Up scaling guava water balance in the Petrolina-Juazeiro growing area, Northeast Brazil.

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Delimitation of guava water productivity in the Brazilian Northeast.

The intensification of agricultural crops in the Brazilian northeast results in a change of natural vegetation, making the quantification and evaluation of the additional water use important. Applications of a Geographic Information System (GIS) are presented in this paper to estimate the guava water productivity (GWP) on a large scale. Long-term weather data were used together with regression models involving crop coefficient (Kc), reference evapotranspiration (ET0) and accumulated degree days (DDac) to quantify the guava water requirements (GWR) in the Brazilian Northeast producer states, considering an average growing season of six months and the cultivar ‘Paluma’ as a reference. By coupling GWR data with total precipitation for a growing season, it was possible to quantify the guava water deficit (GWD) giving an estimate about irrigation needs. Considering the whole region, the variation of the averaged GWD values ranged from 50 mm for pruning dates in January to 520 mm, with pruning done in May. Associating the average GWR values with yield data for 2010 from the Brazilian Geographical and Statistical Institute (IBGE), the average biophysical and economic values of GWP were estimated for each guava producer state. The biophysical values were between 0.86 and 4.95 kg m-3 for pruning dates in July and January in Rio Grande do Norte and Pernambuco states, respectively, while the economic ones ranged from 0.40 to 3.18 R$ m-3 for the same pruning periods, however, with the lowest averaged value being for Paraíba state. The states of Pernambuco, Bahia and Piauí presented the largest biophysical and economic GWP values. The spatially presented analyses can subsidize programs for the expansion of rainfed guava crop as well as water allocation criteria under irrigation conditions, aiming at improvements for water resource use.Edição do Proceedings of the III International Symposium on Guava and other Myrtaceae, Petrolina, sept. 2012

Modelagem hídrica na cultura da mangueira no pólo produtor brasileiro Petrolina-PE/Juazeiro-BA.

Dados climáticos de um rede de estações agrometeorológicas automáticas e resultados de experimentos de balanço de energia foram usados para modelar variáveis hídricas na cultura da mangueira no pólo brasileiro de produção Petrolina-PE/Juazeiro-BA. Foi evidenciada uma maior necessidade de aplicação de água nas fases do florescimento ao crescimento dos frutos, chegando à 150 mm mês-1. Dados adicionais de produção de mangas permitiram as análises da produtividade da água (PA), resultando em menores valores para Petrolina, com média de 1,60 kg m-3, enquanto que para Juazeiro esta foi de 1,80 kg m-3. Pôde-se concluir que no primeiro município, o manejo de água da cultura deve ser mais ineficiente, existindo espaço para uma melhoria em PA.IV Winotec 2012

Up scaling guava water balance in the Petrolina/Juazeiro growing area, Northeast Brazil.

Weather data for 2011, from a net of 15 automatic agro-meteorological stations and previous field energy balance results, were used together with regression models for modelling the guava water requirement (GWR) in the growing area of Petrolina (Pernambuco state) - Juazeiro (Bahia state), Brazil, considering a 6.5-months average growing season (GS). GWRGS joined with rainfall, allowed the acquirement of the regional water balance and the application of a guava water indicator (GWIGS) calculated as the ratio of the total precipitation during a growing season (PGS) to GWRGS. The variation of the averaged GWRGS values for Petrolina, was from 750±6.9 to 950±10.5 mm, while for Juazeiro, it was from 730±6.2 to 900±9.2 mm, with pruning periods in January and June, respectively. Considering the GWIGS indicator, its values for both municipalities were found similar, which were around 0.38 and 0.08 for pruning done in January and June, respectively. Quantifying the differences between PGS and GWRGS, it was evident that a higher amount of irrigation water needed to be applied between September and October for growing cycles starting in June. Additional data from IBGE (Brazilian Geographical and Statistical Institute) allowed the inspection of the guava water productivity (GWP) at the municipality level. The GWP values for Petrolina were 4.1 and 3.3 kg m-3, while for Juazeiro they were 1.8 and 1.5 kg m-3, for pruning periods in January and June, respectively. It could be concluded that the lower GWP values for Juazeiro was because of a poorer crop management, resulting in lower yield, evidencing scope for improvements. The analyses spatially presented, can subsidize water allocation and irrigation management criteria, when aiming improvements on guava water productivity and yet, avoiding environmental damage by the fast climate and land use changes in the Brazilian semi-arid areas.Edição do Proceedings of the III International Symposium on Guava and other Myrtaceae, Petrolina, sept. 2012

Determinação da evapotranspiração através de imagens de satélites de diferentes resoluções com e sem a banda termal.

O objetivo do presente artigo é testar a aplicação de uma nova metodologia de obtenção da evapotranspiração com a temperatura da superfície obtida com ou sem a banda termal com satélites MODIS e Landsat e posterior aplicação com sensores RapidEye, para ver a viabilidade de utilização deste último satélite no monitoramento da ET em agros-ecossistemas envolvendo culturas irrigadas e vegetação natural tomando-se como referência a região semiárida brasileira

Application of Landsat images for quantifying the energy balance under conditions of land use changes in the Semi-Arid region of Brazil.

In the Nilo Coelho irrigation scheme, Brazil, the natural vegetation has been replaced by irrigated agriculture, bringing importance for the quantification of the effects on the energy exchanges between the mixed vegetated surfaces and the lower atmosphere. Landsat satellite images and agro-meteorological stations from 1992 to 2011 were used together, for modelling these exchanges. Surface albedo (0), NDVI and surface temperature (T0) were the basic remote sensing retrieving parameters necessary to calculate the latent heat flux E) and the surface resistance to evapotranspiration (rs) on a large scale. The daily net radiation (Rn) was obtained from 0, air temperature (Ta) and short-wave transmissivity (sw) throughout the slob equation, allowing the quantification of the daily sensible heat flux (H) by residual in the energy balance equation. With a threshold value for rs, it was possible to separate the energy fluxes from crops and natural vegetation. The averaged fractions of Rn partitioned as H and E, were in average 39 and 67%, respectively. It was observed an increase of the energy used for the evapotranspiration process inside irrigated areas from 51% in 1992 to 80% in 2011, with the ratio E/Rn presenting an increase of 3 % per year. The tools and models applied in the current research, can subsidize the monitoring of the coupled climate and land use changes effects in irrigation perimeters, being valuable when aiming the sustainability of the irrigated agriculture in the future, avoiding conflicts among different water users

Eficiência no uso da água da vegetação na microbacia hidrográfica do córrego Cabeceira Comprida.

Este trabalho teve por objetivo estimar a evapotranspiração, a biomassa e a produtividade da água da microbacia do córrego Cabeceira Comprida que sofreu mudança espaço-temporal no uso do solo e nos diferentes agrupamentos de espécies presentes, especialmente na área definida como de preservação permanente