The lithology, structure and thickness of Quaternary aquifer in North China Plain have horizontal variation law. The aquifer in piedmont plain is fan-shaped, and the lithology of fan axis is mainly gravel and pebble, with a large thickness; The particle size and thickness of aquifer medium between fans become thinner. In the central plain, the aquifer gradually changed into a tongue-shaped structure with lacustrine deposits mixed with river deposits, and the lithology of the aquifer was mainly medium-fine sand. Towards the eastern and southern coastal plains, the aquifer transits to lake island structure, and the lithology of the aquifer is mainly silty sand.
Quaternary water-bearing rock series can be divided into three aquifer groups from top to bottom (Table 2- 1), and divided into saline aquifer group (body) (salinity greater than 2g/L) and shallow aquifer group (body) (salinity less than 2g/L) based on groundwater salinity.
Table 2- 1 Formation Characteristics of Quaternary Aquifer in North China Plain
(According to Zhang et al., 2009)
(1) Hydrogeological characteristics of the first aquifer group
The buried depth of the floor of the first aquifer group is generally 40 ~ 60m, including Holocene and Pliocene. The aquifer in alluvial-diluvial fan area has large particle size, thickness of 30 ~ 50m, strong vertical continuity, single-layer or double-layer structure, strong water permeability, hydraulic conductivity of more than 5000m2/d, unit water inflow of 20 ~ 30m3/h m, and salinity of less than1g/L. In fan and fan edge zone, the aquifer thickness becomes thinner and the particles become finer. There are clay layers with different thicknesses between aquifers, and the hydraulic conductivity is mostly 100 ~ 500m2/d, and the unit water inflow is mostly 5 ~10m3/h m, and the groundwater recharge conditions are also poor. The aquifer in Fanqianwa area is composed of silty sand, the thickness is mostly less than10m, the permeability coefficient is generally less than100m2/day, and the unit water inflow is less than 5m3/h/m ... The groundwater runoff condition is poor, and salt water with salinity of 5 ~ 10g/L is developed.
In the ancient river belt of Central Plains, the aquifer is mainly silty sand and fine sand, with a general thickness of 1240 ~ 50m, a permeability coefficient of 100 ~ 300m2/d, and a unit water inflow of 5 ~10m3/h m .. In the ancient Yellow River and Luanhe River, the aquifer thickness is generally 20. The permeability coefficient is 300 ~ 500m2/d, and the unit water inflow is10 ~15m3/h m. The aquifers in the main river belt are mostly single-layer and double-layer water-bearing structures, and the overlying strata are highly permeable, which is beneficial to precipitation infiltration. The aquifer is phreatic-slightly confined water, and the water quality structure is "light-salty". The buried depth of the bottom boundary of overlying fresh water body is 20 ~ 40m, most of which is more than 30m. The ancient Yellow River and Zhangwei reach 60 ~ 70m, or both are freshwater areas with small distribution scale.
The aquifer in the central plain is undeveloped, with single layer, thin layer and multi-layer structure, and the lithology is fine sand, and the thickness is less than 10m. In the south of Haihe River, there are sand-free areas of different scales in the middle and lower reaches of each river. Clay or sandy clay develops between the aquifer and the overlying aquifer, and the rainfall infiltration recharge and runoff conditions are poor. The hydraulic conductivity is 50 ~ 100 m2/d, and the unit water inflow is mostly less than 5 m3/h m ... There are fresh water bodies or no fresh water bodies with a thickness less than 10m on the upper part, and the salinity of salt water is generally 3 ~ 5 g/L. ..
The aquifer in coastal plain is mainly silty sand and fine sand, and its thickness is generally less than 10m, and locally it is 10 ~ 20m. To the south of Tianjin, the aquifer permeability coefficient is 10 ~ 50m2/d, and the unit water inflow is mostly less than 2.5m 3/h·m, which is mostly covered by clay or sandy clay, and the precipitation infiltration recharge is poor. Except for the weak runoff in the river area, it is generally in a state of stagnation, the groundwater is under obvious pressure, and the salinity of groundwater is mostly above 5 g/L.
