Mountain, Tanggula Mountain, Jiuzina Mountain, Nyainqentanglha Mountain and other steep terrain, the rest are mostly dome-shaped, with rounded and gentle slopes, basins and valleys generally spread in NWW-SEE direction, and the valleys are wide and shallow with gentle terrain. Therefore, except for the northern slope section of Kunlun Mountain, Yangbajing-Lhasa section belongs to a valley with steep slope, while the central sections such as Fenghuo Mountain, Kekexili Mountain, Kaixinling Mountain, Tanggula Mountain, Jiuzina Mountain and Nyainqentanglha Mountain have steep slopes, while the rest sections belong to high plains landform macroscopically, with ancient planation and flat and open terrain. Generally speaking, there are mountains and hills along the line, as well as high plains Basin between mountains. The lowest elevation of the whole line is 2220m (Xining Station) and the highest elevation is 5067 m (Tanggula Station). The section above 4000 m is 960km, accounting for 49% of the whole line, of which the frozen soil section is 550km, accounting for 28% of the whole line.

2.2 climate

The Qinghai-Tibet Railway passes through high-altitude areas and lives inland, far from the ocean. Except the southeast monsoon to the east of Guanjiao Mountain, the southwest monsoon to the south of Nyainqentanglha Mountain and the inland arid climate of Qaidam Basin, other sections have unique cold, arid and semi-arid climate characteristics. Cold and cold, there is no summer all year round, the four seasons are not clear, and the climate is complex and changeable. In mountainous sections, with the increase of altitude, the climate presents a vertical zone.

The solar radiation along the Qinghai-Tibet Railway is strong and the sunshine time is long. Because of high altitude, low air pressure, thin air, low dust content and good transparency, solar radiation is absorbed, reflected and scattered in the atmosphere with little loss, so the intensity of solar radiation is far greater than that in other regions, ranking first in the country.

The Qinghai-Tibet Railway passes through the alpine region, with low average temperature, small annual variation and large daily variation.

The Qinghai-Tibet Railway is built in cold, arid and semi-arid areas, with less precipitation and uneven distribution in time and space. The annual precipitation in most areas along the line is 200-300mm, which varies greatly during the year, with uneven distribution and distinct wet and dry seasons. May-September is the rainy season, with the same season of rain and heat, with more convective precipitation, accounting for 90% of the whole year. It is the golden season of the climate along the railway, with less snowfall in dry season10-April. In terms of spatial distribution, Huangshui River Basin and Lhasa River Basin are less affected by the southeast monsoon and southwest monsoon respectively, with an annual precipitation of 300 mm Except for a few windward slopes in mountainous areas, the annual precipitation in most areas is less, especially in Qaidam Basin, where the annual precipitation is less than100 mm.

There are many windy days and strong winds along the Qinghai-Tibet Railway, which appear continuously for a long time. The annual average wind speed of most sections is 3-4, which exceeds the critical wind speed of sand blowing. A windy day refers to the day when the instantaneous wind speed is 8, and the total number of windy days in a year is the number of windy days in that year. The Qinghai-Tibet Railway is characterized by high and open terrain, drought and strong wind, especially in winter and the long dry and cold season of half a year, which is controlled by the westerly belt, mainly the westerly wind. At the same time, the Qaidam basin is affected by the cold front, and the wind is strong, which is the high value area of wind speed and gale days distribution in China. The number of windy days along the railway line is 50- 150d, with obvious seasonal variation, which is concentrated in winter and spring, synchronized with drought.10-May is the most, accounting for 75% of the number of windy days in the whole year, of which February-May accounts for half of the number of windy days in the whole year, especially in March, with more than two-thirds of windy days and less in summer and autumn. Strong winds are mainly concentrated in Wudaoliang-Amdo section. Among them, the number of windy days in Wudaoliang section is 135. 5d, extreme maximum wind speed; The number of windy days in Tuotuo reach is 167.8d, and the extreme maximum wind speed is 40.0m The number of windy days in Cuona Lake section is 148.8d, and the extreme maximum wind speed is 38.0m ..

