Energy Partitioning and Evapotranspiration over a Rice Paddy in Southern Brazil
Authors:Timm, Andrea Ucker Roberti, Debora R. Streck, Nereu Augusto de Goncalves, Luis Gustavo G. Acevedo, Otavio Costa Moraes, Osvaldo L. L. Moreira, Virnei S. Degrazia, Gervasio Annes Ferlan, Mitja Toll, David L.
Volume:15
Published:2014
Document Type:Article
Abstract:During approximately 80% of its growing season, lowland flooded irrigated rice ecosystems in southern Brazil are kept within a 5-10-cm water layer. These anaerobic conditions have an influence on the partitioning of the energy and water balance components. Furthermore, this cropping system differs substantially from any other upland nonirrigated or irrigated crop ecosystems. In this study, daily, seasonal, and annual dynamics of the energy and water balance components were analyzed over a paddy rice farm in a subtropical location in southern Brazil using eddy covariance measurements. In this region, rice is grown once a year in low wetlands while the ground is kept fallow during the remaining of the year. Results show that the energy budget residual corresponded to up to 20% of the net radiation during the rice-growing season and around 10% for the remainder of the year (fallow). The energy and water balance analysis also showed that because of the high water table in the region, soil was near saturation most of the time, and latent heat flux dominated over sensible heat flux by up to one order of magnitude in some cases. The estimate of evapotranspiration ET using the crop coefficient multiplied by the reference evapotranspiration KcETo and the Penman-Monteith equation ETPM, describing the canopy resistance through leaf area index (LAI) obtained by remote sensing, represent well the measured evapotranspiration, mainly in the fallow periods. Therefore, using a specific crop parameter like LAI and crop height can be an easy and interesting alternative to estimate ET in vegetated lowland areas.
Author Information
Corresponding Author:Roberti, DR (通讯作者)，Univ Fed Santa Maria, Dept Phys, Av Roraima 1000, BR-97105900 Santa Maria, RS, Brazil.
Reprint Address:Roberti, DR (通讯作者)，Univ Fed Santa Maria, Dept Phys, Av Roraima 1000, BR-97105900 Santa Maria, RS, Brazil.
Addresses:[Timm, Andrea Ucker] Fac Serra Gaucha, Caxias Do Sul, RS, Brazil; [Roberti, Debora R.; Moraes, Osvaldo L. L.; Degrazia, Gervasio Annes] Univ Fed Santa Maria, Dept Phys, BR-97105900 Santa Maria, RS, Brazil; [Streck, Nereu Augusto] Univ Fed Santa Maria, Dept Phys, Dept Fitotecnia, BR-97105900 Santa Maria, RS, Brazil; [de Goncalves, Luis Gustavo G.; Moraes, Osvaldo L. L.] Inst Nacl Pesquisas Espaciais, Ctr Previstio Tempo & Estudos Climat, Sao Paulo, Brazil; [Moreira, Virnei S.] Univ Fed Pampa, Itaqui, RS, Brazil; [Ferlan, Mitja] Slovenian Forestry Inst, Ljubljana, Slovenia; [Toll, David L.] NASA, Goddard Space Flight Ctr, Hydrol Sci Lab, Greenbelt, MD 20771 USA
E-mail Addresses:debora@ufsm.br