Impact of reservoir on downstream runoff and baseflow recession
characteristics: a case study of Chaersen Reservoir in Northeast China
Abstract
The number of reservoirs in the world is increasing year by year, which
will inevitably affect the downstream runoff and baseflow recession
characteristics. In this paper, the impact of Chaersen Reservoir
(Northeast China) on downstream runoff and baseflow recession
characteristics is studied using a pre post comparison method, and the
influence of climate change is excluded using two upstream
sub-watersheds as control basins. In addition, the impact mechanism of
the reservoir is further explored. The results show that the increased
direct and indirect water consumption after the construction of the
reservoir results in a 14% reduction in the average streamflow of the
downstream Zhenxi Station. At the same time, the construction of the
reservoir causes the baseflow at the recession stage to increase by a
relatively constant value (about 1m3/s), which leads the
log(|dQ/dt|) vs. log(Q) points at the low flow stage
to shift to the right. This eventually results in a decrease in the
recession coefficient a by about 60% and an increase of b by about
24%. The log(|dQ/dt|) vs. log(Q) scatter of the
recession process after adding a constant flow is no longer in a strict
linear relationship. And the master recession curve obtained by the
traditional linear parameterization method is only an average
approximation, which will overestimate the streamflow in the middle
recession stage and underestimate the streamflow in the late stage.