1. Analysis of geological-ecological environmental issues in Qingdao
(1) Environmental engineering geological issues in Qingdao
1. Mining environmental engineering geological issues< /p>
The minerals in Qingdao are mainly non-metallic minerals, which can be divided into two categories: one is stone and sand, including granite, marble and construction sand. Granite is mainly distributed in Laoshan and Dashan. Zeshan, Xiaozhushan and other places, marble is mainly distributed in the Jingshan Group and Fenzishan Group in Pingdu, Laixi and other places, and construction sand is mainly distributed in the lower reaches of the Dagu River; the other type is other than stone. There are many types of non-metallic minerals and they are widely distributed, but graphite is mainly found in Jingshan Group and Fenzishan Group. Metal minerals are sparsely distributed, mainly gold, mainly produced in Pingdu, Laixi and other places.
Ore environmental geological problems are mainly caused by mining, including damage to vegetation and farmland, debris flow and water pollution caused by the rainy season, collapse and water accumulation in goafs, and landslides caused by simple roads in mines. , mining, and sand mining damage to scenic spots and nature reserves, etc. The most important ore environmental geological problems in Qingdao are the damage to vegetation and farmland caused by mining and the pollution of groundwater caused by sewage discharge from mining areas. The most serious problems are in the Pingdu graphite mining area and Laixi area.
2. Collapse
Collapse in Qingdao mainly refers to the collapse of rock mass, which mostly occurs in steep areas such as Laoshan Mountain, Xiaozhu Mountain, and Daze Mountain, where there are many dangerous rocks. , fault zones are cut vertically and horizontally, cracks are developed, and weathering is intense. The rock mass that makes up the mountain slope is cut into polyhedrons of varying sizes by several sets of structural planes. Under the action of gravity, surface water, and vibration, the rock mass becomes unstable and falls rapidly, with some Rock blocks slide, avalanche, collapse and other different ways. In recent years, with the rapid development of economic construction, road construction, engineering construction and exhaust quarries have destroyed the natural balance of ground stress on mountain slopes and increased the risk of collapse. During the rainy season every year, rocks of varying sizes collapse. Body collapses and landslides occur from time to time, causing certain harm to people's lives and property, highway transportation and tourism.
3. Ground fissures
Ground fissures are geological phenomena in which surface rock and soil crack under the action of natural or man-made factors, and cracks of a certain length and width are formed on the ground. The reasons are complex and varied.
After a heavy rain in mid-September 1983, a road with a direction of 25°, 80m long and about 0.3~0.4 in width was found along Qingqing in the northwest of Quzhong Village in Chengyang City, Qingdao City, more than 10 meters east of the highway. m. Ground fissures with a depth of about 1.5m began in early 1981, and then appeared twice in July 1982 and September 1983. They both occurred after rain and were extended successively.
4. Coastal erosion
Since most of the coasts in Qingdao are bedrock coasts, erosion disasters mainly occur on local sandy coasts. As we all know, sandy and silty coasts are valuable tourism resources. However, unplanned development of coastal areas in the past few years, especially unrestricted predatory sand dredging, has brought a series of disasters to the sandy coastal environment. For example, sand dredging in the Liuqing River area of ??Qingdao has intensified coastal erosion, affected the safety of highways and bridges, and forced highways to be relocated inland.
(2) Environmental hydrogeological problems in Qingdao
1. Original environmental hydrogeological problems
The main endemic disease in Qingdao is dental caries (dental fluorosis) ) and bone fluorosis, one of the biogeochemical diseases, are mainly caused by long-term drinking of water with high fluoride content and eating high-fluoride foods and vegetables, which causes excessive fluoride to accumulate in the body. Drinking water is the source of human fluoride. The main source, accounting for about 65% of the total. The fluoride disease-affected areas in Qingdao are mainly distributed in the low-lying areas of the piedmont alluvial plain between the west bank of the middle and lower reaches of the Dagu River and the Jiaolai River. The area with the highest fluoride content is in the northwest area of ??Zhongzhuang Town, Pingdu City, with the highest fluoride content reaching the national standard drinking water standard. 13.75 times, it is a key prevention and control area for high fluoride disease. In addition, it is also scattered near Xiagezhuang, Jiangshan Town, Jimo Taizizhuang and other places in Laixi City.
