Hidrológiai Közlöny 1960 (40. évfolyam)

5. szám - Károlyi Z.: Zátonyvándorlás és gázlóalakulás – különös tekintettel a magyar Felső-Dunára

358 Hidrológiai Közlöny 1960. 5. sz. Károlyi Z.: Zátony vándorlás és gázlóalakulás nEPEMELUEHHE FIEPEKATOB H OOPMJ1EHHE EPO^OB, B MACTHOCTH HA BEHPEPCKOM yqACTKE BEPXHErO ^YHAH 3. KapoAbu KaHfl. TexH. HayK y peKax, HMeromHx CBOSOAHO nepeMemaiomeroca pycjia npii ecTecTBeHHOM COCTOHHHH nepeiwemeHiie nepeKaTOB coBnaaaeT nepeMemeHiie.w peKii. í(Bn>KeHHe HaHOCOB Ha nepeicaTe H306pa>KeH0 Ha (pue. 1. a nepeiviemeHne nepei<aTOB BCJieflCTBiie BiwTOBoro ABiiweHim noTOKa BHflHO Ha (pue. 2. ECJIH öepera peKH yKpenneHbi, HJIH OHH MoryT conpoTiiBjiíiTbCíi, TO nepeKaTbi nepeiwemaioTCM OTAeJibHO. no HaSjnoAemiíiM 3a ABiiweHHeM BOflbi H H3H0C0B B nonepenHbix ceHeHiiHx pycjia ((pue. 3.) MO>KHO A0Ka3aTb, HTO XB0CT006pa3HbIM yAJIHHeHHeM HH>KHeH iacTn nepeKaTa Bbi3biBaeTca nepe.wemeHiie cjieAviomero nepeKaTa. ripoqeccy nepeiviemeHiiH nepeKaTOB HC npenHTCTByeT aawe H mnopa. OflHai<o nepeiwemeHHe npei<pamaeTCH Ha pe3Knx n3rn5ax ((pue. 4;), HO STHM Bcerj;a Bbi3biBaercH Bpe^Hoe npeoöpa30BaHne. no HaÖJiiofleHHflM, npoBeaeHHbiM 3a SpoflaMH MO>KHO ycTaHOBiiTb, MTO npaBHJibHoe ceneHHe o6pa3yeTCH B cjiyiae cTaönjibHbix, HenoABH>KHbix nepeKaTOB. A B cjiywae nepeMemaiouiHxcH SpoAOB HIDKHHH, xB0CTOo6pa3Ha*i HacTb nepenaTa qacTO CHJibHO vajihhhctch, B HeK0T0pbix CJiyiaax no cjreAyromero nepeKaTa H npe«CTaBJiíieT co6oii npoAOJibHbiií HJIH KOCOH rpeSeHb. npn noHHwcHiin yPOBHH BOÁM Ha rpeSHe MejiK03epHiicTbie HaHOCbi pa3MbiBai0TCH, B03HiiKaeT KpenKHÍi noKpbiBatomnií CJIOÍÍ, Mepe3 KOTOpbin BOAa nepejiiiBaeTCH ((pue. 5.). 3Ta ocoöaH ((top/na öpoAa HBJiHeTCH CBOHCTBeHHOCTbio nepeiviemaiomiixcH nepeKaTOB. C npeKpameHiieM nepeMeinemifl nepeKaTOB MO>KHO owHAaTb ii yjiymueHne SpOAa. C TaKHM TiinoM SpoAa BCTpeTHjiHCb He TOJibKO Ha BepxHeM flyHae — rAe ímeeTCH CHJibHbiií n0T0K — a H Ha Apvrnx HaHOCHbix peKax B BeHrpHH, HO H Ha 3arpammHbix peKax, o <ieiviCBIiAGTejIbCTBy K)T AaHHbie TeXHHHCCKOH JIHTepaTypbl ((pue. 6.). HacneT npitMUHbi nepeMemeHHH nepeKaTOB MHCHHH CHJibHO paCXOAHTCH. M3 3T0T0 MOHCHO CAeJiaTb BblBOA, iTO npn Haiajie nepeMememin AOJDKHM c0BepuieHCTB0TaTbCH cJieAyiomne ycJiOBHH : ycjiOBiia yKJiona, CKOpocTH, H3ni6a H HaHOCHoro pe>KiiMa, KOTopbie BecbMa TpyAHO Bbipa3HTb. ECJIH nocjie 3Toro, pa3pyineHiie BepxHeii iacTH nepeKaTa coBepuimiocb, TO ABH>KeHHe ocTajibHbix nepeKaTOB jiBjmeTca BCJieACTBiieM sToro. Ha BepxHeM flyHae nocJie 6ojiee npoAOJi>KiiTejibHoro oTHOciiTejibHoro noKon BHe3anH0 Haiajiocb Mpe3BbinafiHO cHJibHoe nepeMemeHne nepeKaTOB, npinviepHO Ha 10 KM-BOM ynacTKe, MacTb KOToporo MO>KHO BHAeTb Ha ((pue. 7.). 3tH H3MGHeHHH pyCJia B 3aBHCHM0CTH OT BpeMeHH, H3o6pa>KeHbi Ha ((pue. 9.). 3flecb H3o6pa>KaioTCfl H3MeHeHiie ropii30HTajieH no npOAOJibHOMy npo(j)Hjno, B3HT0My Ha 1/4 II 3/4 MaCTH HlHpíIHbl. PycJio HIí3KHX rOpHSOHTOB BOAbI MGCTaMH nepeXOAHT C OAHOÍÍ CTOpOHbl Ha Apvrvio ([pue. 8.). OrpOMHbie H3MeHeHiifl, nponcuieAiune 3a 2 1/4 roAa HarjiHAHo H3o6pa>KeHbi Ha (cpua. 10 H 11.), c noMOiubK) H3MeHeHHH njiomaAeii nonepeHHbix ceHeHiiií. njiomaAH onpeAeJinuncb c otmctkh 1,0 M HaA HaHMeHbiiiHMH cyAOxoAHbiMH ropn3onTa.Mii (peryjiHnnoHHblMIl) BOAbI AJIfl Toro, ITOŐbl nOJiyMIITb nOJlHblíí OSTJÖM nepeKaTOB. 3a 2 1/2 roAa Ha 11 KM-BOM yqacTKe nojiyHiijiocb 3aiiJieHiie B oő^eMe 4 220 000 m

