Impacts of climate change and human activities on the water discharge
and sediment load of the Pearl River, southern China
Abstract
In this study, long-term hydro-meteorological data from 1954 to 2018
from the Pearl River basin were used to investigate the impact of
climate change and human activities on water discharge (WD) and sediment
load (SL). The results revealed that the SL of the Pearl River exhibited
a significant increasing trend at a rate of 1.38 × 104 t/yr from 1983 to
1988 and a significant decreasing trend at a rate of −2.24×104 t/yr from
1989 to 2018. WD exhibited a non-significant increasing trend of
0.3416×108 m3/yr during the entire period. The increasing trend of the
SL can largely be attributed to exacerbated rocky desertification in the
drainage basin, whereas the decreasing trend was mostly caused by an
increase in the construction of dams and reservoirs. Mann-Kendall and
double mass curve analyses revealed that a significant abrupt downward
change occurred in the SL in 1998. However, the construction of dams and
reservoirs in the Pearl River basin seems to have little influence on
annual WD. The changes in annual WD were mainly caused by variations in
precipitation. Although significant long-term changes in SL were
detected, inter-annual fluctuations were found to be in good agreement
with precipitation and WD data. Furthermore, El Niño/Southern
Oscillation (ENSO) events are often associated with low precipitation,
resulting in low WD and SL, indicating that changes in ENSO periodicity
could affect the inter-annual periodic variations of WD and SL. Climate
change and human activities contributed 63% and 37% to the increases
in WD, respectively. The human-activities-induced decreases in SL were
1987 × 104 t/yr in the 1990s, 4143.17 × 104 t/yr in the 2000s, and
5259.83 × 104 t/yr in the 2010s. These results should serve as a
reference for better resource management in the Pearl River basin.