Regular Monitoring of the Quality of Water

In recent years, researchers from the Zuckerberg Institute for Water Research (Ben-Gurion University) have been conducting a study about the daily, seasonal and multi-seasonal changes in the quality of water in the Yarkon.

The team of researchers includes Prof. Shai Arnon, Zafrir Adar and Noam Yogev who operate the monitoring array and develop algorithms to assess the river’s state of health. Data about the quality of water is measured using advanced sensors which send the data in real time to the researchers and decision makers in the Yarkon River Authority and assist in locating pollution events and making decisions regarding rehabilitative actions in the river.

What does the River Authority learn from this data?

The Authority is interested in understanding how the river behaves along the year, the dynamics of the quality of water in the river, and how it is possible to improve its quality of water. In order to improve the quality of water, it is important to understand the regularly occurring processes in the river, therefore we have created partnerships with different research teams from different universities in the country.

The sensor pack that has been set in the river is one of the advanced in the world and includes about fifteen different parameters through which the health of the river is assessed. The most important index values can be seen in real time.

In the following link >>

An explanation about the index values:

  1. The water level in the stream (one meter above the sensor)- The water level in the sensor depicts the relative height above the sensor. In the summer the height above the sensor is about 0.2 meters. This level is about four meters lower than the bicycle trail in the park. A hard rain event will cause a flood raising the level above one meter. The water level allows us to calculate the river’s rate of flow.
  2. Oxygen (% saturation)- The oxygen in the water is crucial to the existence of healthy life in the river. An oxygen saturation rate of 100% tells of a situation in which the water cannot absorb any more oxygen from the air. A saturation of less than 100% signifies that there is breathing activity of animals and bacteria in the stream. Oxygen levels dropping below 25% signifies that the ecosystem is becoming distressed.
  3. Temperature (Celsius)- The water temperature changes with the seasons and normally shifts from about 30 degrees in the height of summer and 14 degrees in the winter. When rain events occur there are more drastic shifts in temperature. Changes in temperature affect animal activity as well as oxygen saturation (cold water can melt more oxygen).
  4. Electric conductivity (µS/cm) – This measure depicts the water’s ability to conduct electricity and points to the amount of salts in the water. The higher the value, the more conductive the water is, and the higher the concentration of salts. Most of the year, the electric conductivity is between 1000 to 1200. During a flood, the river’s water is diluted by rainwater in which the salt level is very low, and the conductivity value drops. By reviewing the drop in electric conductivity we can calculate the amount of rainwater flowing through the stream.
  5. Opacity (NTU)- This measure depicts the density of particles in the water. The higher the opacity, the less light enters the depths of the body of water and thus the ability of algae within it to photosynthesize (a process which enhances the water with oxygen) is damaged. Particles can come from a geological source (for example: clays) or a biological one (for example: algae). In the summer, the typical opacity is between 50 to 70. During a flood, strong forces from the flow reach the bottom of the river, floating up different substances which cause an increase in opacity. In strong floods the opacity may rise above NTU. Opacity measures also allow us to calculate the amount of substance moving through the river from land to the Mediterranean Sea.
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