INVESTIGATION ON THE VALIANTZAS' EVAPOTRANSPIRATION MODELS FOR PENINSULAR MALAYSIA

• Published in: Journal of urban and environmental engineering Vol. 13; no. 1; pp. 174 - 182
• Main Authors: Ahmad, Nor Farah Atiqah Binti, Harun, Sobri, Hamed, Haza Nuzly Abdull, Askari, Muhamad, Ibrahim, Zulkiflee, Hanapi, Muhammad Nassir, Ali, Md Hazrat
• Format: Journal Article
• Language: English
• Published: Jao Pessoa Journal of Urban and Environmental Engineering 2019
• Subjects: Agricultural management; Catchment area; Climate change; Evaporation; Evapotranspiration; Humidity; Hydrology; Irrigation water; Methods; Neural networks; Organizations; Rain; Root-mean-square errors; Sensitivity analysis; Trends; Water management; Water scarcity; Weather; Malaysia
• DOI: 10.4090/juee.2019.v13n1.174182

The search for an accurate evapotranspiration (ET) continues when the world has responsibility to cope with the water scarcity issue, population outgrown and uncertain change of weather. Measuring actual evapotranspiration (ETa) can be tedious and requires a lot of time and cost. Therefore, numbersof empirical ETmodels have been developed to overcome this problem. The Valiantzas' modelsare quite familiar to the hydrologist community as it has been developed based on Penman evaporation equation. This paper presents the evaluation on the selected six Valiantzas' models by comparing to Food and Agricultural Organization Penman-Montieth (FAO-PM) empirical model in estimating ET in the Peninsular Malaysia. Seventeen meteorological stations around Peninsular Malaysia with data gathered from 1987 till 2003 were tested. The performance for each model was evaluated by root mean square error (RMSE), coefficient of determination (R2), percentage error (PE) and mean bias error (MBE). All the six models showed good agreement to FAO-PM with R2> 0.90. The PETval2 model which gave R2 of 0.97 was the best performer with the lowest RMSE, PE and MBE of 0.26, 5.5% and 0.14,respectively. The good and sensible performance on the ET estimation displayed by Valiantzas' model may promise an accurate method for calculation on the water management for irrigation and catchment studies.