The evaluation and improvement of the maximum entropy production (MEP) evapotranspiration method at graduated spatial scales – point, catchment and continental scales

Author: Lanre Abiodun

Abiodun, Olanrewaju, 2019 The evaluation and improvement of the maximum entropy production (MEP) evapotranspiration method at graduated spatial scales – point, catchment and continental scales, Flinders University, College of Science and Engineering

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Abstract

The aim of this research is to develop evaporation and transpiration products for Australia based on the maximum entropy production model (MEP). We introduce a method into the MEP algorithm of estimating the required model parameters over the entire Australia through the use of pedotransfer function, soil properties and remotely sensed soil moisture data. Our algorithm calculates the evaporation and transpiration over Australia on daily timescales at the 5 km2 resolution for 2003 – 2013.

The MEP evapotranspiration (ET) estimates are validated using observed ET data from 20 Eddy Covariance (EC) flux towers across 8 land cover types in Australia. We also compare the MEP ET at the EC flux towers with two other ET products over Australia; MOD16 and AWRA-L products. The MEP model outperforms the MOD16 and AWRA-L across the 20 EC flux sites, with average root mean square errors (RMSE), 8.21, 9.87 and 9.22 mm/8 days respectively. The average mean absolute error (MAE) for the MEP, MOD16 and AWRA-L are 6.21, 7.29 and 6.52 mm/8 days, the average correlations are 0.64, 0.57 and 0.61, respectively. The percentage Bias of the MEP ET was within 20% of the observed ET at 12 of the 20 EC flux sites while the MOD16 and AWRA-L ET were within 20% of the observed ET at 4 and 10 sites respectively. Our analysis shows that evaporation and transpiration contribute 38% and 62%, respectively, to the total ET across the study period which includes a significant part of the “millennium drought” period (2003 – 2010) in Australia.

Keywords: evaporation; transpiration; Maximum Entropy Production; remote sensing, evapotranspiration, eddy covariance

Subject: Hydrology thesis

Thesis type: Doctor of Philosophy
Completed: 2019
School: College of Science and Engineering
Supervisor: Okke Batelaan