The beginning of the term of suretyship is determined by various factors.

Through the hydraulic experiment for flowing ability of curved weir which used on the over-flow earth-rock dam,we found that the initial position water depth of arc weir and airfoil weir are less then 0.

This paper takes Dashuipo GPS network as an example that only adopting the original data of the plane network and the adjustment method of the GPS network in the plane control system,moreover analysing and comparing th.

When restriction adjustment or united adjustment on GPS framework,It s necessary of checking quality of Original data to ensure not to reduce the preci-sion of GPS framework because of the effect of restriction conditions.

Being due to the initial data errors,the result accuracy from the popular adjustment will decrease.

This paper introduces the data analysis and processing of Wujiang D-grade GPS control net,specially the connection of the old and new GPS control networks,disscussing the method of how to select starting points,and supplying some suggestions on how to use the independent coordinate system of Suzhou City.

According to methods and accuracy requirements of checking starting point data of GPS control network by current specifications and regulations, this paper analyses the checking methods and effect and discusses the methods for selecting starting point.

This paper introduces several practical methods of the compatibility analysis of starting point for GPS surveying network, and then base on a practical example, makes some analysis on these methods.