Main geological environment problems and types of geological disasters

Land degradation is one of the outstanding problems in the ecological environment and an obstacle to the sustainable development of agricultural production. Land degradation in the whole province is mainly reflected in soil erosion, land desertification and soil salinization.

1. Soil erosion

Water and soil erosion in Shandong Province is mainly hydraulic erosion with various types. In terms of erosion intensity, moderate erosion accounts for the largest proportion, accounting for 159. 1000 hm2, accounting for 10. 16% of the total area of the province. Intensity erosion ranks second, with an area of 975,200 hm2, accounting for 6.21%of the total area of the province; The lightly eroded area is 790,000 hm2, accounting for 5.03% of the whole province. The area of extreme intensity erosion (water erosion) is 265,438 0.35 million hm2, accounting for 65,438 0.36% of the whole province. Serious erosion and engineering (man-made) erosion are the least, covering an area of 26,200 hm2, accounting for 0. 17% of the total area of the province.

According to investigation and statistics, by 2004, the area of soil erosion in the whole province was 36,065,438+10,000 hm2, accounting for 22.93% of the total area. Among them, the hilly area is 3,245,400 hm2, accounting for 20.66%; The plain sandstorm area is 355,600 hm2, accounting for 2.26%.

2. Land desertification

Desertification land is widely distributed, from the eastern coast to the western plain, from the hills of Jiaodong to the mountainous areas in the south-central part of Shandong Province, and the whole province 17 cities have different degrees of distribution. However, according to the monitoring principle of "continuous area is greater than 0.0 1 10,000 hm2" stipulated by the desertification monitoring standard, the whole province involves 14 cities and 7 1 county (city, district). According to the geographical location, causes and distribution characteristics of desertification land, the whole province can be roughly divided into three desertification areas: the desertification area of the Yellow River Plain in northwest Shandong, the coastal sandstorm area in Jiaodong and the sandstorm area along the river in central and southern Shandong. See table 4- 1 for the distribution of different desertification types in the three major desertification areas and desertification land types in the whole province, and table 4-2 for the distribution of desertification land counties (cities, districts) in the whole province.

Table 4- 1 Distribution Table of Different Desertification Types Unit: 10,000 hm2

3. Land salinization

Salinized land is mainly distributed in the Yellow River Plain, Yellow River Delta, Bohai Bay and Laizhou Bay in northwest Shandong, with flat and low terrain, mainly involving some counties (cities, districts) in Dongying, Binzhou, Weifang, Dezhou, Liaocheng and Heze. According to statistics, the total area of saline soil in the province is1027,500 hm2, accounting for 6.6% of the total land area. Among them, saline fluvo-aquic soil and saline soil are mostly distributed in shallow depressions, gentle slopes and along the Yellow River plain in northwest Shandong, accounting for 64.5% of the saline land in the whole province. Coastal saline soil is mainly distributed in the Yellow River Delta, Bohai Bay and Laizhou Bay from Jiaolai Estuary to Majia Estuary, with the altitude below 13m, accounting for 35.5% of the saline land in the province. Heze, Lubei and other places have a small area of alkaline fluvo-aquic soil and alkaline soil. Because the salt content is mainly carbonate, it is difficult to improve. At present, most of them are abandoned farmland. See Table 4-3 for the areas of mild, moderate, severe and extremely severe saline soil in each city.

Table 4-2 Regional Distribution of Desertification Land in the Province

Table 4-3 Statistical Table of Saline Soil Area in Shandong Province

Second, groundwater pollution.

The recharge sources of groundwater are mainly atmospheric precipitation and infiltration of surface water, so the pollution of groundwater is closely related to the discharge of "three wastes" in industry and life, the application of agricultural fertilizers and pesticides. The pollution degree of towns and industrial concentrated distribution areas is higher than other areas, the pollution degree of Quaternary pore water is generally higher than that of fractured karst water, and the shallow groundwater is higher than that of deep groundwater.

