TITLE:
Numerical Investigation on Downstream Increase in Peak Discharge of Hyperconcentrated Floods in the Lower Yellow River
AUTHORS:
Zhijing Li, Zhongwu Jin
KEYWORDS:
Hyperconcentrated Flood, Abnormal Phenomena, Peak Discharge Increase, Sediment Transport, Mathematical Model
JOURNAL NAME:
Journal of Applied Mathematics and Physics,
Vol.4 No.4,
April
13,
2016
ABSTRACT: Hyperconcentrated floods in the Yellow
River usually accompanied with some peculiar phenomena that cannot be explained
by general conceptions of ordinary sediment-laden flow (e.g.,
downstream increase in peak discharge, instability flow, ripping up the
bottom). Up to date, the mechanisms for the abnormal phenomena
are not well understood. The aim of this paper is to facilitate a new insight
into the abnormal downstream increase in peak discharge of hyperconcentrated
floods in the lower Yellow River. Numerical model experiments have been
conducted on a typical flood occurred in August 1992 in the Lower Yellow River during which the peak
discharge at Huayuankou station was 1690 m3/s larger than the value at
Xiaolangdi station at upstream. It is found that a fully coupled model that incorporates
the contribution of bed evolution to the mass conservation of the
water-sediment mixture, can reasonably well capture the characteristics of peak
discharge rise and severe bed scour, while separate numerical experiment using
a decoupled model, which ignores the feedback effects of bed evolution, shows
no rise in the peak discharge. This leads us to comment, if only briefly, that
the entrainment of sediment due to bed erosion is the main reason for causing
peak discharge increase along downstream course.