Nevşehir Province Angstrom-Prescott Coefficients and Reference Evapotranspiration Comparisons

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Ünlükara A., Şimşek Ü.

5th World Conference on Sustainable Life Sciences, Nevşehir, Türkiye, 7 - 10 Aralık 2023, cilt.1, ss.135-148

  • Yayın Türü: Bildiri / Tam Metin Bildiri
  • Cilt numarası: 1
  • Basıldığı Şehir: Nevşehir
  • Basıldığı Ülke: Türkiye
  • Sayfa Sayıları: ss.135-148
  • Erciyes Üniversitesi Adresli: Evet

Özet

Atmospheric evaporation demand on crop water consumption have been presented by reference evapotranspiration. Crop water consumption was estimated by multiplying reference evapotranspiration with crop coefficients depending on crop growth stage. Recently, FAO Irrigation and Drainage Paper 56 Penman-Monteith method was offered as a sole standard method to estimate reference evapotranspiration. Local Angstrom-Prescott (AP) coefficients are required to convert sunshine duration to short wave solar radiation (Rs), which is driving force for crop evapotranspiration. Sunshine duration data has been recorded since 1965 but Rs data since 2016 in Nevşehir province. Using limited daily Rs data, local AP coefficients of Nevşehir provinces in The Central Anatolian Region of Türkiye were determined as yearly and monthly. Then, reference evapotranspiration (ETo) series were computed by these local AP coefficients and AP coefficients (as= 0.25 and bs= 0.50) offered by FAO 56 for the regions without any AP coefficients.  Control ETo series were computed monthly by Rs series for their recording period between 2016 and 2019. Mean absolute error (MAE) and root mean square error (RMSE) were used to compare the ETo series to the control ETo series. ETo series computed with yearly local AP coefficients (as= 0.2361 and bs= 0.5368) resulted in reasonable error (MAE= 35.9 mm/year and RMSE= 41.8 mm/year) that were not considerably different from ETo series computed by AP coefficients (as= 0.25 and bs= 0.50) with negligible error differences (MAE= 38.2 mm/year and RMSE= 46.2 mm/year).  Monthly local AP coefficients resulted in the least error (MAE= 7.8 mm/year and RMSE= 10.7 mm/year) and improved ETo estimations. Annual ETo values were 1065 mm for FAO 56 AP coefficients, 1085 mm for yearly local AP coefficients and 1088 mm for monthly local AP coefficients in Nevşehir.  Therefore, FAO 56 AP coefficients work as good as yearly local AP coefficients, but monthly local AP coefficients work better for ETo estimations for Nevşehir province.