The DiHPS project aims to develop a novel, distributed monitoring network that will enable real-time, spatially distributed collection of soil moisture, soil temperature and soil thermal property data.


The system is based on distributed temperature sensor (DTS) technology, which measures the temperature-dependent backscatter of a pulsed laser signal through a fibre-optic cable, in order to provide temperature measurements at high spatial resolution and frequency. DTS has mainly been applied qualitatively, i.e. using existing thermal anomalies as tracers. However, by combining DTS with an active heat source (A-DTS) and observing flow–related heating and cooling patterns along the actively heated cable, the method can be used for the quantification of water and heat fluxes within the soil. This distributed heat pulse, A-DTS technology provides the basis for the development of the DiHPS network. While broader applications in heat and water flux assessments will be possible with DiHPS, in this project we will focus on demonstrating its suitability to quantify the moisture content and thermal properties of the soil.


Soil moisture is a key state variable in controlling land–atmosphere interactions and an early indicator of changes in the hydrological system, e.g. those associated with daily evapotranspiration, event-based recharge cycles or extreme events (i.e. droughts or floods). It is widely used in agriculture (e.g. irrigation management), forestry (e.g. plantation water demand estimations), meteorology (e.g. local and regional weather forecasts), water resource management (e.g. estimation of groundwater recharge) as well as a state indicator variable in drought or flood early-warning systems.

Soil thermal properties influence the partitioning of energy within the ground and at the ground surface, and are related to soil temperature and the movement of heat and water within the ground and their transfer across the ground surface. For these reasons, soil physicists, crop scientists and micrometeorologists study thermal properties, and these properties are also important in engineering applications (e.g. determining the electric current rating of buried cables and ground heat-exchanger design).


This current project builds on earlier work that has demonstrated the capacity of A-DTS to measure soil moisture under controlled conditions in flat, bare soils. This project will enhance the existing technology by:

  • increasing the spatial resolution of soil moisture content and thermal properties measurements to sub-centimetre scale
  • testing the technology in field-based environments including:
    • a forested hill slope in Staffordshire, UK
    • a wetland in Berkshire, UK
    • a field-based laboratory/experimental site in Hertfordshire UK
  • developing real-time and intelligent (autonomous) system operation, controlled by external triggers that activate/stop the DTS active mode and equipped with real-time processing capabilities to provide instantaneous soil-moisture content and thermal property data.