4.3.1 Flood Peak and Three-day Flood Volume Changes
In this section, flood peak and three-day flood volume data recorded at
the Runcheng Station in the Qinhe River Basin during the flood season
from 1971 to 2006 were analyzed to investigate their characteristics
during different periods. As shown in Figure 9, peak flow during the
flood season demonstrated an increasing trend in the baseline period,
followed by a decreasing trend in change periods I and II. Additionally,
the three-day flood volume exhibited a significant decrease during the
baseline period, which could be attributed to the construction of small
and medium-sized reservoirs and a decrease in precipitation in the basin
during the 1970s (Yang et al., 2004).
Despite continued construction of reservoirs in the basin, their flood
detention capacity remains limited. Therefore, peak flow remains high
following heavy rainfall. However, water and soil conservation measures
implemented during change period I in the Qinhe River Basin have yielded
positive results. The completed reservoir has effectively reduced peak
flood volume, resulting in a decreasing trend in flood peak and
three-day flood volume data. In change period II, the water and soil
conservation measures, including water conservancy projects, in the
basin impacted flood detention and peak cutting. Furthermore,
precipitation in the basin decreased during the same period, leading to
a further decrease in the three-day flood volume and peak flow. These
results demonstrate that the construction of reservoirs has
significantly enhanced the prevention of water-related disasters in the
basin.