Seeing that you know so well, I dare to ask you a deep-seated question: the basic information of central Harbin: net recharge, groundwater depth, lithology and soil type.

Lin Province is located in the middle of northeast China, bordering Heilongjiang Province in the north, Inner Mongolia Autonomous Region in the west, Liaoning Province in the south, Russian Federation in the east and North Korea and China across the river in the southeast. Geographical coordinates are: 40 52' ~ 4618' north latitude and12138' ~1319' east longitude. The total land area is 18.74× 104km2, accounting for about 2% of the total land area in China, ranking 14 in China.

The geological environment belongs to the natural environment system and is a part of the lithosphere closely related to human activities, which mainly includes the following contents:

I. Topography

(1) Terrain

The general trend of terrain change in Jilin Province is high in the southeast and low in the northwest. It is divided into two regions, Changbai Mountain in the east and Songliao Plain in the west, which belong to the second uplift zone and the second subsidence zone of Neocathaysia respectively, accounting for 60% and 40% of the whole province respectively. The highest point in the province (Bai Yunfeng, Changbai Mountain) is 269 1m above sea level, which is the highest peak in Northeast China. Most of the low plains are above 120m, and the lowest point in the province is located at the junction of China, North Korea and Russia in the lower reaches of Tumen River in Fang Chuan Village, Jingxin Town, Hunchun City, with an altitude of only 5.0m.

(2) topography

Jilin province can be divided into two major units: mountainous area and plain area. Among them, the mountains are divided into Changbai Mountain and the hills on the eastern slope of Daxinganling, and the plains are divided into high plains, low plains and sloping plains before Daxinganling.

1, Changbai Mountain in the east

Including the eroded volcanic landforms in Changbai, Fusong, Antu, Dunhua, Jingyu and Huinan counties (cities); The erosive tectonic landform is located in the south of Tonghua and Baishan areas, in Yanbian area and in the east of Jilin area. Tectonic denudation landforms in Liaoyuan area, Siping and southeast Changchun. The area 1 14384.4km2, with an altitude of 500—900m, and the highest altitude of 269 1m, is the main peak of Changbai Mountain. Among them, there are many intermountain basins, such as Hunchun Basin, Yanji Basin and Songjiang Basin, which are generally 200-500 meters above sea level.

2. Hills on the eastern slope of Daxing 'anling Mountains

Located on the east slope of Daxing 'anling Mountain in the northwest of Taonan, the distribution area is 1963. 13 km2, and the highest peak is 300—500m above sea level. The top of the mountain is round, and the valley is wide and shallow.

2. Gaopingyuan Central District

Mainly distributed in Siping and Changchun areas, it consists of two geomorphic units: platform and valley. The platform is mainly distributed in the north-south direction of Yangdachengzi-Fulongquan-Wang Fu, the northwest direction of Yushu-Sanchahe and Gongzhuling, Nong 'an and other counties (cities). The valley plain is mainly distributed along Songhua River, Lalin River, Yinma River, Yitong River, Dongliao River and their tributaries. The area is 28626.53km2, and the altitude is generally 150-290m.

3. Western low plain areas

Distributed in Songyuan, Baicheng and Shuangliao. It is mainly divided into the wind-blown sand-covered plain in the transitional zone between Songliao River and Liaohe River, the inclined plain covered by wind-blown sand in Liaohe River, the salt-developed low plain in Songnen River and the low plain filled with lakes and swamps in Songnen River. It covers an area of 39,289.29 square kilometers. The altitude is generally 120-200m.

4. Inclined plain area in front of Daxinganling Mountains

It is distributed in front of Daxinganling Mountain in the west of Baicheng, and the terrain is inclined from west to east. It consists of sand platform and alluvial fan, with an area of 3108.27km2. The elevation of platform is 160-240m, and that of alluvial fan is160-240-200m.

Second, meteorology and hydrology.

(1) Meteorology

Jilin province belongs to temperate continental climate, with long winter, cold and dry, short summer, warm and rainy, windy and dry spring, changeable weather and short autumn. The annual sunshine hours are 2000~2300 hours, and the sunshine rate is 50%~70%. The freezing period is as long as 6 months, and the freezing depth is1.7 ~ 2.0m. ..

