Palaeoflood Hydrological Studies in the Middle Reaches of the Beiluohe River
北洛河中游黄陵洛川段全新世古洪水研究

After the investigation on the middle reaches of the Beiluohe River, we chose the slackwater deposits for the palaeohydrology study, which were obvious along the bedrock gorge of the study reaches. On the basis of field survey, we collected samples of the slackwater deposits and analyzed the grain size distribution, the magnetic susceptibility variation, the loss on ignition and the content of calcium carbonate. All of these evidences showed that the slackwater deposits were typical in the study area, and we concluded that the corresponding palaeoflood occurred in the middle and late Holocene through the stratigraphic correlation. When we applied the hydrological technique to the slackwater deposits series, the reconstructed peak discharges of the palaeoflood recorded by them were 12350-14730 m3s-1. We also measured the muddy mark on the pier at the Dongwanghe cross at a distance of 20 km from the previous cross. The reconstructed peak discharge was 6670 m3s-1, which showed that the calculation of the palaeohydrolodgy was credible and reasonable. The results provide significant information for engineering construction, flood control and disaster alleviation in the middle reaches of the Beiluohe River.