1) The Yumen-Tashik, Anshi-Dunhuang, and Huahai basins in the basin are sedimentary basins since the Cenozoic, in which huge thicknesses of land-sourced semi-colluvial-loose foothill-phase and river-lake-phase materials have accumulated. The boundaries of the basins are controlled by regional ruptures and tectonic uplift, and the basement boundary is dominated by the Upper Neogene (N2)-Lower Pleistocene (Qp1) strata.
2) The main aquifer in the study area mainly consists of the Middle and Upper Pleistocene pore submerged and pressurized water aquifer and the Holocene pore submerged aquifer, which are distributed in the alluvial and alluvial-lake formations of each basin, and the lithology of the aquifer is alluvial gravel and cobble, sand gravel, sand, and alluvial-lake sand, sub-sand, and sub-clay. In addition, in the Yumen Township area of the underground Pliocene - Lower Pleistocene gravel, endowed with water richness, good water quality, water supply significance of underground freshwater.
3) Under the double influence of climate aridification and human activities, the groundwater level in Shule River Basin has shown a regional downward trend in the past 50 years, and the decline rate is larger in the southern Yumen - Tashil Basin, smaller in the northern Huahai Basin and Anxi - Dunhuang Basin, and the southern and northern basins have the characteristics of gradually becoming smaller from the mountain front to the fine soil plains.
4) At the end of 2002, the water level of top of the floodplain fan decreased significantly after water storage of Changma Reservoir to realize the joint regulation of three reservoirs. After the storage of water in Changma Reservoir in late 2002, the water level at the top of the flooding fan decreased significantly, while the water level in some receiving areas of Changma, Shuangta and Huahai Irrigation Districts increased. The water level in the Danghe Irrigation District is on a downward trend due to over-exploitation of groundwater, and the Yueya Spring is also threatened as a result. The spring water resources at the front edge of the Changma flooding fan show a decreasing trend year by year, decreasing from 244.7 million m3 in 1977 to 156.8 million m3 in 2004, a decrease of 087.9 million m3, and the spring brain is generally shifted downward.
4) Groundwater is mainly distributed within the dry delta of Shule River and Danghe River. Various forms of seepage in the Gobi zone after the rivers come out of the mountains are its main sources. Among them, the seepage of river, canal and field water is very large, accounting for 56.5% to 93.2% of the total recharge. Groundwater depletion, on the other hand, depends on the overflow and evaporation of springs in the oasis plains zone. Groundwater in the basins is mainly formed by evaporation enrichment on the basis of surface water. The formation age of groundwater in the lower lakes and plains has evidence of old age, which is consistent with the hydrogeological characteristics of the region, which is characterized by stagnant subsurface runoff and slow alternation of the water cycle. Meanwhile, the study shows that the runoff alternation of the lower pressurized water is relatively slower than that of the upper dive.
5) The groundwater system of the basin is divided into three levels. The first-level partition represents the groundwater circulation system of the whole Shule River basin. According to the groundwater recharge, runoff and discharge characteristics are divided into three secondary sub-districts. The second-level zone is divided into five third-level subzones based on geomorphology and geological structure boundary features. Based on the lithological and structural characteristics of the aquifer, the tertiary zoning is divided into 6 groundwater subsystems. Analyzing the borehole data, it is vertically determined as single-layer submersible subsystem and submersible-pressurized water multi-layer subsystem.
6) The groundwater chemical field in the Shule River Basin Basin exhibits horizontal and vertical zonal evolution patterns, and from upstream to downstream it can be divided into a freshwater zone, a freshwater-slightly brackish water zone under the cover of salty water, and a brackish water zone. Freshwater is distributed in most of the Shule River and Yulin River floodplain fan and part of the leading edge zone in the southern part of the Yumen-Tashii Basin in the middle reaches, in most of the Canghe River floodplain fan and the delta zone in the eastern part of the Anxi Basin in the lower reaches, and in the Petroleum River floodplain fan zone in the Huahai Basin, which is roughly in line with the distribution of a single submerged zone, with the groundwater TDS of less than 1 g/L, and with the hydrochemistry of the water type being dominated by bicarbonate-sulphate species.
Slightly brackish water is distributed in the vast fine-soil plains of the North and South Basins, and the hydrochemical types are generally HCO3-SO4-Mg-Na, SO4-HCO3-Mg-Na, and SO4-Cl-Mg-Na. The brackish water zone in the basin only appears in the ancient lake area, and the water chemistry type belongs to Cl-Na-Ca, Cl-SO4-Na, SO4-Cl-Na-Mg type, and the TDS is generally greater than 5g/L.
