320 KB0 KB199920252001Smolar-Žvanut, Natašaletnik:19številka:30Str. 65-86ISSN:1581-0267COBISSID_HOST:1844577URN:URN:NBN:SI:doc-5L52AYBRenslFakulteta za gradbeništvo in geodezijoActa hydrotechnicaecologically acceptable flowekološko sprejemljiv pretokodvzem vodeperifitonske algeperiphytic algaewater abstractionVloga perifitonskih alg pri določanju ekološko sprejemljivega pretoka vode v tekočih vodah| The role of periphytic algae in the determination of the ecologically acceptable flow in running waters|To determine ecologically acceptable flow (EAF), it is vital to have knowledge of the periphyton community, since the algae represent the initial stage of the food chain in running waters, and respond quickly to environmental changes and act as substrata and refuges for a number of water organisms. The EAF value should assure such quantity and quality of water that substantial changes in the composition and functioning of the periphyton community do not occur. In different seasons of the years 1998-1999, during the period of low flows, the impact of abstractions on the periphyton community and on hydrological characteristics was assessed in the Sava Dolinka river in the abstraction section for the Moste power plant, and in the Soča river, in the abstraction sections for the Doblar and Ajba plants. The role of periphytic algae in the determination of EAF in flowing waters was defined. Results of the study show qualitative and quantitative hydrological, biological, and physicochemical changes downstream of the dams. The results of the hydrological analyses show substantial changes in the hydrological regime and a predominance of gravel deposits with a considerable proportion of coarse grains downstream of the dams. Due to abstractions, the physicochemical composition of water downstream of the dams is no longer defined by conditions in upper reaches of the river, but by tributaries downstream of the catchment area. A constant flow, as well as a rare occurrence of high waters downstream of the dams has given rise to a great diversity of periphyton and differences in the periphyton biomass here, compared with reference sites upstream of the damsPri določanju ekološko sprejemljivega pretoka (Qes) je treba poznati združbo perifitonskih alg, ker predstavljajo začetek prehranjevalne verige v tekočih vodah, se hitro odzivajo na spremembe v okolju in ponujajo podlago in zatočišče številnim vodnim organizmom. Vrednost Qes mora zagotavljati količino in kakovost vode, da ne pride do bistvenih sprememb v zgradbi in delovanju združbe perifitonskih alg. V različnih letnih obdobjih, v času nizkih pretokov vode v letih 1998-1999, smo v reki Savi Dolinki na območju odvzema vode za HE Moste, in v reki Soči, na območju odvzema vode za HE Doblar in HE Ajba, ocenili vpliv odvzema vode na združbo perifitonskih alg in na hidrološke značilnosti obeh rek ter opredelili vlogo perifitonskih alg pri Qes v tekočih vodah. Rezultati hidroloških analiz so pokazali na bistveno spremenjen hidrološki režim in prevladovanje prodnatih plavin s precejšnjim deležem grobih zrn pod pregradami. Posledica odvzema vode je, da fizikalno in kemijsko sestavo vode pod pregradami ne uravnavajo več razmere v zgornjem delu porečja, temveč jo določajo dotoki pod mesti zajetja. Stalen pretok in redko pojavljanje visokih voda pod pregradami sta vzrok za veliko raznolikost perifitonskih alg in razlike v biomasi perifitonskih alg, v primerjavi s primerjalnimi mesti nad pregradamiTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaUniverza v Ljubljani, Fakulteta za gradbeništvo in geodezijo