Air tanah sangat potensial untuk mengairi tanaman pangan terutama palawija di lahan tadah hujan. Salah satu cara pemanfaatan air tanah tersebut dengan membuat sumur pantek. Hal ini memungkinkan karena kedalaman air tanah relatif dangkal (10-15 m dari permukaan tanah). Pengembangan air tanah tersebut akan berdaya guna apabila manfaat yang diperoleh cukup besar dibandingkan dengan biaya yang dikeluarkan. Frekuensi pemberian air tiap 14 hari tidak berpengaruh nyata terhadap hasil kedelai dan jagung di Sukamandi (Subang), Haurgeulis (Indramayu) dan Adipala (Cilacap) dibandingkan pemberian air tiap 7 maupun 10 hari. Penyaluran air yang berasal dari pompa menggunakan slang plastik untuk mengurangi kehilangan air selama penyaluran sehingga menghemat bahan bakar pompa. Besar biaya untuk pengoperasian pompa rata-rata Rp 240.000,- dan Rp 265.000,- masing-masing untuk kedelai dan jagung sedangkan keuntungan bersih rata-rata budidaya kedelai dan jagung masing-masing Rp 374.000,-/ha dan Rp 321.000,-/ha

O presente trabalho foi desenvolvido com a finalidade de avaliar um sistema de bombeamento de água acionado por painéis fotovoltaicos instalados nas dependências da Universidade Tecnológica Federal do Paraná, Câmpus Medianeira - PR. O município está localizado no oeste paranaense (25º17'43" S; 54º03'38" e 500,7 m). O sistema trabalhou em situação real de funcionamento, bombeando água à altura de 20 m. Foram coletados dados de fevereiro a novembro de 2005; utilizou-se coletor de dados computadorizado da Campbell Scientific INC. , que possibilitou adquirir e armazenar os dados de irradiância solar no plano do painel, tensão e corrente gerada, temperatura no painel e vazão. Por meio de cálculos, obtiveram-se os valores de potência e eficiência do sistema. O solstício de inverno apresentou eficiência de 9,58% com bombeamento diário de 2.056 litros, enquanto o solstício de verão apresentou eficiência de 9,07% com bombeamento diário de 2.377 litros. A maior eficiência nos dias de inverno está ligada às menores temperaturas se comparada aos dias de verão, e o fator que provocou a maior vazão de água bombeada nos dias de verão está atrelado ao tempo de insolação, que é maior se comparado aos dias de inverno.<br>The main objective of this paper is to evaluate a water pumping system powered by photovoltaic panels installed at Federal Technological University of Paraná - UTFPR, in Medianeira, State of Paraná, Brazil. The city is located at the West of Paraná (25º17'43"; 54º03'38" and 500.7 meters - 1,642.72 feet). The system operated in a real working situation, pumping water to 20 meters (65.62 feet) of elevation. The data were collected, from February 2005 to November 2005, by means of a computerized data collector made by Campbell Scientific Inc that made possible to acquire and store irradiance values in the panel plane, generated current and voltage, panel temperature and outflow. Through calculations, the power and the system efficiency were obtained. Winter solstice showed 9.58% efficiency with daily pumping of 2,056 liters (543.14 gallons) whereas summer solstice confirmed 9.07% efficiency with daily pumping of 2,377 liters (627.86 gallons). The higher efficiency in winter days is associated to the lowest temperature in those days compared to summer days, and the factor that led to a larger pumped water outflow in the summer days was related to solar insolation time that is longer if compared to winter days.

Groundwater depletion in India is a result of water, energy, and food policies that have given rise to a nexus where growth in agriculture has been supported by unsustainable trends in water and energy use. This nexus emanates from India’s policy of providing affordable calories to its large population. This requires that input prices are kept low, leading to perverse incentives that encourage groundwater overexploitation. The paper argues that solutions to India’s groundwater problems need to be embedded within the current context of its water-energy-food nexus. Examples are provided of changes underway in some water-energy-food policies that may halt further groundwater depletion.

O presente trabalho foi desenvolvido com a finalidade de avaliar um sistema de bombeamento de água acionado por painéis fotovoltaicos instalados nas dependências da Universidade Tecnológica Federal do Paraná, Câmpus Medianeira - PR. O município está localizado no oeste paranaense (25º17'43" S; 54º03'38" e 500,7 m). O sistema trabalhou em situação real de funcionamento, bombeando água à altura de 20 m. Foram coletados dados de fevereiro a novembro de 2005; utilizou-se coletor de dados computadorizado da Campbell Scientific INC. , que possibilitou adquirir e armazenar os dados de irradiância solar no plano do painel, tensão e corrente gerada, temperatura no painel e vazão. Por meio de cálculos, obtiveram-se os valores de potência e eficiência do sistema. O solstício de inverno apresentou eficiência de 9,58% com bombeamento diário de 2.056 litros, enquanto o solstício de verão apresentou eficiência de 9,07% com bombeamento diário de 2.377 litros. A maior eficiência nos dias de inverno está ligada às menores temperaturas se comparada aos dias de verão, e o fator que provocou a maior vazão de água bombeada nos dias de verão está atrelado ao tempo de insolação, que é maior se comparado aos dias de inverno. | The main objective of this paper is to evaluate a water pumping system powered by photovoltaic panels installed at Federal Technological University of Paraná - UTFPR, in Medianeira, State of Paraná, Brazil. The city is located at the West of Paraná (25º17'43"; 54º03'38" and 500.7 meters - 1,642.72 feet). The system operated in a real working situation, pumping water to 20 meters (65.62 feet) of elevation. The data were collected, from February 2005 to November 2005, by means of a computerized data collector made by Campbell Scientific Inc that made possible to acquire and store irradiance values in the panel plane, generated current and voltage, panel temperature and outflow. Through calculations, the power and the system efficiency were obtained. Winter solstice showed 9.58% efficiency with daily pumping of 2,056 liters (543.14 gallons) whereas summer solstice confirmed 9.07% efficiency with daily pumping of 2,377 liters (627.86 gallons). The higher efficiency in winter days is associated to the lowest temperature in those days compared to summer days, and the factor that led to a larger pumped water outflow in the summer days was related to solar insolation time that is longer if compared to winter days.