Vízügyi Közlemények, 1988 (70. évfolyam)
4. füzet - Laczay István: A folyamszabályozás és az ipari kotrás hatása a Nagymaros-Budapest közötti Duna-szakasz mederviszonyaira
566 Laczay István количества 2,8-4,5 млн. м 3 составляет осаждение наносов в зонах добычи гравия (таблица III). Изменение гранулометрического состава донных материалов суммировано по семи точкам в поперечниках иллюстрируется на рис. 5 и в Таблице IV. Среди местных и общих характеристик взаимосвязи реки и водозаборов береговой фильтрации автором отмечены следующие факты: - наблюдается слой намыва над крупнозернистым береговым материалом мощностью 2-3 м супесчаного и мелкозернистого песчаного состава в зонах естественных изменений и добычи гравия; - на участках добычи гравия за последние 20 лет поверхность песчано-гравийного фильтрирующего слоя понизилась на 2-3 м; - не наблюдался намыв однородным мелкозернистым материалом (илом) в зонах добычи гравия за последние 10-15 лет вдоль островов Сентендре и Чепель. * * * The consequences of river-training and industrial dredging on the bed-conditions of the Danube-stretch between Nagymaros and Budapest by Dr. I. LACZAY. С. E. The present state of the bed-morphology was investigated by the author over the Danubestretch between Nagymaros and Budapest, and in the Danube branch of Szentendre affected by river training structures (largely spur dikes) built since the beginning of the 50's and excavated between 1970 and 1980. To help comparison between past and present fluvial survey and sampling of bed-material the survey executed in 1969 has been repeated in 1 987. The objective of this comparative work was to obtain possibly accurate data for analyses to clarify interrelations between the system elements of shorebank water resources, and for the simulation of the side-effects triggered by the motion of water during water exploitation. The present situation in the main branch of the Danube and in the side-branch of Szentendre has been heavily influenced by - branch cutoffs and supplementary regulation executed in 1937-58 to foster navigation and the passing of ice ( Table I) , - series of largely industrial dredging activities resulting in a gain of 16,4 million m 3 of gravel from the main branch and of 4,1 million m 3 from the side-branch of Szentendre (Table II). Evaluation of the results of this survey indicated that the bottom level of the excavated strips in 1987 was comparable with the permitted depth of excavation with a tolerance of ± 1 m. ( Fig. 3). Deposited volumes of sediment during these 18 years investigated amounted to 8.5-10.2 million m 3 out of which 2.8-4.5 million m 3 has been found in the earlier excavated strips. Changes in the river-bed are summarized in Table III. Changes in bed-material - in 7-7 points of each profile are shown in Table IV. and Fig. 5. According to the author the characteristics of interrelations between shorebank water bodies and river water are - in the local and general aspect - the following : - Due to natural changes and man-made interferences (over affected points and stretches) the coarse material of the river-bed can be overtopped by a 2 to 3 m thick silty layer of sand and fine sand. - During the past 20 years, the sandy gravel filter-layer of the river has reached a level that is underneath the original level by 2 to 3 meters along the dredged sections. - Significant refill consisting of characteristically finer material (silt) could not be detected over the dredged strips excavated 10-15 years ago along the stretches at the isles of Csepel and Szentendre. * * *