3, a pa3MbiB B o6i.eMe 4 040 000 m

3. OcTaBaiomeecH 3an^eHiie B poav cocTaBJiHCT 7300 M

3/KM, MTO HBJiaeTca Bcero Jiniyb 4,5%Hon AOJIH OT cyMMapHoro nepeMemeHMH. B nepnoA Sojibiniix nepeMememiií nepeKaTOB HH»(ejie>Kainne 5poAbi CHJibHO yxyAiuajincb TaK, MTO cvaoxoaHblíí nyTb MOHCHO 6bIJI0 yjiyMIIIHTb TOJibKO MHOTOKpaTHHMH 3eMJieHepnaTejibHbiMH paSoTaMH. fljiH npeKpameHiiH abhjkchhh ycTpoeHbi HJIH AonojiHeHbi uinopbi B BepxHefi TpeTbii oTAejibHbix nepeKaTOB. Bar Travel and the Development of Crossings with Special Regard to the Hungárián Upper-Danube By Z. Károlyi Candidate of Teohnieal Sciences In the natural state, in the case of rivers where the path of flow is not restricted, bank travel is identical with that of the bed. The movement of sediment over a bar is shown in Fig. 1, while the development of travelling bars due to helical water movement can be seen in Fig. 2. If the river banks are stabilized, or if they show adaquate resistance, the bars will travel independently. Observations of water- and sediment movement in the bed (Fig. 3) suggest, that the extension of the lower, tail-like part of the bar gives rise to the downward travel of the bar following immediately downstream. Frequently not even spurs are capable of preventing tho process of bar travel, which is, however, effectivoly impeded by a sharp bend (Fig. 4.), although this results always in the deterioration of the bed. It was found from the observation of crossings, that regular, bowl-lilte sections occur in the case of stable bars, which show no tendency towards movement. In the case of travelling bars, the tail-like downstream part thereof greatly increases in length, sometimes as far as the next bar and forms a longitudinal, or oblique erest. With receding stages the fines are scoured from the erest and a resistant cover is förmed over which water falls laterally (Fig. 5). This peculiar type of bar is characteristic for travelling bars. Having once prevented bar travel, the improvement of the crossing may alsó be expected. This type of bar has been encountered not only on the highly movable bed of the Upper Danube and on other Hungárián rivers carrying a heavy sediment load, but, as revealed by numerous references in the literature, alsó on watercourses abroad (Fig. 6). Widely diverging opinions have been voiced as far as the causes of bar travel are concerned. These lead to the conclusion, that certain conditions of surface slope, velocity, curvature and sediment transport, which can be expressed but with difficulty, must prevail at the beginning of travel. Once the upper end of the bar is disturbed, the movement of the others ensues as a consequence thereof. After an extended period of relatíve stability, extremely violent bar travel started suddenly over an about 10 km long stretch of the Upper Danube, a part of which is shown in Fig. 7. Changes in the bed can be seen plotted against time in Fig. 9, where depth changes of the profiles taken at % and % width are recorded. The low-water bed shífted at places from one bank to the other (Fig 8). Appreciable changes that occurred during a period of 2 l/

i years are illustrated by changes in the cross sectional areas in Figs. 10 and 11. Areas have been related to a dátum 1 m above the minimum navigation level (regulation level) in order to obtain the full volume of the bars. Over the 11 km long section 4 220 000 cu. m of deposits and 4 040 000 cu. m of erosion took place during 2 '/i years. Actually the annual rate of silting was 7300 cu. m/km, which amounts to but 4,5 per cent of the totál sediment movement. At times of violent bar travel alsó the downstream crossings deteriorated appreciably and repeated dredging was required to improve the navigation way. In order to arrest movement spurs have been built, respectively restored and extended at the upper third of each bar.