Supporting the soldiers to cut down how handsome Liang Jia Hailu to the East Chen waved through the Liang Xiangyang
(Guangdong Provincial Institute of Geological Surveys, Guangzhou 510080)
According to the geologic surveys in recent years, the ecological environment of the Pearl River Delta Economic Zone: 250,000 geological survey work has made new progress!
In the trend of urbanization, vulnerability characteristics of the geological environment of human activities and environmental geology of the results of the summary information on the issue, there is a new understanding.
The fragile ecological environment of the geo-environmental geological problems of the Pan-Pearl River Delta Economic Zone in the process of urbanization of sustainable urbanization
The Pearl River Delta Economic Zone in the southern and central edge of the South China Sea, adjacent to Hong Kong and Macao, Guangdong Province is one of China's coastal belt is among the most developed and fastest-growing economies of the 3 economic units but also one of the most populous agglomerations! The country has a large mobile population, with only a very small number of cities and rural areas where basic integration has been achieved by the accelerated process of rapid urbanization, a series of environmental and geological issues have become areas of sustainable development? Socio-economic constraints.
In recent years, the China Geological Survey organized the implementation of the ecological environment, the Pearl River Delta Economic Zone 1:250,000 under the unified deployment of the Geological Survey of Guangdong Province Geological Survey Institute. In this paper, based on the project data, review the progress of the survey in recent years, environmental geology.
Understanding the trend of urbanization and the characteristics of human activities
The trend of urbanization is the objective manifestation of the most important physical characteristics of changes in the socio-economic structure and the highest level of social formations development, the level of urbanization is a significant degree of modernization of a country or region. Since the reform and opening up, the Pearl River Delta Economic Zone has experienced a historic social and economic leap forward, and soon entered the disease of industrialization process, the rapid rise of Guangzhou, Shenzhen and other cities of the core group of the overall level of urbanization interaction development, rural "town" town "town ", county towns and small cities "metropolis" and large and medium-sized cities "internationalization". Since 1995, the vast rural areas have reached a mature stage of urbanization in this regard, basically realizing urban-rural integration with increasing degrees of urbanization and internationalization. After more than two decades of development, the Pearl River Delta Economic Zone is mainly concentrated in two mega-cities, Guangzhou and Shenzhen, as well as nearly 10 large and medium-sized cities, 20 central cities above the county level, and more than 400 towns and cities, and the trend of pan-urbanization is gradually emerging (Figure 1). From the urban connotation of the mature countries in the region, the urbanized areas are not cities in the strict sense, there is a huge difference between the "resident population" and the "household population", but as a whole in the sense that the land landscape of the region forms a Metropolitan area, pan-urban core? The trend of maturity continues, extending to the surrounding areas, non-Pearl River Delta regions gradually promoting integration with the Pearl River Delta, and Delta's influence on the surrounding areas and drive, pan-urban areas will continue to expand ①.
The trend of pan-urbanization has a clear regional character in human activities in the region.
(1) Methods of increasing the number of human activities. From agricultural activities, mining activities, land reclamation, embankment construction, such as the extension to
Figure 1 Thumbnail of urbanization pattern extracted from remote sensing imagery in the Pearl River Delta Economic Region
Description: The region of pan-points has been completed, and the urbanization process of the areas of Foshan, Guangzhou, Dongguan and Shenzhen is clearly visible.
Urban development, economic construction closely related to all aspects of human activity, now covers the utilization of space resources on the earth's surface.
(2) Human activities and the impact of diversity. Different types of human activities may be caused by the same type of ecological environment and geological problems. For example, the area of reclamation? may lead to siltation of estuarine ports, wetlands, degradation of coastal mangrove ecosystems, upwelling of salty tides, surface water contamination, groundwater contamination, and soil contamination caused by mine development and agricultural activities.
