V. Macura, J. Kralova, P. Ivan, J. Vojtkova, Z. Macurova
Monday 5 August 2013 by Libadmin2013

References: 13th SGEM GeoConference on Water Resources. Forest, Marine And Ocean Ecosystems, www.sgem.org, SGEM2013 Conference Proceedings, ISBN 978-619-7105-02-5 / ISSN 1314-2704, June 16-22, 2013, 393 - 400 pp


The article is focused on the objectification of the aquatic habitat assessment of the mountain and piedmont streams by Instream Flow Incremental Methodology (IFIM). Habitat quality is specified on the basis of bioindication, which is represented by ichthyofauna in habitat suitability curves. The curves are based on the frequency sorting of the fish in microhabitat, which were determined on the ichthyological survey basis. Accuracy assessment of the suitability curves is one of the most important steps in the IFIM methodology. Their evaluation was verified on the 20 streams in Eastern Slovakia in rivers catchment of the Poprad, Bodrog and Hornád. The generalization of the suitability curves and a discharge impact on the shape of the suitability curves were in detail analyzed on the reference reach of the Drietomica stream.
From the results it can be assumed, that during the minimum flows fish prefers shelters with maximum water depths. With moderate increase of the flow fish still stay at the same shelter. This is the reason why depth increases with increasing the flow. This trend was confirmed by ichthyological survey realized by three different water levels on the Drietomica stream in the all 14 target microhabitats. From the initiate outcomes follows, that suitability curve should be derived for the minimum flows and the maximum suitability range stay sustentative till the discharge, when a fish is forced to move to find another hiding place in consequence of higher discharge. Optimum solution would be to have a range of a minimum flow surveys up to flow, when a fish prefer to change of the habitat. Than, the increasing part of the curve would be extrapolated from the curve of the minimum flow and the decreasing part of the curve would be extrapolate from the part of the curve, when the changes in hiding places by fish start. Using this method was in the thesis extrapolated suitability curve for Drietomica stream. In practice is sufficient to extrapolate increasing part of the suitability curve from the minimum flow and the decreasing part is possible to determine by expert approximation, because, this part of the curve doesn’t have an important impact on the minimum flow assessment.

Keywords: habitat quality, IFIM, RHABSIM model, weighted usable area (WUA), suitability curve