A Research On The Methods Of Establishing Independent Coordinate System Of Rivers

The control network of rivers belongs to the control network of line project.The main characteristics of it are that its distance is long and narrow,it crosses different projection zones and the synthetical length deformation is obvious.The rule of engineering surveying in our country is that the coordinate system of plane control network is supposed to ensure the synthetical length deformation within 2.5 centimeters per square kilometer,however,most zones can’t meet the requirement,which has disadvantages for river engineering construction.Therefore,the research on the methods of establishing the independent coordinate system of rivers is greatly worthy of being studied.Establishing the independent coordinate system of rivers not only satisfies the requirements of synthetical length deformation with our country’ s permission,but also chooses fewer projection zones as possible as we can in order to decrease the frequency of the coordinate transformation.The Gauss Projection is totally used for the coordinate system in our country,and also for the engineering construction to analyse the deformation of projection and independent coordinate system.The thesis is aimed at the methods of establishing the independent coordinate system of rivers by analysing the synthetical length deformation,whose achievements are analysed systematically and put into practice.The steps are done mainly:(1)It has researched on the basic theories of the coordinate system,Reference Ellipsoid,and Gauss Projecton.(2)It has analysed the reason why the errors in the projection deformation appear and the methods of being corrected.It has also systematically summarized the method of establishing independent coordinate system and limit of the methods.(3)It has worked out the forms of relevant ellipsoid parameter,the forms of calculation of Gauss Coordinate,the change in volume of the latitude of control points which are different by transforming ellipsoid,the new forms of calculating the latitude and the forms of coordinate transformation between different projecion zones according to related formulas with the help of Excel.(4)According to the working practice,I summarized the method of establishing independent coordinate system by zooming the distance of control points.The method is mainly about the reason why synthetical length deformation happened through considering reversely.I project reversely the side length between two endpoints of Gauss plane control points which is calculated under the national coordinate system to the reference ellipsoid.Then I calculated the distance of two endpoints of reference ellipsoid into the horizontal distance which is measured from the distance of two endpoints of geoid.Finally,I calculated the horizontal distance which is measured from the distance of two endpoints of geoid into the certain elevation planes under regulation.Compared the calculation of average elevation planes of measuring areas or horizontal distance of the certain elevation planes under regulation with the side length of two endpoints of Gauss plane control points which is calculated under the national coordinate system,I got the zooming coefficient of the side length of two endpoints.The independent coordinate system is established according to the zooming coefficient of the side length between the two endpoints(5)Combining with the establishment of GPS control network of Wei He downstream,the process that is carried into establishing the independent coordinate system of rivers is analysed systematically and summarized.At last,the achievements are analysed accurately.