TY - JOUR ID - bastiaanssen2000 AU - Bastiaanssen, Wim G. M. AU - Molden, David J. AU - Makin, Ian W. TI - Remote sensing for irrigated agriculture: examples from research and possible applications UR - http://www.sciencedirect.com/science/article/pii/S0378377400000809 DO - 10.1016/s0378-3774(00)00080-9 T2 - Agricultural Water Management PY - 2000 SN - 0378-3774 VL - 46 IS - 2 SP - 137-155 AB - Researchers in various international programs have studied the potential use of remotely sensed data to obtain accurate information on land surface processes and conditions. These studies have demonstrated that quantitative assessment of the soil-vegetation-atmosphere-transfer processes can lead to a better understanding of the relationships between crop growth and water management. Information on land surface can now be obtained at a wide range of spatial (5–5000 m) and temporal resolutions (0.5–24 days). However, even though considerable progress has been made over the past 20 years in research applications, remotely sensed data remain underutilized by practicing water resource managers. This paper seeks to bridge the gap between researchers and practitioners, first, by illustrating where research tools and techniques have practical applications and, second, by identifying real problems that remote sensing could solve, albeit with additional research and development. As freshwater becomes an increasingly scarce resource, all opportunities to better manage water uses, particularly in irrigated agriculture, must be taken. An important challenge in the field of water resources is to utilize the timely, objective and accurate information provided by remote sensing. KW - Remote sensing KW - Irrigated farming KW - Land management KW - Water resources management KW - Crop yield KW - Water use efficiency KW - Water rights ER - TY - JOUR ID - penuelas1993 AU - Penuelas, J. AU - Filella, I. AU - Biel, C. AU - Serrano, L. AU - Save, R. TI - The reflectance at the 950–970 nm region as an indicator of plant water status UR - http://dx.doi.org/10.1080/01431169308954010 DO - 10.1080/01431169308954010 PR - Taylor & Francis T2 - International Journal of Remote Sensing PY - 1993 SN - 0143-1161 VL - 14 IS - 10 SP - 1887-1905 AB - We present new remote sensing indices of plant water status: the ratio between the reflectance at 970 nm, one of the water absorption bands, and the reflectance at a reference wavelength, 900 nm (R970/R9000; the first derivative minimum in this near-infrared region (dNIRminimum ) and the wavelength where this minimum is found ( ?NIRminimum). In order to evaluate them, we carried out three experiments. Daily irrigated gerbera plants were allowed to dry until almost wilting and then daily irrigation was restarted; pepper and bean plants were grown for four months submitted to two different irrigation treatments; and bean detached leaves were submitted to progressive dehydration whereas pressure-volume curves were being carried out. In gerbera plants, the trough about 950?970 nm decreased as the drought was increasing. Therefore, the R970/R900 index and the dNIRminimum closely tracked the changes in relative water content (RWC), leaf water potential, stomatal conductance and the foliage-air temperature differences. The ?dNIRminimum tracked even better these changes in gerberas. However, these water status indices began to be significant when the water stress was already well developed, at RWC smaller than 85 per cent. The same happened to detached leaves of beans which did not present differences above ?1·55 MPa water potential. Beans and peppers growing at soil matric potentials larger than ?0·04 MPa presented higher R970/R900 values than those growing at soil matric potentials only larger than ?0·01 MPa. In all the cases, the maximum response of these indices was found in the varieties or the species that lost cell wall elasticity in response to drought stress. This could indicate an important structural component in these indices changes. Relative water content itself seemed to be, however, the most important factor as shown by the highest correlation coefficients with these spectral indices. These spectral signals were more evident at canopy level than at leaf level. They seem to be useful as water status indicators at ground level, especially when there are not important changes of LAI and when plants wholly cover the soil. ER - TY - ELEC ID - idb AU - Henrich, V. AU - Krauss, G. AU - Götze, C. AU - Sandow, C. TI - The IndexDatabase UR - https://www.indexdatabase.de/ CY - Bonn PY - 2011 DA - 2011 ER -