Helicity of convective flows from localized heat source in a rotating layer

Experimental and numerical study of the steady-state cyclonic vortex from isolated heat source in a rotating fluid layer is described. The structure of laboratory cyclonic vortex is similar to the typical structure of tropical cyclones from observational data and numerical modelling including secondary flows in the boundary layer. Differential characteristics of the flow were studied by numerical simulation using CFD software FlowVision. Helicity distribution in rotating fluid layer with localized heat source was analysed. Two mechanisms which play role in helicity generation are found. The first one is the strong correlation of cyclonic vortex and intensive upward motion in the central part of the vessel. The second one is due to large gradients of velocity on the periphery. The integral helicity in the considered case is substantial and its relative level is high

Helicity of Convective Flows from Localized Heat Source in a Rotating Layer

Experimental and numerical study of the steady-state cyclonic vortex from isolated heat source in a rotating fluid layer is described. The structure of laboratory cyclonic vortex is similar to the typical structure of tropical cyclones from observational data and numerical modelling including secondary flows in the boundary layer. Differential characteristics of the flow were studied by numerical simulation using CFD software FlowVision. Helicity distribution in rotating fluid layer with localized heat source was analysed. Two mechanisms which play role in helicity generation are found. The first one is the strong correlation of cyclonic vortex and intensive upward motion in the central part of the vessel. The second one is due to large gradients of velocity on the periphery. The integral helicity in the considered case is substantial and its relative level is high

Soil loss tolerance of brown forest soils of Northwestern caucasus under intensive agriculture

yesБелГУThe graded actions in substantiation soil erosion control measures in foothill agrolandscapes are discussed. Several approaches for the evaluation of soil loss tolerance were investigated. The values of this loss were used as normative indicators in the development of measures on soil erosion contro

Soil loss tolerance of brown forest soils of Northwestern caucasus under intensive agriculture

The graded actions in substantiation soil erosion control measures in foothill agrolandscapes are discussed. Several approaches for the evaluation of soil loss tolerance were investigated. The values of this loss were used as normative indicators in the development of measures on soil erosion controlyesБелГ

THE PROBLEM OF SUBSTANTIATING THE EROSION-INDUCED PERMISSIBLE SOIL LOSS AND AN APPROACH TO ITS SOLUTION

Показано, что для разработки стратегии рационального использования почвенных ресурсов необходима методология, которая должна включать методы решения следующих задач: объективную оценку почвенных ресурсов; оценку их динамики за прошедшее время; долгосрочное прогнозирование динамики этих ресурсов; поиск компромиссов между необходимостью уменьшения деградации (эрозии) почвы и имеющимися экономическими возможностями. На примере эродированных черноземов пахотных земель Курской области рассмотрены решения указанных задач. Количество почвенных ресурсов оценивалось площадью пашни и мощностью гумусового горизонта, а их качество (плодородие, продуктивность) - запасами гумуса в слое 0-50 см. Динамика почвенных ресурсов оценивалась по изменению этих параметров. Приведены данные по сокращению ресурсов черноземов ориентировочно через 200-250 лет после распашки целины. Показано, что на восстановление мощности гумусового слоя эродированных черноземов потребуются тысячелетия, а на восстановление запасов гумуса - столетия. На большой площади пашни остановить эрозию за относительно малое время практически невозможно. Стратегия уменьшения эрозии включает этапы, для которых предложен подход к оценке допустимых эрозионных потерь почвы (ДЭПП). Этот подход представляет собой поиск компромисса между скоростью почвообразования, изменением мощности гумусового горизонта, продуктивности (качества, плодородия) почвы, случайным характером эрозионных процессов и, с другой стороны, противоэрозионных мероприятий в соответствии с имеющимися экономическими возможностями. Значения ДЭПП должны уменьшаться от этапа к этапу, приближаясь к скорости почвообразования. Разработаны значения ДЭПП для первого этапа (без экономической оценки)

Assessment of soil infiltration capacity by using portable rainfall simulator

Under study was the possible assessment of soil infiltration capacity by using a portable rainfall simulator to irrigate a small area and avoid the development of rill erosion. For soil infiltration capacity an equation has been suggested, including erosion rain index AI as a criterion of similarity. The equation was verified for natural rainfalls (for catchments and runoff plots) and for artificial rain (for a runoff plot 5 m long and 5 m2 in size). To evaluate the soil infiltration capacity, the small runoff plots can be used, on which no rill erosion doesn’t take place. To verify this affirmation two experiments were conducted. In the first experiment a large rainfall simulator and a runoff plot 3 m long having the area 3 m2 in the field were used. Rill erosion took place on this runoff plot. In the second experiment a portable rainfall simulator and a runoff plot shaped as a circle with the area 0.05 m2 were used (rill erosion did not take place). The experiment was conducted in the laboratory by using the soil monoliths taken in the same field. For both rainfall simulators the raindrops were of the same size, they fell down from the same height, the rainfall intensity was constant, but the values of these parameters seemed to be different. In experiments a close dependence between the soil infiltration capacity and the index AI was established. The use of the portable rainfall simulator requires expenses to a lesser extent