(2) Hydrogeological characteristics of the second aquifer group
The buried depth of the bottom interface of the second aquifer group is generally 120 ~ 170 m, which is generally equivalent to the Middle Pleistocene. In the piedmont plain and central plain of northern Henan, there is no stable aquifuge between them and the first aquifer group, and there is a good hydraulic connection between them. There are 2 ~ 3 sets of medium fine sand-medium coarse sand-gravel rhythmic layers, and the water permeability and hydraulic conductivity of the aquifer are stronger than that of the first aquifer group. At present, the mixed exploitation of two aquifers has artificially enhanced the hydraulic connection between them.
The aquifers in the central plain are mainly medium-fine sand and fine sand formed by river alluvial and limnetic deposits, and their water permeability and hydraulic conductivity are obviously weaker than those in the piedmont area, with the unit water inflow of 5 ~ 65438+100 m3/h m. Clay or sandy clay usually develops between the second aquifer group and the first aquifer group. Under natural conditions, groundwater recharge is weak and runoff is slow. In the south of Haihe River, the upper part of aquifer group is saline water body, and the lower part is fresh water body. The thickness of salty water body gradually thickens from west to east and from north to south. The salty water bodies in the northwest of Hengshui and the west of Ziya River in Cangzhou are thin and have strong hydraulic connection with the lower fresh water bodies, while the south of Zhangwei is almost full of salty water. The fresh water in the lower part of the second aquifer group is an important water source for industrial and agricultural production.
In the coastal plain, the aquifers are mainly silty sand and fine sand, the upper salty water body is continuous with the first aquifer group, and the lower salty water body is fresh water body. With Haihe River as the boundary, it is roughly divided into north and south areas. Compared with the south area, the aquifer in the north area has coarse grain size, strong groundwater recharge conditions, high water abundance and conductivity, and low salinity. The salty water body in the upper part of the southern district gradually thickens from north to south, and the area near Dagang in the south is full of salty water body.
(3) Hydrogeological characteristics of the third aquifer group
The buried depth of the bottom boundary of the third aquifer group is 250 ~ 420 m, which is generally equivalent to the Lower Pleistocene. Except for local depressions and coastal areas, it generally contains underground fresh water.
The aquifer in piedmont plain is fan-shaped and fan-shaped, consisting of 3 ~ 4 sets of medium-fine sand, medium-coarse sand and gravel lithology, and the lower aquifer is weathered to varying degrees. To the north of Shijiazhuang, the unit water inflow in the fan body is 20 ~ 50m 3/h·m, and the unit water inflow in the fan belt is10 ~ 20m3/h m, and some areas, such as Baodi area in Jixian County, Tianjin, are underdeveloped. In the foothills south of Shijiazhuang, the third aquifer group is thin, the aquifer is discontinuous, there are many gravel layers, and the water abundance is weak. Generally speaking, the unit water inflow is 5 ~ 65438+100 m3/h m, which is weaker than that in the north of Shijiazhuang. There is no continuous water-resisting layer between the large fan and the overlying second aquifer group, and the hydraulic connection between them is good. Other areas are generally single-layer clay or sandy clay with a thickness of 5 ~ 10m, and the hydraulic connection is weak.
The aquifer in the central plain is banded and consists of 3 ~ 4 sets of fine sand and medium sandstone rhythms. Compared with the second aquifer group, it is coarse in particle size, good in sorting, thick in single layer, strong in hydraulic conductivity, and the unit water inflow is 5 ~15m3/h m. The aquifers in Wuqing, Tianjin and the north of Ninghe, Hebei, Wen 'an, Dacheng and Qingxian are mainly medium sand, with a single layer thickness of 20 ~ 30m, stable in distribution and a cumulative thickness of 70 ~/. Generally, there is sandy clay with a thickness greater than 10m between it and the overlying aquifer group, and the aquifer is mostly calcified clay.
The aquifer in coastal plain is mainly silty sand and fine sand, and the unit water inflow is generally 5 ~ 65438+100 m3/h m, which is slightly smaller locally.
