北洛河中游黄陵洛川段全新世古洪水研究

通过在北洛河中游黄陵洛川段河谷的考察， 选择典型的古洪水平流沉积剖面进行了古 洪水水文学研究。在野外考察测量的基础上， 采集平流沉积层样品， 进行粒度成分、磁化率、 烧失量、CaCO₃ 含量等分析， 证明研究地点具有典型的古洪水平流沉积层， 并且通过地层学对比分析， 确定其为中晚全新世特大洪水的沉积物。利用水文学原理计算出该组古洪水沉积层所记录的特大洪水的洪峰流量在12 350 m³/s~14 730 m³/s 之间。同时通过对该断面下游方 向20 km 处的东王河铁路桥1994 年9 月洪水洪痕的测量， 利用相同方法计算其洪峰流量， 证明古洪水水文学计算结果合理可靠， 从而为北洛河中游的工程建设及沿岸地区的防洪减灾提供重要的数据资料。

Palaeoflood Hydrological Studies in the Middle Reaches of the Beiluohe River

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.