(3) The spatial aggregation and spread of human activities. Metropolitan contiguous belt of the region, the scope of human activities are mainly concentrated in the region and social development programs, including Guangzhou City (excluding the increase in the city of Conghua City), Dongguan City, Shenzhen City (including Shenzhen City, Bao'an District), Foshan (Chancheng District, Foshan City, Nanhai District, Shunde District), Zhongshan City, Jiangmen City (urban areas, Xinhui District), Zhuhai (including Doumen District). In the plains of urban construction activities, railroads, highways and other linear construction, landfills, such as point-like construction projects, agricultural activities are mainly; mountain - Taiwan area, hilly - low mountain building materials, mines, slopes, environmental resources, human activities, the development and use of coastal zone development and utilization is mainly; the area of reclaimed mudflat development and use of major resources.
(4) The intensity of human activities has been firm. Especially after the reform and opening up the intensity of increasing human activities since 1990. In Table 1, the data are listed in Table 2 in three phases reflecting the trend of increasing human activities. Remote sensing interpretation of the urbanization process in the eastern economic zone in the urban construction areas of the results of large-scale expansion in 1990 increased by 8.6% in 2000 increased to 14.8%, nearly
doubled; arable land decreased from 19% in 1990 to 13.6% in 2000 (Table 3). With the signing of the "9 +2" Pan-Pearl River Delta Regional Cooperation Framework Agreement, the pace of urban development in the region will be further accelerated. According to the statistical planning area of each township, the area in the region and urban areas in 2010 will be more than 1.0×104 square kilometers, and the non-agricultural construction land will be 1.5×104 square kilometers (accounting for more than 1/3 of the region's total land area), when the region's total land area will be more than 1/3 of the region's total land area. More than 1/3), when more than 70% of the ground in the region will be building land. It can be predicted that the unprecedented scale of human engineering activities in the coming years and even decades.
Table 3 Comparison of zoning values of NDVI index in 1990 and 2000
The zoning type of NDVI values, the percentage of the total area in 1990 (%) The percentage of the total area in 2000 (%)
-1 to -0.5 Water bodies (rivers, lakes, sea) 24.3 24.1
8.6 14.8 -0.5 to -0 urban buildings
0 to -0.5 crops, arable land, farming 19.4 13.6
0.5?0.75 bamboo forests, shrubs, grasses (plants) 25.4 24.9
0.75 to -1 forests (plants) 22.3 22.6
(5) Step-by-step and orderly human activities. The disorder of human activities will be alleviated. The so-called obstacles to human activities, because blindly, without regard to the ecological-geological environment of the lack of guidance and supervision of the consequences are likely to lead to mutation and derivation of the ecological condition of the environmental-geological problems. With a high level of education, legal and regulatory system that strengthens the rules to raise people's awareness of environmental protection, as well as the development of related technologies, human activities will have standards in order to curb unorganized activities to a certain extent. However, a large number of planned human activities will also need to take full account of the possible consequences.
2 Geoenvironmental Vulnerability: From the geological point of view, environmental geological problems
For the development of raw materials, external factors, environmental geological problems and geoenvironmental vulnerability, human activities are internal. The understanding of the geo-environmental vulnerability, undoubtedly contributes to the study of environmental geological problems. The vulnerability of the geo-environment of the Pearl River Delta Economic Zone is mainly reflected in the following aspects.
2.1 Greater development of residual soils in bedrock areas
The bedrock area of the region accounts for about 60% of the total land area, with the distribution of the major magmatic intrusive rocks (granite) accounting for about one-third of the area. Strong rock weathering bedrock area residual soil development. Granite distribution of feldspar, mica and other unstable mineral content is high (usually about 70%), the thickness of the residual soil is usually relatively large (& gt; 20 m), less than 5 m, in addition to the mountain high, coastal island weathering residual layer hills - Taiwan region has become a major soil erosion-prone areas, metamorphic rocks, volcanic eruptive rocks are distributed mostly as a mixture of breccia fragments of the residual soil thickness of the clay is generally & lt; 3 m, distribution is generally greater than 5 m, the clay thickness of the residual soil is generally & gt; 3 m, distribution is generally greater than 5 m. 3 meters, the distribution is generally greater than 5 m section of mudslide prone to occur.