(4) hydrogeochemical characteristics
The salinity of Quaternary groundwater in piedmont plain area is generally less than 1g/L, which is mainly HCO 3-Ca Mg type. The hydrogeochemical characteristics of the Central Plains are complex, and there are two water quality structures from top to bottom, namely "light-salty-light" and "salty-light", which makes the hydrochemical types complicated in the vertical direction. From the surface or below 10~50m ~ 50m to 80 ~ 250m (or deeper locally), it is a salty water body with salinity greater than 2g/L. Generally, the hydrochemical types are upper SO4 HCO3-Ca Mg and lower SO4 Cl-Na Mg. Salinity is 2 ~ 3g/L, and local salinity is 5 ~10g/L.. Generally, the fresh water covered on the salty water body is HCO _ 3SO _ 4-Camg type in the upper part and HCO _ 3Cl-NAMG type in the lower part, and the salinity also varies between 0.5 ~1.0g/L ~1.0 ~ 2.0g/L. HCO _ 3-calcium-magnesium type and HCO _ 3-calcium-sodium type water are common in ancient rivers. ..
The chemical types of deep fresh water are relatively simple, generally HCO3-Na type water or HCO 3 Cl-Na type water, HCO3-Na type water is common in the lower part, and the salinity is generally 0.5 ~ 0.8g/L, and it is 1.0 ~ 1.5g/L in the south, which is slightly higher locally.
There are two kinds of water quality structures in coastal plain, namely "salty and light" or "all salty". The buried depth in the north of Dagang is 60 ~ 100 m, and it gradually deepens to 150m in the south, and it is 200 ~ 250 m locally. The chemical type of brine is generally Cl (or Cl HCO3)-Na (or Na Mg). The fresh water below is usually single sodium bicarbonate or HCO sodium bisulfate. The salinity is 0.5 ~ 0.8g/L, and it is 1.0 ~ 1.5g/L in the south, which is slightly higher locally.
2. Songliao Plain
Songliao Plain is surrounded by mountains on three sides, facing the sea on one side, Daxing 'anling and Liaoxi Mountains in the west, Xiaoxing 'anling in the north, Changbai Mountain and Qian Shan Mountains in the east and Bohai Sea in the south, including Songnen Plain, Xiliaohe Plain and Xialiaohe Plain. The terrain is high in the north and low in the south. Gongzhuling and Taipingchuan uplift in the middle form Songliao basin, and Songnen Plain in the north belongs to Songhua River basin. The south is divided into West Liaohe Plain and Lower Liaohe Plain, both of which belong to the Liaohe River Basin.
In the northern Songnen Plain, the sediments are thick in the west and thin in the east, roughly to the west of Shuangliao-Fuyu-Anda line, with Neogene sandstone and mudstone. Quaternary loose sediments are developed on it, with a thickness of 80 ~ 150 m, and the west of Qiqihar is thick gravel with single lithology. The eastern part is high plains, and the western and southern parts are piedmont inclined plains controlled by uplift belts. The Quaternary sedimentary thickness is relatively thin, generally 10~30m ~ 30m, and the lithology is mostly loess, with discontinuous gravel lens underneath. In Suihua, Harbin, Yushu, Fuyu and Fulongquan, the thickness of Quaternary strata has increased to 60 ~ 100 m, and there is a stable gravel layer at the bottom.
Quaternary strata in the West Liaohe Plain in the south have a single lithology and are extremely thick sand layers. It thickens from the edge of the basin to the center, with a thickness of 80 ~ 2 10m. From upstream to downstream, the particles become finer, the clayey soil interlayer becomes thicker, and it gradually transits to Songnen Plain, which is connected with the stable thick clay layer. Groundwater flows from southwest to northeast to Songnen Plain, and part of it is injected into Lower Liaohe Plain through Liaohe River Basin.
In the Lower Liaohe Plain, Quaternary strata are widely developed, from north to south, from piedmont to plain, from thin to thick, generally 40 ~ 300 m thick. The sediment particles in the west of the plain are fine, while those in the east are coarse. Its genetic types range from alluvial or alluvial loam, gravel, sandy pebble and loess loam in the piedmont slope zone to alluvial sand and silty sand in the central plain, local lacustrine loam, and alluvial marine fine sand and muddy interlayer in the coastal low plain.
Songliao Plain is a basin rich in groundwater, and the formation and distribution of groundwater are mainly controlled by structural, lithologic and geomorphological conditions. The main source of groundwater recharge is the atmospheric precipitation in the plain area, and the surface water and groundwater in the mountainous areas on both sides also recharge the plain groundwater. The groundwater runoff is mainly horizontal movement, and the surface water system is an important drainage channel, which evaporates and discharges in the valley flood area and swamp. The groundwater flow direction changes with the topographic conditions.