1. Pore water pollution in south-central and eastern Shandong.

Groundwater pollution is mainly pore water, mainly distributed in valleys, river valleys, coastal areas, piedmont plains and mountain basins, and most of them are densely populated areas. Due to the recharge of surface sewage and the existence of underground water level drop funnel in some areas, some areas have been seriously polluted.

From Xiazhuang to Taozhuang, Xuecheng District, Zaozhuang, the groundwater along the banks of the Panlong River is zonally polluted due to the recharge of surface sewage, and the over-standard rates of fungi, total hardness, sulfate and dissolved total solids are 46.7%, 43.8%, 29.2% and 20.8% respectively. The eastern part of Tengzhou is a vegetable growing area. Affected by a large number of chemical fertilizers, the nitrate content in groundwater reached 185.33mg/L, exceeding the standard by 0.09 times, and the total hardness exceeded the standard by 0.57 times, resulting in nitrate point pollution. Affected by gypsum mining area, the sulfate and hardness of groundwater exceeded the standard by 0.79 times and 0.67 times respectively. The chloride, sulfate, salt and total hardness of groundwater along Fuxiaohe River and Longjiang River in Zibo City are relatively high. The northern Weifang, Changle, Anqiu and Gaomi are affected by the seawater intrusion in the south, resulting in salinization of water quality and many factors of groundwater exceeding the standard, generally exceeding 1 ~ 3 times, and some as high as 5 times; In addition, due to the double pollution of life and industry, the pore water quality on both sides of Guhe River and Xishuanglong River in Tai 'an City is extremely serious, and the karst water in the lower part is polluted by overflow. Due to the poor groundwater movement conditions in Ningyang County and the northern Dawenkou Basin, domestic sewage is concentrated and the pollution is very serious.

Groundwater pollution in eastern Shandong is caused by over-exploitation of groundwater and other human factors. The main pollutants in groundwater are fluoride, chloride, sulfate, nitrate, total hardness, salinity and so on. , exceeding the standard by 0. 12 ~ 8.97 times. All pollution points are located in the lower reaches of rivers and coastal areas, such as the lower reaches of Dagu River, Baisha River-Chengyang River, Zhang Cun-Licun River and Yanghe River. In the northern coastal areas and estuaries of Laizhou-Longkou-Zhifu-Mu Ping, the chloride exceeded the standard by 1 ~ 8.94 times (the maximum was Panjia, Tushan Town, Laizhou), and the sulfate exceeded the standard by 1 ~ 8.97 times (the maximum was Zhuangzi, Wu Jia, Xiyou Town, Laizhou). Nitrate in Xibuqian, Laiyang, Yongfu Garden, Shengli East Village and Yi Gang Forest Farm of Yangjun Town in Fushan District exceeded the standard by 7.8 times and 6.4 times respectively. In addition, due to groundwater exploitation and seawater intrusion, the chloride content in Changfeng Village of Weihai is as high as 1066.8mg/L, which is 4.3 times higher than the standard. Because Wendengdaokou village is close to the river, the nitrate content in groundwater polluted by industry and life is as high as 560mg/L, which is 6.2 times higher than the standard. The pollution of Shanjia, Xukou Village and Taishanglinjia in Rongcheng is also serious, and the multiple of pollutants exceeding the standard is between 0.12 and 5.22 times.

2. Shallow groundwater pollution in northwest Shandong plain.

In addition to industrial pollution, agricultural pollution of shallow groundwater in northwest Shandong plain is also obvious. Agricultural pollutants mainly include "three nitrogen", organic phosphorus and organic chlorine. The heavily polluted areas are mainly distributed along the sewage river, towns and industrial concentration areas.

The detection rate of five poisons in Heze city is 100%, but there are few points exceeding the standard, and the single exceeding the standard rate is 5%. Only in Dongguan 1998, Cao Xian County, the detected value of mercury in groundwater reached 0.009mg/L, which was 8 times higher than the standard. The detection rate of "bhc" and "DDT" in agricultural pollution monitoring is 100%, but the detection value is small, and neither of them exceeds the standard. The detection rate of nitrate is 86.4%, only Yuncheng Zhangji 1999 exceeds the standard, and the detection value reaches110.58 mg/L. In addition, the total oil content of shallow groundwater in Zhongyuan Oilfield Development Zone has gradually increased in recent years. Compared with 1992, the total oil content in Gaocun and Chunting areas increased by 3 ~ 5 times.

