Unmanned Boat Applied in Brine Lake of High salinity | OceanAlpha

Location: Lop Nur, Xinjiang

Platform: ME120 unmanned surface vessel

Equipment: Single beam echo sounder

In early July 2020, an OceanAlpha ME120 unmanned surface vessel(USV) joined the national potash mining project in Xinjiang to conduct routine bathymetry surveys.

Lop Nur, the former second largest saline lake in northwestern China, lies within the Tarim Basin of the eastern Takla Makan Desert, in the Uygur Autonomous Region of Xinjiang. In the mid to late 20th century, the flow of the Tarim River decreased severely, resulting in drastic desertification and caused the Lop Nur to shrink rapidly and eventually dry up at the end of 70 century.

How does an unmanned boat get into functioning in a dry lake? 

It turns out that, discovered by geologists, there is a potash mine in the northern area of the dry-up Lop Nur. The mine contains 12.2 billion tons of muriatic of potash, a potassium-containing salt used widely by farmers in fertilizer, which can supply the consumption of the whole world for more than 200 years.

In recent years, Xinjiang has launched a 1.2 million-tons mining project, which is to extract brine from the ground and discharge it to depressions for natural evaporation to produce potash fertilizer. The annual precipitation in Lop Nur is only 30 mm, while the annual evaporation is as high as 4000 mm, which is very conducive to the crystallization of potassium salt. It is because of this project that the sparkling water body reappeared in Lop Nur, giving the unmanned boat a stage to perform.

View of Lop Nur Salt Lake

In the process of potash fertilizer production, the brine pumped from the ground forms a salt lake, and the water level of the salt lake is constantly changing during the process of evaporation.

In order to learn the salt lake storage capacity and crystallization amount in time, it is necessary to regularly measure the water depth and underwater topography to provide accurate data support for the subsequent production plan.

Equipped with a single-beam depth sounder, the OceanAlpha ME120 USV can conduct autonomous surveys, thereby obtaining the underwater topographic data more efficiently, accurately, and safely.

ME120 working on the salt lake

The salinity of the brine in Lop Nur is 353.46g/L, which is ten times of seawater. The anti-corrosion and anti-salt spray capabilities of ME120 USV and instrument successfully met this huge challenge. At the same time, the smooth communication of video and data can be well achieved through the private network of the unmanned ship, regardless of the poor public network communication in the remote Tarim Basin.

The unbearable high temperature above 40°C in summer makes the working environment for mining staff extremely torturous. The USV can survey with equipment autonomously, while the staff can operate remotely and obtain measurement data from the office or engineering vehicle. The arrival of the unmanned boat has greatly reduced the cost and intensity of work.

Staff perform remote measurement operations in more comfortable environments

The water level of the salt lake changes frequently. Due to the deep draft, manned ships cannot enter most shallow water areas and near-shore locations, otherwise there is a risk of stranding and damaging the survey equipment. In addition, it is difficult to maintain the same survey route every time, and the distance between each survey line is broad. Incomplete data acquisition and low data accuracy are the inevitable shortcomings of manned ship surveying.

ME120 USV surveying closely against the shore line

The unmanned boat was born to solve these problems. Its shallow draft allows it to survey on extreme shallow water areas, reducing blind spots. GPS is used for automatic positioning so that the position is highly matched with the data. More comprehensive and accurate data can help develop more reliable production and mining plans.

The enlistment of ME120 USV was ardently welcomed by the mining staff. Its arrival provides an intelligent solution for the salt lake measurement and liberates the staff from the harsh and arduous working environment.

The technician from OceanAlpha training users for the operating skills of ME120 USV

The staff carefully cleaned the USV which had just finished working from the salt lake