2.2 Quaternary loose sediments soft soil commonly developed
Pearl River Delta Economic Zone Quaternary loose sediments in the widespread distribution, distribution area? Accounting flood deposits, alluvial, alluvial marine and Red Sea area of the land area of 2/5, genotype curve. Mountain valleys and river terraces alluvial, flood, alluvial flood deposits are mainly distributed in the delta margins of the thickness generally does not exceed 10 meters, often with binary structures, fine sand or silty clay sand in the upper part, the lower part of the charred wood blocks of the folder coarse sand and gravel formed by the terrace alluvial peat 14C dating for the dating of 7580±170 one. Alluvial marine deposits, marine laminar pressure large area distributed in the delta plain and coastal areas, mainly in the late Holocene sea erosion in the bay deposition and coastal river interaction products of the flat? The average thickness of 25.1 m, the maximum thickness of 63.6 m, the upstream area is mainly yellowish gray or grayish brown powdery clay, powdery clay, the downstream area is mostly dark gray silt, silt.
The distribution of the soft soil area is nearly 8,000 square kilometers, accounting for about 1-fifth of the region's land area, of which the area of the delta plain is the most densely populated city is the widest distribution of the soft soil in the distribution of the area of? The area of soft soil accounts for 82.25% of the total area of economic soft soil distribution. From the Pearl River Delta, the increase of the thickness of the top soft soil, the increase of the degree of consolidation deterioration, leading to the estuarine area of the marine transition of the river floodplain stratigraphic lithology stage into the muddy soil silt opposite. Based on the borehole data, 14C dating, sporulation analysis, the delta soft soil can be roughly divided into three levels vertically, respectively, the delta area Late Pleistocene - Holocene occurred three times the big sinistral corresponds to the new age of deposition of the soft soil, greater thickness, water content, liquid limit, liquidity index, pore ratio, greater age of deposition of greater age greater age greater mechanical properties of the strength of the compression coefficient, with the increasing becomes smaller, compressive elastic modulus and cohesion (Table 4). Natural dynamics, the influence of human activities, soft soil, prone to ground settlement and ground engineering and construction hazards.
In addition, the delta river network area, the East River is easy to liquefy the sand body distribution area of 2.13 million square kilometers, the depth is generally 1.5 to 12.8 meters, the thickness of 1.5?10.5 meters, the standard penetration, from 2.3 to 7.4. saturated loose silt, fine sand and silt dynamic loading (earthquakes, piling, blasting, mechanical vibration), prone to liquefaction and damage to the ground engineering and construction.
Table 4 Qualitative characteristics of physical and mechanical properties of soft soils in the Pearl River Delta
Top of the sludge layer thickness of the depth of the deposition process of the main characteristics of the physical and mechanical properties of the index (average)
General average maximum W0 WL IL E0 A1-2 ES?
