| Popis: |
Due to its topographical characteristics extensive flat areas present thesurfaces where high waters might spill and retain. This has a significant impact on the transformation of flood waves, i.e. peak attenuation and lengthening of the propagation time and, consequently, positive impact on flood safety of downstream areas. The impact of theretention area on the flood wave propagation over the studied area depends on the quantity of water mass spilled into the retention area and run off regime on it. The conveyance and retention capacity of the area is significantly influenced by the land use. Since agricultural useand shrub or forest vegetation on the flood areas are generally permitted, the paper presents the results of a hydraulic analysis of the impact of vegetation extensiveness, as one of theland use, on the runoff regime in a retention area and thereby on flood wave propagation. By selected indicators the impact of the land use in the retention area on the runoff regimeand flood hazard within the studied area was analysed, as well as the impact of the landuse in the retention area on downstream conditions for theoretically assumed geometry of the riparian areas. The findings are then compared with the hydraulic response of the floodarea of Krško-Brežiško polje, where HPP Brežice is under construction. Obsežna ravninska območja zaradi svojih topografskih lastnosti predstavljajo prostor, kjer se visoke vode lahko razlijejo in zadržijo. To ima pomemben vpliv na preoblikovanje poplavnih valov, tj. znižanje konice in podaljševanje potovalnega časa vala ter posledično ugoden vpliv na poplavno varnost dolvodnih območij. Vpliv retenzijskega prostora na potovanje visokovodnega vala čez obravnavano območje je odvisen predvsem od količin vodne mase, ki se prelijejo na retenzijsko površino, in odtočnih razmer na njej. Na pretočno in zadrževalno sposobnost med drugim pomembno vpliva tudi raba prostora. Ker je na poplavnih območjih praviloma dovoljena kmetijska raba oz. grmovna ali gozdna zarast, prispevek podaja rezultate hidravlične analize vpliva obsežnosti zarasti, kot ene od rabe prostora, na odtočne razmere v retenziji in s tem na potovanje poplavnih valov. Z izbranimi kazalniki je analiziran tako vpliv rabe prostora retenzije naodtočne razmere in poplavno nevarnost znotraj obravnavanega območja kot tudi vpliv rabe prostora retenzije na dolvodne razmere za teoretično predpostavljeno geometrijo obvodnega prostora. Ugotovitve so nato primerjane z odzivom poplavnega območja Krško-Brežiškega polja, kjer se pripravlja gradnja HE Brežice. |