7) The positive alternation of the groundwater in the pre-mountain Gobi zone of the middle basin (especially in the pre-mountain front of the larger rivers is the most typical) has kept the aquifer skeleton in the state of drenching and filtration, with the content of soluble salts being extremely low, and formed the insoluble but stable geochemical zone. The geochemical background is insoluble and stable, and the degree of groundwater salinization is very low and the increase of TDS is slow. From the mountain front Gobi belt to the fan edge overflow zone, horizontal runoff is dominant, and the groundwater along the way is constantly dissolving and filtering the medium, and the concentration of various ions in the water increases, and the TDS gradually increases. In the fine-soil plain zone downstream of the overflow zone, the groundwater runoff becomes relatively slower and the water level is shallow. Surface diving is dominated by vertical alternation, and evaporation and transpiration are obvious. Groundwater runoff in the tailrace area of the downstream basin is very slow, evaporation and concentration of surface diving is absolutely dominant, and groundwater TDS is very high, and even salt brine is formed.
8) The total amount of natural groundwater recharge resources is 955,804,000 m3. In terms of basins, 493,410,900 m3 in Yumen-Tashil Basin, 38,351,760,000 m3 in Anxii-Dunhuang Basin, and 80,727,900 m3 in Huahai Basin; in terms of counties and cities, 32,010,800,000 m3 in Yumen, 514,669,800,000 in Anxi County and 21,669,800,000 in Dunhuang City; the amount of groundwater recharge resources is 955,804,000 m3. m3, Dunhuang City is 221,969,700 m3.
P=50% of the conditions of groundwater extractable resources for 300,585,300 m3, divided by basins, Yumen - Tashil, Anxi - Dunhuang, Huahai Basin groundwater extractable resources for 129,356,400 m3, 14,010,037,000 m3, 31,123,200 m3; divided by counties and cities, Yumen City Yumen City, Anxi County, and Dunhuang City are 113,356,400,000 m3, 153,294,400,000 m3, and 45,662,500,000 m3, respectively.
Groundwater storage resources are 520,328,000,000 m3, of which 471,750,000,000 m3 are freshwater storage resources, 45,954,000,000 m3 are brackish storage resources, and 2,624,000,000,000 m3 are brackish-saline water storage resources. basins, the Huahai Basin is the smallest, with 62.696 billion m3; the Yumen-Tashil Basin is larger, with 128.430 billion m3, and the Anxi-Dunhuang Basin is the largest, with 329.203 billion m3; and according to the counties (cities), the Yumen City is the smallest, with 86.867 billion m3, Anxi County is larger, with 130.309 billion m3, and the Dunhuang City is the largest, with 303.153 billion m3.
9) According to the groundwater quality standard (GB/T 14848-93), in the middle and upper part of the flood fan in each basin, the diving quality is good-good grade, and the diving quality in the fine soil plain area at the front edge of the flood fan is poor-extremely poor grade. Most of the remaining areas in the basin are of good-good grade, except for Dry Hai Zi, Yitang Lake, Xihu, and Yumenguan West, where the quality of the pressurized water is of poor-extremely poor grade.10) The groundwater potential coefficients of Yumen - Tashi, Anxi - Dunhuang, and Huahai basins are 3.16, 1.51, and 5.66 respectively, with large groundwater potentials. The groundwater potential of Anshi-Dunhuang Basin is mainly concentrated in Shuangta Irrigation Area and peripheral development areas.
11) The upper and middle parts of the flood fans in each basin, and the middle and southern parts of each irrigation area, are the strong sustainability zones; the middle and lower parts of the flood fans in Yulin, the northern and western parts of the dry delta of the Shule River in the downstream Anxi-Dunhuang Basin, the middle and western parts of the flood fan of the Danghe River, the periphery of the Huahai Irrigation Area and the pre-san Francisco area of Kuantan Mountain are the strong sustainability zones; the most part of the Changma Irrigation Area in the middle Yumen-Tsubaki Basin, and the fine-soil zone in the forefront of the flood fan of Yulin, are the stronger sustainability zones. The downstream Anxi - Dunhuang Basin Shuangta Irrigation District in the western barren area, the Danghe Irrigation District, the middle and lower part of the Danghe Flood Fan, the lower part of the Karatashtag Mountain Front Flood Fan Slope, the Petroleum River Flood Fan in the Huahai Basin, the Qingshan Farm and the central-eastern part of the basin as the average sustainability zone; the middle Yumen - Tadashii Basin Rabbit Hulu - Qiaozhi Nature Reserve, the lower part of the Luguogou, the downstream Anxi - Dunhuang Basin Xihu Irrigation District, the Yitang Lake, and the periphery and north part of the Yumen West Haukeng - Bay Yao Nature Reserve periphery and north, northern Huahai Basin Nature Reserve, and the middle and eastern part of the well irrigation area are weak sustainability areas; the downstream basin Shule River ancient channel, Yumen Guanxihoukeng to Wan Yao Nature Reserve, and the eastern part of the well irrigation area in Huahai Basin are weak sustainability areas.