The annual average temperature in the whole province is -2~6℃, 0℃ in the eastern mountainous area and 5~6℃ in the western plain area. The monthly average temperature in the whole province is 65438+ 10, the extreme minimum temperature is about-18~-20℃, the average temperature in the hottest July is about 20~24℃, and the extreme maximum temperature is about 38℃. Frost-free period 125~ 160 days, in which the mountain area is less than 100 days and the plain area is less than 140 days. The average annual precipitation is 500 ~ 600 mm, and more than 60% of the annual precipitation is concentrated in summer, especially in the southeastern mountainous areas. Precipitation has a decreasing distribution law from southeast to northwest. The average annual precipitation in the southeastern mountainous areas is 700~800mm, of which the Ji 'an area in Tonghua can reach 900~ 1000mm (influenced by the Bohai Sea), the central plateau is 500~700mm, and the northwest low plain is 400~500mm, showing obvious humid-semi-humid and semi-arid climate characteristics. The evaporation in the whole province is increasing from southeast to northwest, and the average annual evaporation is increased from 1000mm to more than 2000 mm, and the average annual evaporation in the southeastern mountainous area is1000 ~1400 mm.

(2) Hydrology

There are 22 1 rivers with a length of more than 30 kilometers in Jilin Province, which belong to the Second Songhua River, Liaohe River, Yalu River, Tumen River and Suifenhe River respectively. Among them, the second Songhua River system occupies an important position in many water systems because it covers many rivers, large basin area and long rivers. The second Songhua River is Erdaobaihe River, the source of which is Baitoushan Tianchi, with a total length of 920km and a drainage area of about132,200 km2. It is the largest river with surface water resources in the province.

The river is bounded by the Daheishan Mountains, which is the dividing line between the eastern mountainous area and the western plain, and the characteristics of the rivers in the east and west are completely different. The hydrological network in the eastern mountainous area is dense, starting from the volcanic cone of Changbai Mountain, and the second Songhua River, Tumen River and Yalu River flow radially to the east, north and west. The upper reaches of the river are turbulent, the bed width in the middle and lower reaches is elongated and the water flow is stable. The riverbed is mainly composed of gravel, gravel and fine sand. The main characteristics of rivers in eastern mountainous areas are large amount of water, abundant water resources and low sediment concentration. Most rivers in the west originate from Daxinganling region outside the province, with gentle mountains along the way, and hills, plains and sand dunes in the middle and lower reaches. There is a great loss of water resources, and the amount of water decreases gradually from upstream to downstream, and even the blind tail of the river (Huolin River) appears. The main characteristics are that the seasonal flow changes greatly, the dry season is interrupted, and groundwater is replenished through leakage, which has a great impact on the ecological environment.

There are many lakes and marshes in the province, among which natural lakes (lake bubbles) are all over the western plain, such as Moon Bubble, Chagan Bubble, Xianghai Lake, Dabusu Bubble and Polo Bubble. The eastern mountainous areas are represented by artificial lakes and volcanic lakes, such as reservoirs such as Songhua Lake, Hongshi Lake and Baishan Lake, and volcanic lakes such as Tianchi and triangle longwan. There are large, medium and small reservoirs 13 12 in the whole province, with a total storage capacity of 29.62 billion m3, including large reservoirs 13, accounting for more than 80% of the total storage capacity.

Three. geological survey

(1) structure

Jilin Province is located in the compound part of the eastern end of Yinshan-Tianshan banded structure and the Neocathaysian tectonic system. Under the action of Yinshan-Tianshan banded structure and NNE structural system, various structural systems intersect and unite with each other, and after many times of structure, magmatic activity and recent volcanic eruption, the structural framework and landform outline of the whole province have been formed.

The banded structure developed in our province is the eastward extension of Yinshan-Tianshan giant complex uplift and fold belt. The northern boundary of its main body is roughly located at 42 40 ′ north latitude, which is a complex structural belt formed by many long-term tectonic movements since Anshan Movement. It consists of depressions, folds, faults, gneiss, pre-Sinian, Variscan, Indosinian, Yanshanian granite, Himalayan basalt and compressive fault zone in Archean, Proterozoic, Paleozoic and Mesozoic magmatic rocks. Most of them are distributed in the east, northeast, northeast and northwest directions. Due to the intersection of various structures, the traces are fragmented. The east-west structures in the area mainly include faults such as Changbai, Erdaojiang and Tianchi. See Figure 2-3.

