中文摘要：

通过对渭河上游天水段基岩峡谷的详细考察，在杜家坪村附近发现典型的全新世古洪水平流沉积剖面，对其进行了沉积学和水文学研究．经过对剖面沉积学特征的观察和样品的粒度和磁化率分析表明，该剖面为典型的古洪水平流沉积物．通过与宝鸡峡固川全新世古洪水沉积剖面的地层学对比，及与泾河、北洛河和漆水河古洪水的对比分析，确认其发生的时间为4300-4000aBP．利用水文学方法求出该组古洪水沉积层所记录的特大洪水的洪峰流量介于23460-25480m^3／s之间．同时，通过对现代洪水平流沉积层，采用同样方法计算其流量，同时对于古洪水洪峰流量计算结果进行了科学验证,本研究获得了一万年尺度渭河干流特大洪水的水文学数据，有效延长了洪水水文数据序列，为渭河流域的水利水电和交通工程设计、城镇建设和防洪减灾等方面提供了第一手科学依据，具有重要的应用性价值．

英文摘要：

Abstract：Based on the survey of the Weihe River valley in its upper reaches, the palaeoflood slaekwater de- posit cross-section near Dujiaping Village in Tianshui Section was discovered and the relevant study in light of sedimentology and hydrology was conducted. Observation of the cross-section characteristics, the grain size of samples and analysis of magnetic susceptibility showed that the cross-section belonged to the typical palaeoflood slackwater deposits. Compared with the stratigraphy of the holocene palaeoflood slackwater deposit cross-section in Guchuan, Baoji and the analysis of the palaeoflood in the Jinghe River, the Northern Luohe River abd Qishui River, the palaeoflood was found to have occurred in 4200 -- 4000a BP. By adopting the same method to calculate its discharge of the modern slack water deposit, the calculation of the palacoflood discharge was verified in a scientific way. The hydrological date of extreme floods in the upper reaches of the Weihe River on a 10000-year scale was obtained, which effectively prolonged the flood data sequence of the Weihe River and provide significant data for engineering construction, flood control and disaster alleviation in the Weihe River basin.