Uncertainty analysis of different models in estimating potential evapotranspiration

Jamsari, Nur Aiman Haziq (2020) Uncertainty analysis of different models in estimating potential evapotranspiration. [Project Paper] (Submitted)

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Abstract

Potential evapotranspiration is the key aspect in determining water requirements for irrigated crops. Estimating the potential evapotranspiration can be done by using FAO-56 Penman-Monteith but the limitation of the meteorological data needed for computation makes it difficult for some regions in Malaysia. The planning is important for sustaining the crops where it includes the water irrigation or water scheduling for supply the water needed for the crops. Therefore, for the past few decades, a lot of simplified models have been developed for calculating the potential evapotranspiration. Hence, the aim for this study was to investigate on which simplified models that are suitable for estimating the potential evapotranspiration at the region where did not have the ability to provide a full set data of parameters. A full set of data was obtained at the meteorological station at Subang Jaya. The study site will be at Tanjong Karang where it is one of the biggest regions that practice a lot of agricultural activities. The FAO-56 Penman-Monteith model was being computed to act as a reference model and a total of twenty-two simplified models were used. There are three categories that separated all the models (Mass-transfer, Radiation-based and Temperature-based models). Five statistical indicators had been used to indicate the best models the, weighted score method was used to determine which models has the highest rank. The results for these studies summarize that Trajkovic, Modified Irmak (I) and Caprio models were the best models. Trajkovic model had better results at the five indicators (R2 = 0.003, NRMSE = 51.57, PE = -51.14, MAE = -1.95 and d = -0.00168). However, different findings was obtained for the monthly comparison where the mass-transfer models (Albrecht, Mahringer and WMO) shows a better results where the gap of average monthly potential evapotranspiration was shorter (Albrecht = 22.23 mm/day) compared to the best three models for the daily computation. Hence, based on the issue that rises from the comparison of daily and monthly potential evapotranspiration, all twenty-two models are not quite suitable to be used for estimating the future ETo.

Item Type:	Project Paper
Faculty:	Faculty of Engineering
Depositing User:	Ms Siti Mariam Giman
Date Deposited:	21 Nov 2022 08:24
Last Modified:	21 Nov 2022 08:24
URI:	http://psaspb.upm.edu.my/id/eprint/616

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