Hidrológiai Közlöny 1960 (40. évfolyam)

1. szám - Szigyártó Zoltán: A mederváltozások hatása a kisvízfolyások vízhozamára

m Szigyártó Z.: A mederváltozások hatása a kisvízfolyásokra Hidrológiai Közlöny 1960. 1. sz. 15 B maóA. 2. aaeTcji pa3őop cpeflHnx pacxoflOB 1957/58. rnapojiorHMecKoro roaa. B STOÍÍ Taöjume conocTaiiJiaioTCH cpeflHiie BejumuHbi pacxo^oB, onpeflejieHHbix no pa3HbiM cnocoöaM nnn 12 Mecíiua, aJifl 3HMHero n jieTHero nojiyroflHH, aajiee nojiHoro ro/ia. B 1-ofi CTpoKe yKa3aHi>i caMbie aocroBepHbie BejnmiiHbi, onpe«eJieHHbie C nOMOLUbK) KpiIBblX, H30Őpa>KeHHbIX Ha ifiue. 2., CTpOKII 2. H 3. COCTaBJieHbl Ha OCHOBaHIIH KpiIBblX, H306pa>KCHHbix Ha <pue. 3. H na (pue. 4. B 8-oíí h 13-oíí cTpoiox npiiBefleHbi pe3yjibTaTbi npiiö.ni>KeHHbix pacneTOB /yifl onpe/tejieHiiíi cpe«HeMecHHHbix pacxoflOB. 3TII BejiimHHbi onpeAeJiiuiiicb c IIOMOIUblO KpHBblX paCXOflOB, H30Öpa>KeHHbix Ha (pue. 4. ToMHee B 8-oií CTpoKe yi<a3aHbi BejiHHHHbi, onpe«ejieHHbie no MeTOfly Cecmau [9], a npii onpeflejieHHii aaHHbix 15-oii cTpOKH cpeflHeMecHHHbiíí pacxoA npiiHiiMajiCH paBHbiM BeJiHMHHe pacxo.ua, eooTBeTCTByiomero cpeaHeMecHMHOMy ypoBHio Ha KpHBoíi pacxo.ua. B ocTajibHbix cTpoKax TaőJiHUbi npHBeACHbi pacXOSKFLEHHH cpeflHiix PACXOFLOB OT BCJIHMIIH, yKa3aHHbix B 1-OÍÍ II 5-OH CTpoKax. Ha OCHOBaHIIH pa36opa (jwryp n Taőnmi MO>KHO caejiaTb cjie/iyiomiie BbiBOflbi: Onnpaíicb na KOHTpojibHbie M3MepeHHfi, npoBeaemibie no MecHnaM, npw onpefleJieHHH MHHHMaJIbHUX paCXOflOB MOryT 6bITb CAeJiaHbl Becb.via 6ojibmne OUIHÖKH, «a>Ke N öojibiue 50%, BCJieACTBiie nepeMemeHHji pycjia npw uccjieflyeMOíi cTaHumi, HO npn onpeAeneHHH MaKCHMajibHbix pacx0«0B MO>KHO CMHTaTbCH C HeSOJlblLHIMH OllIHÓKaMH. KpaíÍHCH OIHHÖKOÍÍ cpeaHeMecHMHbix pacxoflOB, onpeflejieHHbix Ha OCHOBanim noMecflMHbix ii3MepeHHH, HacneT BJHI>IHII5I nepeMeineHiia pycjia MOWHO H33HamiTb B 40%, a cpeaHioio ouniöKy B 15%. KpaftHee pacxow/ieHiie N0JIYR0FL0BBIX cpeaHHx pacxoflOB npiiMepHO oaeinmaeTCH B 15%, cpenHee pacxowaeHiie B 6%, a Kpaímee pacxo>KAeHiie cpejHeroAOBbix BCJIIIMIIH npnöJiH3iiTejibH0 10%, cpeflHee pacxo>KfleHiie 4%. NOJIYNEHHBIE OUIHÖKH ABJUIIOTCH FLOBOJIBHO BMCOKHMH HeCMOTpSI Ha TO, MTO uccjie/iyeMaH CTaHUIIH no npewHHM onbiTaM cmiTacrcfl OTHOCHTejibHO OflHOií 113 ca.vibix JiymiIHX. TaKHM 0Öpa30M HeBblCTpOCHHMMH CTBOpa.viH Majibix BOAOTOKOB Booöme nojiymijiHCb 6bi 3HamiTcjibiio xy^ume pe3yjibTarbi B 3aBiicnM0CTM OT BGJIHMHHIII nx BoaocőopHOH njiomaan. HaKOHeu B 3aKJiK)MeHiiii ycTaHaBJiHBaeTCH, MTO BbicTpoemie CTBopa SIBJIHL'TCH Heii36e>KHbiM ocoóeHHo npn peniCTpaHHOHHblX CTBOpaX, HMeiOIHHX BOflOCŐOpHOÍÍ n.iomaan MeHbme, »ieiw 200 KM

