Translated from Gidrotekhnicheskoe Stroitel 'stvo, No. 12, December 2009, pp. 28 -32. Food provision and rationing of the supply are basic factors when preserving a variety of fish species and their populations in a water body.In conformity with effective nature-conserving legislation of the Russian Federation where farming activity is conducted in water entities of piscicultural value, including the operation of hydroelectric power plants, measures should be specified for the preservation of the water entities, biological water resources, and the water regime, and measures should be taken to preserve the habitats of the animal world, and conditions for their reproduction, feeding, and migration paths.Based on the Water Code of the Russian Federation [1] and the Status [2], water resources are utilized in accordance with the Rules of reservoir usage [1]. Organizations operating water-power and water-development works are obliged to ensure filling and drawdown regimes of reservoirs, observing piscicultural demands in sections assuming significance for the preservation and reproduction of fish resources.The Rules for utilization for the water resources of a reservoir represent the principal document on which management of the water regime of a reservoir is based. Dispatcher schedules for structure operation as a function of the water reserve in the reservoir at the time that a decision is made are developed as a component part of these Rules. The punctuality of decision making from several days to one month will depend on irregularity of the water influx to the reservoir, and on the requirements of water consumers as to the operating regime of the structures. A characteristic of water-level dynamics in a reservoirthe rate at which the horizon rises or falls in a specified time interval -is not stipulated on despatchers' schedules. This characteristic assumes critical, frequently determining significance, for both the safety of the water-development works, and also for pisciculture in the reservoirs. Such a position results in noncorrespondence with, and occasionally in contradiction to the reservoir's water-or power-supply demands in a zone of the despatcher's schedule on the one hand, and with respect to the rate at which the reservoir must drawndown to provide this supply on the other. This situation is characteristic when the interests of pisciculture are considered in the requirements for the reservoir's operating regime.In this paper, one approach to development of a regime for the filling and drawdown of reservoirs with consideration of piscicultural requirements is analyzed using the Kovda series of reservoirs as an example.The reservoirs in the Kovda series are referred to as lacustrine reservoirs, and are large water bodies with an overall surface area of 2, 800 km2 at the normal backwater level. These reservoirs are component parts of the White Sea Basin (Kandalaksha Gulf), and are located in the territory of Karelia and the Murmansk Oblast (Fig. 1).The water resources of the Kovda River Basin are util...
The development of the power industry necessit@tes the creation of cascades of hydroelectric stations with reservoirs regulating the streamflow, which are an integral part of power and water-management systems.Streamflow regulation by reservoirs, among which carryover reservoirs are gaining ever greater influence, leads to an increase of the range of variations of the water level in reservoirs during drawdown and filling.During fluctuations of the level between the normal pool (NPL) and dead storage level (DSL), periodic storage and release of groundwaters occur, i.e., the "subsurface" reservoir also participates along with the main reservoir in streamflow regulation.In water-management and hydropower calculations a quantitative evaluation of the interaction of subsurface and surface waters, as a rule, is not taken into account.Qualitatively, the indicated interaction of subsurface and surface waters during fluctuations of the water level in a reservoir related to its drawdown in the low-flow period and filling in the flood period is expressed in the following.During a rise of the water level additional seepage into the bank zone occurs in the form of a groundwater wedge and during falling of the level the part of the water stored in the soil is released into the reservoir.The water-management effect of the operation of the subsurface reservoir can be estimated by means of the water-balance equation used in calculating streamflow regulation in the following form:where Qsti~ is the storage discharge, i.e., the difference between the inflowing Qinij and regulated Wregij discharges; Quseii, Qseepij, Qwdrij, respectively, the discharge being used, s e . . . . eepag discharge, and withdrawals of water from the reservoir; At, duration of the calculated time interval; i, number of the section; j, number of the time interval.With consideration of the interaction of subsurface and surface waters Eq. (I) will take the following form:where Qsubsij is the effect of interaction of the subsurface and surface runoffs.The effect of the interaction of the subsurface and surface runoffs depends on the hydrogeological parameters of the water-bearing rocks (permeability coefficient, hydraulic diffusivity, storage coefficient, etc.).Furthermore, the selection of the scheme of the hydrogeological conditions and method of calculation is important.The dynamics of groundwaters in such a formulation corresponds to a free-surface, unsteady, nonuniform seepage flow.It is necessary to verify that in an examination of the given problem, seepage into the bank strip, which does not enter into the zone of influence of seepage under the retaining structures, is taken into account.In the general case the problem reduces to the solution of a nonlinear differential equation of three-dimensional seepage flow.For the case of flow in a homogeneous bed the equation looks so:Translated from Gidrotekhnicheskoe Stroitei's
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