%% - MPA-1 MPa kPa
First layer of Late Holocene shell fragments of 0.0?5.0 1.5?21.9 9.5 42.7 60.2 45.7 1.89 1.66 1.44 2.45 6.90
Second layer of Holocene modern period, oyster shells, often interspersed with fine sand 2.6 20.8 1.5 11.0 6.0 37.5 50.6 40.1 1.64 1.34 0.97 3.76 11.77
Third layer of Late Pleistocene marine shell fragments, river floodplain phase decaying wood 5.3?24.0 0.6 `7.9 3.7 20.4 42.3 38.6 1.26 1.18 0.75 5.01 13.79
2.3 Neotectonically active
Neotectonically active, since the Late Cretaceous - Tertiary successional activity. According to the geological area of Guangdong Province NE-NNE to deep fault zone Lianhuashan, Zijin - Boro Fracture Zone, Donghe Fracture Zone, Enping - Xinfeng deep fault Wuchuan - four deep large fracture, EW Gaoyao - benefit to deep large fracture zone and north-west Xijiang Fracture, Zhuhai - Xinda Fracture Zone traversed [4]. Gao Yao Fracture, Enping City - Taicang City, Jinji - Hecheng, Guangzhou - Gulao, extensive Kangzang Fracture broken, Shenzhen Fracture, Pinghai Road Fracture, Tanghu Fracture, Chishi - Shatian Fracture Xijiang Fracture, Fracture Shajiao, Nga Men Fracture is still active. For example, according to the monitoring data, the Seismological Bureau, extensive fault activity from the fracture from 1973 to 1979, 26.5 mm to 4.4 mm, the average annual event rate, Guangzhou City, Leaning Dog Ridge Fracture Fracture part (Hsing-Tsang) in 1998 months the maximum value of the two altitude difference change of 3.34 mm, the Xijiang Fracture Hengkeng section in November 1997 for 2.38 mm, from 1991 From 1991 to 1995, the average activity rate was 0.56 mm/a. The monitoring results of Shenzhen Geological Bureau in the past five years show that ①Shenzhen rupture stress creep state, in a slow release trend, sperm activity rate from 0.17?0.35 mm/a.
2.4 Carbonate karst development
Zhaoqing around, Guanghuaban, Enping City - Kaiping City, Longgang District, Shenzhen City, Danshui Township Shoupi Town, Zengcheng City, sending lake carbonate rocks in an area of 1,474 square kilometers, but most of them covered by the Quaternary Loose Sediment. Carbonate rocks are mainly exported from the Ordovician Lolion - Luodong Formation, Devonian Tianziling, Quanwan Formation - Tianziling Formation, Carboniferous County, Shidengzi Formation (CS), measured Shui - Ziqiao Formation, Ziqiao - Tai Po Formation, Tai Po Formation, Hutian Formation (CH), and Permian Qixia Formation Hutian Formation, Shidengzi Formation, Tianziling Limestone karst is the most developed, see the holes 7.5-15.0%, 5.7%, 2.0-7.0%, 5.7%, 2.0-7.0%, 2.0%. The Guanghua Basin, for example, the Quaternary Guanghua Basin, for example, the Quaternary loose sedimentary layer thickness is generally 10?25 meters of the surface of the bonded soil base (local sludge), often sand or gravel layer at the bottom of the contact with the limestone, karst strong development area is located in the underground -20?-80 meters elevation section. Hidden karst hydrogeological conditions of the region and geological formations, is very conducive to the formation of ground subsidence.
2.5 Vulnerability of soft rock engineering
Cretaceous - Tertiary red beds, and the distribution of the delta margin Jurassic Gao Yao - Sanshui - Guangzhou - Dongguan City, Enping - Kaiping, Huizhou, Boro Yangcun, Huiyang, Huidong - Baipenzhu and other assignments - Carboniferous coal-bearing strata are often interbedded with relatively low mudstones, sandy mudstones, shales, charcoal shales, coal, gypsum, saltpans. Mechanical strength of soft rocks. Easy weathering of these rocks outcrops, often appear dilated, soaking water easily softened softening coefficient from 0.26 to 0.5, saturated compressive strength of 0.14?1.2 MPa, gypsum, salt rock is prone to produce long-term groundwater dissolution dissolution holes, dissolution trenches. If you choose these stones for the foundation holding layer, the building is prone to engineering foundation slip, non-uniform deformation, mountainous areas and engineering construction site slopes along the weak side of landslides and other geological hazards, so this type of rock layer is unfavorable to the construction project.
3 environmental geological problems: classification of the causes and socio-economic impact
The process of urbanization, population concentration, industrial agglomeration, economic growth and social production, lifestyle changes, but also large-scale consumption of resources, spatial agglomeration patterns, and destruction of the natural landscape of the urban landscape pattern of the formation of the process. Socio-economic development, urbanization on the one hand constrains the impact of geo-environmental vulnerability factors, and on the other hand, due to human economic drive - engineering activities inevitably lead to environmental geological problems. The environmental geological problems of the Pearl River Delta Economic Zone and sustainable socio-economic development are mainly soft foundation settlement, coastal ports, rivers, inlet siltation and urban flooding, water and soil pollution, lack of water and soil pollution, lack of water from different degrees of influence of hidden karst subsidence, natural soil erosion, man-made soil erosion and collapse, landslides, mudslides, water, lack of water, and stability of the structure, which can be divided into the local primary genesis types, secondary primary natural secondary combinations of three types of environmental geology problems.
