scholarly journals Trend Analysis of Reference Evapotranspiration in the São Francisco River Basin, Brazil

Author(s):  
Neilon Silva ◽  
Aureo Silva de Oliveira

Abstract An important requisite in any water resources management program is the knowledge of the natural processes that regulate the hydrological cycle, especially for spatial and temporal analyses of these processes. This work aimed to explore spatial and temporal trends of reference evapotranspiration (ETo), evaluate ETo variation dynamics and quantify the contribution of each one of the meteorological variables in ETo calculation in the São Francisco River basin. Daily data of maximum and minimum air temperature, mean relative air humidity, wind speed and net radiation from 101 weather stations, for the period from 1961 to 2015, were used and are part of the network of the National Institute of Meteorology (INMET). Climate trend analysis was performed using the non-parametric Mann-Kendall statistical test and the sensitivity analysis for the Penman-Monteith equation was carried out based on partial derivatives as a function of the key meteorological variables of ETo (air temperature, net radiation, wind speed and actual water vapor pressure). A significant increase (p<0.01) in vapor pressure deficit (VPD) associated with the increase in mean air temperature contributed to increments in ETo along the studied period. The scenario in the entire São Francisco River basin is of increase in the values of the climatic variables, particularly evapotranspiration (85% of basin area with increments) and rainfall (52% of basin area with decrements). Results indicate an increase in ETo variation rates of approximately 2.424 mm year-2, on average, in the entire basin. The energy term represents higher weight in ETo calculation in 81% of the basin territory.

Water ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1957
Author(s):  
Papa Malick Ndiaye ◽  
Ansoumana Bodian ◽  
Lamine Diop ◽  
Abdoulaye Deme ◽  
Alain Dezetter ◽  
...  

Understanding evapotranspiration and its long-term trends is essential for water cycle studies, modeling and for water uses. Spatial and temporal analysis of evapotranspiration is therefore important for the management of water resources, particularly in the context of climate change. The objective of this study is to analyze the trend of reference evapotranspiration (ET0) as well as its sensitivity to climatic variables in the Senegal River basin. Mann-Kendall’s test and Sen’s slope were used to detect trends and amplitude changes in ET0 and climatic variables that most influence ET0. Results show a significant increase in annual ET0 for 32% of the watershed area over the 1984–2017 period. A significant decrease in annual ET0 is observed for less than 1% of the basin area, mainly in the Sahelian zone. On a seasonal scale, ET0 increases significantly for 32% of the basin area during the dry season and decreases significantly for 4% of the basin during the rainy season. Annual maximum, minimum temperatures and relative humidity increase significantly for 68%, 81% and 37% of the basin, respectively. However, a significant decrease in wind speed is noted in the Sahelian part of the basin. The wind speed decrease and relative humidity increase lead to the decrease in ET0 and highlight a “paradox of evaporation” in the Sahelian part of the Senegal River basin. Sensitivity analysis reveals that, in the Senegal River basin, ET0 is more sensitive to relative humidity, maximum temperature and solar radiation.


2020 ◽  
Vol 27 (4) ◽  
pp. 98-102
Author(s):  
Haqqi Yasin ◽  
Luma Abdullah

Average daily data of solar radiation, relative humidity, wind speed and air temperature from 1980 to 2008 are used to estimate the daily reference evapotranspiration in the Mosul City, North of Iraq. ETo calculator software with the Penman Monteith method standardized by the Food and Agriculture Organization is used for calculations. Further, a nonlinear regression approach using SPSS Statistics is utilized to drive the daily reference evapotranspiration relationships in which ETo is function to one or more of the average daily air temperature, actual daily sunshine duration, measured wind speed at 2m height and relative humidity


1998 ◽  
Vol 41 (3) ◽  
pp. 309-314 ◽  
Author(s):  
Yoshimi Sato ◽  
Nelsy Fenerich-Verani ◽  
José Roberto Verani ◽  
Hugo Pereira Godinho ◽  
Edson Vieira Sampaio

