Potential and Challenges in Use of Thermal Imaging for Humid Region Irrigation System Management

Abstract

Thermal imaging has shown potential to assist with many aspects of irrigation management that include scheduling application of water and detecting leaking irrigation canals and delivery systems. There are particular challenges for use of thermal imaging for scheduling irrigation in humid subtropical climates, which include the need for fine delineation of canopy temperatures under low vapor pressure deficits, proper accounting for micrometeorological conditions, and altitude effects on canopy temperature represented at the camera. A review of pertinent issues involved in using thermal methods for sensing canopy temperature is presented that can be applied to the imaging problem. Altitude effects were demonstrated in a new field experiment, and multiple regression was used to indicate and model weather and altitude effects. The use of spatial statistics was shown to enhance the value of thermal imagery using sensor fusion. Thermal imagery was also useful in detecting leakage from irrigation systems in the context of overall irrigation system management.

UAV Flight Experiments Applied to the Remote Sensing of Vegetated Areas

“…The results obtained by Baluja et al [51] and Gago et al [50] showed that all three thermographic indices are well correlated with the stomatal conductance measured directly on the ground (with coefficients of determination (R 2 ) ranging from 0.54 up to 0.70). Thomson et al [76] discuss the potential and challenges involved in using thermal methods for sensing canopy temperature in humid subtropical climates, where small increases in canopy temperature can be difficult to detect. They also demonstrate the effect of altitude (in their experiment, altitude accounted for 58% of the variability in canopy temperature), and validate the use of thermal imagery to detect leakage from irrigation systems.…”

Assessment of soybean injury from glyphosate using airborne multispectral remote sensing

“…Remote sensing technology has been widely used and developed in agriculture and can provide a rapid, cost‐effective method for assessing crop injury caused by glyphosate drift. Studies using a convenient agricultural aircraft platform for remote sensing have been documented for weed discrimination and CHL‐a detection in catfish ponds, and studies using thermal imagery have been reported for water stress, zonal soil suitability and irrigation system diagnostics …”

“…Studies using a convenient agricultural aircraft platform for remote sensing have been documented for weed discrimination and CHL-a detection in catfish ponds, 21 and studies using thermal imagery have been reported for water stress, zonal soil suitability and irrigation system diagnostics. 22 Henry et al 23 indicated that multiple indices formulated from the band information extracted from hyperspectral reflectance could distinguish between healthy and injured soybean and corn plants to which herbicides, glyphosate and paraquat had been applied. Huang et al 24 examined the effect of glyphosate drift from aerial application on non-GR cotton by spray drift sampling and aerial multispectral remote sensing.…”

Leak Detection in Water Transmission Systems by Multispectral Remote Sensing With Airplane and UAV

“…Wet areas should show a lower radiance temperature as compared to drier areas during sunny day hours, whereas the opposite is expected after the sunset and before the dawn [4]. Thermal infrared (TIR) sensors are used on this basis to assess the soil moisture or the evaporation rate over vegetation canopy areas [5][6][7][8][9][10][11][12]. However, the detection accuracy of the TIR [5,6,10] is low leading to false positives and misinterpretations caused by diverse scenarios like dense vegetation or shadows.…”