Terahertz Laser Leaf Scanner to Reduce Urban Ecosystem Water Expenditure

The Challenge

Plant water use accounts for a major portion of the total water use in Los Angeles. Reducing water use in irrigation systems from lawns and gardens to parks is essential to achieving significant reductions in water expenditure across the urban landscape, while still maintaining critical urban greenery for public health and wellness. However, current technologies that monitor the water status of plants are time-consuming and destructive to the plants themselves. Thus, a new technology that efficiently estimates leaf water status in plants using noninvasive remote sensing technology will aide in managers’ ability to maximize water use efficiency in parks and open space.

The Solution

Researchers applied terahertz laser technology to develop an instrument and sensor capable of measuring leaf water potential (MPa) and relative water content (%) within leaves:

• The instrument, either designed as a hand-held device or deployed on a drone, will rapidly and nondestructively determine leaf water status for lawns and urban trees.
• A networkable sensor that can be deployed for automated measurements will interface with irrigation systems –residential and commercial landscapes, parks, and campuses–to greatly reduce water used for irrigation purposes.

Upon wide adoption in Los Angeles County, this new technology will lead to significant savings of water and reductions in water expenditure, by enabling only the use of water required for the growth and survival of urban vegetation. For there is no other technology to this date capable of offering similar specifications for rapid, nondestructive estimation of leaf water content, the proposed technology will have a transformative impact not just regionally, but for the entire U.S. urban ecosystem.

Next Steps

When the development of the proposed technology is complete, the instrument and sensor will enable predicting the water use and needs for urban vegetation without having to excise any leaves or tissues. Reducing water needs and improving the selection of urban vegetation, based on drought tolerance and low water use, will greatly improve the sustainability of water resources in Los Angeles County and beyond.

Additional Outcomes to Date

Researchers were additionally funded by the U.S. National Science Foundation Grant and Anthony and Jeannie Pritzker Family Foundation to publish a study, about terahertz spectroscopy application on predicting leaf water status, in April 2020.

Publications and Reports

Browne, M., Yardimci, N. T., Scoffoni, C., Jarrahi, M., & Sack, L. (2020). Prediction of Leaf Water Potential and Relative Water Content Using Terahertz Radiation Spectroscopy. Plant Direct,4(4). doi:10.1002/pld3.197