3.1 Local major environmental geological problems
3.1.1 Tectonic stability problems
Small amplitude, high frequency, dense clusters of earthquakes in the Pearl River Delta Economic Zone tectonic stability problems. Regional earthquakes occur at the intersection of active rupture zones, often distributed in clusters, magnitude earthquakes active rupture zones along the north-east direction of the earthquake. Mainly modern historical felt earthquakes occurred after the 1970 earthquake, more distributed in Enping - Taishan - Doumen - Shenzhen, Guangzhou, Shunde, Zhongshan, Xinhui, Taishan City, Zhaoqing City, Sihui City, etc. in the Pearl River Estuary to the west, the southern coastal areas. From the point of view of earthquake history, the total amplitude of the region exceeded magnitude 3 earthquakes 215 times, 13 destructive earthquakes, of which more than 4.75. Since the instrumental record since 1970, the region has more than 2.0 earthquakes have occurred 212 times, the average annual frequency of sub-7/3 earthquakes 59 times, 4 times (4 earthquakes were not more than 5).
3.1.2 Resource water shortage
Huidong Pinghai - Huiyang Xiachong - Daya Bay - Shenzhen - Pearl River Estuary east coast of the coastal belt and islands highlight the problem of water shortage. The city's water supply mainly relies on long-distance dispatch of Dongjiang water to solve the lack of local surface water and groundwater sources, the city's central water supply, in terms of quantity and quality of water resources, changes in the event of annual droughts or the level of pollution caused by upstream and other reasons, the water supply problem will be even more serious. Shenzhen has become China's seventh city in the world with a severe water shortage.
3.1.3 Mudslides
Districts are occurring in 11 of the 36 small mudslides, the most susceptible to Jurassic lava (JKN, JKB, JR), Huidong Lotus Mountain - Coastal Range high mountainous areas and on steep slopes. Volcanic lava distribution area, low mountains - hills, steep terrain (usually on the slopes, slope > 30 °) rock formations weathering affects the joints and fractures of thick residual soils and weathered rocks in contact with the obvious interfaces, the multi-structures are loose gravel mixed with clayey soils, events, rainy seasons, in the residual soils of the clay minerals in contact with water expansion - softening, conducive to the conditions of water catchment and weathering of the steep slopes in the The rocks, soil along the ravine, a cascade of mudslides formed, but the weathered rocks are thin, small catchment area, so small landslides; however, the residents in the vicinity, engineering construction near the mountain a great deal of damage, not only destroying the woodland, mudslides affect the landscape, but also a direct threat to the people's lives and property, has become a major factor in the danger of the area of ground instability and the construction of the regional ecological environment In 1997, five villages in Huadu District, Guangzhou City, mudslides destroyed a two-story building at the foot of the mountain, all 10 people were killed in construction and household accidents.
3.1.4 Natural soil erosion
More patchy distribution is the widest distribution of natural soil erosion in the area of granite residual soil, sparse vegetation, hills and Taiwan, Huidong County, Conghua City, Huadu District, Taishan City, Jiangmen City, southwest coastal granite distribution (including islands), the largest negative impact. Area of natural soil erosion of natural soil erosion area of ?630 square kilometers, accounting for ? 43% of the total area of soil erosion.