Rhinelepis aspera is the largest Loricariidae species found in the São Francisco river basin where it is now rarely caught. Brooders kept in tanks were hypophysed with crude carp pituitary extract (CCPE). Approximately 82% of the females responded positive to the treatment. The egg was opaque, demersal, round, yellow and adhesive. Egg stripping was done at 212 hour-degrees (= 8.2 h) after application of the second dose of CCPE (water temperature = 25-26 ºC). Hatching of the larvae occurred at 1022 hour-degrees (= 42.2 h), after fertilization of the eggs (water temperature =24-25 ºC). Fertilization rate of the eggs was 72%. Absolute fecundity (AF), initial fertility (IF) and final fertility (FF) in relation to the females' body weight are expressed, respectively, by the equations: AF = - 33993 + 122308 Wt (r² = 0.88), IF = - 14823 + 58619 Wt (r² = 0.71) and FF = - 6553 + 29741 (r² = 0.61)


2015 ◽  
Vol 24 (2) ◽  
pp. 129-135 ◽  
Author(s):  
Danielle Priscilla Correia Costa ◽  
Cassandra Moraes Monteiro ◽  
Marilia Carvalho Brasil-Sato

A total of 103 specimens of Hoplias intermedius (Günther, 1864) and 86 specimens of H. malabaricus (Bloch, 1794) from the upper São Francisco River, State of Minas Gerais were collected between April 2011 and August 2013, and their parasitic fauna were investigated. Four species of Digenea were found: metacercariae of Austrodiplostomum sp., and Ithyoclinostomum sp.; and adult specimens of Phyllodistomum spatula Odhner, 1902, and Pseudosellacotyla lutzi (Freitas, 1941) Yamaguti, 1954. The prevalence of the metacercariae was higher than that of the adult digeneans of erythrinids from the upper São Francisco River as a result of piscivorous feeding habits of these adult erythrinids. The presence of metacercariae and adult digeneans indicate that they act as intermediate and definitive hosts, respectively, in their biological cycles. Hoplias intermedius is a new host for the four species of Digenea, and the São Francisco River basin is a new location for the known geographical distributions of P. spatula and P. lutzi.


2016 ◽  
Vol 20 (7) ◽  
pp. 2573-2587 ◽  
Author(s):  
Zhongwei Huang ◽  
Hanbo Yang ◽  
Dawen Yang

Abstract. With global climate changes intensifying, the hydrological response to climate changes has attracted more attention. It is beneficial not only for hydrology and ecology but also for water resource planning and management to understand the impact of climate change on runoff. In addition, there are large spatial variations in climate type and geographic characteristics across China. To gain a better understanding of the spatial variation of the response of runoff to changes in climatic factors and to detect the dominant climatic factors driving changes in annual runoff, we chose the climate elasticity method proposed by Yang and Yang (2011). It is shown that, in most catchments of China, increasing air temperature and relative humidity have negative impacts on runoff, while declining net radiation and wind speed have positive impacts on runoff, which slow the overall decline in runoff. The dominant climatic factors driving annual runoff are precipitation in most parts of China, net radiation mainly in some catchments of southern China, air temperature and wind speed mainly in some catchments in northern China.


2016 ◽  
Vol 38 (2) ◽  
pp. 15
Author(s):  
R. M. G. VIEIRA ◽  
C. P. DERECZYNSKI ◽  
S. C. CHOU ◽  
J. L. GOMES ◽  
A. C. PAIVA NETO

Irriga ◽  
2018 ◽  
Vol 21 (2) ◽  
pp. 269 ◽  
Author(s):  
Vágna Da Costa Pereira ◽  
Gilberto Chohaku Sediyama ◽  
Magna Soelma Beserra De Moura ◽  
Thieres George Freire Da Silva ◽  
Luciana Sandra Bastos De Souza

