Green Global
Foundation   Journal
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ANOMALIES OF REFERENCE CROP EVAPOTRANSPIRATION AND RELATED CLIMATIC PARAMETERS IN SYLHET AND MAULBIBAZAR OF BANGLADESH (Pages : 9 - 17)

Understanding the variability in reference crop evapotranspiration (ET0) is a vital issue for sustainable agriculture under the projected consequences of global warming and climate change. The objectives of this study were to estimate ET0 and evaluating the variation of ET0 between two neighboring districts. The ET0 was estimated based on the United Nations Food and Agriculture Organization Penman-Monteith (FAO-PM) model from daily weather data of Sylhet sadar and Shreemangal upazila of Maulbibazar district meteorological station for a period of over 21 years (1988-2013) using FAO CROPWAT 8.0 software. In Sylhet the mean annual temperature (T), relative humidity (RH), vapor pressure deficit (VPD), wind speed ( ), sunshine hour, solar radiation (Rn) and ET0 were 25.5±0.5°C, 78.9±1.4 %, 0.7±0.1 kPa, 1.3±0.1 m/s, 5.9±0.3 hrs day-1, 16.0±0.3 MJ m-2 day-1 and 1246±35 mm year-1, respectively. Whereas in Shreemangal the mean annual temperature (T), relative humidity (RH), vapour pressure deficit (VPD), wind speed ( ), sunshine hour, solar radiation (Rn) and ET0 were 25.1±0.3°C, 80.8±1.0%, 0.6±0.0 kPa, 1.1±0.2 m/s, 6.3±0.4 hrs day-1, 16.7±0.5 MJ m-2 day-1, and 1267±42 mm year-1, respectively. The annual T and VPD showed increasing pattern in Sylhet whereas Shreemangal showed comparatively slight increasing pattern. Annually Rn and showed decreasing trend in Sylhet whereas Rn showed slightly decreasing trend and showed slightly increasing trend in Shreemangal. The results indicated that the values of ET0 in the two stations were approximately the same (correlation coefficient 0.94). Specifically, ET0 ranged from 0.9 to 8.6 mm day-1, 1.0 to 7.5 mm day-1 and the average values were 3.4 mm day-1 and 3.5 mm day-1 in Sylhet sadar and Shreemangal, respectively with the maximum values were recorded in March, April and May in both sites. Download