3.2 Secondary major environmental and geological problems
3.2.1 Hidden pollution
Pearl River Delta region, more than 6,000 small-scale, decentralized layout of towns and villages, two seriously polluting enterprises, the general lack of effective sewage treatment facilities, a large number of sewage discharged into the distribution of rivers, and the current annual wastewater discharges more than 20,108 tons of industrial solid waste produced annually. Solid waste 180×104 t and garbage 300×104 tons per year. Rivers flowing around the urban area are polluted to varying degrees, and the border rivers around the city are seriously polluted. Toxic and harmful heavy metal contamination of water and sediments in the Pearl River network and entrance areas, especially persistent organochlorine pesticides, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and other organic contamination of the ecological and environmental safety sounded the alarm. Geological survey results by the Geological Survey of Guangdong Province showed that the quality of soil environment in the Pearl River Delta is not optimistic about the results of the work of the Institute, has got a wide range of regional pollution and a large area of the main toxic heavy metals such as cadmium, mercury, arsenic, copper elemental fluorine, sulfur, and other harmful elements of contamination, soil contamination and the impact of the toxic elements is worrisome. Zhang G., confirmed the presence of soil organochlorine pesticides and polycyclic aromatic hydrocarbons pollution. Guangdong Provincial Geological Environment Supervision Station, completed groundwater resources evaluation report discusses the status of non-organic pollution in groundwater. Fu Jiamu academician author of persistent organic pollutants in the environment and cause environmental pollution. Department of Earth Sciences, Chinese Academy of Sciences published a paper in Earth Sciences published a large amount of data on soil and water pollution in the Pearl River Delta.
Groundwater pollution investigation and evaluation of the pilot work in 2005 in the Pearl River Delta region in the groundwater found six categories of 35 kinds of organic pollutants, including nine halogenated hydrocarbons, eight kinds of monocyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons, organochlorine 11 pesticides, ketones, phthalate esters of three kinds.
A large number of facts, water and soil pollution, water resources, land resources, biological resources, resulting in qualitative changes, such quantities can be utilized to reduce the direct threat to the survival of the environment and jeopardize human health, the socio-economic impact of the economy's sustainable development.
3.2.2 Lack of water
Limited surface water resources, water and soil pollution, although the area of per capita water resources is 14,580 cubic meters, much higher than the national average per capita level of 2,500 cubic meters, but in line with the standard for drinking water quality, coupled with the salty tide of its roots, the sewage charging superimposed on the impact of the main groundwater salinity & gt;? 1 salt water, so that Guangzhou City (including Panyu Nansha Development Zone), Dongguan, Foshan (including Shunde District, Nanhai District), Zhongshan City metropolitan area of the Pearl River Estuary, Zhuhai and other serious water shortages ②.
3.2.3 Anthropogenic soil erosion
Human beings? 840K square meters, soil erosion area accounted for? 57% of the total area of soil erosion. Human erosion is mostly patchy, in the development of cities or towns in dense areas, human construction sites near the main types of erosion, mostly used for construction sites and the lack of vegetation protection, construction site slope (including traffic engineering and construction of the development of the site), steep land reclamation and mining, soil extraction areas, human activities are powerful, economically developed Shenzhen, Dongguan City, Zhongshan City, ? The largest distribution area. In addition, in the local mining operations caused by soil erosion are more serious.
Accompanied by the occurrence of man-made soil erosion, resulting in silt and shallow rivers, ponds, reservoirs silted riverbed pressure, frequent floods, crop failure failure. Such as the river level Wuxi Shangde kaolin mining field 5 kilometers of the river is a serious siltation, a large area of fertile land was flooded, the river siltation (6 meters thick), the pit village, buried houses more than a dozen, destroyed more than 20 when the entire village was forced to relocate 10 meters; from the city of Aotou, Shizuizui village kaolin mining field caused by the downstream of the river channel siltation thickness of about 3 to 5 meters, the river on both sides of the farmland is buried, stretches several kilometers.
