Naderyan far, Elham (2016) Comparing Different Processes for Mapping Annual and Monthly Reference Evapotranspiration in Iran. Masters thesis, University of zabol.
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Abstract
Accurate estimation of reference evapotranspiration-(ET0) is essential to determine water requirements of crops and achieve a high irrigation efficiency. This study presents a comparison of two different processes namely "first interpolate then calculate (IC)" and "first calculate then interpolate (CI)" for estimating and mapping annual and monthly ET0 over Iran. In the first process, an interpolation of meteorological parameters required to calculate ET0 were performed and then ET0 were calculated on a network defined on the study area using the FAO - Penman-Monteith equation. In the second approach which is more common, first ET0 was calculated for the selected station given meteorological parameters and then interpolated over the study area. These techniques used were include ordinary kriging (OK) with and without axiulary variable, radial basis functions (RBF), local polynomial (LPI) and inverse distance weighting (IDW). The results showed that ET0 has a moderate to strong spatial correlation with a spherical structure. Overall, ignoring the interpolation method used, IC performed better than CI for majority of months and aanual scale. The best interpolation method (according to RMSE and MAE) in IC procedure was IDW for September and October and for annual case, OK for Juanuary and March and COK for Febuary, April, November and Desember. IDW with CI procedure was the best method for estimating ET0 for May, June, July and Agust. Further, the comparison of interpolation methods indicated that for both IC and CI, OK, COK and IDW, which incorporate the separation distance in estimation procedure, performed well. Based on the ET0 generated maps, the highest reference ET0 occurs in southern, southwestern and eastern parts of the study area.
| Item Type: | Thesis (Masters) |
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| Uncontrolled Keywords: | Evapotranspiration, Penman-Monteith, Spatial variation, Interpolation, Kriging. |
| Subjects: | S Agriculture > S Agriculture (General) |
| Depositing User: | admin admin1 admin2 |
| Date Deposited: | 23 Sep 2017 08:44 |
| Last Modified: | 23 Sep 2017 08:44 |
| URI: | http://eprints.uoz.ac.ir/id/eprint/1622 |
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