Bezerra, Bergson GuedesMutti, Pedro Rodrigues2018-04-062018-04-062018-02-22MUTTI, Pedro Rodrigues. Estimativa da evapotranspiração sobre a bacia hidrográfica do Rio Piranhas-Açu utilizando dados de sensoriamento remoto. 2018. 117f. Dissertação (Mestrado em Ciências Climáticas) - Centro de Ciências Exatas e da Terra, Universidade Federal do Rio Grande do Norte, Natal, 2018.https://repositorio.ufrn.br/jspui/handle/123456789/25004The Piranhas-Açu River Basin (PARB) is located in Brazil’s semiarid region, where the occurrence of long draught periods associated with water resources allocation conflicts may put its water availability at risk, impacting human supply and agriculture development. Because of that, research on hydrological cycle processes is crucial to water resources management in water basins. Among these processes, evapotranspiration (ET) is of uttermost importance given its critical role in water, soil and vegetation interactions, hydrometeorological modelling and in the energy fluxes dynamics of semiarid regions. Therefore, the objective of this study is to quantify daily ET during a wet and a dry year in all the PARB, by using remote sensing data and formulations based on the Simplified Surface Energy Balance Index (S-SEBI) and the Simplified Surface Energy Balance (SSEB) algorithms. Land surface temperature, albedo and NDVI data from MODIS sensor and solar radiation data from weather stations located in the basin were used. Precipitation analysis was carried out using data from rain gauges located in the basin. It indicated 2009 as being an unusually wet year and 2012 as an unusually dry year, which were selected for the ET quantification. The proposed algorithm was calibrated and validated with energy balance components data from a flux tower equipped with eddy covariance system. Daily ET estimates showed good agreement with observed values (R²=0.64, RMSE=0.79 mm.d-1) and annual ET relative error was of 7,3% (33.7 mm.year-1). In 2009 the highest monthly ET rates were found in water bodies (96.4 mm) and in the Caatinga (93.0 mm) during March and April. In this year, ET monthly rates were higher than 30.0 mm in all land cover classes until October. In 2012, the highest rates were also found in March and April in water bodies (100.9 mm) and the Caatinga (87.4 mm). In June of this year monthly ET rates were as lows as 30.0 mm, with a minimum of 17.6 mm in bare soil areas in September. Water surplus was calculated using precipitation data from the TRMM satellite. During 2009 it was observed a surplus of 721.5 mm in the PARB, which was 4.7 times greater than the deficit observed in 2012 (-153.2 mm). This indicates that, neglecting consumptive water usage in the basin, wet years can potentially compensate up to four years of intense draughts.Acesso AbertoS-SEBISSEBMODISBalanço de energiaRecursos hídricosmasterThesisCNPQ::CIENCIAS EXATAS E DA TERRA: CIÊNCIAS CLIMÁTICAS