Evapotranspiration data to determine agro-climatic zones in Egypt

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 (LSD 0.05 ). 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.

Required Interval of Weather Data for Proper Irrigation Scheduling

“…Daily weather elements for these sites were collected for 10 years (2008-2017) from the following website: https://power.larc.nasa.gov/ data-access-viewer. The recent 10-year interval was selected because it reflected the recent variability existed in the weather pattern in Egypt as indicated by Ouda & Noreldin (2017). The selected weather elements were maximum, minimum, and mean temperature (Tmean), dew point temperature (Td), as well as solar radiation (SRAD) and wind speed (WS).…”

“…To help agricultural extension workers to instruct farmers on the time and the amount of irrigation water application, information is needed on the number of years of weather data should they use to calculate ETo. Ouda & Noreldin (2017) stated that ETo values became higher in the former 10-years interval from 2005 to 2014, compared to the average of former 20-year interval, as well as 30-year interval. Recently, there is a noticeable variability in weather elements, especially temperature as a result of the effect of climate change.…”

“…Gardner et al (1985) stated that ETo is a combination of two processes water evaporation from soil surface and transpiration from the growing plants. The latest research in Egypt by Ouda & Noreldin (2017) reported that ETo values in the former 30 years exhibit an increasing trend. Many researchers reported the same increasing trends of ETo globally.…”

“…Whereas, R 2 values between dew point temperature and ETo was 0.60. A 10-year weather data was used by Ouda & Noreldin (2017) to calculate ETo in the Nile Delta and Valley. They also reported that R 2 values between ETo and mean temperature were 0.79 and between ETo and dew point temperature were and 0.21.…”

“…The FAO Penman-Monteith method has been regarded as a worldwide standard method to estimate ETo (Allen et al, 1989;1994 and1998). Many researches, internationally and nationally, analyzed ETo values calculate by FAO Penman-Monteith method from the viewpoint of its spatial or temporal dispersal (McVicar et al, 2007;Buttafuoco et al, 2010;Song et al, 2010;Khail et al, 2011;Noreldin et al, 2016 andNoreldin, 2017). Furthermore, comparison between FAO Penman-Monteith and other equations calculating ETo was done (Maulé et al, 2006;Paltineanu et al, 1999;Sumner &Jacobs, 2005 andOuda et al, 2016).…”