(1) Songnen Plain
Songnen plain is a depression area in geological structure, which belongs to a part of Songliao Mesozoic-Cenozoic fault depression zone. The northern, eastern and southern parts of the plain are uplift areas, the western part is slope area, and the middle part is large depression area. The neotectonic movement since the late Cenozoic not only controlled the thickness and granularity of topography and Quaternary sediments, but also controlled the occurrence and distribution of groundwater. In the eastern high plains, the Quaternary deposit is more than ten meters thick, and the Cretaceous system is underlying. Local sedimentary grooves are formed in Yushu, Shuangcheng, Suihua and Hailun, and the Quaternary deposit is 80 meters thick. The Mesozoic and Cenozoic sedimentary thickness of the central and western low plains and piedmont plains is 5000m and 300m respectively (Zhang Bofu, 1989). Alluvial fan is distributed in the piedmont inclined plain of Daxing 'anling Mountain in the west, and it is a single structure phreatic aquifer system. The low plain is a multi-layer confined aquifer, and Yushu-Suihua in high plains in the east is a confined water basin. Groundwater flows from all directions to the second Songhua River in the center. The contents of macro and trace elements in groundwater in the piedmont plateau of Xiaoxing 'anling Mountain are abnormal, which is an endemic disease prevention and control area. In the middle of the plain, the terrain is flat, the diving is shallow, and the runoff is sluggish. Most of it is consumed by evaporation, and the salt in the diving water is gradually concentrated, which leads to salinization in the inland and widespread distribution of saline soil. Lake bubbles in low-lying areas are used as local flow benchmarks.
Songnen basin is a large-scale phreatic and artesian basin composed of Cretaceous, Neogene and Quaternary aquifer systems. According to the topographic and geological conditions, it can be roughly divided into three types: single-layer aquifer structure in piedmont plain, double-layer aquifer structure in high plains and multi-layer aquifer structure in low plain (Figure 2- 15).
Fig. 2- 15 schematic diagram of water-bearing system in Songnen plain
The single-layer aquifer structure type is distributed in the western piedmont inclined plain, but slightly smaller than the piedmont alluvial-diluvial fan group, and consists of fan-shaped land and platform. From south to north, the main fan areas are: Huolin River alluvial fan, Taoer River alluvial fan, Chu Er River alluvial fan, Yarlung Zangbo River alluvial fan, Ailun River alluvial fan and Nuomin River alluvial fan. The fan-shaped land is composed of alluvial and diluvial gravels of the Middle-Upper Pleistocene, and the platform is composed of kaolin-bearing gravels accumulated in the ice water of the Lower Pleistocene. From the top of the fan to the front edge, it is fan-shaped, and from the shaft of the fan to both sides, the gravel particle size changes from coarse to fine, and the water content changes from strong to weak. There are fine-grained material accumulation zones with different widths among the fans, and the formation age and geological structure of each fan are obviously different. The southern Huolin River and Taoer River formed late, and their piedmont alluvial-diluvial fans are mainly middle-upper Pleistocene gravel layers with a thickness of 20 ~ 30m, coarse grain size, loose structure and a small amount of cohesive soil layer. The alluvial fans in northern rivers developed earlier, including Pliocene Taikang Formation to Quaternary alluvial fans. Among them, the early and middle Pleistocene was the most developed, with a sedimentary thickness of 50 ~ 100.
The structure types of double-layer aquifer are mainly distributed in the vast area of eastern high plains, mainly composed of Quaternary loess and its bottom gravel layer and underlying Cretaceous aquifer system. The Quaternary is dominated by phreatic water, and the Cretaceous is dominated by confined water, but some areas are anhydrous aquicludes. Quaternary sandy gravel aquifer is often distributed as lens, so loess layer sometimes covers directly on Cretaceous. In Suihua, Shuangcheng, Yushu and other places, loess directly covers the sandy pebble layer, forming the local Quaternary confined water basin.
