Effect of local calibration on the performance of the Hargreaves reference crop evapotranspiration equation
Obtaining accurate estimates of reference crop evapotranspiration (ET0) using limited climatic inputs is essential in data-short situations where the preferred FAO-56 Penman–Monteith (PM) equation cannot be implemented. Among several available for ET0 estimation, the empirical temperature-based Harg...
| Main Authors: | , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
IWA Publishing
2021-09-01
|
| Series: | Journal of Water and Climate Change |
| Subjects: | |
| Online Access: | http://jwcc.iwaponline.com/content/12/6/2654 |
| _version_ | 1818842713594789888 |
|---|---|
| author | S. Niranjan Lakshman Nandagiri |
| author_facet | S. Niranjan Lakshman Nandagiri |
| author_sort | S. Niranjan |
| collection | DOAJ |
| description | Obtaining accurate estimates of reference crop evapotranspiration (ET0) using limited climatic inputs is essential in data-short situations where the preferred FAO-56 Penman–Monteith (PM) equation cannot be implemented. Among several available for ET0 estimation, the empirical temperature-based Hargreaves–Samani (HG) equation remains a popular alternative. However, accurate HG estimates can be obtained by local calibration and replacing the mean daily temperature with the effective daily temperature. Therefore, the present study was taken up to evaluate the effects of site-specific calibration of model parameters and the use of effective air temperature on the accuracy of ET0 estimates by the HG model. For this purpose, climate records for the historical period 2006–2016 of 67 stations located across 10 agro-climatic zones of Karnataka State, India, were used and the analysis was carried out using a monthly time step. Calibration and statistical performance evaluation was performed using FAO-56 PM ET0 estimates as a reference. Overall results showed significant improvement in HG estimates across all zones with the use of locally calibrated parameters, whereas the use of effective air temperature did not lead to any significant gain in prediction accuracies. The derived information on the spatial distribution of calibrated parameters will help obtain accurate ET0 estimates with only air temperature inputs. HIGHLIGHTS
Local calibration of the Hargreaves–Samani (HG) ET0 method with reference to Penman–Monteith ET0 estimates.;
Significant improvement in accuracy of ET0 estimates with the local calibration of three parameters in the HG equation across agro-climatic zones.;
Replacing the mean temperature variable in the HG equation with effective temperature yielded minor improvement.;
Spatial maps of optimized HG model parameters were derived.; |
| first_indexed | 2024-12-19T04:46:21Z |
| format | Article |
| id | doaj.art-e77e3183c0e34046b0c6ab3ee245a493 |
| institution | Directory Open Access Journal |
| issn | 2040-2244 2408-9354 |
| language | English |
| last_indexed | 2024-12-19T04:46:21Z |
| publishDate | 2021-09-01 |
| publisher | IWA Publishing |
| record_format | Article |
| series | Journal of Water and Climate Change |
| spelling | doaj.art-e77e3183c0e34046b0c6ab3ee245a4932022-12-21T20:35:29ZengIWA PublishingJournal of Water and Climate Change2040-22442408-93542021-09-011262654267310.2166/wcc.2021.360360Effect of local calibration on the performance of the Hargreaves reference crop evapotranspiration equationS. Niranjan0Lakshman Nandagiri1 Department of Water Resources and Ocean Engineering, National Institute of Technology Karnataka, Surathkal, Srinivasnagar P.O., Mangaluru, Karnataka 575025, India Department of Water Resources and Ocean Engineering, National Institute of Technology Karnataka, Surathkal, Srinivasnagar P.O., Mangaluru, Karnataka 575025, India Obtaining accurate estimates of reference crop evapotranspiration (ET0) using limited climatic inputs is essential in data-short situations where the preferred FAO-56 Penman–Monteith (PM) equation cannot be implemented. Among several available for ET0 estimation, the empirical temperature-based Hargreaves–Samani (HG) equation remains a popular alternative. However, accurate HG estimates can be obtained by local calibration and replacing the mean daily temperature with the effective daily temperature. Therefore, the present study was taken up to evaluate the effects of site-specific calibration of model parameters and the use of effective air temperature on the accuracy of ET0 estimates by the HG model. For this purpose, climate records for the historical period 2006–2016 of 67 stations located across 10 agro-climatic zones of Karnataka State, India, were used and the analysis was carried out using a monthly time step. Calibration and statistical performance evaluation was performed using FAO-56 PM ET0 estimates as a reference. Overall results showed significant improvement in HG estimates across all zones with the use of locally calibrated parameters, whereas the use of effective air temperature did not lead to any significant gain in prediction accuracies. The derived information on the spatial distribution of calibrated parameters will help obtain accurate ET0 estimates with only air temperature inputs. HIGHLIGHTS Local calibration of the Hargreaves–Samani (HG) ET0 method with reference to Penman–Monteith ET0 estimates.; Significant improvement in accuracy of ET0 estimates with the local calibration of three parameters in the HG equation across agro-climatic zones.; Replacing the mean temperature variable in the HG equation with effective temperature yielded minor improvement.; Spatial maps of optimized HG model parameters were derived.;http://jwcc.iwaponline.com/content/12/6/2654hargreaves–samani equationlocal calibrationpenman–monteith equationreference crop evapotranspiration |
| spellingShingle | S. Niranjan Lakshman Nandagiri Effect of local calibration on the performance of the Hargreaves reference crop evapotranspiration equation Journal of Water and Climate Change hargreaves–samani equation local calibration penman–monteith equation reference crop evapotranspiration |
| title | Effect of local calibration on the performance of the Hargreaves reference crop evapotranspiration equation |
| title_full | Effect of local calibration on the performance of the Hargreaves reference crop evapotranspiration equation |
| title_fullStr | Effect of local calibration on the performance of the Hargreaves reference crop evapotranspiration equation |
| title_full_unstemmed | Effect of local calibration on the performance of the Hargreaves reference crop evapotranspiration equation |
| title_short | Effect of local calibration on the performance of the Hargreaves reference crop evapotranspiration equation |
| title_sort | effect of local calibration on the performance of the hargreaves reference crop evapotranspiration equation |
| topic | hargreaves–samani equation local calibration penman–monteith equation reference crop evapotranspiration |
| url | http://jwcc.iwaponline.com/content/12/6/2654 |
| work_keys_str_mv | AT sniranjan effectoflocalcalibrationontheperformanceofthehargreavesreferencecropevapotranspirationequation AT lakshmannandagiri effectoflocalcalibrationontheperformanceofthehargreavesreferencecropevapotranspirationequation |