Qaidam Basin

The Qaidam Basin is located in the northwest of Qinghai Province and is one of the famous inland arid basins in my country. The basin connects to the Tibet Autonomous Region in the south, Gansu Province in the north, Xinjiang Uygur Autonomous Region in the west, and Haibei and Hainan Tibetan Autonomous Prefectures in Qinghai Province in the east. It is the center of exchanges between Qinghai, Gansu, Xinjiang and Tibet. The geographical coordinates are 90°00′～99°20′E, 34°40′～39°20′N, with a total area of ??254,900 km2, of which the plain area is 127,400 km2 and the mountainous area is 127,500 km2. In terms of administrative divisions, the Qaidam Basin is mostly under the jurisdiction of Qinghai Province, except for a small part in the west that is under the jurisdiction of the Xinjiang Uygur Autonomous Region and the northeastern Gansu Province.

The Qaidam Basin is located on the northeastern edge of the Qinghai-Tibet Plateau. It is a typical inland arid basin. The basin is surrounded by mountains, with the Altyn Mountains in the northwest, the Qilian Mountains in the northeast, the Kunlun Mountains in the south, and the Ora Mountains in the east. . The Seshteng Mountain, Xiti Mountain and Amunike Mountain in the middle of the basin divide the main basin into Gaskul Lake, Sugan Lake, Mahai, Yuka, Dachaidan, Xiaoqaidan, Delingha and Ulan. and Chahanwusu and other secondary basins, forming a special landform landscape with basins within basins and basins connected to each other. Macroscopically, from the periphery to the center of the basin, extremely high mountains, mountains, hills, piedmont flood plains, alluvial flood plains, alluvial lake plains and lake plains develop in sequence. Swamps, salt marshes and lake marshes are superimposed on the alluvial lake basin. On plains and lake plains.

(1) Groundwater function evaluation index system

In the Qaidam Basin groundwater resource function evaluation index, indicators related to groundwater storage resources are not considered. In the ecological environment function evaluation, three aspects: lake landscape, vegetation and land are mainly considered. In the Qaidam Basin, due to the small scale of groundwater exploitation, the geological environmental function of groundwater is not obvious. Except for Lenghu Town, which caused local saltwater intrusion due to unreasonable well placement, no ground subsidence or saltwater was caused in other areas. Move the question down. In the decay of the groundwater system, considering that the increase in groundwater salinity in the Qaidam Basin is related to the shallow depth of groundwater and strong evaporation, the spring flow is mainly affected by changes in groundwater levels, and the groundwater level is mainly controlled by groundwater infiltration and recharge, we selected groundwater The correlation between quality and water level, the correlation between spring changes and groundwater, and the ratio indicators of groundwater recharge variability and water level variation (Figure 8-15).

(2) Groundwater function evaluation zoning

The Qaidam Basin groundwater system is a unified whole for groundwater function evaluation. According to the burial conditions of the groundwater system in the basin and the status of groundwater exploitation and utilization, it is divided into 14 first-level areas, 47 second-level areas, and 101 third-level areas (Figure 8-16). Each first-level area maintains a complete system of groundwater recharge, runoff and discharge cycles. Within the first-level area, the second-level area is divided according to hydrogeological conditions, mainly based on the distribution of the hydrochemical field of groundwater and the conditions of the groundwater system in the secondary basin. Within the secondary area, three-level areas (zones) are divided according to groundwater supply, runoff and discharge conditions. On this basis, the units were divided into 2 × 2 km2 grids, uniformly numbered, and there were a total of 27,933 effective units.

Figure 8-15 Qaidam Basin groundwater function evaluation index system

Figure 8-16 Qaidam Basin groundwater function evaluation zoning map

(3) Groundwater function evaluation results

1. Groundwater resource function status

The Qaidam Basin groundwater resource function evaluation results are shown in Figure 8-17. In the supply runoff zone of the Naringol River Basin, the resource function of groundwater is the strongest. In the discharge zone downstream of it, the supply runoff zone of the Golmud River Basin and the Tartaling River Basin, the resource function of groundwater is stronger. In the Lenghu Basin and Quanji River Basin, the resource function of groundwater is weak. Among them, the groundwater resource function in the salt brine distribution area is the weakest. In this basin, areas suitable for large-scale mining are only distributed in the groundwater supply runoff zone of the Nalingol River Basin. Areas that can be concentrated are mainly distributed in the discharge zone of the Nalingol River Basin, the supply runoff zone of the Golmud River Basin and the Tajikistan River Basin. Taling River Basin. In the salt brine distribution area, it is an area that cannot be mined because it has become a liquid mineral deposit and is not a freshwater resource.