2. nocjie 3Torc B cTaTbe paccMOTpMBaioTCH Bonpocw no npiiŐJiii/KfHHMM pacMeTaw cpe«HeiviecímHbix pacx0«0B n Ha OCHOBaHIIH cpe^Hero peuaTHBHoro pacnpefleJieHiw TOHCK H3MepeHHÍI 0K0JI0 KpHBOÍÍ paCX0A3 peKOMeH^yeTCH MeTOA pacMeTa cpeflHeMecHHHbix pacxo^OB. Tho Effecl of líod Changes on the Aecuraey of Flow Records of Small Watercourses By Z. Szigyártó Candidate of Technical Sciences The network of flow recording stations has been organized in Ilungary after the second World War | 1], [2], Conditions prevailing here called for the inclusion intő the recording system of small watercourses currying a mean discharge of 1 cu. m/sec, or even less. Corrolary to the establishment of the recording network 011 small watercourses, attempts have been started to clear various problems involved as well in [4], [5], [6], [7], [8], \\ ithin the framework of these investigations the rate of processes taking place at unprotected measuring sections is considered in the present paper and it is endeavoured to determine the significance of stabilizing of the section for the establishment of the recording system including the small watercourses. Considerations are related to a practical problem. Results of a series of observations conducted for over a year at the gaging station Bánhorvát I. on the Bán— Broolc, having a catcliment area of 232,7 sq. km (Fig. 1) are made use of in this paper. The cross section of this gaging stat ion, and the location of flow measurement.s are shown in Ills. 1 and 3, and in III. 2, respectively. Changes in the rating curve between the lst May, 1957. and 30th November, 1958. are shown in Fig. 2. The single rating curve fitted between observed values is reproduced in Fig. 3. Rating curves determinál on basis of a single flow measurement every month, according to the generally accepted method in Hungary are shown in Fig. 4. Characteristic data of major importance for the hydrological year 1957/58, investigated for determining the accuracy of flow-record data are summarized in Fig. 5. In Table 1 characteristic data for the same period have been compiled, comparing data for the summer and winter half year, as well as for the hydrological year, determined by various data. Table 2 contains an analysis of the mean discharges for the hydrological year i957/58. A comparison is givfen of the mean values determined by various methods and relating to each of the twelve months, to the winter and summer half year as well as for the entire year. Most reliable values determined by the aid of the curves in Fig. 2 can be found compiled in the first row. Curves in Figs. 3 and 4 have been used for compiliug rows 2 and 5, respectively. Results of approximating computations of monthly mean discharges are reproduced in rows 8 and 13. These values have been determined using the rating curves shown in Fig. 4. In effect, row 8 contains the values determined by the method developped by Szesztay [9], wliile in computing row 15 the monthly mean discharge has been taken identical with the discharge corresponding to the monthly mean stage on the rating curve. The remaining rows in the table indicate the deviations of these mean discharges 'related to row 1, respectively 5. An analysis of these figures and tables leads to the following conclusions : Relying on monthly control measurements a significant error exceeding even 50 por cent may be committed due to changes in the bed at the station under consideration in determining the least discharge, while but a small error is likely to occur at the determination of the peak flow. Extrémé and mean errors due to bed movement, in the monthly mean discharges determined on the basis of monthly observations may be estimated at 40 and 15 per cent, respectively. The extreme error of semi-annual mean discharges may be assumed at 15 per cent, the mean error at (i per cent, while the corresponding values for annual mean figures are about 10 and 4 per cent. The deviations obtained are rather liigh, although on the basis of previous experience the station in question was considered among the most reliable ones. It would follow, that unprotected gaging sections of small watercourses yield appreciably less accurate values, depending upon the magnitude of the catchment area. As a conclusion it is statod in the paper, that gaging sections must, in generál, be stabilized at especially those having catchment areas smaller than 200 sq. km. Problems relating to the approximating computation of monthly mean discharges are discussed hereafter and founding on the basis of the average relatíve standard deviation of observation data regarding to the rating curve a computation method of the monthly mean discharges is suggested.