Research On The Trend And Evolution Of Luanhe River Delta

Along with economic development and global climate change,the research into the delta area which formed on land and sea interaction become the focus of attention gradually. Delta States has currently been done a more in-depth research by many countries, and made considerable progress. However, these researches have mainly concentrated on the large delta with relatively rich resources and an important location while the research into a large number of small and medium-sized delta of general distribution, still needs to be enhanced. Luanhe River Delta is a typical representative of small and medium-sized delta, and from the scientific point of view, Luanhe River Delta sedimentary system formed a number of superimposed delta complex because of several times shifting, and formed an integrated and typical sediment and the sedimentary sequence, and the nature of the overlying and underlying layers is of great significance not only to the causes of delta system, but also to the research of the entire ancient geographical environment. From the point of economic development perspective, Luanhe River Delta is the hinge of communications joining land and sea, the construction of the port in this area has obviously natural and economic advantages. From the point of protection of the ecological environment, Luanhe River Delta is located in the juncture of land and sea and with the strong intervention of human activities, so the ecological environment is relatively fragile, and needs to explore reasonable ways and means of protection. In recent years, the upper reaches of Luanhe River carry into execution of water management-Panjiakou, Daheiding, Taolinkou and so on large water conservancy hinge will open and the sand into the sea reduced year by year, and how the modern evolution of Luanhe River Delta draws domestic scholars'attention again.This paper referring to Hebei Province"908"Project , " the Survey and Evaluation of Marine Resources ", does a systemetic research into Luanhe River Delta region from the point of view of geology and geography. And, this paper on the basis of the collection of various types of information and previous results, the study of sedimentary characteristics of Luanhe River Delta and the systematic analysis of the evolution of geological environment of Luanhe River Delta, through field investigation and laboratory analysis, with the theory of geology and paleontology, deals with the formation and the trend of the evolution of Luanhe River delta .Besides, the paper, in conjunction with the advantages of the position of Luanhe River delta , discusses the economic development. The result shows that:①Luanhe River has formed three alluvial fans with the vertex of Fengrun County, Xixiakou and Luanxian after several diversions of the route of the river one after another since the late Pleistocene Epoch influenced by the tectonic activities.②Five accumulations of Delta have been formed in succession on the basis of the formatation of alluvial fan since Holocene Epoch, incluing the remaining delta near Qilihai formed in early Holocene Epoch, the delta with Macheng at its vertex in the middle Holocene Epoch, the one with Tingliuhe at its vertex in the early history , the one with Mazhuangzi at its vertex in the late history and the modern one with Lianhuachi at its vertex.③The lagoon system, the different stages of dams, has been formed at different times. Caofeidian, one of the sandy islands, is the front part of sandy dam of the delta formed in mid-Holocene Epoch. The sandy dam of Dawanggang , Shijiutuo and Yuetuo is the front part of sandy dam of the delta formed in the early history, and other sandy dams ,like Shegang, Denglongpu, Hulinkou and Shagang is the front part of the sandy dams in the late history . A lot of tidal branch roads suitable for building ports have been formed during the evolution of the delta because of the terrain and hydrological conditions.④A number of factors lead to evolution of Luanhe River Delta, mainly including tectonic activities, hydrometeorology, sea-level changes and human activities, and so on. During the active period of the tectonic movements, the diversions and formation of the river was promoted or weakened mainly as a result of tectonic activities being the basic driving force and some other factors, thereby affecting the evolution of the delta. During the quiet period of the tectonic movements, the original structure of the river is the basis of diversions of a river, the climatic factor plays a leading role in the diversions of Luanhe River and the formation of the delta since Holocene Epoch and hydrological factors and human activities correspondingly promote or weaken the trend of the diversion of Luanhe River, thereby affecting the formation and evolution of the delta.⑤Because Luanhekou is a weak tidal estuaries, the delta is mainly formed because of the influence of both the river and wave. The dynamic changes in the quantity of silt depends on the quantity of sand flowing in . The strong changes in the discharge of the river and the quantity of sand carried by it leads to obvious changs in other factors affecting the formation and evolution of the delta.⑥Through the comprehensive study of the characteristics of tectonic activities, climate and meteorological characteristics and the extent of human activities, it is found that the unpredictability of the evolution of the delta increases.Luanhe River Delta has obvious advantages of position, and the evolution of the delta provides a vast space for economic development. On the basis of the protection of the environment, we can rely on the construction of the port and development of oil and gas resources to promote both the local economy and the economic development of Hebei Province.