The groundwater pollution in rural areas of Liaocheng is relatively light. For Donggucheng Town, guanxian, which is irrigated by sewage, although nitrate, nitrite, fluoride and pH value have all increased, the increase rate is small. The shallow groundwater pollution in Liaocheng and its vicinity is serious, and the "five poisons" in some areas exceed the standard. For example, the maximum contents of phenol and mercury in groundwater near chemical plants are 0. 16mg/L and 0.02 mg/L, respectively; The mercury content of shallow groundwater in Linqing City also exceeded the standard.

Agricultural pollution in Texas is more serious. Among them, the detection rate of dimethoate was 100%, and the content was between 2.5 ~ 19.8 μ g/L, with the highest content in the south of Linyi and the west of Decheng. The detection rate of dichlorvos is between 50% ~ 100%, and the content is between 0.2 ~ 2.5μg/L, with the highest content in the south of Pingyuan County. The detection rate of bhc was 100%. The detection rate of 4049 in groundwater in each section is 100%, and the content is 1. 1 ~ 6.8 μ g/L, with the highest value appearing in the south of Linyi County. The detection rate of nitrate in this area is 68.8%, which exceeds the standard by 8.3%. The nitrate content is generally 26 ~ 159 mg/L, and the highest is1320 mg/L. The over-standard rates of salinity, total hardness, sulfate and chloride content are 87.5%, 85.4%, 60.42% and 64.58% respectively.

The over-standard rates of chloride and sulfate in Binzhou groundwater are 59% and 55% respectively, and the over-standard rate of nitrate nitrogen content is 29%. In Changshan area in the south of Zouping, although the water level is deeply buried, the content of nitrate nitrogen reaches 1998 and 1999/84.0 mg/L and 162.8mg/L respectively. In addition, there are resident in Lize Town, Zhanhua County, Huimin Hefang and Pangjiaji, Wudi County. Because Binzhou City vigorously promotes the use of pesticides with high efficiency, low toxicity and low residue, the content of some pesticide components in shallow groundwater in this area has decreased. However, the detection rate of petroleum in groundwater of Xiahe, Bincheng, Dansi, Dudian, Xiaoying and Chunhua in Zhanhua is 100%, and the contents are 0.2 1mg/L, 0. 10mg/L, 0.08mg/L and 0.06mg/L respectively.

The groundwater pollution in Dongying city is generally serious, and the areas with serious pollution are mainly distributed along the sewage river, towns and industrial concentration areas. According to the investigation, the shallow and deep groundwater along the coast of He Zi are polluted to varying degrees due to the influence of sewage infiltration, and there are laws that the pollution near the river is heavy, the pollution far away is light, the flood season is heavier than the dry season, and the shallow layer is heavier than the deep layer. Petroleum is the main pollution factor, followed by chemical oxygen consumption, volatile phenol, salinity, total hardness, chloride, sulfate, nitrate and other components. The maximum content of petroleum in shallow groundwater is 2.8mg/L, and that in deep groundwater is1.32 mg/L; Followed by Cr6+, with a minimum value of 0.025mg/L. ..