The distribution range of multi-layer aquifer structure types is basically the same as that of the low plain, with a width of 180 ~ 200 km in the northwest-southeast direction and a length of 400 ~ 450 km in the northeast-southwest direction, covering an area of about 70,000 km2. It is mainly composed of Quaternary, Neogene and Cretaceous aquifer systems in different periods, which are superimposed on each other to form a unified complex aquifer system. The mutual combination relationship varies from place to place. Because most areas of Paleogene, Neogene and Cretaceous are deeply buried, mainly mudstone, which can be regarded as aquifuge. However, there is no obvious boundary between the Neogene Pliocene Taikang Formation and the Lower Pleistocene Baitushan Formation, so the Quaternary and Taikang Formation are regarded as a unified aquifer system, which is divided into three subsystems according to burial conditions, among which shallow water (burial depth less than 50m) is mainly diving, middle-deep water (burial depth 50 ~ 150m) and deep water (burial depth greater than 65430). Near Daqing in the east of the low plain, the middle-deep aquifer gradually evolved into a thick muddy clay layer, which was divided into two parts: shallow groundwater system and deep confined water system.
1) Quaternary pore phreatic aquifer: mainly distributed in piedmont inclined plain and low plain. The piedmont plain is a single structure phreatic aquifer, and the gravel platform area is mainly composed of gravel and kaolin-bearing gravel with a thickness of 5 ~ 30m. The water abundance is moderate and strong, and the buried depth of water level is generally 10~20m ~ 20m. The lithology of the fan-shaped aquifer of gravel is mainly composed of alluvial and diluvial pebbles and gravel layers in the Middle and Lower Pleistocene, mixed with thin clayey soil. Particle size changes generally have the characteristics of coarse upper and fine lower, or coarse upper and fine lower and fine middle. The aquifer thickness is generally 10~60m ~ 60m, and the water level is 5 ~ 8m, so it is rich in water, and groundwater often overflows at the fan-shaped front. The low plain area is mainly composed of loess clayey silt and silty sand, with a thickness of 3 ~ 20m and generally containing pore water. The buried depth of water level is mostly less than 5m. Due to the fine particles, thin thickness and weak water abundance of the aquifer, the water inflow of a single well is generally less than1100m3/d/d.
2) Pore confined aquifer of Quaternary Lower Pleistocene: it is widely distributed in low plains, with the eastern boundary mostly reaching the western part of high plains in the east, the southern boundary crossing the Songliao surface watershed, and the western boundary in Qiqihar-Tailai-Taonan area, which is connected with alluvial fan-shaped land in the piedmont of Daxinganling Mountains. In the south of Songliao basin, the aquifer thickness is thin in the local uplift area. In Zhaoyuan-Jin Kui area in the middle, Songhua River and Nenjiang River cut off the confined aquifer and turned to diving. The lithology of the aquifer is mainly kaolin-bearing gravel, and some areas are in direct contact with the underlying Taikang Formation sandstone, forming a unified water-bearing rock group. The thickness of aquifer decreases gradually from north to south and from west to east. Northwest 10~50m, southeast 5 ~ 30m, thickness of Qiqihar area 10 ~ 50m. The water quantity varies with the particle size and thickness of aquifer. The northeast and west are rich in water resources, and the east and Songliao basin are poor in water resources. The aquifer is covered by stable Middle Pleistocene muddy clay, which constitutes a regional aquiclude.
3) Neogene Taikang Formation fissure pore confined aquifer: this confined aquifer is located under the lower Pleistocene confined aquifer, and its distribution range is much smaller than the overlying confined water. The lithology of the aquifer is mainly sandstone and glutenite, with poor diagenesis and loose structure, and the overall trend of its grain size structure changes from coarse to fine, from north to south and from west to east in the horizontal direction. The aquifer thickness is 10 ~ 100 m, and the water-resisting roof of the aquifer is mudstone in the upper part of Taikang Formation, with a buried depth of 40 ~ 140 m, which gradually becomes shallow from south to north. Because of the discontinuous distribution of roof mudstone, it is often connected with the upper and lower Pleistocene confined aquifers to form a unified water-bearing body.
4) Neogene Miocene Daan Formation pore fissure confined aquifer: this confined aquifer is buried under the Pliocene Taikang Formation, with narrow north and wide south. Baicheng-Jin Kui area in the south is about 200 kilometers wide from east to west, and Nenjiang River in the north is only 30-40 kilometers wide. The lithology of the upper aquifer is mostly fine-medium sandstone, and the lower aquifer is mostly glutenite, showing a sedimentary rhythm of coarse bottom and fine top. The aquifer thickness on the east and west sides of the basin is 10~30m ~ 30m, and that in the middle of the basin is 30 ~ 60m. The buried depth of roof is 60 ~180m. The aquifer has good water storage conditions, poor recharge conditions and difficult discharge.
