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In-situ rainwater harvesting and gravel mulch combination for corn production in the dry semi-arid region of China 总被引:7,自引:0,他引:7
A field study was conducted to determine the effect of a combination of ridge and furrow method of in-situ rainwater harvesting with gravel mulch on corn production, soil moisture storage, and water-use efficiency in the dry semi-arid region of China. Results showed that plastic-covered ridges had an average runoff efficiency (runoff/rainfall) of 87% as compared to 7% for bare ridges, and could generate runoff at a threshold value of 0·8±0·2 mm rainfall. Bare ridges produced runoff only under high intensity rainfall events, and was ineffective for harvesting rainfall in the study area. The plastic-covered ridge and gravel-mulched furrow method of rainwater harvesting was effective in conserving moisture and increasing yield and water-use efficiency. The grain yield in this treatment was 1·9 times that of the conventional flat soil cultivation (control), and the water-use efficiency was 1·8 times that of the control. The good performance of the film-covered surface ridges and gravel-mulched furrows is attributed to the better utilization of light rains, improvement of infiltration in the root zone, and suppression of evaporation losses. 相似文献
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A novel concept catamaran equipped with a suspended cabin, named Wave Harmonizer Type 4 (WHzer-4), is proposed and evaluated. The mass-spring-mass system is constructed by mounting four sets of suspensions in-between the cabin and the twin-hull. Two sets of dual motor/generators (M/Gs) are attached on the center beam of the cabin's deck fore and aft. Each shaft-end of the dual M/Gs is connected to the twin-hull through a rack-pinion gear unit. In this way the vertical relative motion between the cabin and the twin-hull can be transferred into the rotational motion of the M/Gs, and vice versa. A semi-active motion control system, which contains a proportional-integral (PI) controller, is designed and applied to each of the dual M/Gs for the aim of absorbing wave energy under the condition of suppressing the local vertical velocity of the cabin as much as possible. A 1/5 scale model ship with a length of 1.6 m is built, and a forced-oscillation bench test is implemented to validate the performance of the control system. Then, a series of towing tank tests is carried out in regular head waves. The heave and pitch responses of the cabin, those of the twin-hull and the corresponding wave energy capture width ratio (CWR) at five control scenarios and two reference scenarios are investigated. Discussion on the results of the tank test shows that the motion reduction of the cabin and the wave energy harvesting can be achieved simultaneously at a few wave conditions. However, at other conditions, although noticeable amount of wave energy is harvested, motion reduction of the heave and pitch of the cabin could not be obtained at the same time. It is suggested that varying the gain settings of the PI controllers according to the location of the controllers may improve the effectiveness of the proposed control system. 相似文献
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本文阐述了环境同位素在地下水研究中的作用和饮马河流域水文地质概况。运用稳定同位素D和~(18)O千分偏差值分析了地下水成因、地表水与地下水的补排关系。采用放射性同位素~3H、~(14)C和地下水动力学等方法计算了地下水年龄。通过分析和讨论,对地下水成因和地下水循环周期有了新认识。因此利用环境同位素示踪地下水,对选择供水水源地具有重要意义。 相似文献
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In order to solve water resources problems in the North China Plain, this paper explored human-nature compound water circulation system from three aspects including urban flood control, surface drainage and saline water in the central and eastern of the North China Plain. Results show that: (1) The technical methods have achieved zero increase in rainwater runoff in urban areas, (2) surface drainage depletion problems can be solved through abandoned water and river water separation method, (3) and technical method through promoting rainwater infiltration would be used to solve problem of saline water in the central and eastern parts. This research provides a new perspective to the ultimate solutions to water resources problems in the North China Plain, and a fresh research direction for the development of hydro-geological science. 相似文献
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一次伴有雷暴大风的飑线天气过程分析及数值模拟研究 总被引:1,自引:1,他引:0
利用NCEP/NCAR(1°×1°)的逐6 h再分析资料、WRF中尺度预报模式,对2014年7月30—31日发生在江淮地区的一次强飑线天气过程进天气学分析和数值模拟研究。研究结果表明,此次飑线过程是在高空槽后有强冷空气输送、中层阶梯槽引导干冷空气南下并叠加在低层暖湿气流之上的有利背景条件下产生的,低空切变线是此次飑线过程的重要触发机制。在飑线成熟阶段,气流下沉速度极大值区在高(低)层与霰(雨水)混合比极大值区有很好的对应关系,水凝物粒子下落时对周围空气的拖曳作用是下沉气流形成的关键。雨水蒸发率影响飑线维持期间地面冷池的强度和分布,雨水蒸发率越大,地面冷池强度越强、范围越广;雨水蒸发率越小,地面冷池越弱,甚至消失。雨水蒸发率与地面风速也有很好的正相关性,增大雨水蒸发率可使地面风速增大,使模拟的地面最大风速更接近实况。 相似文献
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A model was developed for Typha, to examine the effects of latitudinal changes in temperature and radiation on the partitioning of total biomass during the growing season into rhizomes, roots, flowering and vegetative shoots, and inflorescences.Regardless of initial rhizome biomass, both above and belowground biomasses converge on a equilibrium value, with the balance between total production and metabolic loss being latitude-specific. If aboveground biomass is harvested just once, then both above and belowground biomasses return to equilibrium values after several years. If the aboveground biomass is harvested annually, then both above and belowground biomasses converge on smaller equilibrium values, which are determined by the balance between the sum of production prior to harvesting and after harvesting, and the sum of annual metabolic losses and a loss due to harvesting.The model could be used in wetland management activities to predict the potential growth of Typha in given conditions as well as the responses of Typha stands to harvesting over a wide range of latitudes for times ranging from a season to several years. 相似文献
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