As can be seen from the figure, except for the development of banded structures in Tonghua, Baishan and Yanbian, the whole province is mainly a Neocathaysian structural system with large scale, wide distribution and deep influence. It has controlled the sedimentation and modern landscape since Mesozoic. Under the influence of NEE Neocathaysian tectonic system, the whole province is divided into three giant first-class tectonic zones. Namely, the Changbai Mountain giant uplift belt in the southeast, the Songliao Plain subsidence belt in the middle and west and the Daxinganling giant uplift belt in the northwest.

1, the giant uplift belt of Changbai Mountain in southeastern China.

Refers to the vast mountainous areas east of Siping-Changchun-Yushu and south of Daheishan. Besides lava platform and basalt platform formed by volcanic eruption, horizontal fold uplift and compression fault zones are also developed in this uplift zone, mainly including Yitong-Lan Shu and Dunhua-Mishan faults in the northeast, as well as Siping, Jiaohe and Chunhua faults.

2. The giant subsidence zone in Songliao Plain in central and western China.

Songliao subsidence zone is a large-scale faulted basin formed since Yanshan movement, and it is a large-scale syncline with northeast axis, which constitutes the Songliao accumulation plain with modern landform.

The subsidence zone can be roughly divided into three parts. East of Guo Qian-Changling is the eastern uplift zone, north of Changling is the central subsidence zone, and west of Tongyu-Zhenlai is the western rift zone.

3. Giant uplift belt in Daxinganling, northwest of China.

Located in the Daxinganling Mountains in the west of Baicheng City. It is bounded by Zhenlai-Yongmao iron mine fault and adjacent to Songliao subsidence zone. Affected by the NE-trending compressive fault, the Songliao subsidence zone rose as a whole, forming Daxinganling.

(2) Strata

The strata in Jilin Province are well developed in various geological and historical periods, with outcrops from Archean to Cenozoic.

1, Archaean (Longgang Group, Jiapigou Group)

The Lower Archaean Longgang Group and the Upper Archaean Jiapigou Group are the most developed in Tonghua area. It is mainly composed of a set of deep metamorphic amphibolite, granulite, biotite gneiss and various migmatites.

2. Lower Proterozoic (Ji 'an Group)

Mainly distributed in Ji 'an area of Tonghua area, it is a set of deep metamorphic schist, gneiss, granulite and thick graphite marble.

3. Mesoproterozoic (Laoling Group and Seluohe Group)

Distributed in Tonghua, Fusong and Antu. It is a shallow metamorphic marine clastic ~ carbonate deposit, which is mainly composed of shallow metamorphic quartzite, schist, phyllite and thick marble.

4. Sinian system

Mainly distributed in Changbai, Xiangzishao, Hunjiang and Antu basins. It is a set of clastic rocks and carbonate rocks in shallow sea. It is dominated by sand and shale, and the upper part is carbonate caprock.

5. Paleozoic. Originally known as PRIMARY

The Lower Paleozoic is mainly distributed in Hunjiang, Yalu, Liuhe, Ji 'an, Changbai and other places, and also exposed in Jilin and Yanbian areas. It is a set of shallow sea ~ coastal facies detritus ~ carbonate rock and sand shale.

Upper Paleozoic is scattered in the province. Carboniferous and Permian are marine sedimentary sandstone shale coal-bearing formations, which are distributed in Yangzishao, Hunjiang (Baishan), Yalu River and other basins in the form of caprocks, while Silurian and Devonian are scattered in Yitong and Shuangyang in central and southern Jilin.

6. Mesozoic and Cenozoic

Mesozoic is a set of volcanic rocks and continental detritus, lacustrine facies and coal-bearing formations, all of which are distributed in the whole province. Triassic, Jurassic, Cretaceous and Tertiary are mainly a set of coal, oil and oil shale strata, such as pyroclastic rocks, land and lake sandstone, shale and tuffaceous volcanic rocks. Distributed in fault basins of different sizes in the province.

The Cenozoic is mainly a set of loose accumulation layers of rivers, lakes and ice water. The lens of ice-water gravel mixed with gray-white clay in the lower Pleistocene is widely distributed below the middle-upper Pleistocene in Songliao Plain.

The middle-upper Pleistocene is interbedded with alluvial blue-gray thick silty clay, medium-fine sand and brown loess silty sand. The marginal zone is transformed into gravel, and the Baicheng sector is alluvial gravel.

Holocene loose deposits were exposed from mountains to plains, from residual slope accumulation to flood accumulation to alluvial accumulation to alluvial accumulation to aeolian accumulation. The alluvial layer of the valley has a dual structure, with gravel in the lower part and cohesive soil in the upper part. The low plain area in the northwest of China is mainly composed of alluvial-lacustrine muddy loam, clayey silt and aeolian sand.