The terrain of the high fluoride area is mainly a gentle or closed saline-alkali low-lying area. The overlying Quaternary silty clay is generally sandwiched with irregular calcareous nodule layers, which contain high fluorine content and the bottom foundation. The rocks are Cretaceous Qingshan Group and Wangshi Group clastic rocks, with a fluorine content of (545-600)×10-6 and a high solubility coefficient.
The characteristics of groundwater in high fluoride areas are: slow alternating groundwater runoff, alkaline, pH=7.5~8.3, and Ca dominates the cations.
2. Man-made environmental hydrogeological issues
(1) Sea (salt) water intrusion
Sea (salt) water intrusion in Qingdao mainly occurs in In areas where groundwater is relatively abundant, mining is concentrated, large volumes are mined, and are close to sea (salt) water, this may also be caused by changes in farming methods or improper development of coastal beaches.
(2) Regional groundwater pollution
Groundwater quality pollution refers to changes in the physical, chemical and biological characteristics of groundwater that are unfavorable to human life or production under the influence of human activities. As a result, the originally scarce groundwater resources cannot be utilized or the treatment of contaminated groundwater results in increased water costs and waste of resources. Groundwater circulates slowly and is difficult to recover once contaminated, so it is very important to prevent and control groundwater quality pollution.
Select indicators such as Cl-, SO2-4, salinity, hardness, NO-3, NO-2, phenol, manganese and other indicators that can represent the groundwater quality pollution status in Qingdao to conduct groundwater quality pollution analysis. The results show that the supply area in the upper reaches of the Xiaogu River is an area where gold mines and graphite mines are concentrated. Industrial pollution is relatively serious. Coupled with agricultural pollution, the water quality has seriously exceeded the standard. In recent years, through treatment and rectification, the pollution trend has been controlled; the tributary Dagu The river is mainly affected by the sewage discharge from Laixi City. After pollution control, Cl- has a downward trend, but the water quality still exceeds the standard, such as the Sunshou-Pumu section; the lower reaches of the Dagu River, the lower reaches of the Baisha River-Chengyang River, and the Zhangcun-Licun River The lower reaches of Yanghe River, Caowen-Daoer River and Wanggezhuang River are mainly caused by urban industrial pollution and seawater intrusion. In particular, urban planning in recent years has mostly classified this area as an industrial radiation area. With the development of economy and cities, the pollution rate is relatively high. Fast, the main exceeding standards include Cl-, SO2-4, NO-3, mineralization and total hardness, phenol, manganese, etc. It is urgent to strengthen rectification to curb the trend of worsening pollution.
(3) Groundwater falling funnel
Long-term overexploitation of groundwater resources will cause the groundwater level to continue to decline, forming a groundwater falling funnel. The main existing groundwater mining funnel in Qingdao is located in Nanwa District, Pingdu City. The center of the funnel is located near Liaolan-Zhongzhuang. It is mainly caused by over-exploitation of Liaolan Xinhua Paper Mill and agricultural irrigation. The Pingdu Nanwa funnel was gradually developed in the late 1970s and early 1980s. Since the 1980s, drought has lasted for a long time, resulting in a long-term state of groundwater extraction exceeding replenishment. The area of ??this funnel has expanded and contracted over a long period of time, basically within the allowable range of many years of adjustment, and it is not expanding infinitely. The main reason for the formation of this funnel is industrial and agricultural mining. The funnel extends towards the Jiaolai River in a skip shape and extends to Gaomi City. Its main characteristics are: the funnel develops within the allowable range of many years of adjustment, and the scope is small, the depth is shallow, and it is far from the coast. The main environmental geological problems caused by this are the reduction of groundwater resources, the depth and difficulty of water extraction, and the abandonment of a large number of shallow wells, which can easily cause groundwater runoff pollution.
The current situation of the funnel in Pingdu Nanwa in 2002 is: in the dry season, the funnel area is 146km2, the funnel center water level is 12.03m deep, and the lowest water level is -1.56m; in the wet season, the funnel area is 199.7km2, and the funnel center water level is buried deep 12.94m, the lowest water level is -2.37m. Generally speaking, the current situation of Pingdu Nanwa funnel is in a period of contraction, which is the inevitable result of the suspension of production of Liaolan Xinhua Paper Mill, the reduction of mining volume, and the westward recharge of regional groundwater runoff.