Figure 8-17 Functional distribution map of groundwater resources in the Qaidam Basin

2. Groundwater ecological function status

Ecological function evaluation results of groundwater in the Qaidam Basin , as shown in Figure 8-18. The ecological function of groundwater in the drainage zone of each river basin is strong, while the ecological function of groundwater in the recharge runoff zone is weak. The areas with the strongest ecological functions of groundwater are mainly distributed in various oasis zones. When the ecological function level of groundwater is above average, the protection of ecological functions of groundwater must be paid attention to in the development and utilization of groundwater, and the development and utilization of groundwater should be carried out on the premise of protecting the ecological functions of groundwater.

3. Groundwater geological environment function status

The evaluation results of the geological environment function of groundwater in the Qaidam Basin are shown in Figure 8-19. In the oasis zone and its surrounding areas within the drainage zone of each river basin, the geological environmental function of groundwater is relatively strong. In the salty brine distribution area downstream of the oasis belt, the geological environmental function of groundwater is average. In the oasis belt, due to the widespread distribution of springs, changes in groundwater levels have a greater impact on spring dynamics. Therefore, the geological environment function of groundwater in the oasis belt is strong. Therefore, when developing and utilizing groundwater in this area, it is necessary to pay attention to the protection of the geological environment function of groundwater.

4. Sustainability status of comprehensive groundwater functions

Based on the resource function, ecological function and geological environment function of groundwater, the sustainability evaluation results of comprehensive groundwater functions in Qaidam Basin were obtained. As shown in Figure 8-20. Areas with strong sustainable utilization of groundwater are mainly distributed in the supply-runoff zones of the three major river basins of Naringol River, Golmud River and Tartaling River. The functions of groundwater resources in these areas have obvious advantages, and the ecological functions of groundwater are The environment function is weak. The sustainable utilization of groundwater in the piedmont recharge runoff zone of the rest of the basins is average-strong. The sustainable utilization of groundwater in the recharge runoff zone in the central area of ??the Qaidam Basin and the saline brine distribution area in the discharge zone of each basin is the weakest. The groundwater can be Areas with weak sustainable utilization are mainly distributed in the oasis areas of drainage belts in various river basins.

Figure 8-18 Distribution map of groundwater ecological functions in Qaidam Basin

Figure 8-19 Distribution map of groundwater geological environment functions in Qaidam Basin

Figure 8 -20 Sustainability distribution map of comprehensive groundwater functions in the Qaidam Basin

(4) Groundwater functional zoning

Based on the evaluation results of groundwater functions in the Qaidam Basin, 3 secondary areas are divided , 8 third-level areas (Figure 8-21).

1. Groundwater resource functional area

The areas where groundwater resources can be exploited on a large scale in the Qaidam Basin are mainly distributed in the supply runoff zone of the Nalingol River Basin in the Qaidam Basin and the Golmud River The watershed recharges the runoff zone (Figure 8-21). The above two zones have strong sustainable utilization of groundwater resources, and the functions of groundwater resources dominate. Groundwater has basically no direct relationship with the surface ecological environment and geological environment. They can provide a large amount of underground freshwater resources and can lay out water sources on a large scale.

The areas where groundwater can be exploited concentratedly in the Qaidam Basin are mainly distributed in the groundwater recharge runoff zone or runoff zone around the basin, including the gaskule Lake watershed recharge runoff zone and runoff zone, and the Dalangtan watershed groundwater runoff zone. Belt, Lenghu Basin groundwater runoff zone, Mahai Basin groundwater recharge runoff zone, Dachaidan Basin groundwater recharge runoff zone, Tataling River Basin groundwater recharge runoff zone, Xiao Qaidandong Basin groundwater runoff zone, Barogengol River Basin Groundwater recharge runoff zone, Bayingol River Basin groundwater recharge runoff zone, Gahai Lake groundwater recharge runoff zone, Keke Salt Lake-Dulan Lake Basin recharge runoff zone, Mangya Lake Basin recharge runoff zone and runoff zone, Xidabu The Xun Lake Basin recharge runoff zone, the Tuolahai River Basin groundwater recharge runoff zone, the Hongliugou-Dashuigou Basin groundwater recharge runoff zone, and the South and North Holusun Lake Basin recharge runoff zones (Figure 8-21). In such areas, the sustainable utilization of groundwater resources is strong, the function of groundwater resources is dominant, and the ecological functions and geological environment functions are secondary. The underground freshwater resources are relatively abundant, and small and medium-sized water sources can be concentrated. The relationship between groundwater and surface ecology and geological environment is not obvious, and large-scale exploitation of groundwater will not cause disastrous ecological or geological environmental problems.

