Hydrological reconstruction of Holocene Paleofloods in Baoji—Tianshui gorge, upper Weihe River basin, China

Abstract

A detailed field study was conducted on the palaeoflood deposit profile in the Baoji–Tianshui Gorge in the upper Weihe River. The sequence of palaeoflood events was established through field observation and grain size analysis with chronological supports from Optical stimulated luminescence (OSL) dates and from archaeologically-constrained age frameworks. The paleoflood peak water level and peak discharge were reconstructed using the “pinch-out elevation method” and the “thickness-sediment content relationship.” The results show that three large-scale paleoflood events occurred during a period of 3200–3000 yr BP in the Baoji–Tianshui Gorge, upper Weihe River. The peak water levels varied between 660.48 and 661.40 m and the peak discharge varied between 23,200 and 25,200 m3/s among the three large-scale paleoflood events. The same methodology was used to calculate the modern flood peak discharges that yielded a deviation of only 3.6% between the reconstructed and measured peak discharges, further verifying the acceptance of this method for the reconstruction of paleoflood peak discharges. This studyexpanded the database of the palaeoflood hydrology research in the Weihe River and the expanded database may be useful in providing important information for projects such as water conservancy, hydropower, engineering construction, flood control, and disaster mitigation.