Abstract

Comparison of two methods for ET₀ calculation in the semiarid tropic of Venezuela. Bioagro [online]. 2005, vol.17, n.1, pp.41-46. ISSN 1316-3361.

In the semiarid region of Quíbor, Lara State, in the central west zone of Venezuela, values of reference crop evapotranspiration (ET₀) were estimated, as a basic concept on water management and irrigation planning. The Penman-Monteith and pan evaporation methods were used on the basis of daily and ten day periods of climatic data. The estimations with both methods in periods one (April-July) and two (July-November) in the year 2001 were compared and showed a correlation higher than 75 and 80 %, respectively. The values of ET₀ were very similar in the first period while in the second period the ET₀ from pan evaporation method was higher. When comparing calculated and tabulated Kp values, it was observed that in the first period both Kp were similar, while in the second period the tabulated Kp was higher than the calculated Kp. The values of tabulated Kp table were associated to different values of wind speed in each of the two studied periods of the year.

Keywords : Evaporation; Penman-Monteith equation; reference crop.