Figure 8-21 The comprehensive functional sustainable zoning map of groundwater in the Qaidam Basin

The groundwater resources in the Qaidam Basin can be exploited in scattered areas, distributed in patches in Qaidam Around the Mu Basin, it includes the groundwater runoff zone of the Dalangtan Basin, the groundwater recharge runoff zone of the Bayingol River Basin, the groundwater recharge runoff zone of the Bayingol River Basin, the groundwater recharge runoff zone of the Huahai sub-basin, the groundwater recharge runoff zone of the Quanji River Basin, the sand The groundwater recharge runoff zone in the Liuhe River Basin (Figure 8-21). The sustainability of groundwater in these areas is average, and the conditions of groundwater resources are average. Although it is not conducive to the development and utilization of groundwater, there are no obvious ecological and geological environmental problems in such areas. Among the three major functions, the groundwater resource function dominates. For arid inland basins It is also an important water source, so it can be exploited on a small scale and dispersedly.

2. Groundwater ecological functional zone

The groundwater ecological functional zone in the Qaidam Basin is mainly distributed in the drainage zone in the center of the basin and the recharge runoff zone in individual basins. The groundwater in these areas It has a strong maintenance effect on surface wetlands, lake landscapes, vegetation, and soil. The various attributes of ecological functions are basically in a strong state in these areas, while the groundwater resource functions and geological environment functions are relatively weak. According to the particularity of ecological problems in different zones, they are divided into vegetation protection zones, landscape protection zones, land protection zones and landscape development zones.

In the vegetation protection zone of the Qaidam Basin, the ecological function of groundwater dominates. Among the ecological functional attributes of groundwater in the region, the maintenance of the vegetation environment is dominant. The maintenance of the vegetation environment by groundwater is average-strong. status.

Mainly distributed in the oasis belt of the basin, including the groundwater discharge zone in the Timulik River Basin, the groundwater discharge zone in the Kuangou-Baozigou Basin, the groundwater discharge zone in the Lenghu Basin, the first groundwater discharge zone in the Huahaizi Basin east of Sugan Lake, and the Sugan Lake Groundwater Drainage Zone, Xiaosugan Lake Groundwater Drainage Zone, Mahai Basin Groundwater Drainage Zone, Dachaidan Basin Groundwater Drainage Zone, Yike Qaidam Lake Groundwater Drainage Zone, Tataling River Basin Groundwater Drainage Zone, Barrow Genggol River Basin Groundwater Drainage Zone, Bayingol River Basin Groundwater Drainage Zone, Shuangshixia-Hongyahuo Basin Groundwater Drainage Zone, Mangya Lake Groundwater Drainage Zone, Bayingol River Basin Groundwater Drainage Zone, Nalinguo The groundwater discharge zone in the Lehe River Basin, the groundwater discharge zone in the Utumeiren River Basin, the groundwater discharge zone in the Lalingzao Huohe River Basin, the groundwater discharge zone in the Xiaozaohuo River Basin, the groundwater discharge zone in the Dazaohuohe River Basin, the groundwater discharge zone in the Tolahai River Basin, Golmud River Basin Groundwater Drainage Zone, Hongliugou-Dashuigou Basin Groundwater Drainage Zone, Shaliu River Basin Groundwater Drainage Zone, Nomuhong River Basin Groundwater Drainage Zone, Chahanwusu River Basin Groundwater Drainage Zone, Hongshui River-Yikgoll River basin groundwater discharge zone, Xiangrid River basin groundwater discharge zone. The groundwater in these areas is the water of life in the oasis zone and is almost the only water source for the vegetation in the oasis zone. The oasis zone is the green life zone most suitable for human habitation and production in the entire basin. Therefore, the shallow water in these zones is not suitable for large-scale exploitation. , and the ecological water level of its groundwater should be reasonably regulated to protect the ecological balance of the oasis zone.

