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41.
The study area is located in the Pampean region of Argentina, in the northwest of Buenos Aires Province, covering about 50,000 km2, within an area of great plain with particular hydrologic characteristics, where vertical water movements predominate over
horizontal. The objective of this work is the analysis of the relations between different hydrologic scenarios (characterized
by the soil water balance and the water table levels) and the yields of soybeans that have been increasing in recent years.
It is concluded that water table fluctuations are strongly related to the elements of the local hydrologic balance. On the
other hand, the geographic distribution of soybean yields corresponds directly with the values of the soil water reserve during
the critical stages of the growth. After dry periods, the lowering of the water table makes access to water from the root
zone difficult, and the crop is susceptible to the effects of drought. However, after wetter periods the extra contribution
from the water table situated near the surface is favorable for growth, often preventing its deterioration in conditions of
drought. Nevertheless, an excessive rise of the water table can produce disadvantages at seedtime and during harvest. The
importance of an evaluation of the different scenarios that may have significant implications for agricultural activity is
discussed. 相似文献
42.
Laurent Bonnifait Guy Delrieu Matthieu Le Lay Brice Boudevillain Arielle Masson Philippe Belleudy Eric Gaume Georges-Marie Saulnier 《Advances in water resources》2009
On 8–9 September 2002, an extreme rainfall event caused by a stationary mesoscale convective system (MCS) occurred in the Gard region, France. Distributed hydrologic and hydraulic modelling has been carried out to assess and compare the various sources of data collected operationally and during the post-event field surveys. Distributed hydrological modelling was performed with n-TOPMODELs and assessed for ungauged basins with the discharge estimates of the post-event surveys. A careful examination of the occurrence in time and space of the flash floods over the head watersheds indicates that flooding was controlled by the trajectory of the convective part of the MCS. Stationarity of the MCS over the Gardon watershed (1858 km2 at Remoulins) for 28 h was responsible for the exceptional magnitude of the flood at this scale. The flood dynamics were characterized by an extensive inundation of the Gardonnenque plain upstream of the Gardon Gorges resulting in a significant peak flow reduction downstream. One-dimensional unsteady-flow hydraulic modelling was found to be required to reproduce these dynamics. Hydraulic modelling also proved to be potentially useful for the critical analysis and extrapolation of operational discharge rating curves. 相似文献