1. Coastal landform of Shandong Peninsula urban agglomeration area
Shandong Peninsula is close to Bohai Sea and Yellow Sea, and the peninsula urban agglomeration is closely restricted by these two sea areas, and its land geological-ecological environment is bound to be affected.
Generally speaking, the coastal zone includes the coastline extending 10km to the land and 10 ~ 15 km to the sea, including intertidal zone and subtidal zone, and the coastal zone is affected by high tide level. Shandong province has a long coastline, with a continental coastline of 3 1, 2 1km and a coastal beach area of 3223km2. Peninsula urban agglomeration area includes the coastal length of the whole land in Shandong Province.
Terrestrial coastal landforms include hills, middle and low mountains, erosion and denudation plains and alluvial-diluvial plains. Submarine landforms include underwater delta, sandbar shoal and underwater bank slope. Neoarchean Jiaodong Group, Proterozoic ancient jade, Cretaceous, Neogene and Quaternary strata are exposed along the coast. Neoarchean, the lithology is biotite granulite, biotite plagioclase gneiss, marble, schist, etc. , distributed in Weihai, Sangshuwan and Jinghewan coastal areas. Yuanguyu Jingshan Group is distributed in the coastal areas of Jiaonan, Taigu Town, Zeku Town of Aiden City and Yangmadao Town of Mu Ping, and is characterized by biotite plagioclase gneiss and biotite granulite mixed with plagioclase amphibole. Proterozoic Yufuzishan Group, distributed in Yantai-Penglai coastal zone, is a set of metamorphic rocks with high greenschist facies-low amphibolite facies, and its lithology is marble, biotite granulite, tremolite, graphite tremolite and plagioclase amphibole. The Sinian Penglai Group is only distributed along the twelve coasts of Penglai Pavilion and Longkou. The Cretaceous system is exposed from Aoshan to Rushan in jimo city, and the Quaternary system is distributed in the Yellow River Delta, the coast of Laizhou Bay and the coast of the Bohai Sea in the north of Huangcheng. The distribution of these strata shows that the coastal areas have a relatively long-term and stable land period in the process of geological historical evolution.
Jiaonan-Weihai orogenic belt affects the uplift of Shandong Peninsula and coastal zone, and Shandong Peninsula is located at the junction of North China Plate and Qinling-Dabie Plate orogenic belt. These structural factors caused the segmentation effect of the tectonic movement in Shandong Peninsula, and formed different tectonic units (Table 25).
Table 25 Geotectonic Units in Coastal Zone of Shandong Peninsula
The change of coastline in Shandong Peninsula urban agglomeration area is mainly influenced by the change of the Yellow River Delta. Except for modern estuarine sediments, other ancient estuaries are dominated by erosion. See Table 26 for the delta erosion in various places.
Table 26 Shoreline Length of Different Coastal Types in the Yellow River Delta
(Huang Haijun et al., 2004)
2. Comparison of coastal zone changes of Shandong Peninsula urban agglomeration
In 200 1 year, the maximum erosion of the old Yellow River receded by 9km, and the erosion rate reached 360 m/a. See Table 27 for the coastline changes of Shandong Peninsula and other coastal areas in China.
Table 27 Comparison of coastline changes between Shandong Peninsula and other regions
Note: Data of Fujian and Hebei are up to the end of 20th century, and data of Shandong are up to 2004. (According to Lu Yaoru 1999)
In recent years, due to the influence of upstream reservoir impoundment and strengthening soil and water conservation, the sediment concentration of the Yellow River has decreased to 13× 108m3/a, and the modern estuary has also been eroded. Compared with 1998, the coastline of 200 1 year is 2.3km backward, with an average annual retreat of 766m m.
3. Sea level fluctuation in Shandong coastal zone
Since the late Pleistocene, the change of sea level has also had a great impact on Shandong Peninsula.
In the last glacial period (late Pleistocene), the sea level was lower than it is now 100 meters. Obviously, the sea levels in the Bohai Sea and the Yellow Sea in Shandong Peninsula are also lower than now 100 meters. Peat beds were drilled 90m below the current sea level in Dalian Yellow Sea, dating from 14C to about 12400 years ago (Guo Xudong, 1979), and there were other fossils such as hairy rhinoceros and mammoth in the Late Pleistocene (Figure 16).
Figure 16 Schematic diagram of coastal karst hydrogeological environment change in Dalian area of the North Yellow Sea (according to Lu Yaoru, 1986a, b).
See figure 17 for sea level changes since the late Pleistocene.
During the Holocene warm period, the sea level rose higher than the current sea level. See Table 28 for Holocene sea level rise and fall rates.
At present, Shandong Peninsula is facing the problems of global greenhouse effect and sea level rise. American scientists believe that doubling CO2 will increase the average sea level temperature by 1.5 ~ 4.5℃ (Charrey, 1979), and J.H.Mercer and others believe that the global sea level will increase by 5 ~ 7m (Mercer, 1968). The United States Environmental Protection Agency (EPA) predicts that CO2 will be doubled from 2055 to 2085, when the global sea level will rise by 27 ~ 265 cm, and by the end of 2 1 the sea level will rise by 56 ~ 345 cm, with a possible range of 1 44 ~ 217 cm (Hoffman et al.
Figure 17 sea level rise curve in the late glacial period (according to Lin Guande 1985)
Table 28 Holocene sea level volatility
(According to Lu Yaoru 1999)
According to the Holocene temperature-sea level change, the sea level change can be predicted according to the following prediction formula (Lu Yaoru, 1999):
Study on Geological Ecological Environment and Sustainable Development in Shandong Peninsula Urban Agglomeration Area
Where: lst —— sea level elevation in the t year (the current sea level is 0m), m; Lso-current sea level (or initial year) elevation, m; ρ st-vertical velocity of unit temperature difference plane, mm/a℃; Δ ti —— I-year interval; Ti-t period.
According to the above formula, if the global temperature rises by 2℃ at most in 2030, the sea level will be 27.22 ~ 2 10.3 mm higher than it is now. 2 1 at the end of the century, if the temperature rises by 3 ~ 5℃ due to the greenhouse effect, the sea level will rise by136.21~1051.37mm. ..
Therefore, Shandong Peninsula urban agglomeration area should pay special attention to the greenhouse effect that causes global warming, which will have a great impact on the whole peninsula area.