What Is a Water Level Meter?
A water level meter is a device that quantitatively measures the water level of a river or lake.
A “water level meter” is a water level gauge that visually measures the water level and has a scale (water level board) attached to a post. The pillar is made of a structure that can withstand the pressure from flood waters. A water level meter is equipped with a recorder and reads the water level instrumentally.
Water level meter types include “float,” “bubble,” “reed switch,” “water hydraulic,” “quartz,” and “ultrasonic” types, depending on the mechanism.
Uses of Water Level Meters
Water level refers to the height of the water surface from a certain reference plane.
The purpose of water level observation is to understand hydrological and hydraulic phenomena in rivers, estuaries, lakes, reservoirs, playgrounds, inland water, groundwater, etc.
They are also conducted in various settings, such as water supply and sewage systems, industry, agriculture, factories, and construction sites.
Water level observation of rivers is conducted for the purpose of river management. During floods, they are used to provide information for flood forecasting and flood control activities, while during droughts, they are used in controlling the amount and level of water withdrawal for irrigation purposes.
Principle of Water Level Meters
The float type consists of a float floating on the surface of the water in the observation well. The up and down movement of the float is instrumentally transmitted to the pen via a pulley.
In the bubble type, a tube is opened in the water to emit bubbles, and the pressure inside the tube is measured by a sensor. The sum of the water pressure at the opening and the atmospheric pressure equals the pressure inside the tube, and the water level is obtained by subtracting the atmospheric pressure from the pressure at the opening.
The reed-switch type is the one in which the measuring board is enclosed in a submerged measuring column. The measuring board has reed switches at 1 cm intervals. A float with a built-in permanent magnet moves up and down according to changes in water level, and the corresponding reed switch is made conductive by magnetic force to measure the water level.
The water hydrometer can be classified into two types: one that instrumentally measures changes in water pressure at a pressure receiver in the water, and the other that directly detects water pressure with a pressure-sensitive element (semiconductor, silicon, or quartz crystal) and converts it into an electrical signal.
In the ultrasonic type, an ultrasonic transmitter/receiver is mounted vertically above the water surface, and the time taken for ultrasonic waves to propagate from the water surface is converted into the water level. Although measurements can be made without contact with water, since sound waves propagate through air, wind direction, wind speed, air temperature, and humidity are also observed at the same time.