Modelling Of Microclimate And Reference Evapotranspiration Under Polyhouse

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Date
2015
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MPUAT, Udaipur
Abstract
The present study was undertaken at the Plasticulture Farm of College of Technology and Engineering, Udaipur. The study area falls in 24° 35 N – latitude, 73° 44 E–longitude and at an altitude of 582.17 m above mean sea level. The study was undertaken to determine lengthwise, widthwise and heightwise variation of temperature and relative humidity for 24 points in grids of 6 m x 4 m in 1008 m2 Polyhouse. Horizontal and vertical profiles of the temperature and relative humidity inside the polyhouse were investigated. Results showed that temperature increased from evaporative pad area to exhaust fans area in a horizontal plane, while relative humidity showed an inverse pattern from temperature. In the vertical plane, temperature increased, while relative humidity decreased from lower level to the upper level. ANOVA results showed that in overall, temperature and relative humidity inside the polyhouse were not uniform as there was significant difference at 99% confidence level. It was found that second degree polynomial model was strong correlation coefficient; hence it was considered for estimation of temperature under polyhouse for winter and summer season. It was observed that computed value of the test-statistics was less than its tabulated value in all treatments with and without shadenet during winter and summer season. It was concluded that there was no significant difference between the modeled and the measured relative humidity at 1 % level of significance. The evaporation estimates computed by Dalton model, Combination model and Christiansen model were compared with measured evaporation. The performance of modified Christiansen model was found to be better than original evaporation for prediction of evaporation. Testing of most commonly used model computed by Multiple Regression model Mass Transfer model and Energy Balance model to predict evaporation inside polyhouse. The performance of Multiple Regression model was found satisfactory inside polyhouse under climatic condition of Udaipur. Estimation of Class A pan coefficient by Snyder Method, Sharifan and Qahreman Method, Pereira Method and and FAO/56 Allen Method was used. The performance of FAO/56 Allen Method was found low standard error and coincides with 1:1 line than other methods. Hence from this results for Kp was found 0.98 approximately 1.00 inside polyhouse for Udaipur region. Testing of five reference evapotranspiration models were made on basis of measurement of reference evapotranspiration. The models are (1) FAO Penman model (2) FAO-Penman- Monteith Model (3) Hargreaves temperature based model (4) FAO Radiation Based Model and (5) Priestley Taylor model. Out of 5 models 2 models viz. FAO Penman model and FAO-Penman-Monteith Model found to predict ETOA accurately inside polyhouse under climatic condition of Udaipur region. Models of evaporation rate, modelling of evaporation rate during Kharif Season, modelling of evaporation rate during Rabi Season and modelling of evaporation rate during Summer Season were developed on the basis of time and climatic parameters.
Description
Modelling Of Microclimate And Reference Evapotranspiration Under Polyhouse
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Citation
Madhukar and Bhakar, 2015
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