Simulation of temporal variation for reference evapotranspiration under arid climate
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ORIGINAL PAPER
Simulation of temporal variation for reference evapotranspiration under arid climate Amr Mossad 1,2 & A. A. Alazba 1,3
Received: 26 August 2015 / Accepted: 22 April 2016 # Saudi Society for Geosciences 2016
Abstract Reliable forecasting of evapotranspiration (ET) plays a critical role in the planning and management of water resources. Accordingly, this study aims to investigate the possibility of using autoregressive integrated moving average (ARIMA) models to anticipate monthly reference evapotranspiration (ETo). Thus, a monthly ETo time series of 34 years (1980–2014) is determined according to the FAO PenmanMonteith method. This time series is divided into two sets, which are used for developing and validating the ARIMA models. Subsequently, five tentative ARIMA models are created via the 19-year set (1980–1999). In order to reveal the best ARIMA structure among the developed models, the Akaike information criterion (AIC) and the Hannan-Quinn information criterion (HQC) are computed for comparison. The result of the comparison suggests that the ARIMA (1,0,1) × (0,1,1)12 model is strong enough to justify the goodness-of-fit requirements. Validation of the candidate ARIMA model is then conducted for the 15-year set (2000–2014). The validation result contends that there is a reasonable agreement between forecasted and observed time series with high coefficient of correlation (r = 0.966). Promisingly, it can be concluded that the candidate ARIMA model is capable of anticipating the monthly ETo under arid climate.
* Amr Mossad [email protected]; [email protected]
1
Agricultural Engineering Department, King Saud University, Riyadh 11451, Kingdom of Saudi Arabia
2
Agricultural Engineering Department, Ain Shams University, Cairo 11241, Egypt
3
Alamoudi Water Research Chair, King Saud University, Riyadh 11451, Kingdom of Saudi Arabia
Keywords Hydrology . Climate change . Forecasting models . Time series . ARIMA
Introduction Certainly, water is a scarce resource that will be an everincreasing problem in the future. This is due to tremendous changes in the climate (Abu-Allaban et al. 2015). Such changes cause variations in air temperature, relative humidity, and solar radiation (Haskett et al. 2000) as well as they are expected to cause changes in the hydrological cycle by affecting precipitation and evapotranspiration (ET) (Yu et al. 2013). Therefore, any variations of the hydrological processes induced by climate change can be significantly reflected in ET (Chen et al. 2015; Zhang and Schilling 2006). The importance of ET in sustaining the hydrologic cycle and replenishing the world’s freshwater resources is recognized (Katul and Novick 2009). For the practical purpose of water balance studies, there are three steps to evaluate the implications of climatic changes recommended by Gleick 1989. Firstly, develop the quantitative scenarios of changes in the major climatic variables, such as temperature, precipitation, and evapotranspiration. Secondly, simulate the hydrologic cycle for
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