5) Eocene-Oligocene Yian Formation confined aquifer: it is distributed in the triangle of Nehe, Qiqihar and Daqing in the north of Songnen Plain, and is a closed confined water basin. The lithology of the aquifer is mainly medium-fine sandstone, which is thick in the middle and gradually tapers around, and the upper and lower parts are mudstone aquicludes. The buried depth of the roof in the middle of the basin is 120 ~ 180 m, and the buried depth of the confined water level is generally 5 ~ 25 m, and it can flow locally. Confined water has good enrichment conditions and poor discharge conditions.
6) Cretaceous pore fissure aquifer: distributed in Gaopingyuan area, divided into Mingshui Formation and Sifangshan Formation. The lithology of the aquifer is mudstone mixed with multiple layers of silty sandstone, and the buried depth is relatively large. Zhaodong-Daqing-Placanticline area is shallow buried and the aquifer is 30-50m thick. The aquifer is rich in water, and the single well produces a large amount of water.
(2) West Liaohe Plain
Xiliaohe Plain is a plain dominated by phreatic water, and the aquifer is composed of thick sand layers. Roughly bounded by Tongliao City, the thickness of Neogene in the east is 30 ~ 50m, that of Quaternary is 60 ~ 70m, and that of Quaternary in the west is 150 ~ 200m, which is a single sand layer or gravel layer. From the piedmont plain of Daxing 'anling Mountain in the west to the central plain, the aquifer has changed from a single structure of extremely thick gravel layer to a multi-layer thin silt layer. The upper part of Quaternary unconsolidated rock aquifer is composed of Holocene medium fine sand, silty sand, fine sand, argillaceous fine sand, Upper Pleistocene Guxiangtun Formation and Paitouyingzi Formation. The middle part is composed of coarse sand, medium sand, fine sand and argillaceous silt deposited by alluvial and lacustrine deposits of Daqinggou Formation in Middle Pleistocene. The lower part is composed of glacial water, moraine gravel, gravel, argillaceous gravel, coarse sand and medium fine sand of Baitushan Formation of Middle Pleistocene. The aquifer has the same recharge source, the same water storage conditions and the same runoff discharge mode, thus forming a unified free water surface, interconnected and thick Quaternary loose rock pore water body.
1) quaternary phreatic aquifer
The general change law of lithology: in the horizontal direction, from the piedmont to the plain, from upstream to downstream, the particles are from coarse to fine, from gravel to medium coarse sand, from medium fine sand to fine sand and silty sand, the clay interlayer increases and the thickness increases. The groundwater runoff has changed from unobstructed to sluggish, and the water quality has changed from good to bad. Forming pore confined water in the lower aquifer; In the vertical direction, it has the rule that the bottom is thick and the top is thin (Figure 2- 16).
The aquifer with single structure in the west is mainly composed of pebbles and gravels from Baitushan Formation in the lower part of Middle Pleistocene to fine sand, fine sand, fine medium sand, gravel, gravelly medium sand mixed with fine sand, gravelly medium coarse sand and Holocene fine sand, fine sand and medium fine sand from bottom to top. From Jiaolai River to the north bank of Yangyu River, the aquifer is mainly Daqinggou Formation in the upper part of Middle Pleistocene, followed by the lower part of Holocene, and the aquifer lithology is mainly silty fine sand, fine sand, medium fine sand and medium coarse sand.
From north to south in the east, the aquifer structure changes from complex to simple, and the aquifer particles change from fine to coarse. In the north of Haas-O-Hill, the aquifer structure is complex, with 2 ~ 6 layers of cohesive soil distributed. The aquifer is mainly composed of Daqinggou Formation of Middle Pleistocene, followed by Guxiangtun Formation of Upper Pleistocene and the lower part of Holocene. Baitushan Formation in the lower part of Middle Pleistocene is only intermittently distributed, and its lithology is mainly silty soil, silty fine sand and argillaceous silty soil. However, in the south of Haas-O 'Hill, the aquifer structure becomes single, and there is little or no cohesive soil distribution. The aquifer is dominated by the Middle Pleistocene Daqinggou Formation, followed by the Upper Pleistocene Guxiangtun Formation and the lower Holocene. The lithology of aquifer is mainly silty fine sand, fine sand and medium fine sand.