3. Fissure water and karst water pollution

This type of groundwater is mainly distributed in the central and southern Shandong and the hilly areas in eastern Shandong. This area has a small population and fewer industrial enterprises, and the groundwater quality is good, but there are different degrees of point pollution in some areas, and the pollution is heavier near the town station and mining area. For example, the water quality in Nanguan-Zhaozhuang, Xin Bus Station-Mafang Factory, Ningyang Huafeng Coal Mine and Gangcheng Gao Qiao is poor (the karst water in Xin Bus Station and Xingjiazhai is very poor); In the hilly areas in the west of Rizhao City and the east of Juxian County, the quality of bedrock fissure water is poor because of the large use of chemical fertilizers and pesticides in industry, domestic sewage and agriculture. The main components exceeding the standard in groundwater are nitrate, nitrite and total hardness, and the maximum comprehensive evaluation score of groundwater in Sanzhuang Town, Donggang District is 7. 19. In addition, the quality of karst water in Madian and Mingcun in Qingdao, Qingnigou in Laiwu and Zhuang Yan is poor, and the main components of groundwater exceeding the standard are nitrate, permanganate index and total hardness.

According to the monitoring results of Shandong Geological Environment Monitoring Station, the groundwater quality in Shandong Province is evaluated and divided into four grades: excellent-good water, ordinary water, poor water and extremely poor water (Figure 4- 1).

Three. Collapse, landslide and debris flow

According to statistics, there are a total of collapse, landslide and debris flow disasters 159 in the province, mainly distributed in Luzhong Mountain, Daze Mountain in Jiaodong, Kunyu Mountain and Weide Mountain. According to the deposit amount, it is divided into three categories (horizontal), which account for 10.6%, medium 18.2% and small 7 1.2% respectively. See Figure 4-2 for the distribution of geological environment problems and geological disasters in Shandong Province.

Collapse, landslide and debris flow are all serious disasters caused by the sudden migration of a large number of materials, and their destructive power is second only to earthquakes. Their disaster conditions are:

1. Topography

The height difference and slope determine the scale and speed of collapse and landslide. Rock mass instability, surface water infiltration and slope toe hollowing are most likely to occur. Debris flow is a mixed fluid of soil and rock in a ditch or slope, with the highest disaster rate in a single ditch. The greater the longitudinal slope, the more serious the erosion and siltation disaster.

2. Geological structure and lithology

In the active fault zone and earthquake zone, the weak structural plane in the stratum is prone to landslide or collapse, and the impermeable layer under the loose accumulation layer or the relatively water-proof bedrock is prone to soil landslide. Broken strongly weathered rocks and loose debris deposits are the material basis for the formation of debris flow.

3. Groundwater

The fluctuation of groundwater level in rock mass and soil in rainy season and dry season changes the water pressure and load value, thus affecting the occurrence of collapse, landslide and debris flow disasters.

4. Heavy rain

Rainfall is the main inducing or stimulating factor of collapse, landslide and debris flow disasters. Heavy rain or long-term rainfall permeates the soil, which can cause the above disasters in areas with fragile geological structure.

5. Human activities

Unreasonable exploitation and logging will destroy the natural balance of geological environment, thus inducing or aggravating collapse, landslide and debris flow disasters.

Figure 4- 1 Groundwater Quality Zoning Map of Shandong Province

Figure 4-2 Geological Environment Problems and Geological Disasters in Shandong Province

Table 4-4 List of Classification Results of Collapse, Slip and Flow

Four. Sea (salty) water intrusion

Seawater (salt water) intrusion is a hydrogeological phenomenon that seawater migrates to inland fresh water aquifer through saline aquifer groundwater due to the change of groundwater dynamic conditions. The invasion of sea (salty) water causes the destruction of water supply sources, the salinization of land and the deterioration of ecological environment. Sea (salty) water intrusion in Shandong Province began in the mid-1970s. In recent 30 years, with the increase of groundwater exploitation, the scale of seawater (salt) intrusion in coastal areas has been expanding. At present, there are different degrees of sea (salty) water intrusion from Guangrao to Longkou and the south bank of Laizhou Bay. In the estuaries of Qingdao, Weihai, Yantai and Rizhao, there have also been sea (salty) water intrusions of different scales.