In the landscape protection zone of the Qaidam Basin, the ecological function of groundwater is dominant. Among the ecological functional attributes of groundwater in the region, landscape environment maintenance and water environment correlation are dominant. Groundwater plays a dominant role in the landscape environment and The maintenance of the water environment is in a strong-strong state. It is mainly distributed in the drainage zone where lakes are widely distributed in the center of the basin, including the groundwater runoff zone of Gaskule Lake, the groundwater drainage zone of Gaskule Lake, the groundwater drainage zone of Great Sugan Lake, the groundwater runoff zone of Great Sugan Lake, and the groundwater discharge zone of Sugan Lake. Taking the groundwater discharge zone and the first discharge zone of the Xihuahai sub-basin, the groundwater discharge zone of Dezongmahai Lake, the groundwater runoff zone of Dezongmahai Lake, the groundwater discharge zone of Baga Qaidam Lake, and the groundwater runoff zone of Baga Qaidam Lake , Tuosu Lake Groundwater Drainage Zone, Saishike River Basin Groundwater Drainage Zone, Keke Salt Lake-Dulan Lake Groundwater Drainage Zone, Dulan River Basin Groundwater Drainage Zone, Mangya Lake Groundwater Drainage Zone, Shuangshixia-Hongyahuo Watershed Groundwater discharge zone, east and west Taijinel Lake groundwater discharge zone, west Dabson Lake groundwater discharge zone, east Dabson Lake groundwater discharge zone, south and north Holusun Lake groundwater discharge zone. The groundwater in these areas has a significant role in maintaining surface lakes and wetlands, and the groundwater is mostly highly mineralized salt water, which is not suitable for exploitation and utilization. Therefore, these areas focus on landscape protection.

In the Qaidam Basin Land Reserve, the ecological function of groundwater has significant advantages. Among the ecological functional attributes of groundwater in the region, the correlation with the land environment occupies a dominant position. The maintenance of the groundwater to the land environment is relatively strong - strong. status. This type of area is mainly agricultural land in shallow groundwater buried areas in the basin, including the northern part of the groundwater runoff zone in the Golmud River Basin, the northern part of the groundwater recharge runoff zone in the Hongliugou-Dashuigou Basin, the northern part of the groundwater recharge runoff zone in the Nomuhong River Basin, and the Bayinguo River Basin. Groundwater recharges the southern part of the runoff zone in the Lehe River Basin. The ecological and environmental problems in these areas are mainly reflected in the following: farmland irrigation mainly relies on surface water, using the traditional flood irrigation method. Due to poor drainage and rising groundwater levels, serious secondary salinization of the soil has occurred. Therefore, in these areas, The existing irrigation methods should be changed, mixed irrigation with surface water and groundwater should be used, groundwater should be mined appropriately, water levels should be lowered, and land quality should be protected and improved.

In the Qaidam Basin Landscape Development Area, the ecological conditions are poor. However, due to the special wind erosion landform formed by the special climate of the Qaidam Basin, the area can be developed as a tourist landscape. This type of area is mainly distributed in the groundwater runoff zone of Dalangtan Dry Salt Lake, the groundwater discharge zone of Dalangtan Dry Salt Lake, the groundwater runoff zone of Salt Lake-Lenghu Lake, and the groundwater runoff zone of East and West Taijinaier Lake. The sustainable utilization of groundwater resources is poor. Compared with other areas in the basin, the functions of groundwater resources, ecological functions and geological environment are all weak. It is the area with the worst ecological environment in the Qaidam Basin. It is deserted and is also a source of sand in the Qaidam Basin. The area has a large area of ??wind-eroded landforms. The famous Devil City in the Qaidam Basin belongs to this area. Therefore, it can be used as a tourist landscape development area based on the particularity of its topography and landforms.

3. Groundwater geological environment functional zone

In the groundwater geological environment functional zone of Qaidam Basin, attention should be paid to the protection of groundwater geological environment functions, and groundwater ecological functions can be selective protection. In these areas, it is necessary to demonstrate whether groundwater is suitable for exploitation and utilization, and to reasonably determine the recoverable amount of groundwater.

As mentioned before, the groundwater geological environment problems in the Qaidam Basin mainly occur in the eastern part of the groundwater discharge zone in the Lenghu Basin. The main manifestations are that large-scale exploitation of groundwater causes a significant drop in the groundwater level and leads to salt water intrusion downstream. Therefore, this area is regarded as a groundwater geological environment functional area and named as saltwater intrusion area (B3-1). Although this area is small and has little impact on the entire basin, its separate division has warning significance for groundwater exploitation near the saltwater and freshwater interfaces in other basins.