Safeguarding Groundwater 

The World Bank refers to Groundwater as “the hidden wealth of nations” in its report on the economics of groundwater in times of climate change (2023). 

Groundwater is a vital resource for drinking water, irrigation, and industrial use. However, it is also vulnerable to pollution from a variety of sources, including agriculture, industry, and urban development. Groundwater makes up 99% of Earth’s liquid fresh water and is vital for the sustenance of rivers, lakes, wetlands, and ecological systems. This continual flow of groundwater is a conveyor belt for natural, as well as anthropogenic (human-made), chemicals (The Groundwater Project, 2020). The need for efficient and reliable monitoring tools, that are capable of providing continuous, real-time information on the quality and speed of water and contaminants percolating through the unsaturated zone, is crucial for the wellbeing of groundwater. 

Sensoil’s Vadose zone Monitoring System

The Vadose Zone Monitoring System (VMS) is a powerful, dependable tool for groundwater protection. The VMS continuously monitors the vadose zone, between the land surface and the groundwater table. Thus, real time data and analyses are easily accessible. This allows for early detection of pollution, long before it reaches the aquifer.

The VMS consists of a network of sensors and sampling units that are installed on flexible sleeves. These sleeves are then inserted into diagonal boreholes up to +70 metres, placing the sensors and sampling units at different depths across the vadose zone. Continuous, real time data is collected on a variety of parameters, including soil moisture, temperature, salinity, and electrical conductivity. The VMS data is transmitted to a central data logger, which can be accessed remotely using Sensoil’s secure, cloud-based server. This allows users to view the data in real time including analytics, and to track changes over time. The control panel also provides access to the sampling units, to collect pore water samples for chemical analysis. 

Monitoring the unsaturated zone using Sensoil’s VMS enables: 

  • Reduce risk of groundwater contamination by monitoring the vadose zone and identifying potential sources of pollution, reducing the risk of groundwater contamination.
  • Improved understanding of vadose zone processes including water percolation and contaminant transport. This data can be used to develop better models of groundwater flow and contaminant transport, which can be used to improve groundwater management and protection strategies.
Sensoil’s Vadose zone Monitoring System setup.


In the SCENARIOS project, Sensoil’s Vadose zone Monitoring Systems (VMS) have been specifically designed to suit each of the selected sites in Denmark, Sweden and Israel. The depth and number of sensors and sampling units has been customised and adjusted to meet specific site conditions. In general, the VMS is designed to provide continuous in-situ measurements on water percolation and contaminates’ transport across the entire unsaturated zone, from land surface to the water table. The flexible sealed sleeves hosting sets of sampling ports and water content sensors distributed along its length, were installed in uncased slanted boreholes. Each monitoring unit was placed under a different undisturbed sediment profile.  

VMS Sleeve installation- SCENARIOS, Korsor.
VMS Control Panel – SCENARIOS, Trelleborg.

VMS have been installed to enable measurement of PFAS migration in the unsaturated zone and the underlying groundwater. VMS has been installed in two types of sites with typical PFAS sources: (1) unlined, non-active landfills, and (2) PFAS contaminated lands, such as firefighting training zones.

The VMS provides data, analyses and insights from the SCENARIOS sites. By providing real-time data on water flow and contaminant migration in the unsaturated zone, the VMS is used to identify PFAS migration patterns in different hydro-geological, chemical, and climatic conditions. 

SCENARIOS Korsor, Drawing porewater samples via the VMS control panel, from varied depths across the vadose zone, for PFAS lab analysis.

These VMS sampling units are currently providing pore water samples and measurements of variations in the sediment volumetric water content. The collected VMS data is enabling scientists to measure, research and understand PFAS behavior in the subsurface and aid in environmental risk assessment, remediation process tuning, and early warning of contaminant migration towards groundwater. 

Data from VMS Korsor – Water infiltration and PFAS transport across the unsaturated zone (with courtesy of Ben Gurion University & Geo Denmark).
Data from VMS Korsor – Water infiltration and PFAS transport across the unsaturated zone over time (with courtesy of Ben Gurion University & GEO Denmark).

VMS Data is set to have a significant impact on prevention and mitigation measures for PFAS contamination. Sensoil’s VMS technology will contribute to the development of more effective monitoring, prevention and mitigation measures for PFAS contamination, ultimately leading to a safer, healthier and cleaner environment. 

Safeguarding Groundwater in Varied Applications

VMS facilitates Decision Support Solutions (DSS) in various environments. There are over 150 VMS installed on five continents, many used for both scientific and applied research. VMS applications include: groundwater protection and regulation; groundwater recharge, levee and earthen dam seepage monitoring, agricultural monitoring and optimization, landfills and land remediation, and smart mining (tailing dams). 

Sensoil’s Vadose Zone Monitoring System is a powerful tool for groundwater protection. The VMS can be used to detect pollution early, improve understanding of vadose zone processes, and reduce the risk of groundwater contamination. The VMS is being used in a variety of applications around the world to protect the earth’s groundwater.