1. Salt water intrusion

It appears in the coastal low plain from Guangrao-Shouguang-Hanting-Changyi to Pingdu. The terrain of this section is flat, and the beach width is 10 ~ 18 km, and the elevation is below 5m, which is mostly beach saline-alkali land. Groundwater runoff is slow, mainly vertical evaporation and discharge. Coupled with the influence of ocean tides, the salt content of groundwater is very high, mostly salt water or brine. South of salt water is the piedmont alluvial plain. The groundwater runoff in this area is gentle, the alternation of water is strong, and the water quality is low salinity fresh water. Under natural conditions, groundwater flows from south to north, and part of it discharges supplementary salt water. In recent 30 years, due to the massive exploitation of underground fresh water in this area, the exploitation intensity has exceeded the natural recharge capacity, and meteorological factors have caused the water level in the fresh water area to drop sharply, forming a descending funnel, and the water level in the funnel area is lower than the salt water level, resulting in the reverse recharge of fresh water and the formation of salt water intrusion.

As can be seen from Table 4-5, the seawater intrusion area increased sharply from 1979 to 1985. Since 1990s, the total area of salt water intrusion has not increased, especially in 1999. However, in 2000, due to the decrease of precipitation and other reasons, the salt water intrusion area expanded again, increasing by 154.8km2 compared with 1999, which was1999 and12000. It can be seen that as long as we enter the dry season, the exploitation of fresh groundwater will increase, the groundwater level will drop greatly, the intrusion speed of saline groundwater will accelerate, and the intrusion area will expand, and vice versa.

Table 4-5 List of Salt Water Invasion Area over the Years Unit: km2

2. Seawater intrusion

Mainly produced in Laizhou-Zhaoyuan-Longkou area, Laizhou Bay east coast accumulation plain. The area is narrow and banded, with a width of 3 ~ 5 km. Under natural conditions, the groundwater level is higher than the sea surface, and the groundwater is discharged in the direction of seawater. When the local groundwater is overexploited, the groundwater level drops sharply. When the groundwater level in coastal areas is lower than the seawater level, seawater will replenish the underground freshwater aquifer inland, resulting in seawater intrusion. The estuaries of Yantai, Weihai, Qingdao and other cities are the main local water supply sources. Due to over-exploitation of groundwater, the groundwater level on both sides of the river has dropped significantly, leading to seawater intrusion. By 2005, the seawater intrusion area in the whole province has reached 89 1.4km2 (Table 4-6).

Table 4-6 Statistical Table of Seawater Invasion Area in Shandong Province Unit: km2

Verb (abbreviation of verb) groundwater overexploitation funnel

Many over-exploitation funnels of groundwater have appeared in Shandong Province. See Table 4-7 for the basic information of main over-exploitation funnels.

Table 4-7 Statistics of Basic Situation of Main Groundwater Overexploitation Funnels in Shandong Province

The over-exploitation funnel of groundwater in Shandong Province can be divided into the following types:

1. Overexploitation funnel of fractured karst water

Such as the over-exploitation funnel of Dawu water source in Zibo and the over-exploitation funnel of Tai 'an urban water source.

2. Pore water over-exploitation funnel

It can be divided into two categories: one is shallow groundwater over-exploitation funnel, such as Huantai-Guangrao-Shouguang-Hanting-Changyi over-exploitation funnel, Pingdu over-exploitation funnel, Gaomi over-exploitation funnel and guanxian-Shenxian over-exploitation funnel. The other is the over-exploitation funnel of deep groundwater, such as Dezhou, Binzhou and Heze.

The formation and development of groundwater over-exploitation funnel is mainly due to the long-term over-exploitation of groundwater, which destroys the dynamic balance relationship between groundwater exploitation and compensation in mining areas and makes the groundwater storage resources consume continuously, thus leading to the continuous decline of groundwater level and the partial discharge of aquifer storage, forming an over-exploitation drainage funnel.

Six, the ground subsidence

The land subsidence in Shandong Province is caused by the changes in the dynamic conditions of groundwater and the mechanical relationship between soil and groundwater during man-made engineering activities, especially when pumping groundwater. Ground subsidence caused by groundwater exploitation can be divided into two types.

