Trend Analysis, Modeling And Interpolation of Reference Evapotranspiration Time Series in The Semi Arid Region of Duhok Governorate

BASHEER ISMAIL GOVAY, MARWAN and HAMA KARIM, TARIQ (2023) Trend Analysis, Modeling And Interpolation of Reference Evapotranspiration Time Series in The Semi Arid Region of Duhok Governorate. The Journal of Duhok University, 26 (2). ISSN 2521-4861

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Abstract

Reference Evapotranspiration (ETo) is one of the most important components of the hydrologic cycle. Its assessment, forecasting, spatial interpolation besides climate change effects on this variable are supportive in applying management techniques to water resources and in determining appropriate adaptation strategies. Hence, this study was initiated to forecast, detect changes and generate surface maps for ETo time series at different time scales. The datasets for this investigation encompassed the input climatic parameters from 12 stations within Duhok governorate for a time span varied from 18 to 20 years for estimating reference evapotranspiration according to penman-Monteith formula. The results indicated that about 17% of stations exhibited increasing trend in annual ET, while the remaining station exhibited significant and non-significant decreasing trends. Spearman rank test Sen’s slope and linear regression analysis offered slopes of similar signs but of different magnitudes. Seasonal ARIMA model denoted as (1, 1, 1)(0, 1, 1)12 was the most appropriate model for predicting monthly ETo time series at more than 90% of study stations. The indicated model predicted the monthly ETo with a reasonable accuracy for the coming 36 months. Further, the results indicated that in general, the IDW and spline schemes method exhibited highest and lowest accuracy in most cases. Judging from several performance indicators, it can be inferred IDW, OK and UK methods yielded comparable results.

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