The Study On Shoreline Evolvement In Hebei Province During The Past Century

Coastal zone, the special region between the sea and the land, is the important place to live and product for human beings, and it is also the front region of the economic and civilization in modern society. The shoreline changes, which threaten the ecological environment and economic in coastal zone, are drawn attention by many countries in the world. Therefore, it is very practical to the ecological security and sustainable development of the study on shoreline evolvement in coastal area.There are many types of the coastline, such as the bedrock seacoast, the sandy seacoast and the muddy coast from north to south in Hebei Province. With the development of the society and economic in coastal areas, it plays an important role in the shoreline evolvement and the affections of the surrounding environments. The research paper concluded the characters of the shoreline evolvement after analyzing the progress of the shoreline evolvement about 100 years in Hebei Province. And it analyzed the affections caused by the evolvement of the shoreline. Moreover, it forecasted the nature sandy coast. This research played an important part in planning and using of the coastline in Hebei Province. It was also important to protect and develop the coastal zone, and the result of this paper could offer the science reference in management and programming the large artificial constructions such as ports, wharfs and so on.The data of this research paper was mainly from relief maps, charts, remote sensing imagines and the field data of different years and areas in Hebei Province from 1916 to 2006. Combined with the"3S"technology, the condition of shoreline evolvement and had been concluded after comparing above materials. It also forecasted the shoreline erosion by using the one-line model, and researched the affection of the surrounding beach and environment which caused by the shoreline evolvement by using the theory and method of the ocean dynamics.The major content was following:The first was the character of the whole shoreline evolvement. The length of the shoreline increased 236.24km from 1916 to 1956, and reduced 187.45km from 1956 to 1979, and increased 249.75km from 1979 to 2006. The speed of the evolvement was 1.2m/a before 1979 while it increased to 28m/a between 1979 and 2006. Moreover, the beach area reduced gradually before 1979 and increased 265.43km2 by 2006. The reason for this evolvement was changed from the natural factors before 1979 to the artificial factor after that. And the types of the artificial shoreline, including sea walls, salines, breed aquatics ponds and ports, changed gradually.The second was the character of the bedrock coast. It was that the natural shoreline, replaced by the artificial activities gradually, became the main factors affecting the shoreline evolvement. Another character was that the changing areas mainly lied in the regions where the ports were, such as the region from Tanghe to Shahe which was affected little by the human beings.The third was the character of the sandy coast. It was the construction of the breed aquatics ponds that made the shoreline evolve towards to sea in the south of the sandy coast. By 2006 the forward of the shoreline had got to the offshore bars, while it suffered erosion in the north of the sandy coast, especially on the beach between the rivers. And there were many reasons for the evolvement. For example, it was mainly the construction of the sea walls before 1984, and the breed aquatics ponds which built in the outside of the sea walls after 1984. It was the shoreline of ports, symbol as the construction of the Jingtang Port, that became the determine reason in the early 1990s. Meanwhile, the shoreline of the Luan River delta had changed several times for the different reasons.The fourth was the character of the muddy coast. The reason of the evolvement had changed from the natural factors before 1956 to the artificial factors after 1991. And the type was different from times, which included the salt fields, breed aquatics ponds, ports and so on. The region of the most important development had also changed from the different time. It moved towards to the west in Tangshan City while towards to the south in Cangzhou City.The fifth was the affection analysis of the surrounding beach caused by the coastline evolution. Shoreline evolvement had changed the local circulation and the development of surrounding beach. The phenomenon of partial deposition was formed with the whole erosion condition. The evolvement characters as followed: For one thing, the beach became more and more width with the speed of 0.14 m/a~2.71m/a. The sedimentation got more and more faintness with the the speed of 0.04 m/a~0.7m/a. Moreover, slope of the beach became slower and slower. For example, it had slowed down by 3.8°nearby the beach from the first coal port of Qinhuangdao to the filling area between 1985 and 2006. For another, the radian of the coastline was reduces about 0.083°~0.415°per year, and the top position of the bay moved towards to W and WWS year by year. The third, the component of beach was thinner and thinner with the speed of 0.016 mm/a~0.035mm/a.The sixth was the analysis of the environment affections caused by the shoreline evolvement. The change of the shoreline in Huanghua Port caused by the many environmental factors, such as modifying the direction of the long-shore sediment, the balance condition of the beach, the type of the sediment on the beach and so on. Meanwhile, the change of the shoreline in Caofeidian Port interdicted tide on the riffle, which caused the beach to fill up nearby the road to the Caofeidian Island and the west of the Nanpu. Except that, it also affected the evolvement of the other islands and the offshore bars.The seventh was the establishment of the modal about coastal erosion and forecasting. The result of the study showed that the whole erosion speed would reduce from 2006 to 2026, while the change of the speed was different from one region to another. For example, it slowed down about 62% between Dapu River and Tazigou from the former decade to the later. Meanwhile, it also reduced about 75% between Dai river and Yang River in the same time where the erosion speed was the highest than the other regions. Moreover, the result also showed that the erosion scope would move towards to the south, and the region from Dapu River to Tazigou would become the center area of erosion by 2026.