Meanwhile, new technologies of hydrographic surveying served for the civil engineering such as multi-beam echo sounder, side scan sonar, sub-bottom profiler and even LiDAR for topographic and hydrographic purposes greatly contribute to the work for public authorities and private sectors all over the world.
However, many administrative departments and authorities of water and traffic are facing the great challenges when designing or implementing the design of the city as the urbanization and urban renewal are on their way in a fast speed.
In the past old days, when the surveyors are going to survey the depth of the water, the first thing they have to do is to find and rent boats or ships locally which are always costly. Then the heavy echo sounder and other accessories will put on the boat, finding a proper position to mount the transducer which will require lest interference from the water waves and engine propellers. What’s more, the surveyors have to take care of the actual depth because the water might be too shallow for the boat to float. In case of being stranded, some surveyors might try to hire the bamboo raft or small sampan (small and lightweight boat), which can work perfectly on the shallow water but lack facilities to protect the staff's life and they are easy to be capsized by the waves created by the big ship or torrents. For some occasions, the surveyors need to survey the barrier lakes after the earthquake, the polluted water or even monitor the water level of the tailings ponds.
Some more flexible solutions are needed when surveying the lake in the island where you cannot easily convey a boat there. Similar requirements are also claimed by the surveying tasks on the brooks, which might contain shallow shoal and dams from the upper stream to lower stream. So in these sentences, surveyors are facing the challenges of the safety, accuracy and efficiency challenges.
Here in this paper some projects from China as the solution examples are provided for reference.
Pearl River Delta, intertwined within the water network, and products of richness, now had become one of the most important and main economic engine and industry area in China since 1979. More than 30% of the "made in China" goods are produced or assembled there and exported to all over the world. The water network and hundreds of harbors have been playing a very important role in goods export and raw material import. There was a plan to build some more pipelines for the electricity gas and municipal water across some channels. Before laying the pipelines, the constructor must survey the channels to get the latest water bed situation. One of the main channels that the pipelines are going to cross is called "Modao Gate Channel". 89.5 KM long with more than 30 ports and thousands of factories, 45 million cargo volume and 70,000 boundings, have brought this 3000 tonnage vessel level channel more than 800 vessels daily on the water. Thus, it would be quite difficult for the safety of the surveyors as they had to sail the boat or ship across the river to do the cross-section survey and there is no traffic light on the channel to sort out the heavy traffic.
The Unmanned Surface Vehicle, also known as USV, is an ideal solution for the surveyors to finish the work on time without threats to their security.
This USV, named iBoat BM1, can work for more than 12 hours continuously. With the auto pilot function providing the precision survey, gap between each surveying lane can be preciously implemented (within 10 cm offset). What’s more, the boat can be easily sail back automatically when the signal is lost or the battery is insufficient for the coming work, according to the pre-setting multiple home points. The real time camera data transmission can help surveyors who are on the bank keep monitoring the boat.
This advanced and autonomous system consists of the vessel body, excellent echo sounding module and positioning module. Of course, the data communication system and the controlling system are included.
Firstly, designing the survey lanes backgrounded by online Google satellite images on the USV pilot software. The interval and length of each cross section lane can be easily implemented. The Unmanned Surface Vehicle, also known as USV, is an ideal solution for the surveyors to finish the work on time without any matters on their security.
When the USV started to work, it will sail automatically or manually, users can switch the working mode in real time. In this surveying task, the USV turned away to avoid the heavy ships easily as soon as the controller was sending the interception command into manual mode. The flexibility and swift performance guarantee the lightweight boat's safety and efficiency, which offering a lower risk job than the human surveying.
The data will be transmitted form the boat to the laptop software where the user can easily monitor the position, heading, depth and control the parameter setting for the sounding system on the safe bank area.