Ouda, S. and Noreldin, T( 2017). Evapotranspiration to determine agro-climatic zones in Egypt.Journal of Water and Land Development. 32(I-III):79-86.
Abstract: The objective of this paper was to compare between agro-climatic zones developed from 10-year interval of
weather data from 2005–2014, 20-year interval of weather data from 1995–2014 and the zoning developed by
[NORELDIN et al. 2016] using 30-year interval from 1985–2014 in the old cultivated land of Egypt in the Nile
Delta and Valley. Monthly means of weather data were calculated for each year, and then monthly values for
10-year and 20-years were calculated for each governorate. Basic Irrigation scheduling model (BISm) was used
to calculate reference evapotranspiration (ETo). Analysis of variance was used and the means was separated and ranked using least significant difference test (LSD0.05). Our results showed that agro-climatic zoning using 20-year values of ETo was similar to the zones developed with 30-year values of ETo, with different values of average ETo in each zone. Furthermore, using 10-year values of ETo resulted in higher values of ETo in each
zone, compared to 20-year and 30-year ETo values. However, the average value of ETo over the three classifications
was close to each other. Thus, depending on the availability of weather data, either zoning can be sufficient
to develop agro-climatic zones.
Keywords: (10-year weather data, 20-year weather data, agro-climatic zoning, BISm model, reference evapotranspiration)