(3) Ecological environment issues in Qingdao
1. Vegetation development
The vegetation in Qingdao can be divided into dense forest areas according to its development degree and type. , general forest areas, sparse forest areas, farmland vegetation, swamp vegetation, bare rock vegetation and other vegetation, etc.
2. Soil and water loss
(1) Soil type
The terrain in Qingdao is complex and there are many soil types, but there are five main categories, namely brown soil , sand ginger black soil, fluvoid soil, cinnamon soil, salt soil. The total soil area of ??Qingdao City is 82.55×104hm2, accounting for 74.35% of the total land area.
(2) Current situation of water and soil erosion
The total area of ??water and soil erosion in Qingdao in 2000 was 40.64×104hm2, accounting for 36.6% of the city’s total land area. The areas of light, heavy and medium water erosion were Accounting for 10.83%. The total area of ??water and soil erosion in cultivated land is 22.92×104hm2, accounting for 56.4% of the total area of ??water and soil loss. The area of ??medium water erosion in cultivated land is 9.65×104hm2, accounting for 23.8% of the total area of ??water and soil loss in cultivated land, accounting for 42.1% of the total area of ??water and soil loss in cultivated land.
The grassland water and soil loss area is 880hm2, accounting for 0.22% of the total water and soil loss area.
3. Agricultural pollution
In 2000, the cultivated land area in Qingdao was 54.6×104hm2, and the total amount of pesticide application reached 7451t, with an average of 18.7kg of pesticides per hectare. Chemical pesticides are the most toxic chemicals used in agricultural production, with the widest application area and the highest toxicity. Such high application intensity has polluted groundwater in many areas of Qingdao City, seriously destroying the balance of agricultural ecology, agriculture and forestry. The natural enemies of pests, diseases, and rodents have been exterminated in large numbers, and the quality of agricultural products is worrying.
This ecological and environmental geological survey *** collected 40 samples of groundwater pesticide contamination. The test items were two indicators of organochlorines: 666 and DDT, and organophosphorus: methyl parathion and parathion. The test results show that the groundwater pesticide pollution in Qingdao is mainly distributed in the Dagu River, Baisha River, and Yanghe River basins, with organochlorine pollution being the main factor, especially DDT. The rate is as high as 22.5%, the exceedance rate is 15%, and the maximum exceedance multiple is 80 times.
4. Sewage, wastewater and garbage discharge
The main pollution sources of industrial wastewater in Qingdao are Licang District and Sifang District. The main industries are electric power, chemical industry, food, paper making, etc. COD emissions in industrial wastewater are the largest, followed by ammonia nitrogen, petroleum, volatile phenols, cyanide, arsenic, etc.
There are numerous industrial pollution sources (including small and medium-sized enterprises) within the drinking water source area of ??Qingdao City. There are more than 70 industrial wastewater dischargers that directly or indirectly enter the water source area, with an annual discharge of more than 5 million tons of wastewater. . The largest amount of pollutants and wastewater discharged into the water source area is the industrial enterprises in Laixi City, with wastewater accounting for 70% of the total. The water source area that receives the most pollutants is the section below Jiangjiazhuang, the main stream of the Dagu River, followed by Xiaogu There is a lot of domestic sewage and industrial wastewater produced in the water source areas of the Baisha River and the Baisha River. More than 1.7 million tons of domestic sewage in the city directly enter the drinking water source area per year, accounting for 1.2% of the total. The rest of the sewage is evaporated or discharged on site. Seep into the ground.
Qingdao urban area is located on the east coast of Jiaozhou Bay, facing the Yellow Sea in the south. After urban industrial wastewater is treated or treated by urban sewage treatment plants, most of it enters Jiaozhou Bay directly or indirectly, and a small part is discharged into Jiaozhou Bay. Yellow Sea or Laizhou Bay.
With the continuous expansion of Qingdao’s urban area and the increase in floating population, the amount of urban domestic waste generated has increased year by year. In 2001, the amount of domestic waste generated was 125×104t, which was an increase from the previous year. Domestic waste is mainly disposed of through landfill, and both the clearance rate and the harmless treatment rate are 100%.
2. Current status evaluation of Qingdao’s geological-ecological environment quality
1. Selection of evaluation index system
Based on the characteristics of Qingdao’s geological-ecological environment quality evaluation and requirements, formulate a more detailed evaluation index system, including three systems: natural ecological environment, geological environment and man-made environment, landform type, soil type, vegetation development degree, forest coverage, average precipitation, groundwater richness, and soil erosion problems , seawater intrusion, non-point source pollution problems, rock and soil type, crustal stability, groundwater pollution status, slope environmental variability problems, mine environmental problems, population density, proportion of cultivated land area, groundwater extraction level, gross national product per unit area, etc. index.
