Encontrados 8 documentos, a visualizar página 1 de 1
Efeitos das alterações climáticas nas necessidades úteis de rega na bacia do Gu...
Valverde, Pedro; Serralheiro, Ricardo; Carvalho, Mário de; Shahidian, Shakib; Rodrigues, CarlosInvestigou-se a tendência de variação das necessidades úteis de rega com as alterações climáticas na bacia hidrográfica do Guadiana para as principais culturas agrícolas de regadio com mais importância na região. Nesta análise aplicou-se o modelo de balanço hídrico do solo ISAREG e utilizaram-se as séries de variáveis climáticas registadas localmente entre 1963 e 2009. Os resultados das séries climáticas indica...
Implications of climate variability and future trends on wheat production and c...
Carvalho, Mário; Serralheiro, Ricardo; Leal, João; Valverde, PedroThe effects of climate conditions and its variability are analysed in the context of rainfed agriculture under Mediterranean climate in the south of Portugal. The reference crop is wheat using data from field experiments carried out for several years, using different amounts of nitrogen and two wheat genotypes. Wheat yields can be limited either by drought and excess of water and winter rainfall has a large eff...
Climate change in Guadiana river basin and its impacts on crop water demand
Valverde, Pedro; Serralheiro, Ricardo; Carvalho, Mário; Shahidian, ShakibThis study evaluates climate change tendencies over several climatic parameters observed in the Guadiana river basin, south Portugal and its potential impacts on crop water and irrigation requirements. Parameters analyzed were annual rainfall and its seasonal distribution, temperature and evapotranspiration, collected from available regional meteorological data from a 46-year period (1963-2009). The impacts of ...
Water use, transpiration and crop coefficients for irrigated hedgerow olives gr...
Santos, Francisco L.; Correia, Maria Manuela; Valverde, Pedro C.; Renato, Coelho; Vaz, Margarida; Paço, T. A.Olive trees are well adapted to the Mediterranean-type agro-ecosystems of southern Portugal and have traditionally been cultivated in areas with no irrigation. According to the 2009 agricultural census, the olive tree cultivation area was around 336,000 ha, of which 164,000 ha are in the southern province of Alentejo. In this southern region of semi arid Mediterranean climate where the erratic annual precipitat...
Estimation and mapping transpiration with basal and stress crop coefficients de...
Santos, Francisco L.; Correia, Maria Manuela; Pôcas, Isabel; Valverde, Pedro C.; Coelho, Renato; Vaz, Margarida; Paço, Teresa A.The use of remote sensing for obtaining evapotranspiration (ET) from natural and agricultural surfaces is already widely used. For irrigated agriculture the two basic approaches are: (1) the solution of the energy balance equation, using remotely sensed surface temperatures and reflectances to estimate variables and components of this equation, and (2) the crop coefficient and reference evapotranspiration (ETo)...
Sap flow scaling and crop coefficient of dry-farmed olive orchards converted to...
Santos, Francisco Lúcio; Valverde, Pedro; Reis, João; Ramos, Alice; Castanheira, NádiaTree water uptake is often estimated based in a crop coefficient kc, a ratio of the tree water uptake and a reference evapotranspiration, ET0. The concept behind estimating tree crop coefficient implies that data should be representative of the population of trees analyzed. Ideally it would require the monitoring of a large number of trees in each treatment population. This paper reports on a scaling method to ...
ESTUDO DE ALGUNS IMPACTOS DAS ALTERAÇÕES CLIMÁTICAS SOBRE O REGADIO NO ALENTEJO
Shahidian, Shakib; Teixeira, José; Valverde, Pedro; Serralheiro, Ricardo; Rolim, João; Serrano, JoãoA actividade humana, associada a uma utilização desmedida de combustíveis fósseis, tem produzido efeitos negativos sobre a fauna, a flora e o ciclo hidrológico. Para avaliar os efeitos sobre o ciclo hidrológico na região do Alentejo, foram estudados os registos meteorológicos disponíveis na base de dados do INAG de todas as estações da região. O estudo baseou-se em médias mensais e anuais de precipitação, tempe...
Water use and response of a dry-farmed olive orchard recently converted to irri...
Santos, Francisco Lúcio; Valverde, Pedro; Ramos, Alice; Reis, João; Castanheira, NádiaExperimental results obtained in Southern Portugal from a dry-farmed mature olive tree orchard recently converted to drip irrigation are described. Water use and response to two irrigation management practices by olive trees was monitored with sap flow compensation heat pulse sensors, ‘Watermark’ granular matrix block sensors and a capacitance probe. The 80-plus-year-old mature olive tree orchard planted on a 1...
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