12) As of 2004, the middle and lower reaches of the Shule River **** had 3382 machine wells of various types, and the total amount of groundwater extracted was 168.7 million m3, of which the Anxi-Dunhuang Basin was the largest, with 107.6 million m3, or 63.78% of the total amount of extracted water, and the number of extracted wells was 2,384; the Yumenguan-Tadashii Basin was second, with 49.9 million m3, or 29.75%, and the number of extracted wells was 792; the Hahai Basin was the weakest area of sustainability. 792 wells; the Huali basin is the smallest, only 11.2 million m3, accounting for 6.65%, and 206 wells are exploited.
13) The districts with better environmental quality are Changma, Danghe and Shuangta Irrigation Districts, which are some large irrigation districts. The average environmental quality districts are Yulin Irrigation District, Huahai Irrigation District and Huahai Wasteland. The poor environmental quality area is mainly the deserted area west of Yumen Pass and the deserted area north of Huangdunzi in Anxi - Dunhuang Basin. Summarized, there are the following patterns of geological and environmental quality in the area: better inside the oasis, worse in the peripheral wilderness area; better in the middle reaches, worse in the lower reaches; better in the east and slightly worse in the west.
14) The three options identified: first, the surface water resource utilization option developed in the Shule River migration project; second, the water resource regulation option in which surface water utilization is the main focus, supplemented by groundwater; and third, the soil improvement and ecological balance option under the rational allocation of surface water and groundwater. After model analysis and calculation, Scheme 3 is chosen as the basis of water resource allocation, with the following specific contents: the total water demand of Changma, Shuangta and Huahai irrigation districts is 74,524,000 m3, of which the urban and rural drinking water for human and livestock is 11,000,000 m3 (groundwater supply), the water demand of township and village enterprises is 8,000,000 m3 (groundwater supply), the industrial demand of 404 factories is 82,750,000 m3 (surface water supply), and the water demand of agricultural irrigation is 632,330,000 m3 (surface water supply). Water demand of 632.33 million m3 (of which 477.43 million m3 is supplied by surface water and 154.9 million m3 is supplied by groundwater), and 11.16 million m3 (supplied by surface water) for irrigation of peripheral forest belts and protective forests; the total water demand of Danghe Irrigation District is 29,000,000,000 m3, of which 24,000,000,000 m3 is supplied by surface water and 50,000,000,000 m3 is supplied by groundwater.
15) Suitable for exploitation of the submerged area Located in the front edge of the Changma flood fan Yumen Town - Sijiatan area, Dunhuang Basin, seven miles west of the town of the flood fan front edge, can be used as a centralized mining of large-scale water sources. South of Dunhuang city, Qili Town - Wudun, Tadashi Farm, the central Huahai Basin, Huahai Township - Sanjiu Company Farm south of the section, suitable for decentralized or continuous mining.
Submersible - pressurized water mining area suitable for mining is distributed in the front edge of the Changma flood fan Huanghua - seven ditch - rabbit gourd - the bridge, Anxi Basin climbing waist tree - four work - Anxi County line south to the Shuangta Reservoir, Dunhuang Basin, the front edge of the party River West flood fan, Luchao Jingzi - Mengjiaqiao area, the Flower Sea Basin, the pimple wells in east and west line. The above sections can be mined in layers or mixed according to the needs, but the local shallow diving in Anxi Basin has high TDS and should be strictly stopped to mine the lower pressurized water.
The pressurized water area suitable for mining is located in the front edge of the Changma flood fan in the area of Sandougou-Waizhangzi South-Qiaotong, with the best conditions for mining pressurized water.
The water level is deeper than 100 meters in the top of Changma flood fan, Yulin flood fan and Danghe flood fan. Subject to economic and technical conditions, mining has some difficulties.
The northern edge of each basin and groundwater retention zone, due to high TDS, poor water quality, so it is not suitable for mining. In addition, the Yumen Pass in Dunhuang Basin and the area south of the ancient course of Shule River in the west belong to the natural ecological environment protection zone, and there is no development plan yet, so it is included in the unsuitable mining area.