The scope of this evaluation uses the geological map of Qingdao City as the base map. The evaluation area is divided into 2,765 2.0km×2.0km evaluation units, and each unit is assigned a value based on the corresponding indicator.
There are three ways to assign values ??to the above indicators: one is based on actual measurement results, such as groundwater richness, groundwater exploitation degree, etc.; the other is based on statistical calculations, such as population density, national product per unit area The third is based on the actual situation, using scales of 1, 2, 3, and 4 respectively for the quality of engineering geological environments of categories I, II, III, and IV.
2. Evaluation model and calculation process
The evaluation model still uses the neural network BP model. Referring to the partition indicators, 40 samples (units) are determined as learning samples, and 18 input indicators are used. There is 1 output layer neuron, 1 hidden layer neuron, 20 hidden nodes, the maximum total error is 0.01, the maximum individual error is 0.001, the number of training is only 200, and the normal system error is 0.00996. The result obtained It is required to retain 6 decimal places, and the system converges very well.
After the sample learning is completed, the ownership of the remaining samples can be determined, and based on the output results, it can be determined which type of ecological geological environment quality area a certain sample belongs to. The entire calculation is completed by computer based on the BP model of neural network. Based on the calculation results of this model, a geological environment quality zoning map of Qingdao was compiled (Figure 14-5).
3. Analysis of evaluation results
The calculation results show that Qingdao is divided into Class I, II, III and IV geological-ecological environment quality areas, and their proportions are 28% respectively. , 25.6%, 36% and 10.4%.
1) Areas with excellent geological-ecological environment quality (Class I areas): distributed in the middle and low mountainous areas of Laoshan Mountain in the central and eastern part of Qingdao, the low mountainous areas of Daze Mountain in the north, the low mountains and hills in the south, and the hills in the northern part of Laishi, etc. area, accounting for 28% of the area. This type of area has excellent natural ecological environment, well-developed vegetation, generally no obvious environmental geological problems, a small number of collapse points, few mining and quarrying pits, slight local water and soil erosion, groundwater quality of Level III, and low intensity of human engineering activities. .
2) Areas with good geological-ecological environment quality (Class II areas): distributed in most areas of alluvial plains and denudation accumulation peneplains in the central and northern parts of the country, southeastern Jiaonan City, and around Qingdao City, etc. area, accounting for 25.6% of the area. This type of area has a good natural ecological environment, relatively developed vegetation, and generally has obvious environmental geological problems, such as a small amount of mining and quarrying pits, groundwater quality of Grade III-IV, surface pollution sources, and high intensity of human engineering activities.
Figure 14-5 Qingdao Geology-Ecological Environment Quality Assessment Zoning
3) Geology-Ecological Environment Quality Area with Medium Quality (Class III Area): Pingdu in the north of Qingdao City - The mining sites in Laixi, the western part of Pingdu City, the coastal area of ??Jiaozhou Bay, the northern part of Laoshan Mountain, the eastern and northern areas of Jiaonan, account for 36% of the entire area, accounting for the largest proportion among all types of areas. The natural ecological environment of this type of area is moderate, the vegetation is not very developed, and there are generally obvious environmental geological problems. For example, during the mining process, mining pits and slag piles are formed, and a large amount of wastewater is formed during the mining process, which causes vegetation damage. Issues such as slope instability and groundwater contamination. Surface water and groundwater are highly polluted. Southwest Pingdu generally suffers from endemic fluorosis caused by high groundwater fluoride, groundwater contamination, lack of surface water resources, and groundwater overexploitation causing groundwater funnels. Human engineering activities are intensive.
4) Areas with poor geological-ecological environment quality (Class IV areas): mining sites located in the Pingdu-Laixi area in the north of Qingdao City, the coastal area of ??Jiaozhou Bay, and the northern area of ??Jiaonan City, accounting for 10.4% of the total area of ??the district. The natural ecological environment of this type of area is poor, the vegetation is not very developed, and there are generally obvious environmental geological problems. One is the serious ecological environment damage and geological environment damage caused by mining, and the other is the intrusion of sea salt water. Human engineering activities are intensive.