how to compare multiple cross sections over time hypack

digital depth sounder) will greatly improve the accuracy and efficiency of cross-sectioning survey of rivers(Qiu and Fong, 20 Zhang et al, 2002). Simultaneous utilization of RTK GPS technology and the shipboard sounding method (e.g. The application of real-time kinematic (RTK) GPS positioning technique has opened a new avenue for the crosssection survey of rivers (Wu, 2005). Lack of skills and cooperation among surveyors might result in a low accuracy in the position fix of cross-section points, thus further affects the quality of cross-section survey of the river. Some unfavorable factors such as the flow of the water and the nonlinear movement of the surveying ship make measuring the depth of the water more difficult. These methods are not only prone to the inaccuracy of instruments, distances, weather conditions, intervisibility and communication device, but also involved in tedious workload which leads to low efficiency. Traditional methods of cross section survey of a river such as theodolite intersection, theodolite stadia, electronic distance measurement, depth-surveying bar, leadline, handlead survey and echo sounder are the main methods used for water bathymetry. Cross-section survey of water bodies is a key part in hydrographic engineering survey. The survey of rivers and lakes as well as the protection and exploitation of these resources plays an important role in Chinese economy.

China has a vast expanse of land with intertwining rivers and mountains, abounds in lakes and reservoirs.

How to compare multiple cross sections over time hypack