A.a Sabziparvar, H Tabari, A Aeini,
Volume 14, Issue 52 (7-2010)
Abstract
Soil temperature is one of the important variables in hydrology, agriculture, meteorology and climatology studies. Owing to the fact that soil temperature is only measured at synoptic stations, reconstruction of this variable in other places is of great importance for many relevant agricultural surveys. Using 10-year (1996-2005) daily meteorological observations, including: air temperature, global solar radiation, precipitation, relative humidity, vapor pressure, wind speed and air pressure data, different empirical relationships are suggested. At statistically significant level (P<0.05), the suggested regressions are reliable for estimating soil temperature in various depths (5, 10, 20, 30, 50 and 100 cm) and different climate types. Using soil temperature as the dependent variable and the other meteorological parameters as the independent variables, the multivariable relationships are classified accordingly. The results indicate that the impact of meteorological parameters on soil temperature is not the same. At statistically significant level (P<0.05), the mean daily air temperature presented the highest correlation coefficients with soil temperature for all climate types (on average, from R2>0.91 for warm semi-arid, to R2>0.85 for humid climates). Other results highlighted that the correlation coefficients decreased as the soil depth increased. The behavior of statistical validation criteria of the suggested relations are also discussed for all the mentioned climates.
E. Ebrahimi, M. Gheysari, A. R. Gohari,
Volume 29, Issue 4 (12-2025)
Abstract
Given the rising need for water consumption and the decrease in available water resources, improving water use efficiency appears essential. Using modern irrigation techniques and applying irrigation management based on current, accurate scientific principles will enhance irrigation efficiency. This study aimed to estimate evaporation and windfall losses using meteorological variables and measure these losses in the cities of Isfahan, Golpayegan, and Fereydounshahr under different weather conditions. Evaporation and windfall losses were examined at 3, 6, 9, 12, and 15 hours using two selected equations across three meteorological stations with seven years of weather data. Then, evaporation and windfall losses were estimated using two experimental methods (abbreviated as WD1 and WD2), a science-based method (named droplet size), and field measurements. Results showed that evaporation and windage losses calculated with the empirical equation WD1 were about 2% higher than the field measurement value, while WD2 was about 1.5% lower. The correction factors for WD1 were 0.54, 0.44, and 0.51 for Isfahan, Fereydounshahr, and Golpayegan, respectively, and for WD2, it was 1.62, 1.17, and 1.56, respectively. The differences in evaporation and windage losses at various times of day and months of the year were statistically significant at the 5% level.