Figure 2- 16 Hydrogeological Profile of West Liaohe River Main Stream Area
(According to Li Zhi et al., 2009)
The maximum aquifer thickness is distributed at the junction of Kailu County and Horqin District in the plain sedimentary center, revealing that the maximum aquifer thickness is 196.8m, and the aquifer thickness around the center gradually becomes thinner. It is 80 ~ 100 m away from Shebotu and Zhu Rihe Ranch in the north, and about 20m away from Lubei Town in Zhalute Banner in the north. East to Horqin District, it becomes 120 ~ 150m, from Dalin to about 80m, and from 20 ~ 40m to Baokang Town, Zhongqi, Zuo Ke. South to Chaolutu100 ~120m in Kezuohou Banner, 50 ~ 80m away from Yangmu Valley. It is about 160m west of Kailu Town along Xiliaohe and Xilamulun Valley, and about 100 ~ 120m west of Hailasu Town in Wengniute Banner.
From the piedmont to the central plain, with the grain size changing from coarse to fine and the thickness changing from thin to thick, the water abundance of the aquifer gradually increases. The Baiyintala-Baxiantong-Kailu-Dongfeng area in the middle of the plain is extremely rich in water, and the unit water inflow is mostly above 30m3/h, and it gradually weakens from near this area to the edge of the plain, from10 ~ 30m3/h m to 5 ~ 10 m3/h at the edge of the plain. The unit water inflow of the upper reaches of Xiangshui River and the lower reaches of Mengke River is1~ 5m3/h m, which is in the prospect of the northern Daxinganling region and the southern loess hilly region. Unit water inflow is less than1m3/h m.
The chemical types of groundwater in the West Liaohe Plain are mainly calcium bicarbonate and sodium calcium bicarbonate. Only in the low-lying areas where the groundwater level is small, due to the influence of evaporation and concentration, the chemical types of groundwater are changed to HCO3 Na, Ca, HCO3 Na, Ca and Mg, and the total dissolved solids are less than 1g/L, so the water quality is good.
2) Quaternary pore confined aquifer
It is mainly distributed in the central and northern parts of the plain, starting from Tangjiawopu Township in Horqin District in the south, Kailu Town in Kailu County in the west, shuangliao city in the east, Baokang Town in Horqin Zuoyi Zhongqi in the west, and Yu Zhan and Dongsheng-Xin 'an in Jilin Province in the north. It is connected with the aquifer of Songliao basin through Songliao basin. Beyond this range, there is a unified aquifer of phreatic water and confined water. The aquifer consists of Daqinggou Formation of Middle Pleistocene and Baitushan Formation in the lower part. The main lithology of confined aquifer is gravel, medium coarse sand and medium fine sand; Gravel pebbles are mainly gravel, accounting for 40% ~ 60%, and the diameter of gravel is generally 0.5 ~ 3 cm. The Kailu area near the upstream is dominated by gravel, and the diameter of gravel is mostly 5 ~ 1.5~3cm. Gravel size is mixed and not round. Some areas contain clay and clay lens, and the clay content and interlayer increase from west to east. The thickness of the aquifer is generally 40 ~ 80m in the south and west, and gradually becomes thinner to the north and east. The aquifer in Yu Zhan Town is 27m thick, generally 5 ~ 15m to the east, close to Baokang and Shuangliao areas. Due to the disappearance of the overlying water-resisting layer, confined water is converted into diving. The buried depth of the aquifer is100 ~140m in the south and west, and 3.40 ~ 7.92m in Yu Zhan. The water abundance is divided into strong and extremely strong, and the unit water inflow is above10 ~ 30m3/h m, which is distributed in the vast area west of Kongjiawopu Township in Horqin District, with sporadic distribution in Yu Zhan. The water yield is moderate, and the unit water inflow is 5 ~103/h m, which is mainly distributed in the north and east of Huatugula in the north of Horqin District. Baitushan Formation has become argillaceous gravel, and the confined aquifer is the medium-fine sand layer of Daqinggou Formation, and its water abundance is getting worse. There is also a small distribution in the middle and east of the tertiary groundwater system of Muren River in Wuliji. The water yield is weak, and the unit water inflow is1~ 53/h m, and the distribution area is large, mainly distributed in the northern boundary of the third-level groundwater subsystem of Murenhe River in Wuliji and the area where the confined aquifer is thinner and thinner near Baokang and Shuangliao.