In addition, Mesozoic and Cenozoic are accompanied by basic volcanic eruptions, which are widely distributed in Antu, Fusong, Jingyu, Dunhua and other places, forming a large area of basalt caprock and forming typical basalt platforms and platforms.

(3) Magmatic rocks

The pre-Quaternary magmatism in Jilin Province is very frequent, and magmatic rocks are widely distributed in mountainous areas, which can be divided into six tectonic cycles according to the formation age.

1, pre-Sinian, mainly basic and ultrabasic rocks, potash, sodic migmatite and pegmatite.

2. The Caledonian period was mainly granite intrusion.

3. Variscan is a widely distributed granite.

4. The Indosinian period was granite intrusion with limited distribution.

5. Granite dominated the early Variscan, followed by diorite. However, the distribution in the later period is limited, mainly diorite, diorite porphyry, pyroxene andesite and granite.

6. The Yanshanian period was dominated by fissure and central basic magma eruption, and the central basic magma eruption was dominated by basaltic volcanic slag and lava flow.

Four. Hydrogeological characteristics

The formation and distribution of groundwater are strictly controlled by the regional natural environment and geological structure. In geotectonics, the basic structural framework is characterized by the intersection and combination of the huge Yinshan-Tianshan belt structural system and the Neocathaysian structural system. It controlled the magmatic activity and deposition in various geological and historical periods in the province, and shaped the present landform and groundwater burial conditions. The macro-structural outline of the whole province can be roughly divided into three parts, namely, the strong uplift belt of Changbai Mountain in the southeast, the subsidence belt of Songliao Plain in the middle and the Daxinganling uplift belt in the northwest corner. The bedrock in the southeastern mountainous area is exposed, mainly developing bedrock fissure water, mixed water of pores and fissures in intermountain basins and valleys, and deep circulation structural fissure water (hot water and mineral water) distributed along volcanoes and deep fault zones. The Songliao plain in the middle part is dominated by pore water of Quaternary loose rocks. Changchun-Siping area in the east of the plain is rich in Cretaceous concealed structural fissure water. Lower Pleistocene pore confined water and Tertiary clastic rock pore fissure confined water with abundant groundwater in the northwest low plain; Daxinganling area in the west corner is bedrock fissure water, and the water quantity is poor, but the piedmont sector does contain extremely rich gravel pore water. Therefore, the burial and distribution of groundwater in Jilin Province has the law of gradual change from southeast to northwest.

Diving is widely distributed in the whole province. The distribution area of granite reticular fissure water in the southeast mountainous area is the largest, accounting for about two-thirds of the mountainous area. However, the amount of water varies with the development degree of weathering cracks. Generally, the water inflow of a single well is less than 100 m3/d, followed by pre-Sinian metamorphic rocks, Paleozoic sedimentary rocks and sedimentary metamorphic rocks, with a small amount of water (the spring flow is less than 0.5l/s), and the spring flow in the local structural fracture zone is greater than 1.0l/s, and the bedrock fissure water is mainly replenished by atmospheric precipitation, with great dynamic changes, forming an intermittent overflow spring. However, the underground runoff is strong, the circulating drainage system is good, and the element loss in the water is strong, all of which are bicarbonate fresh water and extremely fresh water with salinity less than 0.3g/L.

Intermountain basin is the gathering place of underground and surface runoff. Usually, the structures and weathering cracks in these areas are developed and covered by Quaternary loose sediments, forming water-rich pore water. In the favorable area of structural reorganization, many water-rich pores and structural fracture vein-like water-rich zones are formed.

Carbonate karst cave fissure water and basalt karst cave fissure water are the main sources of centralized water supply in mountainous areas. Although their distribution range is small, the water quantity is rich and stable.

Clastic pore fissure water is controlled by structure and lithology and distributed sporadically, but its water abundance is stable, which is also of significance for development and utilization.

The groundwater on the loess platform in central high plains is characterized by loess soil with fine sand lenses, which has poor permeability and weak water content. The underlying Cretaceous concealed structural fissure water has good water quality and abundant water quantity, and is the main water source for urban water supply.