EFICIÊNCIA DO USO DA ÁGUA EM VIDEIRA ‘SYRAH’ IRRIGADA NO SUBMÉDIO DO VALE SÃO FRANCISCO1 VÁGNA DA COSTA PEREIRA1; GILBERTO CHOHAKU SEDIYAMA2; MAGNA SOELMA BESERRA DE MOURA3; THIERES GEORGE FREIRE DA SILVA4 E LUCIANA SANDRA BASTOS DE SOUZA51Resultado da Dissertação de Mestrado do primeiro autor2Doutoranda em Meteorologia Agrícola – Departamento de Engenharia Agrícola – Universidade Federal de Viçosa – Campus Viçosa – 36570-900 – Viçosa, Minas Gerais, Brasil, [email protected]. Titular – Departamento de Engenharia Agrícola – Universidade Federal de Viçosa – Campus Viçosa – 36570-900 – Viçosa, Minas Gerais, Brasil, [email protected] – Núcleo Temático de Recursos Naturais – Embrapa Semiárido – 56302-970 – Petrolina, Pernambuco, Brasil, [email protected]. Adjunto – Departamento de Ciências Agrárias – Universidade Federal Rural de Pernambuco – Unidade Acadêmica de Serra Talhada – 56909-535 – Serra Talhada, Pernambuco, Brasil, [email protected]. Assistente – Departamento de Ciências Agrárias – Universidade Federal Rural de Pernambuco – Unidade Acadêmica de Serra Talhada – 56909-535 – Serra Talhada, Pernambuco, Brasil, [email protected]  1 RESUMO O estudo teve como objetivo estimar a eficiência do uso da água (EUA) na videira ‘Syrah’ irrigada no Submédio do Vale São Francisco, com base no rendimento em função da evapotranspiração da cultura e da transpiração máxima. Para isso, a evapotranspiração da cultura foi determinada pelo balanço de energia com base no método da razão de Bowen (ETcBERB), enquanto a transpiração máxima (TR) foi estimada pelo modelo de Penman-Monteith modificado com base no índice de área foliar da cultura. Os dados micrometeorológicos foram monitorados durante um ciclo produtivo por meio de uma estação automática localizada no parreiral. A evapotranspiração de referência (ETo) também foi calculada ao longo do experimento, pelo método de Penman-Monteith parametrizado no boletim 56 da FAO. A ETo e a ETcBERB corresponderam ao valor total de 474,0 e 376,4 mm ciclo-1, com valor médio diário de 3,9 e 3,1 mm, respectivamente. A TR oscilou entre 3,5 e 0,9 mm d-1, com volume total durante o ciclo de 284,4 mm. A EUA, com base no total de água consumida e transpirada, foi de 1,17 kg m-3 e 1,55 kg m-3, respectivamente. O método do BERB e o modelo de Penman-Monteith modificado para plantas isoladas apresentaram resultados confiáveis para estimativa da EUA sob as condições climáticas da região do Submédio do Vale São Francisco. No entanto, torna-se necessário que novos estudos nesse sentido com a cultura da videira para produção de vinhos sejam realizados, principalmente nesta região Semiárida, onde a maioria das pesquisas voltadas para o manejo do vinhedo ainda estão em desenvolvimento. Palavras-chave: semiárido, evapotranspiração, razão de Bowen, transpiração máxima   PEREIRA, V. C.; SEDIYAMA, G. C.; MOURA, M. S. B.; SILVA, T. G. F.; SOUZA, L. S. B.WATER USE EFFICIENCY IN IRRIGATED "SYRAH'' GRAPE PLANTATION AT SÃO FRANCISCO RIVER VALLEY  2 ABSTRACT The objective of this work was to evaluate the water use efficiency (WUE) in  irrigated ‘Syrah’ grapevine plantation at São Francisco River valley, on the basis of yields as a function of crop evapotranspiration and maximum transpiration. To this end, the crop evapotranspiration was determined by energy balance based on the Bowen ratio method (ETcBERB), while the maximum transpiration (TR) was estimated by the modified Penman-Monteith equation based on the crop leaf area index. The micrometeorological data within the vineyard canopy were monitored using an automatic micrometeorological station, during a productive cycle. The reference evapotranspiration (ETo) was also calculated during that period using the FAO parameterized Penman-Monteith equation. The reference evapotranspiration (ETo) and the crop evapotranspiration determined by BREB method (ETcBERB), during the crop cycle, were 474.0 and 376.4 mm cycle-1, respectively, with a daily average of 3.9 and 3.1 mm. The TR rate ranged between 3.5 and 0.9 mm d-1, with total volume during 284.4 mm cycle -1. The WUE, on the basis of the total water consumed and transpiration, was 1.17 kg m-3 and 1.55 kg m-3, respectively. The BERB method and the Penman-Monteith model modified to isolated plants showed reliable results to estimate the WUE under the climatic conditions of São Francisco River valley. However, new studies on grape culture for wine production are necessary, especially in this semiarid region, where most researches focused on the vineyard management are still in development. Keywords: Bowen ratio. Evapotranspiration. Maximum transpiration. Semiarid. 


Author(s):  
Celso Augusto Guimarães Santos ◽  
Reginaldo Moura Brasil Neto ◽  
Richarde Marques da Silva ◽  
Jacqueline Sobral de Araújo Passos

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