1. Ground collapse caused by exploitation of karst water-karst collapse

It refers to a geological phenomenon that the overlying sandy soil layer collapses under the influence of excessive or concentrated exploitation of groundwater. Karst collapse is mostly distributed in carbonate rock distribution areas in middle and low mountains and hills in central and southern Shandong. The reasons are as follows: first, undercurrent: that is, in the distribution area of concealed limestone, due to the exploitation of karst water, precipitation or reservoir storage, the water level changes greatly, the groundwater velocity increases, and the soil particles migrate, resulting in soil layer collapse; 2. Vacuum erosion: When the groundwater level is lower than the floor of the soil layer, a vacuum negative pressure is formed between the water surface and the soil layer. Under the combined action of gravity and negative pressure suction, the soil layer collapses, resulting in ground collapse. For example, land subsidence in Tai 'an, Zaozhuang, Laiwu and Linyi all fall into this category (Table 4-8).

Table 4-8 Land Subsidence Questionnaire of Shandong Province

Take Linyi City as an example. Since 1980s, there have been 18 karst collapses in Linyi City alone (see Table 4-9 for the main karst collapses before 2003), and more than 30 karst caves have been formed. Karst collapse mainly occurred in the groundwater drop funnel in Linyi City and Shuanghou and Qingtuo in yinan county. Karst collapse occurs from time to time on both sides of Miao Zhuang, Sangang, Guomian No.8 Factory and Yanshi Railway, which is near 120km2 in the central and western part of Linyi City. In February 2003, the subgrade slope of Yanshi Railway collapsed, which threatened the normal operation of railway trains. From mid-July to early August, 2002, four buildings in Miao Zhuang residential area were dilapidated due to karst collapse and cracking, resulting in the demolition of three buildings. In addition, the burst of small rivers also caused a lot of surface sewage to be reinjected to pollute underground water sources, and many fish ponds and farmland were destroyed. At present, there have been more than 20 karst collapses in this city, which have damaged 4 buildings and 10 houses, affected a lot of farmland cultivation and social stability.

Table 4-9 List of Typical Land Subsidence Points (Areas) in Linyi City

2. Ground collapse caused by exploitation of pore water

The main reason is that the extraction of pore water in loose sediments changes the dynamic conditions of groundwater, resulting in the loss of silt particles and ground collapse. This type of ground subsidence is mostly distributed in the hydrogeological area of loose rocks in the southwest Shandong plain, especially near the ancient river channel. For example, the ground collapse in some areas of Heze and Jining City is caused by pore water. See Table 4-8 for details.

Seven. land subsidence

Land subsidence mainly occurs in the hydrogeological area of loose rocks in the northwest plain of Shandong Province, which is mainly caused by unreasonable pumping of groundwater by human beings, resulting in tight water discharge from the upper weak aquifer. At present, the obvious land subsidence in Shandong Province mainly occurs near Dezhou, Jining, Heze, Binzhou, Dongying and other cities. Because most of these areas are poor in shallow groundwater, urban and industrial water supply depends on deep groundwater, which is a consumable water source and its recharge and regeneration ability is poor. Long-term continuous mining will inevitably lead to the continuous decline of deep groundwater level. The monitoring of land subsidence in the whole province was carried out late, and the relevant departments paid insufficient attention to it, and the monitoring data was not systematic, which brought some difficulties to the evaluation of land subsidence. Some sporadic ground subsidence monitoring results are shown in Table 4- 10.

Table 4- 10 Questionnaire for Monitoring the Present Situation of Main Land Subsidence Areas in Shandong Province

Eight, ground fissures

Ground fissures mainly occur in the expansive soil distribution areas of Jinan, Zaozhuang, Zibo, Tai 'an and Qingdao. The main reason is that the water level drop caused by long-term artificial exploitation of groundwater causes the cohesive soil in the soil to shrink due to water loss, and the infiltration of precipitation in rainy season causes the water level to rise, and the soil absorbs water and expands, resulting in cracks on the ground (Table 4- 1 1).

Table 4- 1 1 Overview of Ground Fissures in Shandong Province