| The Hukou waterfall and Tenmiles Dragon vally in the Yellow river are unique landscapes in the world,which have international and regional comparison geological significance.Research on the origin and evolution of Hukou waterfall is the core scientific problem of the geopark,which is of great significance to promote the development of river morphology.Considering the integrity of regional natural landscapes and geoheritage landscapes,study on Hukou waterfall landscapes has scientifically unified artificial division of the public administrate on both sides of the Yellow River,and revealed the unity and difference of the geoheritage landscape characteristics of the Hukou region in the Yellow River.Previous studies of Hukou waterfall focused on the tourism landscape characteristics,tourist resources or evaluation,development and protection of geoheritages,tourism management and development,etc..Some authors measured the headward erosion rates of Hukou waterfall,and made the qualitative analysis of its forming conditions.But most of them researched by traditional methods,and did not make quantitative analysis of Hukou waterfall formation and evolution process without considering the geoparks on both sides of the Yellow River.Some researches lacked of integrity research on the geoheritages of natural landscape integrity.This study made the following results:(1)Based on the analysis of the regional geological background of Hukou waterfall in the Yellow River,the types,characteristics and evaluation of regional geoheritages have been researched.Hukou waterfall and Tenmiles Dragon vally are world-class geoheritage landscapes.(2)Landscape features of Hukou waterfall in the Yellow River have been analyzed from 4 aspects:the color change,seasonal change,gap change,and erosion kinetic energy changes.(3)The formation conditions of Hukou waterfall and Tenmiles Dragon vally in the Yellow River have been studied from 4 aspects:horizontal stratum and hard-soft rock lithology conditions,tectonic conditions of joint development,water erosion with sand,and freezing ice erosion.(4)Hukou waterfall formation mechanism has been revealed,and its headward erosion rates have been measured.Based on the topographic map and high resolution satellite imagery processing,the study has determined the Hukou waterfall's location in different periods.From 2004 to 2010,the fall on the spatial location of displacement is 9.24 m,the displacement in 6 years of the fall is 1.42m/a.Comparing 3 phase changes of the data,between 1972 and 2004,average annual waterfall displacement is larger(2.01m/a),and between 2004 and 2010,average annual waterfall displacement(1.42m/a)is smaller.The reasons of displacement decrease have been analysed.One is global climate change in recent years.Less rainfall caused the hydraulic scour erosion.Another reason is that the time interval is lesser.During this period the overall joint collapse phenomenon is less,so large-scale displacement of back did not appear.(5)The change rule of water erosion rate of Hukou waterfall during its formation in 4000 years has been revealed.The river yield gradually becomes smaller,so the headward erosion speed gradually slows down.(6)Nowadays Hukou waterfall is in its young adults.In the future it will develop to form a gentle slope with weak momentum,and it will eventually die.Hukou waterfall has become the fall of the largest headward erosion which falls back fastest in the world. |
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