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Descripción
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| In the calculation of environmental flows (mitigation measure) by means of habitat-based methods (IFIM) it is assumed that the greater impact caused by a dam on the population of the target species is the reduction the mean annual flow, which involves the reduction of the amount of available habitat for this species. A given population can also be affected by the presence of an obstacle, as it is split into two isolated populations each disposing of a smaller river system than the originally occupied by the non fragmented population. An increase in the environmental mean annual flow can be seen as a compensation measure of the impact caused by this dam. We therefore call this environmental flow compensation flow (Qcomp). A property of the population that synthesizes the resistance and recovery ability is the resilience, ?. Knowing the value of the resilience of each of the populations resulting from fragmentation of the original, the intensity of impact, I, produced by the presence of the obstacle can be determined as the resilience loss (%) of the most affected resulting population (the one that has lost more resilience), I = ?fragmented / ?original. If passability, fi, expresses the proportion of the population that passes through the barrier i in a reasonable time, and F = ?fi, expresses the accumulated passabilities of all the obstacles located downstream the dam whose impact is to compensate, we can quantify the compensation flow as a fraction of the natural mean annual flow, Qnat, as Qcomp = Qnat · (1- ?fragmented / ?original) · e-?fi. We applied this approach in an artificially fragmented population of brown trout (Salmo trutta) in La Rioja (Ebro basin, North of Spain), obtaining a flow rate of compensation, Qcomp, equal to 46% of the mean annual value of the natural flow regime. | |
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Internacional
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Si |
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Entidad
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9th ISE 2012, BOKU, Vienna |
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Lugar
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Viena |
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Páginas
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1-8 |
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Referencia/URL
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Tipo de publicación
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Actas de Congreso Internacional con Revisores |