In addition, due to strong convection, frequent lightning, active thunderstorms and more hail along the Qinghai-Tibet Railway. The annual average number of lightning is about 7600, accounting for 66.5% during the day, 33.5% at night, and the ratio of day to night is 2. 0, which is significantly higher than the lightning ratio of 1.2 in other parts of China. It mainly occurs from April to September, accounting for about 95% of the total lightning in the whole year. Especially, the annual average thunderstorm days along Amdo-Naqu section are about 80 days, accounting for 80 days from May to September. There are many hail days along the railway, ranking first in the country. Hail weather mainly occurs from June to September, accounting for about 80% of the annual hail days, of which Naqu is the most, with an average annual hail days of 35 days. Lightning, thunderstorm and hail threaten the safety of railway transportation.

The climate along the Qinghai-Tibet Railway belongs to five obvious types, namely, Xining-Guanjiaoshan section belongs to temperate continental semi-arid climate, Guanjiaoshan-Kunlun section belongs to temperate continental semi-arid climate, Kunlun-Tanggula section belongs to plateau cold region semi-arid climate, Tanggula-Nyainqentanglha section belongs to plateau sub-frigid zone semi-arid climate, and Nyainqentanglha-Lhasa section belongs to plateau temperate semi-arid climate.

2.3 Hydrology

From Xining to Lhasa, the Qinghai-Tibet Railway passes through seven major water systems, namely, the Yellow River, Qinghai Lake, Qaidam Basin, Yangtze River, Zhajia Zangbo River, Nujiang River and Yarlung Zangbo River, among which six major river basins are Sun Moon Mountain, Guanjiao Mountain (Nanshan in Qinghai), Kunlun Mountain, Tanggula Mountain, Touer jiusan and Nyainqentanglha Mountain. The hydrological environment along the railway is influenced by geological structure, lithology, landform, climate, vegetation and other factors. Because of the existence of many rivers and permafrost, the burial and distribution of groundwater in permafrost regions are more complicated.

Numerous lakes are another important feature of the hydrological environment along the Qinghai-Tibet Railway. The larger lakes along the railway include Qinghai Lake in the northeast, Crook Lake near Delingha City, Tuosu Lake, Dabusong Lake near Golmud City, Cuona Lake near Amdo and Namco Lake near Dangxiong. According to the degree of mineralization, there are freshwater lakes and saltwater lakes along the line, and according to the causes, there are dammed lakes (such as Qingshui Lake, Salt Lake and Haiding Ruoer Lake). ), structural lakes (such as Yaxicuo in Tuotuo Valley) and hot melt lakes. In the vast areas along the railway, hot melt lakes and ponds are the main ones, accounting for more than 85% of the total. According to statistics, there are more than 600 hot-melt lakes and ponds in the range of * * * about 1 km on both sides of the Chumar River high plains Railway. The reason why many lakes exist is that the core of Qinghai-Tibet Plateau still retains the ancient planation plane, the erosion of the river source has not yet arrived, and the lake basin has not been cut by rivers.

In addition, swamps and wetlands are widely distributed along the Qinghai-Tibet Railway. In warm season, surface water flow or water in frozen soil layer is blocked during migration, and due to cold and weak evaporation, it gathers in low-lying areas to form wetlands. Generally, it grows on the edge of high plains, valley and alluvial fan with high groundwater level, with relatively flat terrain and poor surface water discharge. It has various shapes, such as ellipse, circle, strip or irregular shape. According to its causes, it can be divided into six types: hot melt type, flood plain type, bedrock fissure water seepage type, structural fissure water seepage type, water accumulation type and alluvial fan edge seepage type. The swamp wetlands of Qinghai-Tibet Railway are mainly distributed in Xidatan, Thawing Spring, high plains of Chuma River, Hoh Xil, Huofeng Mountain, Kaixinling, Buqu Valley, Hot Spring Basin, Tanggula Mountain Basin, Zhajia Zangbo Valley, Touerjiu Mountain Area, the middle and upper reaches of Naqu River and Lhasa River, and in the low-lying areas along the route, and most of them are filled and dug manually.