The phreatic water in the western low plain is widely distributed and low-lying. The southeast, south and northwest are surrounded by loess platform, Songliao basin and Baicheng fan-shaped land respectively, which collect underground runoff from three sides and form a semi-closed flow area open to the northeast. Shallow water level, fine lithologic particles (fine sand and clayey silt) in aquifer, slow underground runoff and strong evaporation concentration form a high mineralization and high fluorine phreatic water area.

Pore diving in Baicheng fan-shaped land and river valley has coarse aquifer particles (gravel), strong water permeability and diversion, gentle runoff, intermittent recharge of precipitation and river water, and abundant water. In the valley area, because of its rich organic matter and high iron and manganese content, most of them form iron-bearing groundwater.

Wang Fu-Fulongquan Ice Water Platform has abundant phreatic water in gravel pores, but the water level is deeply buried (mostly above 10m).

Gravel pore confined water of Lower Pleistocene in northwest low plain is distributed in Maolin-Changling northwest low plain and Fuyu, Yushu and Kacha valleys. The water-bearing lithology is coarse and rich in water. The aquifer thickness is generally 5~40m, and the water level is below the groundwater level 1~3m. Underground runoff flows from the west and southwest to the northeast. The distribution range of pore fissure confined water in the underlying Tertiary is basically the same as that in the lower Pleistocene, but it is missing in the Kacha Valley of Yushu. The water-bearing rock series is composed of sandstone, glutenite and other 1-3 positive rhythmic layers, with a thickness of 30~60m. The lithology is loose, the pores and fissures are developed, the water is abundant, the confined water level is high, and it flows naturally in low-lying areas. The water quality is better than that of overlying Quaternary pore confined water.

Engineering geological characteristics of verb (abbreviation of verb)

The lithology of strata in Jilin Province is complex, including loose rock mass, hard rock and semi-hard rock, with obvious regional distribution. The former is mainly distributed in Songliao Plain and intermountain basins and valleys in the central and western regions, while the latter is mainly exposed in the eastern mountainous areas.

According to the geotechnical types in Jilin Province, the rock masses in mountainous areas are divided into magmatic rocks, sedimentary rocks and metamorphic rocks, and the soil types are divided into cohesive soil, cohesionless soil soil and special soil. Now described as follows:

(1) Rock mass type

1, magmatic rock building

Magmatic rocks are widely distributed in Jilin Province, which is the main rock mass type in Jilin Province.

(1) massive hard granite stratum

Mainly distributed in the eastern mountainous areas of Jiaohe, Lan Shu, Antu, Helong, Hunchun and Wangqing. The granites that make up the rock mass mainly belong to the Variscan period, and most of them are acidic rocks. Rock joints and fissures are developed, and spherical and reticulate weathering is serious. Mud surface is often formed between original rock and weathering crust, which is easy to form landslide and collapse under the influence of external environment.

(2) Weathering crust of weak granite

Mainly distributed in Panshi, Chaoyang, Liaoyuan, Ma Ping, Heping, Daheishan, Jilin and Jinma. Residual slope deposits in hills and mountains formed by granite weathering. This kind of rock mass has medium density, soft, large porosity and weak water content, and it is easy to form soft and hard structural planes with the original rock surface, which is a favorable factor for landslide and collapse.

(3) massive hard basalt stratum

Distributed in Changbai Mountain lava platform, Dunhua, Jingyu and other basalt platforms. Basalt rock types including Holocene, Pleistocene, Upper Pleistocene and Late Pleistocene include olivine basalt, tholeiite basalt and stomatal basalt. Basalt columnar joints are developed and have good connectivity. On steep terrain, it is easy to crack along columnar joints, resulting in rock collapse. Quaternary basalt caprock is easy to collapse, and it is easy to cause disasters such as roof caving and collapse during underground mining.

(4) Thick layered hard pyroclastic rocks.

Distributed in Wangqing, northern Dunhua and other areas. It is mainly Jurassic volcanic rocks such as andesite, dacite and rhyolite, with high density, low porosity, high hardness, good stability and difficult deformation.

2. Sedimentary rock structure

Strata include clastic rocks and carbonate rocks.

(1) The clastic strata in the province mainly include Sinian, Carboniferous, Permian, Triassic, Jurassic, Cretaceous and Tertiary. Distributed in Jiaohe, Antu, Yanji, Hunchun, Yishu, Haihuihua and other basins and valleys. Rock mass is multi-layered, and the strength of structural planes is different, which reduces the stability of rock mass, especially the weak plane formed by coal seam and shale, which softens when it meets fire and is prone to geological disasters such as landslide, ground collapse and ground fissure.

