Browsing by Author "Ijatuyi, O.A."

Now showing 1 - 1 of 1
  • Thumbnail Image
    Item
    A semi-empirical model for estimating surface albedo of wetland rice field
    (International Commission of Agricultural Engineering, 2007) Oguntunde, Phillip G.; Olukunle, O.J.; Ijatuyi, O.A.; Olufayo, A.A.
    Surface albedo plays a vital role in the evapotranspiration component of the wetland rice water balance. This paper examines the influence of the phenological stages of rice (Oriza sativa) field on observed albedo at a tropical site (Ghana) during the year 2002, with a view to parametrizing a simple albedo model suitable for inclusion in models to estimate evapotranspiration in wetland rice cropping systems. Crop management was similar for the two planting dates used in this study. Measurements were taken from 10 m x 10 m plots within rice fields. Four phenological stages were distinguished: emergence, vegetative, flowering and physiological maturity. Surface albedo (α) was measured and simulated, using a calibrated semi-empirical model, at solar zenith angles of 15°, 30°, 45°, 60°, and 75°. Leaf area index (LAI) and crop height (h) were also monitored. Generally, albedo increases from emergence to flowering for both planting dates but slightly decreases after flowering. The correlation coefficient (r) between α and LAI equals 0.985 and the correlation coefficient between α and h equals 0.908. The composed albedo model adequately predicted the observed albedos with an overall r = 0.946 and mean bias error (MBE) of 0.002. The extinction coefficient of the rice crop albedo was estimated as 0.75. Data presented are valuable inputs in agricultural water management, rice production models, and especially as vital sub-routine inputs in calculating evaporation and transpiration from wetland rice.