Pore confined water of Baitushan Formation near Songliao Basin, the aquifer is ice-water gravel layer, containing more argillaceous components, the aquifer thickness is 1 1.30 ~ 20.77 m, the aquifer buried depth is 34 ~ 42 m, the water yield is weak, and the unit water inflow is1~ 53/h m, only near Taipingchuan. The unit water inflow is 5 ~103/h m, the aquifer is under pressure, the water level is generally buried at 1.5 ~ 5m, and some sand dunes are buried at a greater depth of 5 ~ 10m.
(3) Lower Liaohe Plain
The Lower Liaohe Plain is surrounded by mountains in the east, north and west, and faces the sea in the south, and the slope gradually decreases from northeast to southwest, ranging from 0.5 ‰ to 0.02 ‰ to 0.03 ‰. The surface elevation drops from 200m in the north and 50m in the east and west sides to 10m in the middle and 1.5 ~ 3.0 m in the southern coastal areas.
Quaternary aquifer in piedmont plain: it is distributed in the piedmont inclined plain of Lower Liaohe River, and consists of alluvial and diluvial fans of Liaohe River, Hunhe River, Taizi River, Haicheng River, Dongsha River, Yangchang River, Heiyugou River and Daling River. The aquifer consists of coarse sand, gravel and pebbles in Pliocene and Holocene alluvial and diluvial facies.
The upper part is clayey silt and loam with a thickness of 5 ~15m; The thickness of the aquifer at the back edge of the basin is l0 ~ 30m, the middle part of the basin is 40 ~ 60m, and the thickness of the alluvial fan of Taizihe River is 80m；. Small-fan rear-edge shaft with small thickness is extremely rich in water, and the water inflow of a single well is 5000 ~ 10000 m3/d, and the periphery is mostly 3000 ~ 50003/d. ..
The lower part is the middle and lower Pleistocene aquifer, which is gravel mixed with cohesive soil with a thickness of 5 ~ 15m. The front zone of alluvial-diluvial fan has a thickness of 80 ~ 120m and a single well water inflow of 3000 ~ 5000m3/d, which is a confined aquifer and flows naturally in some areas. Such as the front edge of Linghe alluvial fan, the water head is higher than the ground 1 ~ 3m. The water quality is good, it is bicarbonate fresh water.
Quaternary aquifer in Central Plains: It is distributed in central Liaoning and Tai 'an area, and is a river alluvial plain. The total thickness of water-bearing rock formation is 100~250m ~ 250 m, which increases from east and west sides to the center and from northeast to southwest. The particle size of aquifer is from coarse to fine from northeast to southwest, and from medium coarse sand with gravel to medium fine sand. In the longitudinal direction, the upper part is fine and the lower part is thick. The loam at the top of Middle Pleistocene is a regional aquifuge with a thickness of 1 ~ 10m and a buried depth of 60 ~ 120m. The water-bearing formation is divided into two layers, the upper part is phreatic water-bearing formation, and the upper Pleistocene alluvial fine sand, medium fine sand and medium coarse sand are dominant, and the aquifer is 50 ~ 80m thick. The lower part is the pressure-bearing water-bearing rock group, which is composed of medium-fine sand, medium-coarse gravel and mixed soil gravel layers in the middle and lower Pleistocene. It is gravelly loam with a thickness of 50 ~ 1 10m and a single well water inflow of1000 ~ 2000m3/d..
Quaternary aquifer in coastal plain: distributed in Panshan, Dawa and Yingkou areas of coastal delta plain. The total thickness of the water-bearing rock group is 250 ~ 400 m, and the aquifer is gray and gray silty sand with a thickness of 20 ~ 60m, with multiple layers of loamy clay and clayey silty soil interbedded, with fine sand and medium fine sand at the lower part and a loamy layer. The total thickness of the aquifer is 200 ~ 300m, and it belongs to all-salt water-bearing rock group with salinity of 65,438+00 ~ 30g/L. The hydrochemical type is sodium chloride type water, and some parts are brine.