Estimation of irrigated tea evapotranspiration using micrometeorological modeling in data-scarce environment

Water scarcity has become a critical and concerning global issue due to climate variability and demographic changes. The increasing demand for food and fiber places immense pressure on the agricultural sector to meet the needs of a growing population, which often requires large volumes of water for irrigation in water-limited environments. This leads to significant water loss through evapotranspiration (ET), which is the combined water loss through evaporation and plant transpiration. ET also shows the volume of water that must be replenished in subsequent irrigation schedules. In South Africa, a major challenge in irrigation management is the lack of measured actual evapotranspiration (ETa) data due to the limited availability of measurement devices. To address this, micrometeorological models offer a practical alternative. This study estimated crop evapotranspiration (ETc) using the Priestley–Taylor and Makkink models, validated against the Penman–Monteith standard model. The results revealed that both the Priestley–Taylor and Makkink methods effectively quantified ETc, with the Priestley–Taylor method showing higher accuracy. These findings show that in the absence of direct ETa measurements, ETc can be reliably estimated using meteorological data, enabling precise adjustments to irrigation schedules. This contributes to improved irrigation water management, promoting the conservation of scarce water resources while ensuring irrigation efficiency.