16) deep groundwater is a new system - the lower Pleistocene fresh pressurized water, has been proved to have the value of water supply is mainly distributed in the town of Yumen, the Workers shed around the area, can be used as a small and medium-sized industrial or urban drinking water source (water demand of 50,000m3 / d).
Shallow groundwater in the upper Pleistocene Jiuquan Group (including the Gobi Group, the same below) in the fresh diving and pressurized water, can be used as a large-scale industrial and agricultural water supply centralized mining conditions of the water source. Pure well irrigation area is best to use a group of wells convergence centralized irrigation, mixed irrigation area mining wells are best arranged along the branch bucket canal.
Shallow brackish water, especially the lower part of the pressurized water quality is better, is now an effective supplement to the water source of the peripheral development zone. It is best to mix with surface water, or the upper dive and the lower part of the pressurized water mixed mining.
Saline water basically no mining water supply value.
17) Changma Irrigation District in the old irrigation area and the periphery of the wasteland and clamped wasteland suitable well area, the development of 200,000 mu of well irrigation or mixed irrigation area, the new drilling of agricultural irrigation wells 166 eyes, the total number of 724 eyes, the mining of groundwater of 0.98 billion m3, less diversion of canal water of 0.88 billion m3, the water can be abandoned by the Changma Dam to the Gobi or the water from the western trunk to the Shuangta Reservoir transfer to replenish the basin of groundwater and the lower reaches of the ecological water supply.
Shuangta Irrigation District in Anxi County, east of Lianghu sub-farm and the old irrigation areas such as Huancheng, South Fork, Guazhou and the edge of the appropriate well area, the development of 126,600 acres of well irrigation or mixed irrigation area, 176 new wells for agricultural irrigation, the total number reaches 528 eyes, mining groundwater 0.63 billion m3, less diversion of canal water 0.77 billion m3, the remaining water can be released by the Shuangta Reservoir to the natural channel of the Shule River in order to replenish the river ecological water along the banks and downstream.
Huahai Irrigation District in the old irrigation area, Dushanzi Farm, Bijiatan Development Zone, the development of 54,000 acres of well irrigation or mixed irrigation area, 112 new wells for agricultural irrigation, the total number of 157 eyes, the extraction of 0.27 billion m3 of groundwater, 0.26 billion m3 of less diversion of canal water, the remaining water can be used by the Chijin Reservoir to the dry Haiko Lake area to release water, in order to replenish the river and downstream of ecological water use along the ecosystem.
The Party River Irrigation District uses drip irrigation, sprinkler irrigation and changes in crop planting structure and other agricultural water conservation measures to reduce the irrigation quota, compression of the number of agricultural extraction wells, so that the amount of groundwater extraction down to 0.5 billion m3, the number of extraction wells is 575. Among them, the townships south of Dunhuang City, including Qili Township and Yangjiaqiao Township, the current number of agricultural irrigation wells 196, the extraction of 5.56 million m3, this area should be shut down all the agricultural irrigation wells, irrigation tasks are all borne by surface water.
18) Southwest of Yumen Township can be built 100,000 ~ 50,000m3 / d of small and medium-sized water sources. If a large-scale water source larger than 100,000m3/d is built, it should be located in the western part of Yumen Town in the Changma flooding fan area according to the requirements of water transmission, and the source of water is the submerged water endowed in the sand and gravel of the middle and upper Pleistocene System. Due to the abundant recharge sources, the degree of water guarantee is high, there is no source of pollution at the upstream of the water source, and the quality of the water is sufficiently guaranteed, so it can be used as a water source for the future of Yumen Town.
Anxi County can build 50,000m3/d water source in the northern part of the county in the North Gobi, the ancient channel of Shule River. If the construction of more than 100,000m3 / d of large-scale water sources, the other in the county south of the Shule River in the ancient channel construction of water sources, the implementation of the north and south of the water source **** the same operation to meet the water supply needs. Huahai Township currently has a centralized water supply system, the water source in the vicinity of the lake, according to its development needs, the construction of 10,000m3 / d of the water source should be located in the upper reaches of the southwestern edge of the lake Gobi, so as to avoid the water source of the groundwater by the contamination of agricultural irrigation.
Dunhuang City has built the Party River water source, daily mining capacity of 10,000m3, the annual mining capacity of 3.5 million m3, the water source can be expanded to 7.5 million m3, for the most promising development of the lot. At the same time, the Qinghai Petroleum Administration has built a water source in Qili Town, with an annual mining capacity of 12 million m3, and the current proven reserves of 18 million m3, with certain prospects for development and utilization.