Ábrahám Levente: Biomonitoring a Dráva folyó magyarországi szakasza mentén 2000-2004 - Natura Somogyiensis 7. (Kaposvár, 2005)
Závodszky, Szabolcs: Hydroelectricity or national park? - Vízerőmű vagy nemzeti park?
Natura Somogyiensis 7 5-9 Kaposvár, 2005 Hydroelectricity or national park? ZÁVOCZKY SZABOLCS Duna-Dráva National Park Directorate H-7625 Pécs, Tettye tér 9. The importance of Dráva in nature conservation River Dráva, down to on its section shared by Hungary and Croatia (i.e. above the Mura mouth), is loaded with a range of power plants. Despite this fact, its section reaching from the Mura mouth to its confluence with Danube - especially between Őrtilos and Bares - appears quite natural, although river regulation has been done in this section as well. The importance of Drava from the aspect of Hungarian and Europan nature conservation is ensured by rare and threatened habitat types associated with upper and middle section characteristics that are constanly in the state of dynamic change. Such habitats are related with a multitude of morphological structures characteristic of this particular Drava reach. As opposed to the straightened, canal-like, strongly transformed flowing waters typical of other Hungarian rivers, here there are several geomorphological phenomena that cannot be observed today in the majority of transformed and regulated rivers. This Drava reach is characterized with dynamic bank-destructing (high embankments), bank-building (low shorelines) and shoal-creating (gravel and sand shoals) acivity, resulting in a particularly diverse range of habitats. Natural values occurring along river Drava are associated with these dynamically changing habitats. River bed deepening Of course the fact that a series (23) of hydroelectric power stations do exist above the lowermost one at Dubrava cannot be questioned, yet the river section that follows has remained home for a range of protected, strictly protected and internationally significant plant and animal species. The continuation of riverbed deepening is another undoubtable fact, yet the decision to build another power plant or a series of power stations down to the Danube confluence would be nothing but a technocratic solution to that problem, lacking any ecological basis. One of the proved reasons for increasing riverbed deepening besides river regulations is the altered flow dynamics below hydroelectric power plants. In addition to that, the series of dams built along Drava has cut off the natural migration of gravel and boulders, and it is also an obvious fact that each and every cubic metre of gravel excavated from the river further increases the speed of riverbed erosion. In certain parts of Europe (e.g. Austria, Donau-Auen National Park) instead of permitting gravel excavation from the Danube riverbed, what is done instead is that several hundred thousand m 3 of gravel, specified in its grain size fractions, are released into the river annually, in order to stop further deepening.
