Application of USV in Disaster Risk Reduction (DRR)
Disaster risk reduction (DRR) is a systematic approach to identify, assess and reduce the risks of disaster. Improving the strategy and ability to deal with emergencies and provide disaster relief is an urgent task when the disasters occur. 
Many countries often suffer from earthquakes and an earthquake can destroy a whole city. The landslide and resultant barrier lake that follow are also a huge threat to the people and property security. If we do not deal with the threat in time, it will cause great damage. 
Here below let’s take barrier lake for further discussion. 
What is the barrier lake?
A barrier lake or landslide dam is a natural damming of a river by some kind of landslides, such as debris flows and rock avalanches, or by volcanic eruptions. If the damming landslides are caused by an earthquake, it may also be called a quake lake. Some landslide dams are as high as the largest existing artificial dam.
What role does Geospatial information play in DRR?
As we all know, Geospatial information especially the hydrographic data are important for disaster reduction of the barrier lake. The water level and depth information can calculate the volume of the lake, and then assess the threat level. The flow velocity and volume can help us monitor the lake capacity change in real time. Building a hydrographic database can support disaster reduction.
How to gain the hydrographic information?
How should we get the hydrographic information?
Like this? 
A serious earthquake may produce hundreds of barrier lakes. When we suffer a disaster, especially in an emergency and harsh situation, saving time is saving life. We must seek a safe, rapid and efficient solution to acquire the hydrographic data, provide professional and real-time information as reference for the disaster relief in barrier lake.
Today Hi-Target will introduce a solution for the risk reduction which combines the GNSS positioning technology and Hydrographic surveying. The USV has an innate advantage in DRR. It is designed for hydrographic surveying in dangerous areas or other unreachable places. The boat is relatively small and flexible. It can reach the disaster area in a short time and carry out the surveying work, guarantee the personal safety and boost the working efficiency.
Following a common working scene of the USV, the surveyors just control the boat on the shore to conduct the surveying task through the laptop and controller. Besides, it can fit different working environments -- all the shore base equipment can be placed in your car, which is very convenient and portable.         
All the control and monitoring work can be finished on the shore, with only two software: the USV control software and Hi-Max sounding software. First, users can set the related project information, including the coordinate system and some sounding settings. Then set the GNSS equipment for access location data. Generating the survey lines in the USV control software and afterwards conduct the auto-piloting task. For some shallow area close ashore, users can manually control the boat to collect the bathymetric data. The automatic control system of Hi-Max will automatically control the data quality. Two software work together to complete data acquisition. 
The echosounder and ADCP (Acoustic Doppler Current Profilers) mounted on the boat, can provide professional hydrographic data. The HD-510 echosounder designed for USV with the 0.15-300 m sounding range, is able to deal with various complex bathymetric environments easily. The ADCP equipment RP600 carried on the USV, has many advantages compared with the traditional surveying work: it does not need to rely on the bridge and can work more freely without environmental constraints. Additionally, various types of ADCP data is sent back to the base station in real time. It can realize real-time monitoring of river flow rate, estimate whether the reservoir will exceed the maximum water level, and provide data support for flood discharge and flood control of the barrier lake. The advanced split-design GNSS receiver provides centimeter-level high-precision positioning. The host and antenna are separated and will be better protected. 
Independent R&D smart boat control system combined with RTK positioning accuracy, ensure that the USV will cruise along with the planned at the auto mode. The deviation between the actual path and planned routes is usually within 10 cm. 
Ducted propeller design, which is almost equal to the bottom of the boat, make it convenient to use and save. The protective shield outside can effectively prevent the boat from environmental obstacles and the removable propeller is easy to replace and maintain.
The compact hull design that is small enough to fit into the truck of a car make it portable. It weighs only 14 kg and can be move by a man easily. Rugged hull made from Kevlar & carbon fiber high-strength material, resist various harsh surveying environments. High-capacity lithium batteries can work for 4 hours at the speed of 2m/s, which can fully guarantee the operation time and efficiency. The maximal speed is 4.5m/s, coping with the most complex flow environment.
Under the background of global climate change, the extreme weather and climate events continue to increase, surveying and mapping Geospatial information plays a much more important role and it is challenging to provide comprehensive hydrographic and geological information. Building a hydrographic database can support disaster reduction, contributing to analysis and assessment of the threat level. The unmanned surface vehicle system providing a safe, efficient and swift solution, supporting flood control preparation and improving the emergency response capability of relevant government departments. 
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