There are several watercourses around the Salar de Atacama that require a minimum flow to meet the requirements of environmental authorities and community commitments. The technology currently used to determine flow is manual and discrete, requiring on-site workers to carry out each measurement, generating a set of isolated data over time. The general characteristics of watercourses are: • Varying sizes. There are channels ranging from 30 m wide with bottom variations of less than 4 cm up to about 60 cm, to natural channels 1 m wide and 5 cm deep. • Laminar velocities. Very low velocities of up to 1 m/s are present. The average velocity is between 0.3 m/s and 0.6 m/s. • Natural changes in trajectory. The action of the current and the transport of sediments create meanders that are mobile in time. • Natural variations in depth. Due to the presence of silt on the bed, the thickness of which varies with time.

Whenever flow measurement is required

• Potential environmental impact. • Exposure of personnel to risks during the measurement task

Measurement campaigns are carried out using manual sensors to determine the flow velocity (flow meter or current meter) at different points in the channel cross section, together with the determination of the depth at each of these points. The information collected is used to apply the “areavelocity” method, which consists of multiplying the wetted area of the watercourse by the respective velocity obtained.

Ultrasonic sensor

• Consultancy and general engineering studies that do not propose a specific solution to the challenge at hand. • Proposals that require intervention in the natural watercourse. Installation of systems outside the watercourse is possible, subject to prior approval. • Proposals that do not meet SQM safety standards.

Identification of technological solutions for measuring the flow of surface water (streams, natural channels and artificial channels).

Some of the watercourses to be measured are located in national reserves and are catalogued as biological corridors where no intervention is allowed in order to protect the fauna present in them. In addition, some of the watercourses naturally change both their surface and depth over time due to the flow and the presence of silt on the bottom.

• It should determine the flow of natural watercourses, which may change over time, both on the surface and at depth due to the presence of silt on the bed. • It must not result in significant intervention in the watercourse. For example, no permanent infrastructure must be installed to channel or restrict the flow of water. • It must carry out measurements in laminar flows, i.e. in an ordered, stratified and smooth flow without the generation of surface waves. • It must be compatible with the environmental conditions of the Salar de Atacama (salinity, temperature variations, light conditions, humidity, particulate matter, etc.). • The sampling frequency must be at least 4 times/day. • It must have reporting tools. User configuration options (data types, KPIs, graphs, dashboard) are desirable. • Must be able to transmit data from remote locations where power and communications are unavailable. Compatibility with Modbus communication protocol is desirable. • Should be able to detect changes in channel morphology. • Should have minimal maintenance requirements.