3.3 Primary Environment and Secondary Geological Problems
3.3.1 Soft Foundation Settlement
The thickness of the soft soil in the plains of the region near the mouth of the Pearl River is formed in a short period of time, and the key part of the soft foundation settlement. Soft foundation distribution is more concentrated in the soft soil layer thickness greater than 20 m section of the southern Panyu District, Guangzhou City, Zhuhai City, Zhongshan North Road East, Southwest representative. Hengmen Town, Zhongshan City, People's Town, Guangzhou Nansha Economic and Technological Development Zone, West, Zhuhai, Jiangmen City, Xinhui District, ancient and modern African development zones, etc. There are obvious areas? Soft foundation settlement. Zhuhai Avenue, the new highway, Guangfo Expressway, Guangzhu Expressway, Zhongshan, Zhuhai, Panyu District, Guangzhou City within the highway soft foundation treatment part of the phenomenon is also obvious settlement. Comprehensive analysis of the survey data in the soft ground subsidence disaster-prone sub-area.
Survey data show that the cumulative amount of general values in the 0.3?1.7 meters settlement in the area at the end of 2003. Zhuhai Avenue pavement third grade 2003 measurements compared with 1994, Zhuhai Avenue average annual settlement of 10 years, 0.37 meters, the maximum amount of settlement up to 0.73 meters,). Currently found in Jinwan golf ball to solve the maximum cumulative amount of ground settlement of 2.97 meters in the maximum cumulative settlement. The thickness of soft soil is more than 30 meters, and the average sedimentation? rate exceeded 0.1?0.3 M / A group.
Beginning in the recent deposition of soft soil engineering construction, most of which is under the influence of soft foundation settlement, to varying degrees subject to the distribution. Part of the direct construction of soft soil crust layer of low-rise buildings tend to be soft soil areas and overall subsidence, tilted cracking of the ground bedrock of the holding layer of high-rise buildings tend to building fall overhanging feet, highways, roads wavy occurrence of roadbed displacement, roads and bridges connected to the uneven settlement, pavement cracking phenomenon. The serious impact of soft foundation settlement of industrial and civil construction projects, the normal use of embankments, water conservancy and hydropower projects, underground water supply - power supply network infrastructure, or uneven pavement, can not play a normal operator. This has not only caused hundreds of millions of dollars of economic losses along the southern coast, but also led to part of the commercial and residential unoccupied, seriously affecting the investment environment.
3.3.2 Coastal variability from ports, rivers, inlet sedimentation and urban flooding
Before the Tang Dynasty, the district coastline seaward advancement rate was on average less than 10.2 m / a, Tang, Song at about 15 m / A, Song, Ming, after about 20 M / A. Large-scale human economic and engineering activities, so one hundred and twenty years of the coast of the anomalous changes, in order to cross the door, the lantern sand to the Pingsha Farm Wanha Sha most obvious. Pingsha Farm Wanha Sand is the most obvious. From 1883 to the early 1980s, Wanha Sha, Lantern Sand seaward advance rate averaged 63.3 M / A121.7 m / . In the 1960s and 1970s, the period of "food for the program", 80 to 90 years of reform and opening up, the large-scale land reclamation activities in the region, especially the Pearl River Estuary region coastline rapid advancement of the South China Sea (Table 5), the area of the region's sea advancement of 619.23 square kilometers, a large number of Pearl River Estuary Sea 552.95 square kilometers increased. The building area of coastal cities is 4.625 square kilometers in 1986 to 2000, rapidly expanding to 51.585 square kilometers. Cultivated across the XXIII Bay, Panyu District, Zhongshan City outside the territory has been recycled from 11 bays, Zhuhai City, Doumen District, Baiteng Lake, Bureau of leadership Niwan door off the island of Sanzao, Zhuhai, Hengqin Island has been inland with other islands into fragments.
Table 5 Humen crossed the door lantern sand Pingsha Farm coastline advancing to the sea rate (unit: m /)
Lot 1973 to 1990 and 1990 to 2002 Remarks
Wanqinsha 514.7 291.6 forward SE
Longdongdong Island 303.9 583.3 forward SE
Hengmen Island 225.5 527.8 Forward Direction SE
Lantern Sand 250.0 770.8 Forward Direction SE
4 Conclusion