(2) Carbonate-bearing strata in the whole province include Sinian, Cambrian, Ordovician, Devonian, Carboniferous and Permian. It is mainly distributed in Sanyuanpu, Yangzishao and Changbai in Tonghua area, and is mainly composed of thick layered limestone with dolomite and sand shale. Rock mass is soluble salt body, so we should pay attention to the phenomenon of water inrush and leakage in karst pits when mining minerals, which is unfavorable to engineering construction. At the same time, it can prevent bad engineering geological problems such as landslide and collapse on the weak interlayer of carbonate rock.

3. Metamorphic rock structure

Mainly distributed in Tonghua and Baishan areas, it is the main rock that constitutes Longgang Mountain. It consists of migmatite, gneiss, slate, phyllite and schist. Joints, schists and bedding are developed, which are prone to geological disasters such as landslides and collapses.

(2) Soil type

Loose rocks are widely distributed in Songliao Plain, which can be divided into three types according to their grain composition, namely cohesive soil, cohesionless soil soil and special soil.

1, cohesive soil

Widely distributed in plain areas, it can be divided into uniform type and multi-layer type according to structural types. Homogeneous structural types are mainly distributed in the undulating platform and Yishu trough of high plains in the north and south of the plain area, and the lithology is mainly loess loam. Multi-storey structures are mainly distributed in the valley areas of high plains and the valley plains of low plains. The upper part of lithology is loam and the lower part is silty sand. This kind of cohesive soil is prone to swamp because of its plastic deformation, high water content, looseness and large settlement.

2. Cohesive soil

According to the particle composition, it can be divided into sandy soil and gravel soil.

(1) sandy soil

Mainly distributed in Changling, Tongyu, Shuangliao, Lishu and other places bordering Liaoning in Inner Mongolia. Topographically, it is an east-west sand ridge with fine sand, medium sand and coarse sand. This kind of soil is loose and has strong water permeability, which is easy to make the dam foundation unstable, produce sand liquefaction and cause foundation deformation and other engineering problems.

(2) Gravel soil

Mainly distributed in Fulongquan-Wang Fu and Baicheng Pingan Town-Fushun area. This kind of soil has coarse particles, strong water permeability, and contains primary minerals such as quartz and feldspar, with small deformation.

3. Special soil

(1) Silty soil

Mainly distributed in river valleys (Songhua River, Liaohe River and its tributaries), the lithology is loam, clayey silt, silt, etc. The thickness is generally less than 2.0m This kind of soil has high water content and is soft and easy to deform.

(2) Saline soil

Widely distributed in the western plain, the total salt content of soil layer is more than 0. 1%, and the soil viscosity is high, which seriously inhibits crop growth.

Environmental geological characteristics of intransitive verbs

The natural conditions in Jilin Province are complex and diverse, the nature and intensity of human engineering economic activities vary from place to place, and the environmental geological characteristics in different regions are obviously different.

Changbai Mountain is in the east.

The area has beautiful natural scenery, high mountains and dense forests, swift rivers, magmatic rocks, sedimentary rocks and metamorphic rocks all distributed, and rock joints and cracks are developed, which are hard and fragile. Geological disasters such as collapse, landslide and debris flow are prone to occur in middle and low mountainous areas; Soil erosion and mine geological disasters (such as ground subsidence, ground fissures, mine water inrush, spontaneous combustion of coal seam, gas, etc.). ) it is easy to happen in hilly areas.

(2) Central Plateau

The human economic activities in this area are frequent, the population density is high, the land reclamation index is over 90%, the population is concentrated, the industry and agriculture are developed, the climate is suitable and the land is fertile. Environmental geological characteristics are mainly environmental pollution and the downward trend of urban groundwater level, with occasional earthquakes.

Western low plain

The land in this area is barren, mainly animal husbandry, with reclamation index of 20%~50% and dry climate. The main environmental geological problems are land desertification and groundwater table decline.

Looking at the regional differences of environmental geological characteristics in the whole province, in addition to the original natural factors (lithology, strata, groundwater, structure, precipitation, etc. ), there are a lot of human factors, such as building roads and digging slopes, quarrying, deforestation, building reservoirs and dams and developing mineral resources. The combination of natural and human factors leads to frequent occurrence of various geological disasters, which poses a serious threat to people's lives, property and living space. Therefore, environmental geological problems should be solved and avoided in time.