Deriving hourly and daily crop water stress index through the lens of proximal sensing in sugarcane fields

In arid regions, optimizing irrigation scheduling is crucial for water conservation, using key indicators like the Crop Water Stress Index (CWSI). This study assesses the efficacy of proximal sensing technology for detecting hourly and daily CWSI in sugarcane, a high-water-demand crop. Data were collected from July to September 2023 in Khuzestan, Iran, using stationary sensors that measured canopy temperature and relevant climate variables between 6:00 and 18:00. Results identified an hourly stress function of solar radiation and wind speed at 10:00 AM and 14:00 PM as two peak points of water stress. Daily CWSI was minimized two days post-irrigation and was strongly influenced by soil moisture (0–90 cm depth). A CWSI threshold in the range of 0.4–0.5 is proposed for initiating irrigation, supporting high-resolution monitoring for improved field water management.