A Sprinkler Water Droplet Evaporation and Plant Canopy Model: I. Model Development

The development of a computer model is presented for study of water losses during sprinkler irrigation of a plant canopy under field conditions. The model combines equations governing water droplet evaporation and droplet ballistics with a plant-environment energy model. The plant-environment model (Cupid) had to be modified to include droplet heat and water exchange above the canopy, and the energy associated with cool water impinging on warm leaves and soil. The combined model is intended for use in evaluating various sprinkler irrigation systems with respect to water efficiencies during irrigation of a crop. For example, evaporation losses from high pressure impact and spray heads can be compared with losses from a furrow irrigated crop. In general, droplet losses are small (less than 2%) and the main loss arises from wet-canopy and soil evaporation.