Encontrados 27 documentos, a visualizar página 1 de 3
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 ...
Socioeconomic evaluation of drought effects.
Maia, Rodrigo; Vivas, Eduardo; Serralheiro, Ricardo; Carvalho, MárioDrought situations can have significant impacts, affecting large areas and imposing relevant restrictions on multiple economic activities. The severity of those impacts is, normally, assessed through meteorological, agricultural and/or hydrological indices or even through estimation of water deficits or reduction of production yields (for agriculture). However, those assessments usually do not represent the soc...
Irrigation management with remote sensing techniques. Crop water requirements a...
Toureiro, Célia; Serralheiro, Ricardo; Shahidian, ShakibIn irrigated agriculture, increasing water management efficiency is the way to save water and to render irrigation a sustainable activity. In the present work procedures with remote sensing are used to determine the contents of available water in the soil at each moment and therefore the opportunity for the application of the water volume strictly necessary to optimize crop growth (irrigation opportunity and ir...
Practical issues in developing a smart surface irrigation system with real-time...
Shahidian, Shakib; Serralheiro, Ricardo; Serrano, João ManuelAutomation of surface irrigation can be an economic and ecological way of increasing global food production. In this work a fully automated cablegation system is evaluated that adapts the application time and depth to the actual infiltration rate of the soil in real-time. The system calculates the infiltration equation from advance times in a control furrow and then simulates irrigation in every furrow of the f...
Parametric calibration of the Hargreaves–Samani equation for use at new locations
Shahidian, Shakib; Serralheiro, Ricardo; Serrano, João Manuel; Teixeira, José LuísThe Hargreaves–Samani (HS) evapotranspiration equation is very useful for the on-site irrigation management in data-short situations such as small and midsize farms and landscaped areas. Although much work has been performed to improve the precision of the evapotranspiration (ETo) estimates for use at new locations, the results have not been consistent and many have not been confirmed by other works. The purpos...
Comparative Study of smart irrigation control in greenhouses
Shahidian, Shakib; Serralheiro, Ricardo; Serrano, João Manuel; Machado, Rui ManuelWith greenhouses it is possible to increase crop production and reduce significantly the water use. Additionally advancements in electronics and shortage of water have led to the development of “smart” or adaptive irrigation controllers that adjust the water application depth to plant needs, and thus increase water savings. The two most common types are soil moisture based and evapotranspiration based systems. ...
Development of an adaptive surface irrigation
Shahidian, Shakib; Serralheiro, RicardoCablegation is a simple system for automating surface irrigation in small and medium-sized fields using a gated pipe. In this work, a Programmable Logic Control, PLC, was used to develop an adaptive cablegation system capable of establishing the infiltration equation in real time and then adjusting the irrigation times to the infiltration rate and field geometry. A controlling program was developed for the on-f...
Hargreaves and other reduced-set methods for calculating evapotranspiration
Shahidian, Shakib; Serralheiro, Ricardo; Serrano, João; Teixeira, José Luís; Haie, Naim; Santos, FranciscoGlobally, irrigation is the main user of fresh water, and with the growing scarcity of this essential natural resource, it is becoming increasingly important to maximize efficiency of water usage. This implies proper management of irrigation and control of application depths in order to apply water effectively according to crop needs. Daily calculation of the Reference Potential Evapotranspiration (ETo) is an i...
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